Short communication. Evaluation of castor (Ricinus communis L.) induced mutants for possible selection in the improvement of seed yield

Abstract

The aim of the present work was to determine selection criteria suitable for developing castor ideotypes with high yield potentials. Nineteen M4 generation castor mutants were obtained by gamma irradiation (100 to 1000 Gy) of DS30 castor seeds, and evaluated alongside this reference variety over 2006-07 for their possible use in the improvement of castor seed yield. Days to ripening, plant height, number of spikes/plant, length of main spike, number of main spike capsules, capsule weight, 100-seed weight and seed yield per plant were recorded for each mutant. Correlation coefficients were calculated, path analyses performed, and the genetic features of the different traits were determined. A significant, positive correlation was seen between capsule weight and seed yield. The 100-seed weight showed a positive but non-significant phenotypic relationship plus a significant genotypic relationship with seed yield. Capsule weight also showed a strong direct effect on seed yield, plus a strong positive and significant genotypic correlation with this variable. More than 50% heritability was observed for all the traits studied except the 100-seed weight and capsule weight. The number of main spike capsules showed the greatest genetic advance, followed by spike length and number of spikes. Traits such as the number of capsules, spike length and number of spikes showed strong heritability and good genetic advance. These traits are therefore governed by additive genes, and for the improvement of seed yield selection may be based directly on these attributes. In conclusion, for the improvement of seed yield the main emphasis should be placed on the number of spikes and capsule weight, via the selection of the highest yielding mutants among those tested. However, spike length and 100-seed weight should also be taken into account.