Agronomic Characterization of yam genotypes production

Abstract

Data from three agronomic traits were used to assess the genetic dissimilarity between 209 yam (Dioscorea sp.)genotypes. The data were analyzed using the method of nearest neighborand the technique of grouping throughanalysis of variances using the distance Mahalanobis generalized as dissimilarity measure. The genotypes tested were four distinct groups by grouping. The character width of tubercle contributed the most to thetotal genetic dissimilarity. The results allowed to discriminate genotypes that could be used in the genetic breeding programs for the species. Terms for indexing:Dioscorea spp., multivariate analysis, grouping methods I. Introduction Yam belongs to the family Dioscoreaceae and the genus Dioscorea, which has more than 600 species, 14 of which have their tubers used as food. The main species cultivated in Brazil are D. alata,with the types Cara Sao Tome e Principe, Cara Cassava, Cara Florida, followed by D. cayanensis, with various types such as Cara Tabica, Cara Negro, Cara Costa mainly planted in the region Reconcavo da Bahia, the third largest national producer (MESQUITA, 2001), as a promising alternative for the small and medium-sized producers of this State, due to its great potential for exporting and domestic consumption as high nutritional quality food. According to Scarcelliet. al.,(2006),yam is the second most importanttuber crop in Africa after cassava.Therefore, West African farmers produce more than 90% of the world's yams (FAOSTAT 2003). Yamis a tuberous species with high potential rich in vitamin B complex, (containing high levels of thiamine, riboflavin, niacin), vitamin A, ascorbic acid, carbohydrates and starch grains (responsible for high digestibility), constituting an essential foodfor the population, and may also be used in agribusiness (SANTOS et al. , 1998; SANTOS&MACEDO, 2002).Its spread is made of vegetative form, with tubers seeds cut into pieces of approximately 200 g, planted on ridgeswith 0.50 m of height and spacing of 1.20 m between ridges and 0.40 m between plants. The majority of producers in the region Reconcavo uses organic fertilizer in fertilizing the crop and the staking system in rods for the driving of the plants. In spite of the importance of culture for the agribusiness northeastern, your productivity(11,093 kg ha- 1 ) (SANTOS, 2006) is still low, due to the inadequate conditions of crop management, soil fertility, use of tubers seeds of lower quality and phytosanitary problems. In spite of Yam genotypes great plasticity and adaptability to tropical climates , it is necessary to characterize and assess them, using agronomic traits, in order to provide options of right attributes for the program to improve the species as well as preserve part of their variability ex situ. In these circumstances, multivariate techniques appear to beefficient in the description and selection of multiple characters simultaneously, thus saving time and financial resources (CRUZ, 1990). The data generated will be relevant in programs for identification of useful phenotypic characters, enabling the development of technologies and generation of basic knowledge for thesupport and operationof this crop and assist in genetic/breeding programs of the species. The objective of this study was to evaluate the yield and characterize the agronomic potential of yam genotypes from Reconcavo of Bahia.