Survey, collection and characterization of indigenous and non-indigenous cucurbits in Vietnam Dissertation zur Erlangung des akademischen Grades Doctor rerum agriculturarum (Dr. rer. agr.) eingereicht an der Lebenswissenschaftlichen Fakultät der Humboldt-Universität zu Berlin von M.Sc. Nien Chau Nguyen Präsident der Humboldt-Universität zu Berlin Prof. Dr. Jan-Hendrik Olbertz Dekan der Lebenswissenschaftlichen Fakultät Prof. Dr. R. Lucius Gutachter: Prof. Dr. sc. Dr. h. c. mult. Michael Böhme Dr. Narinder Dhillon Dr. Ulrike Lohwasser Tag der mündlichen Prüfung: 30.06.2016 Acknowledgements Acknowledgements I would like to express my great appreciation to my supervisors, Professor Dr. Michael Böhme and Dr. Ina Pinker for their supervisions during my study. The important advices, valuable comments, suggestions, and corrections from my two supervisors were very helpful in order to finalize this dissertation. I am greatly indebted to all staff members of the research greenhouse of Humboldt- Universität zu Berlin in Berlin-Dahlem, for their great help in running and facilitating my experiments. Thanks to my wife, Le Thi Tram Anh, for her love, support, and encouragement, especially her assistance in the field experiments for morphological characterization of cucurbit accessions. I am grateful my parents, sisters, and brothers for taking care of my two sons during the time I am away from home. I thank Dr. Thai Dan Vo and MSc. Huu Nguyen Pham, team leaders of the project “Land use planning for safe vegetables cultivation in Ben Tre province” for their cooperation in survey in vegetable cultivation. My thanks are addressed to Professor Tuan Van Nguyen for his online lectures “Using R in statistical analysis” and “Scientific writing skill”. My friends, Dr. Tien Long Nguyen and Dr. Quoc Phoi Dam, and others, who had come and studied together in Humboldt University of Berlin, are acknowledged for their help and moral support during my study. I am grateful for the financial support for the PhD study from Ministry of Education and Training (MoET) of Vietnam and German Academic Exchange Service (DAAD). Furthermore for the support of the German language course. In addition, I would like to thank for the support of Thuan Hung Seed Co. for seedbanks storage and field experiments. Chau Nien Nguyen iii Abstract Abstract The plant family Cucurbitaceae is highly diverse and comprises about 118 genera and 825 species. Many of these species with its cultivars and landraces are of economic importance because they are used as vegetables and medicinal crops. Some species belonging to the Cucurbitaceae are indigenous, but many of the non-indigenous ones are also well adapted to different geographical regions in Vietnam. The study was focused on four main aims: 1) To analyse the importance of cucurbits in vegetable growing farms and its utilization in southern Vietnam, 2) To collect cucurbit germplasm; 3) To characterize the collected cucurbit germplasm, 4) To determine the stable characteristics for classifying bitter gourd accessions. Considering the aims, following methodologies were used: A survey was carried out in rural areas in those regions where vegetable cultivation is the main agricultural sector. Eight districts with 20 communes were selected for the study. In the survey 1,009 growers were interviewed randomly following the criteria: (1) grower had at least five years of experience for cultivating commercial vegetables, (2) the area used for cultivating vegetable crops was minimum 500m2 per farm, and (3) farmers had cultivated vegetable in previous three crops. Number of cultivated vegetable species, area of cultivation, frequency of growing, and purpose of cultivation were analysed. In the past collection and conservation of cucurbits was done under guidance of AVRDC and VASI mainly in northern Vietnam. Therefore, this study conducted the cucurbit collection in southern Vietnam; 160 accessions of five species including cucumber (Cucumis sativus), pumpkin (Cucurbita moschata), bottle gourd (Lagenaria siceraria), loofah (Luffa cylindrica), and bitter gourd (Momordica charantia) of the collected cucurbit germplasm were analysed based on morphological characteristics. The examined characteristics were grouped into two types of variables, continuous variables (quantitative characteristics) and categorical variables (involving qualitative, pseudo-qualitative and some quantitative characteristics). Calculating the eigenvectors and creating 3D bi-plots enabled us to differentiate clearly the accessions that were collected in different regions. UPGMA (un-weighted pair group method using arithmetic averages) method was used to clarify the diversity of the accessions belonging the five mentioned cucurbit species. Moreover, there were 16 continuous variables and 12 categorical variables of seven bitter gourd accessions evaluated for its stability in two iv Abstract different growing conditions, greenhouse and field. Two-sample test, correlation test, and UPGMA method were used to determine the stable variables within two growing conditions. In result of this study, nine cucurbit species were determined, counting for 16.4% of in total 55 vegetable species cultivated for commercial market whereas more than 45% farmers produced cucurbits. Land used for cultivating cucurbits covered 56.5% of total area of vegetable cultivation. Correlations were calculated between ratios of cucurbit species cultivated and farmers’ characteristics including age of farmers, education levels (grades), members in households (people), and vegetable cultivated areas (m2 per farm). Causes affecting the decision for choosing cucurbits as main crops in vegetable cultivation could be determined, in particular factors as the field size, year round cultivation and way of its utilization. During the studies, 244 accessions from 14 cucurbit species belonging to 12 Cucurbitaceae genera were collected in 24 provinces in southern Vietnam. The accessions were classified in 14 species and one subspecies belonging to 12 genera. The species diversity (H) and evenness (E) indices of the collection were 2.2 and 0.51, respectively. The combination of two methods, 3D bi-plots and UPGMA, for evaluating the diversity of the accessions within species was favourable if the accessions had special characteristics, such as TiGi02 and TiGi03 of cucumber (Cucumis sativus), BaLi01 of pumpkin (Cucurbita moschata), NiTh03 of bottle gourd (Lagenaria siceraria), CaTh01 and HcmC03 of loofah (Luffa cylindrica), and HcmC01 and QuNa01 of bitter gourd (Momordica charantia). The evaluated characteristics provided essential information for understanding the diversity of the accessions that were collected in different regions. Diversity of plant phenotypes is a result of interaction between genetic factors and environmental ones. The presented data suggested that 12 characteristics were useful for evaluating relationships among accessions of bitter gourd (Momordica charantia) as follows: (i) number of leaf lobes, (ii) colour of fruit skin at ripe stage, (iii) present of ridge on fruit, (iv) present of fruit spines, (v) size of fruit warts, (vi) indentation of seed edge, (vii) striation of seed coat, (viii) number of nodes up to node with the 1st male flower, (ix) time of first male flower flowering, (x) fruit length, (xi) fruit weight, and (xii) weight of 100 seeds. Genetic relationships among accessions within species were dependent on the stability of characteristics used for hierarchical clustering. Therefore, determining the stable characteristics was necessary for cluster analysis the accessions within the species. Finally, the thesis provides structured information about the importance of cucurbit species for vegetable cultivation in southern Vietnam; the morphological diversity within the most important species; and the morphological characteristics that can be used for v Abstract determination of the relationships among accessions within bitter gourd. By this, a contribution for establishment a database and seed collection useful for breeding, genetics, and conservation is given. Mapping the diversity of cucurbits according to regions, and based on this planning a strategy for the further collection, conservation, and utilization of cucurbits in Vietnam should be continued. Keywords: cucurbits, accessions, morphological characterization, stable characteristics. vi Zusammenfassung Zusammenfassung Die Familie der Cucurbitaceae ist sehr divers es gehören etwa 118 Gattungen mit 825 Arten zu dieser Familie. Viele dieser Arten mit ihren Sorten und Landsorten haben ökonomische Bedeutung als Gemüse oder Arzneipflanzen. Einige Arten sind indigen, aber auch viele der nicht indigenen Arten sind gut adaptiert in verschiedenen geografischen Regionen Vietnams. Die Untersuchungen hatten vier Hauptziele: 1) Analyse der Bedeutung von Cucurbitaceen in Gemüse anbauenden Landwirtschaftsbetrieben und ihre Verwendung im südlichen Vietnam, 2) Sammlung von Keimplasma der Cucurbitaceen, 3) Morphologische Charakterizierung das gesammelte Keimplasmas, 4) Ermittlung der stabilen morphologischen Charakteristiken um Bitterkürbis Akzessionen zu klassifizieren. Dazu wurde eine Befragung von Farmern in Gemeinden im Mekong Delta, in welchen die Gemüseproduktion der wichtigste landwirtschaftliche Sektor ist, durchgeführt. Acht Distrikte mit 20 Kommunen wurden für die Studie ausgewählt. 1009 Farmer wurden befragt, wobei die Auswahl stichprobenartig auf der Grundlage folgender Kriterien erfolgte: (1) der Farmer hatte mindesten 5 Jahre Erfahrung