Nghiên cứu tuyển chọn giống bơ (Persea americana Miller) thích hợp cho một số tỉnh Tây Nguyên ( TTTA)

  • Số trang: 27 |
  • Loại file: PDF |
  • Lượt xem: 32 |
  • Lượt tải: 0
thuvientrithuc1102

Đã đăng 15337 tài liệu

Mô tả:

MINISTRY OF EDUCATION MINISTRY OF AGRICULTURE AND TRAINING AND RURAL DEVELOPMENT VIETNAM ACADEMY OF AGRICULTURAL SCIENCES HOANG MANH CUONG STUDY ON SELECTION OF AVOCADO VARIETIES (persea americana miller) SUITABLE FOR SOME PROVINCES IN THE WESTERN HIGHLANDS Major Field: GENETICS AND PLANT BREEDING Code: 62.62.01.11 DOCTORAL THESIS SUMMARY HA NOI - 2015 The Doctoral thesis was completed in 2 VIETNAM ACADEMY OF AGRICULTURAL SCIENCES Scientific Supervisors: 1. Prof. Dr. Do Nang Vinh 2. Dr. Le Ngoc Bau Reviewer 1: Reviewer 2: Reviewer 3: Dissertation will be defended before committee in charge for doctoral dissertation in academy level, meeting place ……… on …………, 2015 The PhD thesis may be fount at: - Ha Noi National Library - Library in Vietnam Academy of Agricultural Sciences HA NOI - 2015 1 INTRODUCTION 1. Urgency of research According to FAO’s statistics, avocado trees were grown in 63 countries with a total area of 417 thousand hectares, yield of 3,078 thousand tons per year, the average yield of 7.4 tons/ha, with annual exports of 491.5 thousand tons and exports of 606.6 million USD (Gazit and Degani, 2002; John and Gary, 2012; Pliego et al., 2002). Also according to FAO’s statistics, 2011, countries with major world avocado production were mainly distributed in tropical climates in Central and South America. The country, which had the world's largest avocado productivity, was Mexico (1,264,141 tons), followed by subsequent countries such as Chile (368,568 tons), the Republic of Dominique (295,080 tons), Indonesia (275,953 tons), Canada (238,544 tons), Colombia (215,595 tons), Peru (212,857 tons), Kenya (201,478 tons), Brazil (160,376 tons), China (108,500 tons) and (Bruce et al, 2013). France and the Netherlands were the two countries which imported the world's largest avocado with average amount about 94 thousand tons per year mostly from Mexico, Chile, Israel, Spain and South Africa (Bruce et al, 2013). Avocado yield variations were high from 1.3 tons/ha (Portugal) to 28.6 tons/ha (Samoa), mainly depending on the variety, ability of intensive cultivation and climate conditions (Gazit and Degani, 2002). The goal of the world avocado industry sector is to improve yield up 30 tons/ha in terms of intensive industry conditions with measures such as variety, good grafting, thick growing with adjustable density and shaping, watering and nutritious control for reducing fruit losses, plant protection, etc. In Asia, the avocado trees were quite extensively grown in Southeast Asian countries such as Indonesia, the Philippines, Thailand, Vietnam and China. Indonesia is the country ranked the fourth in the world and the head of the Southeast Asian countries to produce avocado. Our country is on the same latitude line as Mexico and between the two countries growing large avocado in Asia including Indonesia and China (ranked 11th in the world), and there is the ecological conditions very suitable to growth of avocado trees in both Southern and Northern (Bruce et al, 2013). Reality of avocado cultivation over 70 years in the central Western Highlands showed that good growths, quite yields, some good qualities considered as special tree varieties of area were found in avocado trees at altitude over 500 m. However, development of avocado production is still limited by some of the following causes: First, the study of avocado variety selection has remained a lot of limitations, has not specified avocado variety sets suitable for various ecological regions and has not selected to create the avocado varieties spread with harvest time soon, main and late crop. Second, some of the world's commercial avocado varieties have been introduced, however not yet evaluated trials to select good varieties and high adaptation to the ecological conditions in the Western Highlands. Third, no systematic studies on the techniques of cultivation, post-harvest, storage, processing and improving the fruit quality of different avocado varieties. 2 To contribute in overcoming some limitations mentioned above, the implementation of the dissertation "Study on selection of avocado varieties (Persea americana Miller) suitable for some provinces in the Western Highlands" is essential as a basis of the science and practice in order to promote sustainable development of avocado tree on areas of provinces in the Western Highlands. 2. Research objectives 2.1. General objectives To construct the scientific and practical base for selection of avocado varieties with high yield, good quality, different harvest time in the year and good adaptability to the ecological conditions of some major growing regions in the Western Highlands. 2.2. Specific objectives - To identify bio-agricultural characteristics of different avocado varieties selected in the domestic country and abroad in conditions of production in the Western Highlands. - To select some avocado varieties with yield above 50 kg/tree/year, dry matter content over 23%, lipid over 13%, different harvest times in the year and good tolerance to some pests and diseases in the Western Highlands. 3. Object and scope of dissertation 3.1. Object of research - Avocado varieties are grown in the provinces Dak Lak, Gia Lai and Lam Dong in the Western Highlands. - 10 most promising variety materials collected in domestic: TA1, TA2, TA3, TA4, TA5, TA31, TA44, TA47, TA50, TA54, and 2 imported varieties: Booth 7 and Hass. 3.2. Scope of research Comparative and evaluative experiments on 12 promising avocado varieties were conducted in three major growing regions in Dak Lak, Gia Lai and Lam Dong provinces. 4. Novelty of dissertation - The first times in our country, the dissertation had conducted to test, evaluate and compare different avocado varieties in a systematic way in the regions with diverse ecological conditions in the Western Highlands. - The dissertation already examined and evaluated bio-agricultural characteristics of 38 avocado strains and varieties selected in domestic country and import. - The research results of the dissertation selected eight new avocado varieties with high yield and good quality adapting for export standards, in which there were 4 avocado varieties (TA1, TA3, TA5 and Booth 7) recognized by Ministry of Agriculture and Rural Development for trial production in 2011. 5. Contributions of the dissertation 5.1. Scientific significance - For the first times in our country, the dissertation determined important bioagricultural characteristics of many different avocado varieties as well as imported 3 varities planted in different ecological regions of the Western Highlands. The dissertation provided the information, scientific data about breeding, cultivation and biological characteristics, yield, fruit quality of the strains and varieties selected in domestic country and import. New selected avocado strains and varieties could be used as material sources for scientific research on variety improvement in the future in order to enhance the competitiveness of Vietnam avocado varieties. - Deep studies on avocado variety selection are still very few in Vietnam. So, research results of the dissertation can make valuable reference material for pupils, students and faculty at Universities and Research Institutes. The dissertation also provides the scientific arguments for researchers in variety selection and avocado development in Vietnam. 5.2. Realistic significance - Research dissertation of PhD cadidate significantly contributed in selection of new avocado varieties for regions in the Western Highlands. We selected 9 promising avocado varieties including 4 new avocado varieties TA1, TA3, TA5 and Booth 7 with high yield, good quality and suitability for production reality of Western Highlands regions, which were regconized by Ministry of Agriculture and Rural Development for trial production in 2011. - Avocado varieties selected with high yield, good quality and export standards have been propagated quickly to replace the avocado varieties with low yield and poor quality in production. New avocado varieties have been transferred to 5 enterprises, 3 farmer cooperatives in Dak Lak, Dak Nong, Gia Lai, Lam Dong and Dong Nai provinces in the Western Highlands. CHAPTER 1 OVERVIEW 1.1. STUDIES IN ABROAD 1.1.1. Origination and plant classification Avocado trees were originated from Mexico and Central America. The scientific name of the avocado tree is Persea americana Miller., the family Lauraceae, the genus Persea and species P. americana. The avocado is in class of 2 cotyledons, chromosome number 2n = 24; however the species remains in the triploids 3n = 36 and tetraploid 4n = 48 chromosomes. Species of Persea americana Miller are classified into 3 different ecological strains as Mexico, Guatemala and West India (Gary, 2012; Popenoe, 1952). Botanical characteristics of these three ecological strains were described in table 1.1. These three avocado strains could be cross-bred with each other as easily as they are planted close together (Bergh, 1969; Crowley and Arpaia, 2002; Popenoe, 1952). Mexican strain: originated from the Mexican plateau and are resistant to cold, and the leaves smell of anise. However, the disadvantages of this strain are the small fruits, soft skin and relatively large seeds. Hybridization selected from this strain is valuable variety. For example, varieties Fuerte and Zutano are 2 hybridizations between Mexico and Guatemala, having the medium fruit size and smooth skin. 4 Guatemala strain: the varieties of this strain as Hayes, Hopkins and Hass were originated from the Western Highlands; however they are less tolerant than Mexican strain. The varieties of this strain usually have large fruit, thick skin, rough shell structure, and shell color changes from green to black when the fruit is mature. Seeds are small and are held in the fruit. West India strain: this strain is suitable in hot areas with low altitude and humidity. The varieties of this strain are not resistant to cold, big fruits with tough shell, nice design and not thickness as the fruits of Guatemala strain. The popular varieties of this strain are Pollock, Booth 7 and Simmonds. 1.1.2. Development history and distribution in the world Avocado tree development history has proven its good adaptation to the ecological conditions in many countries. Avocado trees were introduced and brought to plant in Indonesia and Philippines in 1750, and Southern Western of Indian Ocean, East of Madagascar in Republic of Mauritius in 1780 and Hawaiian Islands in 1825, and they were grown in Florida in 1833, California in 1871 and India in 1982 (A Profile of the South African avocado market value chain, 2012). However, most of the varieties were planted by seeds, they had been recently started growing in grafted avocado trees since 1890 in the U.S. After that avocado trees have been grown widespread in the tropical regions of Central America and Caribbean in the countries such as islands in Central and the South Pacific including Hawaii, Samoa and Cook islands. To date, commercial varieties have developed very strongly throughout the continents. The largest avocado producing countries in the world are shown in table 1.2, and 1.3. Starting from the 20th century, avocado trees are well developed but are still primarily grown in regions of tropical climates and tropical Asia, and located in between 40 degrees North and South of the equator. Statistics showed that, avocado amounts were produced for 76% in the regions of America, 11% in Africa, 9% in Asian, 2% in the countries of Europe and the South Pacific (Gary, 2012). Statistics of Global Agricultural Information Network in November, 2012 said that commercial avocado was grown with a total area over 150,000 hectares in Mexico with amounts about 85% of the varieties belonging to the Mexican strain. Varieties Hass and Fuerte were 2 commercial varieties grown mainly and accounted for 95%, and also States of Mexico had grown more commercial varieties as Criollo, Bacon, Gwen, Pinkerton, Nabal and Reed but with small areas. Avocado varieties produced under American APHIS's certificates with a total area of 75,000 hectares (Dan Berman, 2012). Mexico is a country with the largest area and productivity in the world today, and it has an altitude between 800-2,500 m above sea level. Most avocado varieties are grown in the strains resistant to cold, high adaptability, average yield (10.1 tons/ha), and ranked fourth in the world behind only the Dominican Republic (19.3 tons/ha); Colombia (16.5 tons/ha); Brazil (12.9 tons/ha); before America and Indonesia (9.8 tons/ha) (Bruce et al, 2013; Ministry of Economy, 2011). 5 1.1.3. Ecological requirement and tolerance 1.1.3.1. Ecological requirement Rainfall: avocado trees have wide adaptability, growth and development in the range from 30 degrees of North to 30 degrees of South, this wide distribution created differences of 3 strains. Avocado trees are very sensitive to humidity, but not drought. During the formation of immature fruit, if weather conditions are too dry, the fruits will be felled very much. Most avocado varieties are sensitive to excess water conditions, high soil moisture and poor drainage. In Hawaii, the avocado tree grows quite with 3,125 mm in annual rainfall on well-drained soils. Requirement of regular rainfall are from 1,250-1,750 mm. In 3 avocado strains, West India strain adapted the high rainfall in the summer, while the Mexican strain was tolerant to conditions of water lackage and low humidity (Douhan, 2009). Temperature: avocado tree's response to temperature conditions depending on the type of genes, the Mexican strain is the highest tolerant to cold, followed by Guatemala, and the West India strain is suitable in the hot region and less cold tolerance. Growth of seedlings: the flowers and fruit bud development of avocado tree will be badly affected when temperature is 00C. Night and day temperature amplitude may also clearly impact to growth and development of plants, especially in the development of the flower. 150C – 200C in night temperature and 200C during the day were suitable for the growth of flowers, pollen tube growth and the periods of the embryo growth (Gazit and Degani, 2002). Land: Many previous recommendations of French and American experts said that we should choose the land for avocado cultivation in moderate slope. Also it is necessary to pay close attention to the depth of the groundwater veins (depth of underground water levels above 1 m). In Puerto Rico, the avocado tree grew better in neutral or alkaline soil in comparison with medium or very acidic soil. In Israel, the varieties belonging to Mexico and Guatemala strains became yellow leaves when grown on the land containing much calcium; also in the Rio Gran Valley belonging to the State of Texas, the Mexico strain must be grafted onto stumps belonging to West India and resistant to salt (Lahav et al, 1989). 1.1.3.2. Tolerant ability The highest salt tolerance was in West India strain, and the lowest one was in Mexican strain. However, each of the 3 salty tolerant strains was also highly variable (Kadman and Ben-Ya'acov, 1976), including real trees borned from the same mother plant (Kadman, 1968). Although yellow leaf tolerance properties due to the high content of lime in the soil can be seen in the varieties belonging to West India strain, this tolerance also has considerable variability between varieties in the strain. West India stumps reacted very poorly in heavy soil and flood conditions; there were reports of selection of salty tolerant stumps and yellow leaves due to the high content of lime (Ben-Ya'acov et al, 1974; Sánchez and Barrientos, 1987). Selected stumps from South Africa's Dusa proved to endure highly with alkaline water in California (Crowley and Arpaia, 2002). West India purebred stumps did not respond well to cold soil conditions in California, but the special hybridizations of Mexico 6 strain seemed very good adaptations. In frost prone areas, it is necessary to have stumps enhancing tolerance of grafting shoots, but these cold tolerant graft-stumps belonging to Mexico strain brought into the research program genetically did not transfer tolerance to grafting shoots (Ben-Ya'acov, 1987, 1998). Cold tolerance: most of the world's avocado cultivation regions occasionally suffer from damages of salt fog, and cold tolerance is a great advantage for the fruit as well as for all plants in general. Cold tolerance is only limited on Mexico strain, meanwhile the temperature over 00C can still be harmful to varieties belonging to the West India strain. Hass, considered the variety belonging to Guatemala strain, has special strength of cold tolerance, but children survey of Hass has about 1/5 of this variety's gene numbers originated from the Mexico strain and supplied evidences that Hass was originated between the two strains (Ben-Ya'acov et al, 1974; Mhameed et al, 1997). This may be explained for the cold tolerance as well as the ripe fruits earlier than those of Hass compared to purebred Guatemala. Cold tolerant ability in the same strain as well as among the strains is different. For example, among the varieties regarded as purebred ones, Nahal and Reed are highly tolerant to cold, but Anaheim is very susceptible to cold. Yama, regarded as the coldest tolerant variety of the Mexico strain, was tolerant to - 80C without any serious harm, which is a proper parent in selecting cold tolerant varieties. In Florida, the varieties of Mexico strain were selected for promising commercial varieties with the high cold tolerant characteristic in conditions to occur in cycles (Knight, 1971). Hot tolerance: hot tolerant ability of the varieties is very high variation. However, the average hot tolerant ability of Mexico strain is higher than other strains, typically in the Mexicola strains: Mayo and Indio. Moreover, because the varieties of Mexico strains make earlier blooms and sooner old fruit, they are little to bear the impacts of hot stages in the spring. Among the varieties belonging to Guatemala strain, Frey and Hass are more sensitization with hot temperatures. Irving hybridization between Mexico and Guatemala showed good tolerance to high temperature and low humidity in California (Bergh and Lahav, 1996). 1.2. STUDIES IN VIETNAM 1.2.1. History, distribution, and actual state of avocado development in Vietnam From the stored documents of the USDA/ARS, the avocado variety of Florida (U.S.A.) was brought to Vietnam before 1933 in Quang Tri, the name of this variety was Pollock, but there were not any documents confirming this event in Vietnam. According to some documents in Vietnam, avocado trees were planted by French and showed abilities to grow well in the Di Linh (Lam Dong) from 1940s. In 1958, an aid delegation of United States brought around 60,000 avocado seeds belonging to 3 strains of Mexico, Guatemala and West India, and planted in Lam Dong – Bao Loc Experimental Center, Hung Loc – Dong Nai Experimental Center and Eakmat-Dak Lak Experimental Center. From these variety corporations, there were comments, initial assessments of growth and yield, as well as a description of fruit characteristics. After the complete liberation of the South in 1976, Fruit-tree variety station in Cao Loc - Lang Son 7 planted for tests of the avocado variety corporation imported from Cuba. The results showed that the avocado trees grew well, yielded quite and had year by year fruiting phenomenon (Phan Quoc Sung, 1986; Trinh Duc Minh and et al., 2005). For the areas with an elevation over 500 m in the Western Highlands, this is an advantage of avocado tree for good growth, quite yield and some trees with the quite tasty quality, which are considered as the region's special crop. Avocado trees, however, have not been developed by a number of limitations. In addition to obstacles such as avocado trees planted by seeds, no selection, strong separation or poor cultivation techniques, which leaded to low yield and poor quality, one of the important elements was the market price affecting products. With the characteristics of the sudden respiratory avocado fruits, fresh consumption and hard storage, so if the ripe time focuses on a given time, it will make the problems of difficult consumptions and low prices. CHAPTER 2 MATERIAL, CONTENT AND RESEARCH METHODOLOGY 2.1. RESEARCH MATERIAL - 26 avocado varieties were locally selected, and 12 avocado varieties were imported from America, which were grown in the corporative garden and the experiments in Dak Lak, Gia Lai, Lam Dong, 2002. - 12 promising avocado varieties TA1, TA2, TA3, TA4, TA5, TA31, TA44, TA47, TA50, TA54, Booth 7 and Hass were planted in Dak Lak, Gia Lai, Lam Dong provinces, 2007. - Variety material: Varieties were grown in the experiments and the corporative garden by grafting them on the stumps of variety TA44. 2.2. RESEARCH CONTENT 2.2.1. Study on some bio-agricultural characteristics of local selected avocado varieties and new imported varieties in Dak Lak - Location: Corporative garden and the comparative experiments of avocado varieties at Western Highlands Agriculturure and Forestry Science Institute. - Scale and planting years: a total of 4 ha, of which 2 ha for corporative garden grown in 2003 and 2 ha for the experimental garden of promising avocado variety comparison, 2007. - Study period: from 2011-2014. 2.2.2 Comparative and evaluative studies on some promising avocado varieties at the ecological regions in the Western Highlands - Location: Comparative and evaluative experiments of avocado varieties at 3 major growing regions in Dak Lak, Gia Lai and Lam Dong provinces. - Scale and planting year: 6 hectares grown in 2008, in which 2 ha for each province. - Study period: from 2010-2014. - Experimental varieties: composed of 12 varieties: TA1, TA2, TA3, TA4, TA5, TA31, TA44, TA47, TA50, TA54, Booth 7 and Hass. 8 2.2.3. Study on determination of harvest time of some promising avocado varieties in Dak Lak - Location: Corporative garden and the comparative experiments of avocado varieties at Western Highlands Agriculturure and Forestry Science Institute. - Scale and planting years: a total of 4 ha, of which 2 ha for corporative garden grown in 2003 and 2 ha for the experimental garden of promising avocado variety comparison in 2007. - Study period: from 2011-2014. - Experimental varieties: 9 avocado varieties: TA1, TA4, TA5, TA17, TA21, TA40, Booth 7, Fuerte and Reed. 2.3. RESEARCH METHODOLOGY 2.3.1. Study on some bio-agricultural characteristics of local selected avocado varieties and new imported varieties in Dak Lak - Analysis of genetic characteristics of autosomal phenotype according to IPGRI's methods, 1995. Polymorphic properties (Polymorphous) of avocado varieties, including canopy shape, canopy size, number of branches at levels 1, 2 and 3, the ability to branch, dwarf, high and medium canopy forms, etc.). - Study on the flowering and fruiting characteristics of varieties according to the method for comparing the phase differences between groups A and B (Bergh, 1969). - Total number of experiment plants: 38 varieties x 10 plants/variety = 380 plants. 2.3.2. Comparative and evaluative studies on some promising avocado varieties at the ecological regions in the Western Highlands - Designed experiments to compare varieties based on biology characteristics of avocado trees by the method of Razeto et al., 1994. - Planting density was 210 plants/ha, and planting distance was 7 m x 7 m - Experimental design according to RCBD (Randomized Complete Block Design), 1 element and 3 replications. -Total experiment area: 6 ha (in Dak Lak, Gia Lai and Lam Dong provinces, 2 ha for each province). Total experiment plants: 12 varieties x 3 locations x 3 replications x 12 plants/variety = 1,296 plants. - Determination of fruit weight and yield of avocado varieties: Each variety was collected for 10 fruits and calculated for average fruit weight; Assessment of yield by counting the number of fruit/plant and multiplying it by the average fruit weight. - Selection criteria: builded on the basis of summarized references of standards in the market, UNECE STANDARD FFV-42 trade and the Codex standard for Avocado-Codex stan 197-1995 of the world and Europe CX/FFV 11/16/5. For plants: plant age is  7 years, yield is  50 kg of fruits/plant/year, good growth and development, less pests and serious diseases. For fruits: fruit weight is  300 g, the fruit is round to oval and is easy to pack. The thick shell is  1 mm and is easy to peel. The dry matter content is  19%, meat ratio is  65%, color is yellow to dark yellow, flesh is little or no fiber, and fat content is  13%. Beads are snugly closed into the flesh of the fruit, but husk are not attached into flesh and easily split when ripe. 9 - Determination of some main pest and disease species on the promising avocado varieties in the Western Highlands. For pests: collect mature pest and bring them to the room to describe colors and measure the size of the pests. Combination with some documents is used for describing the morphological characteristics of pests to determine pest species. For diseases: collect disease samples and bring them to the lab to isolate and identify pathogens. 2.3.3. Study on determination of harvest time of some promising avocado varieties in Dak Lak - Subject was conducted by experiments on the determination of the harvest time on 6 promising avocado varieties selected in our country: TA1, TA4, TA5, TA17, TA21, TA40 and 3 imported varieties: Booth 7, Fuerte and Reed. - Experimental methods: mark plants, braches and fruits to observe, hang tags and note flowering and fruiting dates on each variety. The fruiting time was determined when the fruits had a diameter from 0.5-1 cm. - Harvest time observation: after flowering and fruiting for 4 months, we observed the dry matter percentage in the fruits as following: 20 days for each sample collection times, 5 fruits for each times (four fruits at 4 directions outside and 1 fruit inside the plant canopy) then proceeded to determine the rate of dry matter in the fruit. DIAGRAM OF AVOCADO VARIETY SELECTION IN THE WESTERN HIGHLANDS Evaluate 26 strains and varieties collected in the Western Highlands and 12 imported varieties in the corperative garden in Dak Lak (2002-2014) Test, compare and evaluate 12 promising avocado varieties in the different ecological regions in the Western Highlands (2006-2014) Select 8 promising avocado varieties TA1, TA3, TA5 TA6 TA17, TA40, Booth 7 and Reed (2010) Recognize 4 varieties TA1, TA3, TA5 and Booth 7 (2011) CHAPTER 3 RESULTS AND DISSCUSIONS 3.1. STUDY ON SOME BIO-AGRICULTURAL CHARACTERISTICS OF LOCAL SELECTED AVOCADO VARIETIES AND NEW IMPORTED VARIETIES IN DAK LAK 3.1.1. Morphological characteristics of avocado varieties at the 10th age (2013) 10 Table 3.1. Canopy shape, thickness and diameter of avocado varieties (2013) Canopy Order Variety Canopy shape and thickness diameter (m) 1 TA1 5.00 Medium canopy, flattened circular, weak tree 2 TA2 5.80 Thin canopy, cylinder, weak tree 3 TA3 5.40 Thin canopy, flattened circular, weak tree 4 TA4 6.50 Medium canopy, flattened circular, healthy tree 5 TA5 8.00 Thick canopy, cylinder, healthy tree 6 TA6 9.00 Thin canopy, pyramid, healthy tree 7 TA7 5.50 Medium canopy, flattened circular 8 TA8 7.30 Thin canopy, flattened circular, healthy tree 9 TA9 4.00 Thick canopy, pyramid, health 10 TA16 5.50 Thin canopy, cylinder, weak tree 11 TA17 7.30 Thick canopy, flattened circular 12 TA19 6.20 Medium canopy, pyramid, healthy tree 13 TA20 8.00 Thick canopy, pyramid, healthy tree 14 TA21 8.00 Thin canopy, pyramid, weak tree 15 TA26 6.30 Thick canopy, flattened circular, weak tree 16 TA31 5.90 Medium canopy, flattened circular, cây khỏe 17 TA36 7.30 Thin canopy, flattened circular, weak tree 18 TA37 6.70 Thin canopy, flattened circular, weak tree 19 TA39 6.50 Thick canopy, pyramid, healthy tree 20 TA40 6.40 Thin canopy, pyramid, weak tree 21 TA44 5.00 Thick canopy, flattened circular, healthy tree 22 TA45 6.30 Thin canopy, flattened circular, weak tree 23 TA47 5.50 Thick canopy, pyramid, healthy tree 24 TA48 5.60 Thick canopy, pyramid, healthy tree 25 TA50 7.10 Thick canopy, flattened circular, healthy tree 26 TA54 5.90 Thick canopy, flattened circular, healthy tree 27 Số 5 5.50 Thin canopy, pyramid, weak tree 28 Booth 7 8.00 Medium canopy, cylinder 29 Hass 6.00 Thick canopy, flattened circular, weak tree 30 Tiger 9.00 Thick canopy, pyramid, weak tree 31 Ardith 6.20 Thin canopy, pyramid, weak tree 32 Reed 5.50 Thin canopy, cylinder, healthy tree 33 Edtinger 6.30 Thin canopy, cylinder, healthy tree 34 Fuerte 6.00 Thin canopy, cylinder, weak tree 35 Sharwill 6.30 Thick canopy, flattened circular, healthy tree 36 GA 4.20 Thin canopy, cylinder, weak tree 37 GB 5.20 Thin canopy, pyramid, healthy tree 38 GC 5.60 Thick canopy, flat, healthy tree Trung bình 6.31 CV(%) 18.44 11 The process of monitoring and evaluation of avocado varieties in the garden showed that the largest canopy diameter reached 9 m, and the smallest one reached 4 m. Overall, the varieties could develope good canopy with 6.31 m in average; however, there were big differences among varieties in statistic analysis for very high coefficient of variation around 18%, which proved these differences. In experimental conditions at some provinces in the Western Highlands, the varieties are planted on fertile bazan red soil areas having high fertile levels above 4.5%, the average rainfall for years over 1,800 mm and the average temperature around 220C, which are suitable for development of avocado varieties, particularly the varieties imported from American had very strong growth around double times compared to places planting the native varieties. However, most varieties which developed too strongly will result in low yield due to the ability to take in pollens limited by the too thick canopy. Commonly in many regions belonging to the tropical monsoon climate countries because of high temperatures and heavy rain, avocado varieties strongly developed on the branches and twigs longer than the countries that carry the characteristics of tropical Asia and cold climate. 3.1.2. Growth and development of avocado varieties at the 10th age (2013) Table 3.4. Growth and development of avocado varieties Order Variety Stem diameter (m) Plant height (m) Flower group 1 TA1 0.29 5.80 A B 2 TA2 0.24 5.50 A 3 TA3 0.20 4.50 4 TA4 0.27 4.70 A 5 TA5 0.36 7.20 B 6 TA6 0.34 5.50 B 7 TA7 0.25 4.00 A 8 TA8 0.39 5.70 B 9 TA9 0.29 4.80 A 10 TA16 0.23 5.30 A 11 TA17 0.27 6.40 A 12 TA19 0.28 5.60 A 13 TA20 0.32 6.20 B 14 TA21 0.33 5.80 B 15 TA26 0.33 5.10 B 16 TA31 0.39 5.90 A 17 TA36 0.27 5.70 B 18 TA37 0.30 6.00 B 19 TA39 0.25 4.60 A 20 TA40 0.24 5.80 B 21 TA44 0.20 5.50 A 22 TA45 0.38 5.60 A 23 TA47 0.23 4.40 A 24 TA48 0.34 6.00 A 25 TA50 0.28 6.54 B 12 Order 26 27 28 29 30 31 32 33 34 35 36 37 38 Variety Stem diameter (m) Plant height (m) Flower group TA54 0.25 6.78 B So 5 0.24 5.10 B Booth 7 0.30 6.20 B Hass 0.28 5.80 A Tiger 0.40 5.80 B Ardith 0.26 6.00 A Reed 0.33 6.00 A Ettinger 0.29 5.60 B Fuerte 0.25 5.70 B Sharwill 0.30 4.00 B GA 0.38 4.60 A GB 0.33 4.00 B GC 0.24 3.40 A Mean 0.29 5.45 CV (%) 18.44 15.25 For the stem diameter growth, the varieties had an average diameter of 0.29 m, and the tree had the largest stem diameter of 0.40 m and the smallest one of 0.20 m. Statistical analysis showed the quite high coefficient of variation around 18%. This proved that there was a great difference in terms of the level of growth in the diameter and the uneven growth. Similarly, the ability to grow in the plant height also showed that there were huge differences among varieties in the garden with a rather large fluctuation about 15%. The greatest plant height of the varieties reached over 7 m, reflecting the advantage of height, and the lowest plant height was 3.40 m. In terms of cultivation, the characteristic of the plant height could decide to intensive forms or different intercropping. The TA1, TA20, TA21, TA17, TA5, TA31, TA40, TA48, TA50, TA54, Booth 7, Reed and GA with strong growth speeds proved advantages of these varieties in terms of ecological conditions of Dak Lak. However, variety selection responding for export goals depends on a lot of the more important factors such as yield and quality of the variety. Botanical characteristics of 2 flower groups A and B have been very thoroughly studied by many scientists around the world and proven in both groups on all avocado varieties carrying hermaphrodite without separation of male and female flowers. There are parallel stamens and pistils formed in the same flower; however the structure of these 2 flower groups is very different, and there is only a single flower group A or B. Observation of the structure of 2 flower groups showed that flower group A had 6 stamens surrounding high and vertical distribution equal to the top of pistils, and the anthers cluster inside. Varieties having this flower group can pollinate themselves, but the average rate was very low only 0.47%; in contrast, the flower group B have 6 stamens dumped about two parties outside the pistils, for what varieties having this flower group cannot pollinate. This proved that the avocado trees are species required by the cross pollen exchanges. The exchange of pollen between 13 two flower groups is especially meaningful in improving varieties, reducing the ability to variety degeneration due to pollination in the same flower group. Structure of flower group A and B of avocado tree Flower group A Flower group B 3.2. COMPARATIVE AND EVALUATIVE STUDIES ON SOME PROMISING AVOCADO VARIETIES AT THE ECOLOGICAL REGIONS IN THE WESTERN HIGHLANDS Comparative experiments were conducted to evaluate 12 avocado varieties grown from 2007 in 3 ecological regions of Dak Lak, Gia Lai and Lam Dong. The subject had been conductive in observating and evaluating for many years, and the updated data were collected in the dissertation in the years from 2010-2013. However, in this report, the data were only analyzed focusing on the nearest year 2013, and the data of the previous years were put into the annexes at the tables and 3.18.1, 3.18.2 and 3.18.3 in this report. The data analyzed here will prove the adaptability of each variety at three experimental places in Buon Ma Thuot- Dak Lak, PleiKu - Gia Lai and Bao Loc - Lam Dong. 3.2.1. Growth and development of the avocado varieties at the 7th age in some ecological areas in the Western Highlands (2013) Table 3.20. Growth and development of avocado varieties at the seventh age Province Dak Lak Gia Lai Lam Dong SD PH CD SD PH CD SD PH CD Variety (m) (m) (m) (m) (m) (m) (m) (m) (m) TA1 0.25 6.18 5.05 0.16 4.99 3.43 0.17 3.60 4.83 TA2 0.24 6.14 6.16 0.17 5.03 4.62 0.24 3.72 4.49 TA3 0.26 5.50 6.11 0.11 3.20 3.39 0.26 3.89 4.84 TA4 0.21 5.49 5.61 0.14 4.38 4.39 0.19 3.58 4.72 TA5 0.29 6.68 7.21 0.15 4.11 4.00 0.18 3.93 4.74 TA31 0.24 5.25 5.64 0.13 4.13 3.86 0.04 1.82 1.51 TA44 0.24 5.71 6.86 0.15 4.25 4.27 0.06 2.17 2.03 TA47 0.21 5.62 5.77 0.14 4.27 4.15 0.07 2.71 2.34 14 TA50 0.28 6.54 7.12 0.16 5.18 4.48 0.07 2.58 1.51 TA54 0.25 6.77 5.88 0.16 5.19 3.67 0.07 2.58 1.83 Booth 7 0.26 5.40 5.60 0.13 3.72 3.67 0.25 3.69 4.93 Hass 0.26 5.62 5.31 0.13 3.41 2.80 0.22 3.52 3.61 Mean 0.25 5.91 6.03 0.14 4.32 3.89 0.15 3.15 3.45 CV (%) 9.60 8.99 11.60 12.00 15.57 13.64 55.30 23.20 42.67 LSD0,05 0.51 0.74 0.85 0.32 0.56 0.55 0.47 0.90 0.98 Note SD: Stem diameter; PH: Plant height; CD: Canopy diameter Avocado varieties at the 7th age in ecological condition in the Dak Lak showed that 2 monitored targets of stem diameter and plant height had very small coefficient of variances only about 8-9% and demonstrated that the varieties could grow and develop quite evenly, and also clearly showed relative adaptability of the varieties with the ecological conditions in Dak Lak. The varieties reached 0.25 m in the average stem diameter and 5.91 m in average plant height, and varieties selected in the domestic country had growth speeds and development quite evenly. Similarly, 2 imported varieties equally grew and developed over 0.26 m in stem diameter and 5.40 m in plant height. Another very important norm that influences elements to constitute yield is the canopy diameter. Overall, the varieties had rather good development levels of canopy with an average canopy diameter of 6.03 m; variety TA5 had the strongest canopy development for 7.21 m and variety TA1 had a weaker canopy development just 5.04 m. Coefficient of variation around 11% showed that developments of canopies were fairly uniforms among varieties. To the ecological conditions in the Gia Lai, in overall, growth and development speeds of varieties were in good levels, manifesting themselves in the growth of stem diameter at 0.15 m. Booth 7 and TA3 had the smallest stem diameter at 0.12 m, and TA1 and TA2 had the greatest stem diameters over 0.18 m. Average plant height was 4.33 m in which variety Hass had the lowest plant height at 3.38 m, and variety TA54 had the biggest plant height at 5.24 m. Likewise the average canopy diameter of varieties was 3.94 m, Hass had the weakest level of canopy development at 2.83 m, and TA2 developed the strongest canopy at 4.81 m. Statistical analysis showed; in all monitored targets, stem diameter, tree height and canopy diameter within low coefficient of variation below 15% demonstrated differences but not significant in the monitored targets. To the ecological conditions in Bao Loc - Lam Dong, the varieties grew and developed at an average rate somewhat demonstrated that most of the varieties had good adaptabilities. The varieties had 0.15 m in the average stem diameter, 3.15 m in the plant height, and 3.45 m in the canopy diameter. For statistical analysis, all monitored targets within very high levels of coefficient of variation over 23% and other different values were greater than the theory, showing significant differences among varieties on their ability to grow, develop and adapt to the ecological conditions among regions. 3.2.2. Flowering and fruiting characteristics and harvest time of avocado varieties 15 Table 3.19. Flowering and fruiting characteristics and harvest time Flower Flowering and fruiting Order Variety Harvest time group period 1 TA1 A January - March July - September 2 TA2 B December - February July - August 3 TA3 A January - March August - September 4 TA4 A January - February June - August 5 TA5 B March - April September - October 6 TA31 A February - April September - October 7 TA44 A February - April September - October 8 TA47 A January - February July - August 9 TA50 B December - January June - August 10 TA54 A January - March June - August 11 Booth 7 B January - March October - November 12 Hass A January - March August - October Observation process showed that there are 8 varieties belonging to group A: TA1, TA3, TA4, TA31, TA44, TA47, TA54 and Hass, and the rest varieties belong to group B. Harvest time lasts from 2 to 3 months. 7 late harvest varieties are TA1, TA3, TA5, TA31, TA44, Booth 7 and Hass in August to November, and the rest varieties have the main crop harvest time around June to August. For all three experimental areas, there are cool air temperature ranged from 22-230C and the changes of the high night-day temperatures, which are very suitable for uniform flower sprouts in bulks. Particularly during the period from December to February, most avocado varieties began the sexual releasing period. 3.2.3. Yields of avocado varieties at the 7th age in the ecological regions in the Western Highlands (2013) Table 3.20. Yields of avocado varieties at the seventh age (kg/tree) Province Order Variety Dak Lak Gia Lai Lam Dong 1 TA1 17.33 18.60 21.90 2 TA2 107.97 31.70 21.10 3 TA3 12.31 9.00 57.70 4 TA4 56.53 27.30 57.90 5 TA5 32.44 0.00 78.10 6 TA31 40.95 0.00 0.00 7 TA44 25.97 6.80 0.00 8 TA47 85.80 18.00 0.00 9 TA50 25.60 20.60 0.00 10 TA54 67.00 0.00 0.00 11 Booth 7 66.69 0.00 88.40 12 Hass 16.28 6.60 20.20 Mean 46.24 17.33 49.33 CV (%) 66.08 54.06 57.91 LSD0,05 26.81 10.02 26.74 16 In experimental areas, most of the 7th age varieties only reached yields in average levels. In ecological conditions in Buon Ma Thuot - Dak Lak, all varieties showing uniform fruits with superior yield compared to other regions with an average yield of 46.24 kg/tree demonstrated good adaptability of the varieties with ecological condition in Buon Ma Thuot - Dak Lak. Meanwhile, 7 varieties gave an average yield of 49.33 kg/tree in Lam Dong, and the remaining varieties TA31, TA44, TA47, TA54 and TA50 had not fruits due to the ability to receive the very poor pollen of those varieties in the climatic conditions of Bao Loc - Lam Dong where extremely low air temperatures under 150C during flowering periods from December to March each year. Similarly varieties TA5, TA31, TA54 and Booth 7 grown in the ecological condition in PleiKu - Gia Lai had not any fruit, the remaining varieties had the lowest average yield of 17.33 kg/tree, and 8 varieties had fruits. In all three research areas, 4 varieties TA2, TA47, TA54 and Booth 7 gave the highest yields and relative stability, and initially showed the potential yield of those varieties. In particular, variety TA2 had very high average yield over 100 kg/tree in ecological conditions in Buon Ma Thuot - Dak Lak. Differences in ability to fruit in different varieties are very crisp and significant due to the coefficient of variation and the great different values compared to theory, which proved this element. Table 3.21. Yield of avocado varieties through the years from 2010-2013 in Buon Ma Thuot - Dak Lak (kg/tree) Yield Variety Mean CV (%) 2010 2011 2012 2013 TA1 26.30 6.05 17.33 21.50 17.80 48.58 TA2 35.00 66.56 107.97 78.60 72.03 41.92 TA3 25.50 27.35 12.31 21.70 21.72 30.84 TA4 58.60 41.11 56.53 60.00 54.06 16.19 TA5 31.70 78.26 32.44 20.00 40.60 63.41 TA31 40.70 13.18 40.95 30.00 31.21 41.84 TA44 55.20 16.38 25.97 5.00 25.64 83.83 TA47 55.80 60.28 85.80 120.00 80.47 36.64 TA50 33.40 25.60 25.60 0.00 21.15 68.90 TA54 9.10 67.00 67.00 4.60 36.93 94.18 Booth 7 91.00 87.53 66.69 86.30 82.88 13.24 Hass 1.40 11.86 16.28 10.00 9.89 63.12 LSD0,05 2.22 2.85 3.61 6.01 Table 3.22. Yield of avocado varieties through the years from 2010-2013 in Pleiku - Gia Lai (kg/tree) In Buon Ma Thuot - Dak Lak, continuous yield statistics for 4 years showed that the year by year flowering status occured in most varieties and was partly influenced by erratic changes of the climatic conditions in recent years in Daklak. Especially during flowering and fruiting period, the humidity under 50% made deformitied pollens, strong winds and drought causing low fruiting rates as well as high fruit falling rates due to lack of water. Out of 12 variety experiments, there were 4 varieties TA2, TA4, TA47 and Booth 7 tending to increase yield over the age of the 17 tree, and the fluctuations below 15% showed stability in yields of those varieties. In particular, varieties TA47 and Booth 7 had high and stable yield about 80 kg/tree/year. Varieties TA3, TA4, Booth 7 and Hass had low yield changes from ± 6 to ± 10 kg/tree/year. The value from statistical analysis was more different than the theory, showing the significant differences in the yields of the cultivated varieties in Dak Lak. Those were the source of the promising materials serving effectively in further practice and research. Yield Năng suất (kg/tree) (kg/cây) Picture 3.2. Yield change of avocado varieties over the years in Dak Lak Figure 3.2. Pronounced fluctuations in the yield of the varieties taking part in experiments. Year Variety Mean CV (%) 2010 2011 2012 2013 TA1 12.20 10.00 18.60 4.50 11.33 51.49 TA2 0.00 26.50 31.70 5.00 15.80 98.97 TA3 15.60 0.00 9.00 3.30 6.98 98.17 TA4 34.90 20.00 27.30 6.88 22.27 53.56 TA5 11.70 0.00 0.00 0.00 2.93 0.00 TA31 5.80 0.00 0.00 1.35 1.79 153.83 TA44 19.10 12.50 6.80 0.00 9.60 84.77 TA47 4.30 21.90 18.00 3.30 11.88 79.73 TA50 0.00 3.50 20.60 10.00 8.53 106.20 TA54 0.00 0.00 0.00 19.00 4.75 200.00 Booth 7 12.00 10.00 30.00 8.20 15.05 67.02 Hass 0.00 0.00 6.60 0.00 1.65 200.00 LSD0,05 1.86 1.64 3.34 1.82 18 At Pleiku - Gia Lai, generally the yields of the varieties were much lower than those in Buon Ma Thuot - Dak Lak. Varieties TA5, TA31, TA54 and Hass did not give yield in several years, particularly low average yield in 2013 from 2-22 kg/tree/year, and showed their poor adaptations to the climatic conditions in the region. Explanation for this cause can see on variety Hass belonging to Guatemalan strain originated from the regions of tropical Asia with more cold temperatures than all other experiments on research places. According to many studies in the world, variety Hass could split flower sprouts at 170C at night and about 250C during the daytime, while Gia Lai had a higher temperature than that of requirements of the variety. In contrast, varieties TA1, TA2, as TA4, TA47 and Booth 7 tended to the highest and stable average yield over 11 kg/tree/year clearly showed ability to adapt well to ecological conditions in the region. The yield fluctuations of the varieties for many years were very high over 80%, showing the instability of the observed targets. The value from statistical analysis was more different than the theory, proving the differences in the yields of varieties grown in Gia Lai. Figure 3.3 will demonstrate those fluctuations. Varieties Yield (kg/tree) Picture 3.3. Yield change of avocado varieties by years in Gia Lai Table 3.23. Yield of Avocado varieties through the years from 2010-2013 in Bao Loc - Lam Dong (kg/tree) Year Variety Mean CV (%) 2010 2011 2012 2013 TA1 24.00 31.20 21.90 14.10 22.80 30.86 TA2 30.00 25.50 21.10 15.60 23.05 26.70 TA3 39.20 48.50 57.70 12.20 39.40 49.86 TA4 30.50 30.50 57.90 18.60 34.38 48.45 TA5 22.90 44.50 78.10 6.70 38.05 0.00 TA31 0.00 0.00 0.00 0.00 0.00 0.00 TA44 0.00 0.00 0.00 0.00 0.00 0.00
- Xem thêm -