Abstract:
Indian spinach is an underutilized and underexploited tropical leafy vegetable widely adapted to a variety of soils and climates. Its medicinal and nutritional qualities obviously make it a promising crop for food security in Africa. It exhibits high genetic diversity in its present under-exploited state; therefore, accurate assessment of the existing genetic diversity will be fundamental to its improvement. This study investigated the genetic diversity among twenty (20) accessions of Indian spinach using morphological descriptors and molecular fingerprinting. The field experiments were carried out at the Vegetable Research Farm of National Horticultural Research Institute (NIHORT), Ibadan, Oyo State, Nigeria (Rain-forest zone) (30561E and 70331N 168 m above sea level) during rainy seasons of 2016 and 2017. The experimental design adopted was randomized complete block design (RCBD) with three replicates. The molecular study was carried out at the Bioscience Laboratory of International Institute of Tropical Agriculture (IITA), Ibadan, Nigeria. Data were collected on the vegetative characters, yield and yield related characters. The data were subjected to Analysis of Variance, Principal Component Analysis and Cluster analyses. The first three PCA axes observed for year 2016 and 2017 explained 64.66% and 59.99% respectively of the total variation. The clustering method evolved groups of accessions based on similarities of morphological traits and PCR based molecular makers Random Amplified Polymorphic DNA (RAPD) were able to group the accessions into distinct clusters independent of locality of collections. Heritability estimate above 50% was observed for internode length (66.51%), stem weight (54.55%), leaf weight (72.91%), and total plant weight (58.11%). Yield and yield related characters were highly and positively correlated with one another. Stem weight was positively correlated with leaf weight and total plant weight. Likewise, positive correlation existed between leaf weight and total plant weight. Though Analysis of Variance of ten selected accessions based on yield performance to determine the best forms of propagation revealed no significant differences in yield performance, stem cuttings were found to regrow faster than seeds emergence. Genetic variability existed among the twenty accessions considered in the study although not wide and the reason could be established from an additional study carried out on the floral biology which revealed that Indian spinach exhibits self-fertilization in a permanently closed flower.
