Quantitative Relationship of Root, Shoot and Spike Components in Rainfed and Irrigated Castor (Ricinus communis L.)

A field study was conducted in castor (Ricinus communis L.) under Indo-US collaborative project during kharif season to assess the percentage reduction of root, shoot and spike components in castor under rainfed in relation to irrigated conditions. All the characters studied were grouped into three categories viz., those having i) low reduction (<5%); ii) moderate reduction (5–25%) and iii) high reduction (>25%). The results of the study indicated that all the phenological attributes, number of nodes, effective spike length (%) and oil content recorded a low reduction. All the primary spike components along with internodal length, stem height and diameter were found to have a moderate reduction. All the secondary and tertiary spike components along with the number of green leaves and total seed yield recorded a high reduction. All the root characters also registered a high reduction. The results revealed that the percentage reduction in yield was observed to be low in case of primaries as compared to the secondaries and tertiaries. Therefore, the emphasis on selection criteria should be made on the primary spike components in castor for improvement of moisture stress tolerance under rainfed conditions.