ABSTRACT
Twenty one provenances of Jatropha curcas L. collected from seven states of the Northwestern Nigeria and established in a provenance trial at the Institute for Agricultural Research farm, Samaru, Ahmadu Bello University, Zaria, Nigeria were evaluated using Principal Component Analysis (PCA), Rank Summation Index (RSI) and Genetic Distance (GD) to analyze their pattern of variation, identify the major traits responsible for their variation and suggest appropriate breeding materials to improve the crop. Ten plants were randomly selected in each provenance and evaluated for nine morphological traits and oil content. All the provenances showed highly significant variations except main stem height, which was significant at 0.05 level of probability. Mean performance showed significant differences for all traits with each trait exhibiting a considerable range. Higher genotypic than phenotypic variances were observed for plant height, number of branches on collar, number of lateral branches, number of capsules per lateral and oil content. However, these traits have low genotypic coefficients of variability indicating low range of genetic variation. High heritability estimates were observed for plant height, number of branches on collar, number of capsules per lateral branch and oil content. Three out of the ten principal components extracted had eigenvalues > 1 and altogether accounted for 77.07% of the total variability. Principal component 1 exhibited 34.77% while principal components 2 & 3 showed 24.48% and 17.83% variability, respectively among the provenances for the traits studied. From the associated eigenvectors, Principal Component 1 is associated with number of fruit bunch per lateral, number of capsules per bunch and number of capsules per lateral branch. Collar height, collar thickness and number of branches on collar were important for principal component 2. The third principal viii component however, was more related to plant height and main stem height. The PCA therefore, discriminated and separated the 21 provenances in terms of collar traits, bunch traits and height traits indicating them to be the major traits responsible for the variation in the Jatropha curcas L. provenances. Based on RSI, IARJAT200901, IARJAT2009039 and IARJAT2009036 obtained from Soba, Gwarzo and Ruwan Kanya provenances were the best materials in terms of plant height, number of lateral branches, number of fruit bunch per lateral branch, number of capsules per bunch and oil content. These accessions are therefore considered the best potential materials for the improvement of Jatropha curcas L. in Nigeria. However, considering the high GD between accessions IARJAT200901 and IARJAT2009039 obtained from Soba and Gwarzo provenances (9.15), and the result from PCA, a cross between the two accessions is recommended.