Studying the characteristics bio-agricultural and technical measures to plant and look after tending Rhynchostylis gigantea (Lindley) Ridley in the Northern of Vietnam

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MINISTRY OF EDUCATION MINISTRY OF AGRICULTURE AND AND TRAINING RURAL DEVELOPMENT VIETNAM ACADEMY OF AGRICULTURAL SCIENCES ------------------------------- ĐINH THỊ DINH RESEARCH ON AGRONOMIC AND BIOLOGICAL CHARACTERISTICS AND TECHNICAL MEASURES OF GROWING AND CARING FOR RHYNCHOSTYLIS GIGANTEA (LINDLEY) RIDLEY IN NORTHERN VIETNAM Major: Code: Plant sciences 62.62.01.10 SUMMARY OF AGRICULTURE DOCTORAL THESIS Ha Noi, 2015 The thesis was completed at: VIETNAM ACADEMY OF AGRICULTURAL SCIENCES Supervisors: 1. Dr. Dang Van Dong 2. Prof. Dr. Tran Duy Quy Judge 1: Dr. Pham Thi Minh Phuong Judge 2: Prof. Dr. Nguyen Thi Kim Ly The thesis was protected in the grassroots review panel meeting at: Fruit and Vegetable Research Institute 8.30 am in 17th December, 2014 The thesis can be found in: Library of Vietnam Academy of Agricultural Sciences LIST OF PUBLISHED ARTICLES RELATED TO THE THESIS 1. Dinh Thi Dinh, Dang Van Dong and Chu Thi Ngoc My (2013), "Evaluation results on the growth and development of several Rhynchostylis gigantea (Lindley) Ridley varieties in Gia Lam Hanoi", Journal of Vietnam Agricultural Science and Technology, 3 (42), p.81-88. 2. Dinh Thi Dinh and Dang Van Dong (2014), "The research results on morphological and anatomical characteristics of several Rhynchostylis gigantea (Lindley) Ridl prospective varieties in Northern Vietnam", Journal of Agriculture and Rural Development, Vol 1 - 1/2014, p.33-40. 3. Dinh Thi Dinh, Dang Van Dong and Tran Duy Quy (2014), "The Impact of the ecological zones and treating Gibberilin (GA3) on the growth and flowering of purple-spotted white Rhynchostylis gigantea (Lindley) Ridley", Journal of Science and Development, Vietnam National University of Agriculture, Thematic plant physiology, vol 12, No. 7-2014, p.10491057. 4. Dinh Thi Dinh, Dang Van Dong and Tran Duy Quy (2014), "Research on the impact of technical measures on the growth and quality improvement of Rhynchostylis gigantea (Lindley) Ridley", Journal of Agriculture and Rural Development, 22/2014, p.10-18. INTRODUCTION 1.1 Rationale Orchids are one of the objects of nature, the art masterpieces that nature bestowed on human. Its beauty exotically attracts flower growers. We can say that orchids have all of the valuable features of flowers such as beautiful and varied colors, diverse and delicate flower structrue, long flower durability and especially attractive to flower growers by seductive scent. When admiring the beauty of orchids, the human soul is in harmony with nature. The ancient elders said: orchids bring all the noble characters of the gentleman that are humanity, formality, integrity, mentality and credibility. Due to the valuable characteristics, orchid production industry has constantly developed and increasingly expanded throughout the world, bringing great benefits to the nations that invest in research and production of orchids such as China, Thailand, Taiwan. Vietnam has suitable climate conditions for growth and development of numerous orchids and the source of a lot of orchid species recorded by the orchid researchers. Rhynchostylis gigantea (Lindley) Ridley is one of native and rare orchid species of Vietnam. This flower has pendulous flower clusters, aroma and long durability. It has several tranditional names: Nghinh Xuan in the Central (since the spring bloom), Ngoc Diem in the South, Dai Chau in the North (since looking like string of pearls) and also Me orchid as a folk name. Rhynchostylis gigantea (Lindley) Ridley has high economic value because of blooming in the Lunar New Year. Its usage is quite various such as putting on a pots, decorating in the living rooms, hanging on the balconies and windows, grafting on dead woods and growing trees or on the rockeries forming a very beautiful landscape and a natural appearance. With the development of economy and society, the demand for ornamental plants has been increasing and requiring highly, Rhynchostylis gigantea has increasingly won the hearts of consumers. However, the indiscriminate exploitation of wild orchids have been made Rhynchostylis gigantea decreasing in number and in danger of extinction, while conservation and development of Rhynchostylis gigantea are not really popular in Vietnam. One of the limitations in the production of this orchid is extremely slow growth, especially in Northern Vietnam, leading to the time from planting to flowering takes several years. On the other hand, agronomic and biological characteristics of the plant have not been fully evaluated. Researchs on the cultivation and care in order to overcome the disadvantages and promote the advantages of this flower have not much and no application in production. For the purpose of conservation and wide development of Rhynchostylis gigantea in Vietnam, we conducted the thesis: “Research on agronomic and biological characteristics and technical measures of growing and caring for Rhynchostylis gigantea (Lindley) Ridley in Northern Vietnam”. 1.2 Objectives The research on agronomic and biological characteristics of Rhynchostylis gigantea and technical measures aims to increase the growth, flowering early, flowering rate and flower quality and improve technical procedures to widely develop this orchid in production. 1.3 The significance of science and practice 1.3.1 The significance of science The thesis was to provide scientific data on agronomic and biological characteristics such as anatomy, relative growth and development of Rhynchostylis gigantean varieties. Based on the research results, effective technical solutions in the cultivation and care of Rhynchostylis gigantean were released to build the technical process of producing this valuable flower. Results of the study are the valuable references for teaching, researching and producing of orchids, especially Rhynchostylis gigantean. 1.3.2 The significance of practice Purple-spotted white Rhynchostylis gigantea that has been determined are suitable for ecological conditions in Northern Vietnam. This variety is durable, beautiful, strong growth and development to meet the requirements of production. The thesis has proposed technical measures for planting and caring to increase the growth and development, early flowering, flowering rate and high-quality flowers in Northern Vietnam conditions. These technical measures are feasible, capable of application to the production of goods and effective for florists. 1 1.4 Novelty This is the first systematical study on Rhynchostylis gigantea characteristics of morphology, anatomy, growth and developmet from housing to flowering (3 years old). The thesis researched the correlation between the growth length of leaves and length of flower stems that releases measures to increase plant growth in the nursery stage in hot and humid summer conditions and improve the growth, flowering rate and flower quality in production garden; consequently 2 years plants flowering 47% (1 year earlier than control), 3 years plants flowering 80% in the Northern Vietnam conditions. 1.5 Scope The thesis determines agronomic and biological characteristics and technical measures of a number of Rhynchostylis gigantea (Lindley) Ridley varieties in Northern Vietnam. Implementation period is from 2011 to 2014. CHAPTER 1. LITERATURE REVIEW Rhynchostylis gigantea has aesthetic and high economic values and development potential in Vietnam as well as in the world. There have been several studies on Rhynchostylis gigantea. The new researchs focused on breeding methods. The authors have identified that the materials used for propagation are immature seeds, mature seeds and meristems. Furthermore, they have determined the culture medium, the fast propagation and creating mature plants; after housing seedlings are healthy and possible to meet the production. There have been a number of studies on agronomic and biological characteristics and technical measures of Rhynchostylis gigantea over the world such as temperature, light, GA3 spray to enhance the growth and development of plants. However, the studies of anatomy, growth correlations between vegetative and floral organs have not been mentioned. Especially, there have been very few studies on Rhynchostylis gigantean in Vietnam, people rely on traditional experiences to plant and care for plants leading to slow growth and flowering, poor flower quality. To widely develop Rhynchostylis gigantean in production, the research on agronomic and biological characteristics, cultivation, care and flowering control are needed to improve the process for serving the needs of production and increase income for orchid growers and toward export in the future. The results of previous studies will be the basis for reference and inheritance of the thesis, which results in comprehensive and effective follow-up studies. CHAPTER 2. MATERIALS, CONTENT AND METHODOLOGY 2.1 Materials - Experiments conducted on four Rhynchostylis gigantean varieties, including: one indigenous variety and 3 imported varieties from Thailand. Other materials are substrates, fertilizers, biological pesticides, and GA3 growth stimulants. 2.2 Research Content 2.2.1 Research on agronomic and biological characteristics of Rhynchostylis gigantean - Assess the growth and development of some Rhynchostylis gigantean varieties in Gia Lam Hanoi - Research morphological characteristics of roots, stems, leaves, flowers and fruits; anatomy of the vegetative organs of Rhynchostylis gigantean - The correlation between the growth of leaves, roots and flowers of purple-spotted white Rhynchostylis gigantean. - Growth and development characteristics of the purple-spotted white Rhynchostylis gigantean in some ecoregions 2.2.2 Research on the effect of several technical measures on plant growth in nursery period - Effect of subtrates and watering times on plant growth after housing - Effect of fertilizers and fertilizing times on the growth of seedlings 2.2.3 Research on the effect of some technical measures on the growth and development of plants in the producing garden 2 - Effect of planting season on the growth and development of plants - Effect of water quality on the growth and quality of flowers - Effect of growing media and watering times on the growth and development of plants - Effect of fertilizers and fertilizing times on the growth and development of plants -Effect of GA3 concentrations on the growth and flowering ability of Rhynchostylis gigantean - Effect of the shading levels reducing light in the summer season on the growth and development of plants - Effect of temperature treatment in the winter on the growth and development of Rhynchostylis gigantean - Effect of biological pesticides on occurrence and development of diseases and pests on Rhynchostylis gigantean 2.3 Methodology 2.3.1 Method of experimental designs - The experiment evaluating the growth and development of plants in Gia Lam, Ha Noi is arranged in randomized complete block (RCB) with three replications, 30plants/ formula. Experiment evaluates four Rhynchostylis gigantean varieties: Red, spotted Red, White, Purplespotted White. Experimental plants that are tissue culture plants eligible for housing. - Research on morphological characteristics of roots, stems, leaves, flowers and fruits by observing, describing and measuring randomly some indicators of roots, stems, leaves, flowers and fruits of 10 plants/variety, 4 varieties, 3.5-year-old plants. - Research on anatomical characteristics of roots, stems and leaves of 4 Rhynchostylis gigantean varieties, 3-year-old plants. The method of making anatomical templates carries out the following steps: treating sample, cutting templates, bleaching sample, double dyeing, observing and photographing by a microscope. Analysis of anatomical structure of vegetative parts: roots, stems and leaves according to documents of Tran Cong Khanh (1981). - Research on the correlation between the growth of roots, leaves and some indicators of purple-spotted white Rhynchostylis gigantean flowers: randomly sampling 30 plants grown and cared in the same conditions in Gia Lam - Hanoi. 3-year-old plants are in bloom period. Measuring the indicators of the leaf length, root length, flowering shoot, number of flowers/inflorescence. Counting Pearson correlation coefficient (r), the determination coefficient R2, the regression equation by means of correlation analysis on Excel 2010. Assessing correlation coefficient. - Experiment of assessing characteristics of growth and development of plants in several ecological zones, experiment of planting time (experiment 4.7) are arranged in a not repeated sequential method, 30 plants/formula. - Experiments of technical measures implement on purple-spotted white Rhynchostylis gigantean, arranged in a randomized complete block (RCB) with three replications. In nursery period a formula experiment is 2 m2 (100 plants), in the period of production garden a formula is 3 m2 (corresponding to 54 plants). Tracking plants follows 5 points of cross angle method, 2 plants/point, tracking 10 plants/replication. Tracking 30 days/time. - Method of pests and diseases investigation follows national technical regulations of survey method detecting plant pests (QCVN 01-38: 2010 / MARD). 2.3.2 Experimental conditions (non-experimental factors) - Experimental plants were cared following temporary process of Fruit and Vegetable Research Institute: + Plants were grown in a simple net house. 2 layers of black net covered the net house in summer (from June to August). Nursery period: plants were grown in soft plastic, transparent pots; size 8.5 (height) x 8cm (diameter). Growing media used Seaweed + charcoal + coarse bark (ratio 1: 1: 1). Charcoal and coarse bark size is 0.5-1.0cm. Spraying Growmore 1 - NPK ratio = 30:10:10), the fertilizer concentration is 0.05%, a time/week. + Production garden (1 year and older): Plants were grown in square wooden pots, an edge length of 25 cm, 3 plants/pot, the growing media were seaweed + charcoal + coarse bark (ratio 1: 1: 1). Size of charcoal and coarse bark was 2-3cm. Spraying Growmore 2 - NPK ratio = 20:20:20, the 3 fertilizer concentration was 0.1%. Fetilizers were sprayed by hand sprayer on leaves, stems and roots. Watering a time/day by rain shower nozzle. + Disease prevention: periodically spraying 10 days/time Daconil concentration of 0.1%. Spraying Selecron 500EC 35ml/16 liters sprayer, Reasgant 3.6EC 10ml / 16 liters sprayer, 10 days/time to prevent leaf-eating insects, caterpillars, aphides. Preventing slugs and snails by sprinkling lime powder to create protective strips around the experimental zone. 2.3.3 Location and time - The experiments were conducted in the Center for Flowers, Ornamentals Research and Development – Fruit and Vegetable Research Institute - Trau Quy, Gia Lam, Hanoi. - The anatomical experiments were conducted in the laboratory of Plant Department, Faculty of Agronomy, Vietnam National University of Agriculture. - The experiments that evaluated the ability of growth and development were in some localities such as Gia Lam - Hanoi, Van Giang - Hung Yen, Moc Chau - Son La and Sapa - Lao Cai. Research time: from January 2010 to February 2014 2.3.4 Data Processing Method The data were processed by the analysis method of the standard deviation and variance analysis on the softwares Excel 2010 and IRRISTAT 5.0. CHAPTER III. RESULTS AND DISCUSSION 3.1 Agronomic and biological characteristics of some Rhynchostylis gigantea varieties 3.1.1 Assessing the growth and development of some Rhynchostylis gigantean varieties in Gia Lam - Hanoi 3.1.1.1 The percentage of live plants and green recovery time after housing The results showed that the green recovery time of varieties was from 12-15 days (the time from planting to having new roots), in which purple-spotted white Rhynchostylis gigantean had the shortest green recovery time and red Rhynchostylis gigantean had the longest time. Survival rates of varieties after planting were relatively high (90-95%) in which indigenous variety had highest survival rate, 95%. 3.1.1.2 Leaf growth characteristics of Rhynchostylis gigantean varieties Table 3.2. Leaf growth dynamics of Rhynchostylis gigantean varieties (From 2010 to 2012, in Gia Lam - Hanoi) Surviva 1 year 2 years 3 years Characteristics l rates Number Leaf Leaf Numbe Leaf Leaf Number Leaf Leaf (%) of leaves length width r of length width of leaves length width (cm) (cm) leaves (cm) (cm) (cm) (cm) Varieties Red 90 2.8 8.8 1.5 4.1 15.8 2.8 5.3 21.0 4.2 Spotted Red 90 3.0 8.5 1.5 4.0 15.3 2.7 5.1 21.6 4.0 White 92 2.6 8.1 1.6 3.9 15.0 2.9 5.2 20.3 4.4 Purple-spotted 95 3.9 10.5 1.7 4.9 18.3 3.0 6.0 24.5 4.5 White CV% 4.3 6.1 5.2 LSD0.05 0.6 2.4 0.23 The growth rate of the number of leaves of Purple-spotted White indigenous variety was fairly fast, after 3 years the number of Purple-spotted White leaves was highest 6.0, the lowest was 5.1 leaves in spotted Red Rhynchostylis gigantean. Leaf size was also different in varieties. White Rhynchostylis gigantean had the shortest leaf length 20.3cm, but leaf width had good size reaching 4.4cm. Purple-spotted White variety had the biggest leaf size, leaf length was 24,5cm, and leaf width was 4.5cm. 4 3.1.1.3 Stem growth characteristics of Rhynchostylis gigantean varieties Table 3.3. Growth dynamics of stem height and diameter (From 2010 to 2012, in Gia Lam - Hanoi) 1 year 2 years 3 years Characteristics Stem Stem Stem Stem Stem Stem height diameter height diameter height diameter Varieties (cm) (cm) (cm) (cm) (cm) (cm) Red 2.1 0.54 3.8 0.65 6.2 1.18 Spotted Red 2.1 0.60 3.7 0.72 6.3 1.20 White 2.0 0.61 3.9 0.73 6.0 1.23 Purple-spotted White 2.5 0.78 5.1 0.89 8.8 1.39 CV% 7.3 4.5 LSD0.05 1.24 0.14 Stem height and diameter of varieties after planting a year were a little difference, stem height reached from 2-2.5cm, stem diameter reached from 0.54-0.78cm. However, these characteristics had a clear difference between 2 years and 3 years plants. After 3 years of planting, stem height of varieties reached from 6.2 to 8.8cm, Purple-spotted White indigenous variety gained 8,8cm, while exotic Rhynchostylis gigantean varieties only got 6.0-6.3cm. Stem diameter of Purple-spotted White variety also reached the highest value (1.39cm), while the other varieties only got 1.18-1.23cm. 3.1.1.4 Root growth Characteristics of Rhynchostylis gigantean varieties The number of roots after planting 1 year reached 3-3.2 roots, two years plants got from 4.1 to 4.6 roots, 3 years plants reached 4.8 to 5.1 roots. There was a difference in the root length of varieties: after planting one year the root length of varieties was from 14.6-18.8cm, 2 years plants was from 23.2 to 28.0cm, and 3 years plants was 35.2-41.2cm. Root length of Purple-spotted White variety reached the maximum value, 40.8cm, and the remaining varieties was 35.2-37.1cm. Table 3.4. Root growth dynamics of Rhynchostylis gigantean varieties (From 2010 to 2012, in Gia Lam - Hanoi) 1 year 2 years 3 years Characteristics Number Root Root Number Root Root Number Root Root of roots diameter length of roots diameter length of roots diameter length Varieties (cm) (cm) (cm) (cm) (cm) (cm) Red 3.2 0.25 15.2 4.6 0.56 23.2 5.0 0.77 36.6 Spotted Red 3.0 0.24 14.6 4.1 0.55 25.2 4.8 0.76 37.1 White 3.1 0.24 16.0 4.1 0.67 24.1 5.1 0.86 35.2 Purple-spotted White 3.2 0.32 18.8 4.3 0.62 27.3 5.1 0.87 40.8 CV% 4.50 4.70 7.30 LSD0.05 0.31 0.11 2.80 3.1.1.5 The harmful level of main pests and diseases on varieties Generally harmful levels of main pests and diseases on varieties were from mild to moderate levels. Soft rot disease caused heavy damage to white Rhynchostylis gigantean variety than other varieties; leaf damage rates were 5-25% (Level 5) in the spring/summer season. In all Rhynchostylis gigantean varieties, Purple-spotted White variety had mild harmful levels of some main pests and diseases, pests appear very scattered and diseased leaf rates were below 5% (Level 3). Rhynchostylis gigantean orchid started flowering after planting 3 years, each plant had one flowering shoot and it was uniform in all varieties. The flowering percentage was from 40-51%, highest in Purple-spotted White variety and lowest in White variety. Flower quality of varieties differed: The number of flowers per inflorescence of the varieties reached from 21.5 to 26.3 flowers/ inflorescence, flowering shoot length was 12.6-16.8cm, flowering shoot diameter of varieties gained from 0.45-0.59cm, flower durability ranged from 19 to 24 days. In particular, Purple-spotted White Rhynchostylis gigantean variety had the highest quality indicators compared to remaining varieties. Flower diameter of varieties had no difference. Flowers of all varieties had beautiful color and fragrance; especially flowers of Purple-spotted White variety were fragrant and the remaining varieties had light fragrance. 5 3.1.1.6 The quality and time of flower development of Rhynchostylis gigantean varieties Table 3.6. Flowering rate and flower quality of Rhynchostylis gigantean varieties (11/2012-2/2013, in Gia Lam - Hanoi) Flowering Number of Flowering Flowering Flower Flower Flower Fragrance Char. rate (%) flowers shoot shoot diameter durability color /ìnlorescence length diameter (cm) (days) Varieties (cm) (cm) Dark Light Red 45 21.5 14.2 0.45 2.37 21 Red fragrance RedSpotted Light 47 23.4 13.7 0.47 2.33 22 spotted Red fragrance White Green Light White 40 24.3 12.6 0.52 2.30 19 White fragrance PurplePurplespotted 51 26.3 16.8 0.59 2.33 24 spotted Fragrance White White CV% 6.5 6.7 4.3 5.4 LSD0.05 1.8 2.1 0.06 0.07 Rhynchostylis gigantean orchids usually bloom in the Lunar New Year so are also known as Nghinh Xuan in Vietnamese (Welcome Spring in English). However, depending on weather conditions the flowers can bloom sooner or later. In the weather conditions of the Red River Delta, flowering shoots often appear in November (from 14th to 23th November). Different varieties had different time of appearing flowering shoot. Results of monitoring in 2013 showed that the flowering shoots were appeared earliest in Purple-spotted White variety and latest in White Rhynchostylis gigantean 23th November. Table 3.7. The flower development time of Rhynchostylis gigantean varieties (11/ 2012 - 2/2013, in Gia Lam - Hanoi) Characteristics Date of Development Flowering Flowering Total appearing time of flower time shoot development flowering inflorescence (days) durability time of Varieties shoots (days) (days) flowers (days) Red 19/11 54 14 32 86 Spotted Red 20/11 53 13 34 87 White 23/11 55 12 30 85 Purple-spotted White 14/11 55 16 38 93 Development time of flowering shoots of varieties ranged from 53 to 56 days, the shortest was Spotted Red Rhynchostylis gigantean and the longest was Purple-spotted White variety. Flowering time was from 12-16 days. Flowering shoots durability of all varieties ranges from 30 to 38 days, the longest was Purple-spotted White variety and the shortest was white Rhynchostylis gigantean. The total development time of flowers was between 85 and 93 days and Purple-spotted White variety had the longest time. Comments: The results assessing the growth and development of Rhynchostylis gigantean varieties in Gia Lam - Hanoi showed that: In 4 Rhynchostylis gigantean varieties, Purple-spotted White indigenous variety had healthy growth and development: after growing 3 years a number of leaves were 6, leaf length was 24.5cm, a number of flowers/inflorescen reached 26.3, shoot length was 16.8cm, flower durability was 24 days, pests and diseases were mild level. Beautiful color, fragrance were favored by consumers. 3.1.2 The morphological and antomical characteristics of vegetative organs of some Rhynchostylis gigantean varieties 3.1.2.1 Morphological and anatomical characteristics of roots - Morphological root characteristics 6 The roots of Rhynchostylis gigantean varieties generally is cylindrical and white-gray. On the surface of roots of 4 varieties has very thick velvet, this layer is responsible for transporting water and mineral nutrients into the roots and then those are transported to the stem organs, leaves. The root tips that are green express the plants are growing, these root parts are capable of making photosynthesis and root elongation. Colour of root tips tend to flower color, in which the root tips of red and spotted red flower varieties are purple, root tips of white flower varieties are yellowish blue, root tips of Purple-spotted White flower varieties are blue, and this is the basis for identifying the varieties when the plants have not bloomed yet. All indicators about the number of roots, root length, and root diameter reached the highest value in Purple-spotted White variety. Thus, all Rhynchostylis gigantean varieties typically have morphological characteristics of roots for each variety, in which Purple-spotted White variety have morphological characteristics of roots that are favorable for plant growth such as the largest and longest roots in four varieties. - Anatomical root characteristics Components of Rhynchostylis gigantean roots include the velamen, exodermis, cortical parenchyma, stele, and inner stele having the vascular bundles. Root transection shows that root cover contains single epidermis covered by large and thick cells that are arranged in format of radial wall, followed by a layer of polygonal cells, in which cross-section is the ellipse or rectangle. This cell layer that is capable to absorb water easily and avoid the loss of water from the roots. Root cover also works to reflect light and be fastened to the surface of other coarse bark; this is the characteristic of epiphytic plants. Under the cover (the epidermis) is the cortical parenchyma including many layers having chloroplasts and tubular cells. It is formed by round cells in different sizes and thin-walled. Chloroplast cells of roots may photosynthesise and this is typical for the orchid roots. Cortical parenchyma layers are able to reserve water and nutrients for the plants and can change shape when climbing (cylinder converted into hemisphere) is typical for epiphytic plants. The endothelial cell layer wraps around the stele roots, inner stele roots have many vascular bundles conveying water and the products of photosynthesis. Apart from the research on anatomical structure, we also measured the size of cover layer, stele size, a number of vascular bundles and size of vascular bundles. In particular, the Purplespotted White variety reached the highest value: Stele size was 1232.50μm, a number of vascular bundles were 27.05, and bundle width was 80.5μm. Table 3.9. Anatomical root characteristics (in 2011, in Gia Lam - Hanoi) Number of Size of vascular bundles Characteristics Size of cover (µm) Stele size (µm) vascular layer (µm) bundles Varieties Thickness Width Red 1510.00±102.7 1196.25 ± 55.2 26.95±0.8 193.50±15.3 48.50 ±4.6 Spotted Red 1323.75±84.0 958.75 ± 35.5 26.35±1.4 200.50±12.3 72.00±7.1 White 1580.00±126.0 1228.75 ± 52.0 26.70±2.1 197.50±14.8 67.50±6.6 Purple-spotted White 1463.75± 69.5 1232.50 ± 56.2 27.05±2.2 202.50±10.7 80.50±8.9 Through an assessment of morphological and anatomical roots, Rhynchostylis gigantean orchids are very specific to monocotyledons and able to adapt to the epiphytic conditions. In which root characteristics of Purple-spotted White variety have more advantages for the growth and development of plants such as big roots, thick parenchyma, able to absorb and store water, good nutrition and high drought tolerance. 3.1.2.2 Morphological and anatomical characteristics of stems - Morphological stem characteristics The stems of Rhynchostylis gigantean varieties that were observed are single; their stems are capable of carrying a lot of leaves. Therefore, perennial plants have the more pairs of leaves and high flowering capacity because of flower shoots growing from the leaf axils, so a plant can have multiple flower shoots that make more value of plants. The stem colors of varieties tend to follow the color of the flowers, but the expression is not clear as the color of root tips. Red flower variety has purplish green stems and the remaining varieties 7 have green stems. Stem height of Red flower variety was highest (8.98cm) and the lowest was the White flower variety (6.62cm). The stem diameter was largest in Purple-spotted White variety (1.38cm) and smallest in the Red flower variety (1.17cm). - Anatomical stem characteristics Anatomical cross-section of the stems, the outermost layer is a single epidermis, followed by two rows of thin-walled cells forming a layer of cortical epidermis having multiple stem layers. Under these epidermises, rows of thin-walled cells formed are the cortical parenchyma with air spaces in the cells that are responsible for reserving nutrients, transfering gas and reducing the weight of stem, this demonstrates the adaptation of epiphytic organisms. Stele has numerous vascular bundles messily arranged between light and soft parenchyma. Vascular bundles include sclerenchyma, phloem and xylem vessels arranged in sealed superposition type to transport water and products of photosynthesis. Observing some indicators such as: The total of vascular bundles, size of vascular bundles, sclerenchyma size were highest in Purple-spotted White variety. Table 3.11. Anatomical stem structure of varieties (2011, in Gia Lam - Hanoi) Parenchyma Number Large vascular bundles Small vascular bundles Characteristics thickness of Quantity Size (µm) Quantity Size (µm) (µm) vascular Width Sclerenchyma Width Sclerenchyma bundles thickness thickness Varieties 707.50 404.40 155.20 229.38 139.38 249.20 152.50 73.75 Red ±107.75 ±38.80 ±23.28 ±18.25 ±10.25 ±15.52 ±7.75 ±9.00 997.50 406.80 137.20 228.75 113.75 269.60 148.75 82.00 Spotted Red ± 122.0 ±29.76 ±13.52 ±26.00 ±10.75 ±22.40 ±8.00 ±12.50 745.00 447.20 143.60 227.50 116.25 303.60 145.75 67.00 White ± 95.25 ±23.04 ±6.08 ±17.00 ±11.50 ±16.96 ±10.25 ±11.75 Purple-spotted 961.25 525.60 239.60 255.00 146.25 286.00 153.25 86.25 White ±73.75 ±22.48 ±18.24 ±20.75 ±23.25 ±4.24 ±8.00 ±11.50 Thus, Purple-spotted White variety had the largest stem diameter (1,38cm), the total number of vascular bundles (525.6), the number of large vascular bundles (239.6) and size of vascular bundles (Large bundles: 255,00μm; Small bundles: 153,25μm) also reached the highest value; therefore, the ability transferring water and minerals are better than 3 remaining varieties. This variety also had the largest sclerenchyma size (big bundles: 146,25μm; small bundles: 86,25μm) leading to the best mechanical resistance in 4 researched varieties. 3.1.2.3 Morphological and anatomical characteristics of leaves - Morphological leaf characteristics The leaves of Rhynchostylis gigantean varieties have some general characteristics such as: leaf shape is hollow, the leaf tips that are divided into two deflected lobes have spiky or round thorns, leaf veins are parallel and deep in leaf cells except the midrib, and leaf shape grows erectly. The leaf colors of varieties tend to follow the color of the flowers, but the expression is not clear. Red flower variety has dark green with purplish red leaves, Spotted Red flower variety has dark green leaves with red dots at the base of the petiole, White flower variety has light green leaves and Purple-spotted White flower variety has green leaves. The number of leaves of researched varieties generally had no differences and reached 6 leaves. However, the leaf size depends on varieties: The leaf length ranged from 22.57cm to 25.09cm, leaf width reached from 4.10 to 4.25cm, in which Purple-spotted White variety got the highest value in all indicators. - Anatomical leaf characteristics Structure and the number of stomata of leaves were observed under a microscope on the peeled epidermis leaves. The stomata that are transformed by the epithelial cells are responsible for exchanging gas with the environment. Stomata include: stomatal cells, stomatal slots in the middle, outside stomatal cells having two subordinate cells parallel to stomatal cells. The number of stomata 8 on the upper side of leaves are fewer than the underside of the leaves and stomatal density of the Rhynchostylis gigantean leaves are lower than the other species of monocotyledon, this proves that Rhynchostylis gigantean orchids have high drought tolerance. The mesophyll cells (assimilation tissues) and the vascular bundles are between the upper and lower epidermises. Mesophyll includes parenchymal cells containing chloroplasts to photosynthesise. Vascular bundles of midrib and blade are parallel and responsible for transferring water and products of photosynthesis. Table 3.13. The number and size of stomata on the upper side of leaves of Rhynchostylis gigantean varieties (2011, in Gia Lam - Hanoi) Size of stomatal cells (µm) Size of stomatal slots (µm) Characteristics Quantity/ Varieties mm2 Length Width Length Width Red 10.40 ±0.93 58.58 ±4.29 20.25 ±3.23 24.08 ±2.67 10.30 ±1.70 Spotted Red 10.27 ±1.26 60.70 ±2.62 26.63 ±2.23 25.93 ±3.52 11.58 ±2.41 White 10.17 ±1.02 58.83 ±6.08 25.95 ±2.38 23.38 ±2.59 10.80 ±2.24 Purple-spotted White 12.30 ±1.62 61.93 ±2.99 26.08 ±3.35 25.83 ±3.03 11.93 ±2.49 The length of stomata on the upper side of leaves ranged from 58.58μm to 61.93μm, in which Purple-spotted White variety was longest and Red variety was shortest. The width of the stomata also changes in varieties. White variety was widest (26.63μm) and Red variety was smallest (20.25μm). Size of tomatal slots depends on the size of the stomata, the difference of stomatal slot size in varieties were negligible. Table 3.14. The number and size of stomata on the underside of leaves of Rhynchostylis gigantean varieties (2011, in Gia Lam - Hanoi) Characteristics Quantity/ Size of stomatal cells (µm) Size of stomatal slots (µm) Varieties mm2 Length Width Dài Rộng Red 15.37 ±1.52 52.93 ±3.83 23.80 ±2.19 23.83 ±2.15 10.08 ±1.64 Spotted Red 13.47 ±1.87 61.33 ±3.87 24.18 ±2.96 25.08 ±2.58 11.63 ±2.23 White 15.57 ±1.63 59.33 ±4.84 24.43 ±2.38 23.63 ±2.14 10.70 ±1.82 Purple-spotted White 17.10 ±1.88 62.43 ±4.02 25.43 ±3.35 26.18 ±3.13 12.68 ±2.17 The number of stomata on the upper side of leaves in varieties was from 10.17 to 12.30 stomata/mm2. The number of stomata on the underside of the leaves was from 13.47 to 17.10 per mm2. The number of stomata on the upper side of leaves in varieties was less than the underside of the leaves, in which Purple-spotted White variety had the highest number of stomata (upper side: 12.47 stomata/mm2; underside: 17.10 stomata/mm2). Size of stomata and stomatal slots also reached the highest value in this variety. Table 3.15. Anatomical structure of Rhynchostylis gigantean leaves (2011, in Gia Lam - Hanoi) Varieties Red Spotted Red White Purple-spotted Characteristics White 102.50±9.00 98.75±19.50 107.00±17.00 88.75±7.75 Epidermis Leaf upper side thickness (µm) 91.88±7.25 88.25±15.50 99.50±16.50 79.38±9.25 Leaf underside Assimilation tissue thickness (µm) 2436.25±165.00 2446.25±146.25 2617.50±112.50 2705.00±219.50 328.13±15.25 399.50±82.25 362.50±75.50 503.75±10.75 Size of vascular Length bundles of midrib 210.00±22.00 223.25±10.25 209.50±25.50 275.63±25.00 Width (µm) 12.55±1.05 12.30±1.17 11.60±1.50 13.30±1.75 Large vascular Quantity bundles on blade Size Thickness 278.75±70.00 312.00±53.50 345.00±53.50 351.88±35.25 (µm) 188.25±17.50 187.00±16.00 197.00±19.75 236.88±16.00 Width 28.50±1.79 25.50±1.93 27.40±3.61 31.10±1.37 Small vascular Quantity bundles on blade Size Thickness 161.25±15.50 155.75±27.75 170.75±27.75 193.75±18.50 (µm) 125.63±11.50 110.00±17.50 122.00±17.50 138.75±13.25 Width Epidermis thickness of the blade in varieties ranged from 88.75μm to 107.00μm. Under epidermis thickness was thinner than upper epidermis, ranging from 79.38μm to 99.50μm, in which Purple-spotted White variety had thinnest epidermis and White variety had thickest epidermis. 9 Assimilation tissue thickness, the number and size of vascular bundles were largest in Purplespotted White variety. In brief, Purple-spotted White variety had the longest and widest size of leaves (respectively 25.09cm and 4.25cm), assimilation tissue thickness was also largest (2705.0μm), so the ability of synthesizing and reserving leaf organic materials of this variety are better than 3 remaining varieties. Purple-spotted White variety also had the largest vascular bundles of midrib size, the highest number of vascular bundles on blade and the largest size of vascular bundles compared to 3 remaining varieties. Therefore, the ability of transporting substances in the leaves of this variety is the best. 3.1.1.4 Morphological characteristics and size of reproductive organs - Morphological characteristics and size of flowers The common characteristics of Rhynchostylis gigantean flowers are large, bisexual; grow around the floral axes (flowering shoots), thick sepals and petals, petal lips divided into three lobes. Table 3.16. The characteristics of flowering shoots and flowers of Rhynchostylis gigantean varieties (2011, in Gia Lam - Hanoi) Number of Flowering Flowering Flower Flower Flower Fragrance Char. flowers shoot shoot diameter shoot durability Varieties /inflorescen diameter length (cm) (cm) length (cm) (days) (cm) Red 21.00 ±8.16 0.46 ±0.07 12.61 ±2.93 2.4 ±0.12 2.37 ±0.18 21.30 ±1.89 Fragrance Spotted Red 23.90 ±6.17 0.47 ±0.07 12.64 ±2.93 2.3 ±0.11 1.60 ±0.17 21.20 ±1.81 Fragrance White 23.40 ±3.63 0.49 ±0.06 11.98 ±2.05 2.3 ±0.13 1.62 ±0.12 20.60 ±1.78 Fragrance Purple-spotted Strong 26.80 ±5.65 0.49 ±0.08 12.74 ±1.65 2.4 ±0.08 2.27 ±0.20 23.10 ±2.13 White fragrance Overall, all varieties had a flowering shoot per a plant and quite large number of flowers /inflorescen (over 20 flowers/inflorescen), flowering shoot length varied from 11.98cm to 12.74cm, flower stem length reached from 1.60cm to 2.37cm and flower durability ranged from 20.6 to 23.1 days. In particular, all indicators reached the highest numbers in Purple-spotted White variety. Flowering shoot and flower diameter of all varieties had no difference. The 3 imported varieties had light fragrance; however indigenous variety was fragrant (Purple-spotted White variety). Apart from the indicators of flowering shoots, durability and fragrance, we also assessed the size and color of flower petal lips, sepals and petals. Table 3.17. Size and color of lips, sepals and petals of Rhynchostylis gigantean (2011, Gia Lam Hanoi) Sepal size Petal size Characteristics Lip size (mm) Sepal (mm) (mm) Petal color Lip color color Varieties Length Width Length Width Length Width 20.30 10.63 15.52 9.87 14.05 6.98 Red Dark red Dark red Dark red ±0.60 ±0.59 ±0.59 ±0.56 ±0.50 ±0.44 White 21.12 11.02 14.18 10.30 14.63 6.63 White with Spotted Red with red Red ±0.87 ±0.62 ±0.62 ±0.55 ±0.74 ±0.60 red spots spots 20.72 10.13 13.62 10.55 13.43 6.57 White White White White ±0.72 ±0.43 ±0.88 ±0.75 ±0.84 ±0.65 White White with White with Purple-spotted 20.80 9.27 14.40 9.37 14.53 5.87 with purple purple White ±0.96 ±0.69 ±0.80 ±0.99 ±0.61 ±1.00 purple spots spots spots The Purple-spotted White variety produced not only the smallest-sized lips but also the smallest sepals (14.40 mm x 9.37 mm) and petals (14.53 mm x 5.87 mm). The longest sepals belong to the Red variety (15.52mm); the shortest but widest sepals were produced by the White variety (13.62mm x 10.55mm). The variety of Spotted Red obtained the longest values of petals (14.63mm), meanwhile the Red variety produced the widest (6.98mm). 10 Accordingly, despite insignificant difference in diameter values of the flowers, size of other floral parts, including lips, sepals and petals, varied amongst different varieties in the experiment. - Morphological characteristics and size of fruit Color of fruit also varied amongst different varieties, as the color of their root, stem and leaves. The Red variety produced fruit of purplish green, particularly, of which purple color concentrated in the area of stalk base; fruit of the Spotted Red variety also saw purplish green color in the stalk base area and along the fruit veins; the fruit of both the White and Purple-spotted White varieties were green in color. The fruit length varied from 2.43cm to 3.42cm, in which the greatest value belongs to the Red variety and the smallest value belongs to the Spotted Red. The fruit width of the varieties in the experiment fell in the range from 1.19 to 1.30cm. The results of morphological study on the Rhynchostylis gigantean varieties suggest that the Purple-spotted White obtained advanced characteristics in growth, development and tolerance to pests and diseases since the variety produced large roots with thick cover layer (1463.75± 69.5µm); great-in-size stele (1232.50 ± 56.2µm); large number of root and stem vascular bundles (27.05±2.2µm and 525.60 ±22.48µm, respectively); thick leaves (assimilation tissue thickness of 2705.00±219.50µm), with large vascular bundles of midrib (503.75 ±10.75µm long, and 275.63±25.00µm wide). Therefore, it was proved that the Purple-spotted White was potential for vigorous growth, development and tolerance to pests and diseases, which is in accordance with the results interpreted above. Accordingly, Purple-spotted White was selected for further research and understanding. 3.1.3 Correlation of the growth of leaves with roots and flowers of purple-spotted white Rhynchostylis gigantean Table 3.19. Correlation of the growth of leaves, with roots and flowers of purple-spotted white Rhynchostylis gigantean (2012) Characteristics Leaf length Root length Rachis length No.of (cm) (cm) (cm) flowers/ inflorescence (Flowers) Leaf length (cm) 1 Root length (cm) 0.4562 1 Rachis length (cm) 0.9075 0.4659 1 No.of flowers/inflorescence 0.9012 0.3676 0.8644 1 (flowers) 35 y = 0,4148x + 30,597 R 2 = 0,2081 30 25 20 15 10 5 30 20 15 10 5 5 10 15 20 Chiều dài lá (cm) 25 30 35 20 15 10 0 0 0 25 5 0 0 y = 0,8609x + 4,9414 R2 = 0,8121 35 Số hoa/cành (hoa) 40 Chiều dài cành hoa (cm) 45 Chiều dài rễ (cm) y = 0,7433x - 1,5837 R2 = 0,8236 25 50 5 10 15 20 Chiều dài lá (cm) 25 30 35 0 5 10 15 20 25 30 35 Chiều dài lá (cm) Figure 3.6. Correlation of leaf Figure 3.7. Correlation of leaf Figure 3.8. Correlation of leaf length with root length length with rachis length length with No. of flowers per inflorescence The results indicate the correlation between the length of leaves and roots (R2<0.5). Meanwhile, the correlation of leaf length with florescence length and number of flowers per floresecence were strong (R2>0.5, a>0). Accordingly, in order to improve the flower quality of purple-spotted white Rhynchostylis gigantean (length of florescences, number of flowers per florescence), techniques to increase the length of leaves would play a vital role. Such recommendation is in line with previous study of Jean Cardoso et al. (2012) on Phalaenopsis FSNT 'Dai-Itigo [47]. 11 3.1.4 Growth and development characteristics of the purple-spotted white Rhynchostylis gigantean in different ecoregions 3.1.4.1 Growth characteristics of the purple-spotted white Rhynchostylis gigantean in different ecoregions Table 3.20. Growth characteristics of the purple-spotted white Rhynchostylis gigantean in some ecoregions (2012) No.of Leaf Leaf No.of Root Root Characteristics leaves length width roots length diameter Locations (leaves) (cm) (cm) (roots) (cm) (cm) Gia Lam - Ha Noi 6.2±0.29 24.5±0.39 4.5±0.14 5.2±0.32 40.7±0.49 0.86±0.01 Van Giang - Hung Yen 6.0±0.21 24.6±0.44 4.6±0.15 5.3±0.30 41.0±0.64 0.87±0.01 Moc Chau - Son La 5.1±0.35 20.4±0.35 3.7±0.13 4.4±0.30 34.9±0.20 0.71±0.02 Sa Pa- Lao Cai 5.0±0.30 19.5±0.40 3.8±0.14 4.0±0.26 29.3±0.45 0.69±0.02 The growth indicators of Rhynchostylis gigantean in the Red River Delta were greater than those in the North moutainous regions. Ability to grow of the plants in Gia Lam - Ha Noi and Van Giang -Hung Yen were statistically similar, with number of leaves of 6.0-6.2 (leaves), leaf length of 24.5-24.6cm, number of roots of 5.2-5.3 (roots), and root length of 40.7-41.0cm. In the North mountainous regions, Rhynchostylis gigantean in Sapa - Lao Cai and Moc ChauSon La reached the same level of growth, which was inferior to that of the plants in the Red River Delta. The main reason of the difference was due to low temperature in winter season in the mountainous regions that caused significant reduction in plant growth. Figure 3.10. Growth dynamics of root length Figure 3.11. Growth dynamics of leaf length of Rhynchostylis gigantean in different of Rhynchostylis gigantean in different ecoregions ecoregions Rhynchostylis gigantean in the Red River Delta produced vigorous growth of leaves and roots, which lasted 8 months from March to October. In the mountainous regions, the plants obtained inferior growth to those in the Red River Delta, which began later (in April) but finished earlier (in September). 3.1.4.2 Flowering characteristics of purple-spotted white Rhynchostylis gigantean in different ecoregions Table 3.21. Time of flowering and flower quality of Rhynchostylis gigantean in different eco-regions (November 2012 – February 2013, purple-spotted white Rhynchostylis gigantean ) Char. Time of Percentage Length of No. of Diameter Diameter Flower flower of plants flowering flowers per of rachis of durability bud producing shoot inflorescence (cm) flowers (days) Locations initiation flowers (%) (cm) (flowers) (cm) 16.7± Gia Lam – 7/11 50 26.2±0.20 0.59±0.01 2.33±0.02 24 Ha Noi 0.22 Van GiangHung Yen Moc Chau - Son La Sa Pa - Lao Cai 7/11 51 16.9±0.12 26.4±0.27 0.58±0.01 2.31±0.01 24 3/11 30 13.6±0.14 20.3±0.33 0.44±0.01 2.29±0.01 27 3/11 25 12.7±0.12 18.4±0.30 0.46±0.02 2.30±0.01 27 12 The appearance of flower buds in the North mountainous regions (on 3rd November 2012) was earlier than that in the Red River Delta (on 7th November 2012). The percentage of plants producing flowers was highest in the Red River Delta (50-52%) and lowest in the North mountainous regions (25-30%). Flower quality described by three typical characteristics of flowering shoot length, number of flowers per inflorescence, and rachis diameter of the plants in Hung Yen and Ha Noi was statistically similar. Meanwhile, flowers of Rhynchostylis gigantean in regions of Moc Chau – Son La and Sapa – Lao Cai were of lower quality. However, flowers of Rhynchostylis gigantean in mountainous regions were more durable than those in the Red River Delta. The flowers lasted 27 days and 24 days, respectively. 3.2 Effect of technical measures on growth of Rhynchostylis gigantean seedlings 3.2.1. Effect of growing medium and times of watering on growth of nursery seedlings Table 3.22. Effect of growing medium and times of watering on growth of nursery seedlings (2011, Gia Lam - Ha Noi) Media Times of Survival Number Leaf Leaf Number Root Diameter watering rate of length width of roots length of roots (%) leaves (cm) (cm) (cm) (cm) (cm) GT1 75 3.8 10.1 1.7 3.4 18.5 0.32 GT2 82 4.1 11.2 1.8 3.6 19.6 0.35 GT3 82 4.1 11.3 1.8 3.6 19.4 0.34 LSD0,05 medium 0.11 1.07 0.12 0.12 1.05 0.17 Twice a day 78 3.9 10.4 1.8 3.4 18.3 0.32 Once a day 82 4.1 11.7 1.8 3.6 19.6 0.34 Once / 2 days 82 4.1 11.8 1.8 3.6 20.3 0.35 Once / 3 days 76 3.9 10.5 1.7 3.4 19.6 0.33 LSD0,05 watering times 0.12 1.20 0.23 0.14 1.22 0.20 Twice a day 80 4.0 11.0 1.8 3.6 18.8 0.30 Once a day 76 3.8 10.6 1.7 3.5 19.5 0.32 GT1 Once / 2 days 73 3.8 10.4 1.7 3.2 20.2 0.33 Once / 3 days 70 3.7 10.3 1.6 3.2 20.0 0.31 Twice a day 75 3.8 10.4 1.7 3.2 17.0 0.32 Once a day 81 4.1 11.0 1.8 3.6 18.8 0.34 GT2 Once / 2 days 89 4.4 12.0 1.9 3.9 21.1 0.37 Once / 3 days 83 4.2 11.5 1.9 3.6 20.0 0.35 Twice a day 79 3.9 10.6 1.8 3.5 19.0 0.33 Once a day 88 4.3 12.2 1.9 3.8 20.5 0.36 GT3 Once / 2 days 85 4.2 11.8 1.9 3.7 19.5 0.34 Once / 3 days 76 3.8 10.5 1.7 3.5 18.7 0.32 LSD0,05 medium*watering 0.22 2.15 0.40 0.24 2.11 0.35 times CV% 3.30 6.60 5.20 4.10 6.50 4.30 Note: GT1 (control): charcoal + coarse bark (ratio 1:1), GT2: seaweed + charcoal + coarse bark (ratio 1:1:1), GT3: Cocopeat+ charcoal + coarse bark (ratio 1:1:1) Types of growing media and times of watering had different influence on growth of Rhynchostylis gigantea at level of 95% confidence. The treatment GT2 -with one watering every 2 days, and the treatment GT3 – with one watering a day were recorded to be the most appropriate for growth of the seedlings. 3.2.2 Effect of fertilizers and times of fertilizing times on growth of nursery seedlings The results indicate interaction amongst fertilizers and times of application. Increase in times of fertilizer application - from once every 7 days to once every 3 days - promoted gradual increase in the plant growth. The treatment of Fish Emulsion fertilizer (5:1:1) with one application every 5 days (concentration of 0.05%) produced the highest results with 4.7 leaves of 13.2cm long, and 4.0 roots of 13 22.0cm long. At level of 95% confidence, he same level of growth was recorded in the treatment of one application of the same fertilizer every 3 days. Such increase was due to high content of nitrogen in the fertilizer that was suitable for Rhynchostylis gigantea during vegetative growth period. Table 3.23. Effect of fertilizers and fertilizing times on growth of nursery seedlings (2011, Gia Lam - Ha Noi) Fertilizers Fertilizing times No. of Leaf Leaf No. Root Diameter leaves length width of length of roots (cm) (cm) roots (cm) (cm) PB1 3.9 10.7 1.7 3.1 18.9 0.32 PB2 4.4 12.9 1.8 3.7 21.0 0.35 PB3 3.9 11.1 1.7 3.1 18.9 0.34 LSD0,05 Fertilizers 0.10 0.67 0.10 0.11 1.00 0.18 Once / 9 days 3.8 11.0 1.6 3.1 18.2 0.32 Once / 7 days 4.0 11.1 1.7 3.2 19.0 0.33 Once / 5 days 4.3 11.9 1.8 3.5 20.2 0.34 Once / 3 days 4.3 12.1 1.9 3.5 20.7 0.35 LSD0,05 Fertilizing times 0.11 0.78 0.10 0.12 1.16 0.21 Once / 9 days 3.7 10.0 1.7 3.0 17.5 0.32 Once / 7 days 3.9 10.6 1.7 3.1 18.8 0.32 PB1 Once / 5 days 4.1 11.0 1.8 3.3 19.3 0.33 Once / 3 days 4.2 11.4 1.9 3.3 20.0 0.34 Once / 9 days 4.1 12.5 1.8 3.4 19.1 0.33 PB2 Once / 7 days 4.3 12.8 1.9 3.6 20.9 0.35 Once / 5 days 4.7 13.2 1.9 4.0 22.0 0.36 Once / 3 days 4.7 13.3 2.0 4.0 22.1 0.36 Once / 9 days 3.8 10.5 1.6 3.1 18.0 0.33 Once / 7 days 3.9 10.8 1.7 3.1 18.7 0.34 PB3 Once / 5 days 4.1 11.6 1.8 3.2 19.0 0.34 Once / 3 days 4.1 11.7 1.8 3.3 20.1 0.35 LSD0,05 Fertilizers* F. times 0.20 1.35 0.20 0.22 2.01 0.37 CV% 3.00 6.90 6.80 3.90 6.10 6.50 3.3. Effect of technical measures on growth and developmennt of Rhynchostylis gigantea in the net-house 3.3.1 Effect of transplanting time on growth and development of Rhynchostylis gigantea Above-mentioned results of the research on growth characteristics of Rhynchostylis gigantea suggest that the plants have distinct seasons for vegetative growth. Therefore, research on time of transplanting is necessary. Table 3.24. Effect of transplanting time on growth of Rhynchostylis gigantea (20112012, Gia Lam – Ha Noi) 1 year after transplanting 2 years after transplanting Char. Time of Survival No. of Leaf No. of No. of Leaf No. of rehabilitation rate (%) leaves length roots leaves length roots Treatments (days) (leaves) (cm) (cm) (leaves) (cm) (cm) Feb 15th 81 25 4.9±0.21 15.7±0.12 4.0±0.21 6.1±0.18 25.1±0.1 5.3±0.1 Mar 15th 85 17 5.1±0.1 17.6±0.1 4.2±0.1 6.4±0.1 26.6±0.1 5.9±0.2 Apr 15th 97 10 5.4±0.1 19.0±0.2 5.6±0.2 7.0±0.2 27.4±0.1 6.8±0.1 May 15th 92 13 5.0±0.2 18.1±0.1 4.7±0.1 6.3±0.1 25.4±0.1 6.2±0.1 14 The results describe high rate of plant survival after transplanting, ranging from 81 to 97%, of which highest result belongs to the plants transplanted on April 15th. The earliest rehabilitated plants were also observed in the treatment (10 days after transplanting); meanwhile, plants in the other treatments required 13-25 days to rehabiliate. At different time of transplanting, the strongest ability to grow belonged to the plants transplanted on April 15th, indicated by number of leaves (7.0 leaves), leaf length (27.4cm), number of roots (6.8 roots), and root length (43.2cm) - which were different from those of the other treatments at level of 95% confidence. The difference was because of low temperature in the mountains, which resulted in poor growth of the plants transplanted on 15th of February and Mach. Vegetative growth of the plants transplanted on May 15th was also negatively affected since the temperature in the season highly increased. Table 3.25. Effect of transplanting time to flower quality (November 2012 – February 2013, Gia Lan - Hanoi) Flowering Length of Flowering No.of flowers Rachis Flower Char. rate (%) flowering shoot per length durability shoot (cm) diameter inflorescence (cm) (days) Treatments (cm) (flowers) Feb 15th 47 16.3±0.1 0.59±0.1 25.1±0.3 11.2±0.1 24 Mar 15th 54 16.5±0.1 0.61±0.1 26.0±0.2 11.4±0.1 24 Apr 15th 17.5±0.1 0.67±0.1 28.5±0.1 12.3±0.1 25 56 May 15th 50 16.8±0.1 0.60±0.1 26.4±0.3 11.7±0.1 24 According to the observation of flower quality amongst the treatments, the rate of flowering varied from 47 to 56%, of which the highest value was obtained by the plants transplanted on 15th April. The length of flowering shoot, and number of flowers per inflorescence of the treatment was also of the highest values, with 17.5cm and 28.5, respectively. Values of flowering shoot diameter, flower diameter and flower durability of the treatments indicated no significant difference. 3.3.2 Effect of water quality on growth and development of Rhynchostylis gigantea Table 3.26. Effect of water quality on growth of Rhynchostylis gigantea (2012-2013, Gia Lam – Ha Noi) Characteristics 1 year after transplanting 2 years after transplanting Survival No. No. Leaf Root Leaf Root rate No. of of No. of of length length length length Treatments (%) leaves roots leaves roots (cm) (cm) (cm) (cm) (cm) (cm) Well-water without 87 4.8 16.8 4.1 26.4 5.7 23.0 4.9 38.4 filtration Filtered well-water 95 5.0 18.3 4.4 27.5 6.2 24.7 5.2 40.9 Tap-water 80 4.7 16.3 3.9 25.8 5.5 22.1 4.5 34.7 Rain-water 98 5.6 19.1 5.0 31.6 7.3 27.6 6.7 44.3 CV% 2.90 5.70 2.30 3.90 2.40 6.10 2.90 4.10 LSD0,05 0.26 2.20 0.27 2.02 0.28 2.79 0.28 3.02 Results of the study on water quality suggest that the plants produced vigorous growth when rain water was used for watering, followed by the plants that were applied with water obtained from wells with filtration and without filtration. The least vigorous growth was observed in the treatment with use of tap-water. At level of 95% confidence, the plants in the experiment produced 5.5-7.3 leaves of 22.1- 27.6cm long, 4.5-6.7 roots of 34.7-44.3cm long. Indicators of leaf width and root diameter in the treatment of rain-water were higher than those in the other treatments; meanwhile the indicators of lowest values belonged to the treatment of tap-water. The highest rate of flowering plants belongs to the treatment of rain-water (58%), followed by the plants with filtered well-water (52%), then well-water without filtration (49%); and finally the plants with tap-water (47%). The results of flower quality were of the same ranking. 15 Table 3.27. Effect of water quality to flower quality (November 2013 – February 2014, Gia Lam – Ha Noi) Characterisitcs Flowering Flowering Flowering No. of Rachis Flower Treatments rate (%) shoot shoot flowers/ length durability length diameter inflorescence (cm) (days) (cm) (cm) (flowers) Well-water without 49 16.9 0.59 25.5 11.3 23 filtration Well-water with filtration 52 17.0 0.60 26.5 11.8 24 Tap-water 47 16.2 0.57 24.3 11.0 23 Rain-water 58 18.5 0.69 29.7 13.5 27 CV% 4.10 5.70 8.30 6.50 LSD0,05 1.26 0.08 4.00 1.30 Hence, it is obvious that water quality had influence on growth and development of Rhynchostylis gigantea. Rain-water was proved to be the most suitable for the plants, followed by well-water with and, then, without filtration; tap-water was the least suitable for the plant development. The explaination was due to level of pH and EC in different sources of water. Low EC and pH of rain-water, which were 0.04 and 5.55, respectively, together with the fertilizers applied constituted a favorable condition for the plants to absorb water and nutrients, producing vigorous growth and development. Although filtration reduced pH of well-water, EC remained at high level that required further adjustion for watering Rhynchostylis gigantea. Well-water without filtration and tap-water should not be used for plant watering since these sources of water had high level of pH and EC, particularlly tap-water with too-high pH value of 7.52 and EC of 0.45, inhibiting the plant growth and development. 3.3.3 Effect of growing media and times of watering on growth and development of Rhynchostylis gigantea Different constitutions of growing media and times of watering caused different effect on the growth and development of Rhynchostylis gigantea. Treatments of GT1 (mounted on wood trunks of longan trees) with one watering a day, and treatment of GT2 (seaweed + charcoal + crushed wood) with one watering every 2 days were observed to be the most suitable. Growing medium in treatment of GT3, even with different times of watering, maintained high moisture since the cocopeat composition had high potential of water adsorption that led to unpleasant airless environment, thus, inhibiting the growth and development of Rhynchostylis gigantea. Study on the effects of growing media and times of watering suggested that the drier the environment was, the faster the plants produced flower buds. The earliest emergence of flower buds was recorded in the treatment of well-drained medium (GT1) with one watering every 3 days, of which flower buds appeared on 5th November. Similar situation was recorded in the observation of flower quality. The treatment of GT1 with one watering a day produced flowers of highest and the same quality of those in the GT2 treatment with one watering every 2 days at level of 95% confidence. The longest flowering shoots were 18.6cm and 18.5cm, with highest number of flowers per inflorescence (29.8 and 29.5 flowers). Therefore, reduction of watering times (once every 3 days, and less amount of water) at stage of flower buds initiation would stimulate the plants to produce inflorescence and at higher flowering rate. 16 Table 3.28. Effect of growing media and times of watering on growth of Rhynchostylis gigantea in production garden (2012-2013, Gia Lam – Ha Noi) Media Times of Survival 1 year after transplanting 2 years after transplanting watering rate No. of Leaf No. Root No. of Leaf No. Root (%) leaves length of length leaves length of length (cm) roots (cm) (cm) roots (cm) (cm) (cm) GT1 94 5.2 18.2 4.9 28.7 6.6 26.3 6.5 42.6 GT2 94 5.3 18.3 4.7 28.8 6.7 26.4 6.2 42.9 GT3 93 5.0 17.2 4.6 27.5 6.1 25.2 5.9 40.9 LSD0,05 Medium 0.10 1.00 0.10 1.05 0.11 1.07 0.12 1.06 Twice a day 94 5.1 17.4 4.6 27.3 6.5 25.1 6.0 39.7 Once a day 96 5.2 18.7 4.7 28.2 6.7 26.4 6.2 41.6 Once / 2 days 95 5.3 18.6 4.8 29.0 6.7 26.0 6.3 43.1 Once / 3 days 91 4.9 17.3 4.9 29.5 6.1 25.1 6.5 44.2 LSD0,05 watering times 0.12 1.20 0.13 1.00 0.13 1.24 0.14 1.22 Twice a day 96 5.4 18.5 4.7 27.5 7.0 26.4 6.2 40.2 Once a day 4.8 28.4 6.4 42.0 97 5.4 18.6 7.0 26.6 GT1 Once / 2 days 93 5.1 18.0 5.0 29.2 6.4 25.4 6.7 43.5 Once / 3 days 90 4.9 17.8 5.1 29.9 6.0 25.0 6.9 45.0 Twice a day 94 5.1 17.8 4.7 27.7 6.4 25.1 6.1 40.5 Once a day 95 5.4 18.4 4.8 28.6 7.0 27.0 6.3 42.4 GT2 Once / 2 days 4.8 29.4 6.3 43.9 98 5.7 19.1 7.5 27.7 Once / 3 days 92 5.0 18.1 4.8 29.8 6.2 25.6 6.4 44.8 Twice a day 93 5.0 18.0 4.4 26.7 6.1 25.5 5.5 38.5 Once a day 95 5.0 18.2 4.6 27.6 6.1 25.8 5.9 40.4 GT3 Once / 2 days 94 5.1 17.8 4.6 28.4 6.3 25.0 6.0 41.9 Once / 3 days 92 5.0 17.7 4.8 28.8 6.2 24.9 6.3 42.8 LSD0,05 0.20 2.01 0.21 2.00 0.22 2.15 0.24 2.12 Medium*watering times CV% 2.00 4.00 2.00 2.04 2.00 5.00 2.30 3.00 Note: GT1: Mounted upon a trunk of longan tree of cylinder shape (40cm high x 20cm (diameter)), GT2: Seaweed + Charcoal + crushed wood, GT3: cocopeat + charcoal + coarse bark, GT2, GT3: nestled in wood baskets with a layer of 2-3cm of charcoal, coarse bark, crushed wood. Table 3.29. Effect of growing media and times of watering on flowering ability and flower quality of Rhynchostylis gigantea (November 2013 – February 2014, Gia Lam – Ha Noi) Media Times of Date of Flowering Flowering Diameter Number of Flower watering flower rate (%) shoot of flowers per durability bud length Flowers inflorescence (days) initiation (cm) (cm) (flowers) GT1 6/11 58 17.5 0.64 27.8 24 GT2 7/11 56 17.6 0.65 28.1 24 GT3 9/11 52 16.8 0.62 27.7 23 LSD0,05 Medium 0,72 0,39 1,22 Twice a day 9/11 53 17.0 0.63 27.5 22 Once a day 8/11 56 17.8 0.65 28.5 24 Once / 2 days 7/11 57 17.5 0.64 28.3 24 Once / 3 days 5/11 57 16.9 0.63 27.3 23 LSD0,05 Watering times 0.82 0.45 1.41 Twice a day 8/11 55 17.7 0.66 28.0 23 GT1 Once a day 7/11 0.67 59 18.6 29.8 25 Once / 2 days 6/11 59 17.0 0.61 27.5 24 17
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