Influence of Node Number of Castor Hybrids on Seed Yield in Different Agroclimatic Conditions

Abstract

Castor is an important commercial, industrial and non-edible oilseed crop suitable for both rainfed and irrigated cultivation in tropical and sub-tropical climatic conditions. India is the leading producer (16.6 lakh tonnes from 9.7 lakh ha.) of castor with 85% of the world’s castor production and highest productivity of 1720 kg/ha (2017-18, Ministry of Agriculture and Farmers Welfare, Govt. of India). A set of 150 hybrids, differing in node number and days to 50% flowering, derived from 13 female and different male parents were evaluated for general phenology, yield attributes and seed yield in an Augmented Randomized Block Design (ARBD) along with three checks, DCH-177, DCH-519 & GCH-7 at two locations viz., under rainfed conditions at ICAR-IIOR, Hyderabad and under irrigated conditions at Anand, Anand Agricultural University, Gujarat during 2016-17. Comparative performance of hybrids in two locations indicated that there were significant agro-morphological differences resulting from the G x E interaction. Analysis of variance indicated that there were significant differences among the hybrids for most of the traits at 5% confidence interval and coefficient of variation (CV) was within 18% for both the locations. Node number to the base of primary spike (PNN) played an important role in determining the days to 50% flowering (DF50%) and yield traits. Under both the rainfed and irrigated conditions, as the node number to primary spike (PNN) increased, there was a general tendency for increased plant height (PH), days to 50% flowering (DF 50%), primary spike length (PSL), number of capsules in primary spike (NCAP) and per plant seed yield (SY). However, there was no difference between early (lower PNN) and medium/late flowering (higher PNN) hybrids with respect to 100 seed weight (SW) and oil content (%) within a location, indicating that these two traits were more dependent on specific parental combinations rather than on PNN and flowering nature. Under rainfed conditions, early hybrids (PNN<10 and flowering ≤ 44 DAS), in general, were less yielding. Yield potential, in general, was high in hybrids with PNN≥11 and flowering ≥45 DAS. Some hybrids with PNN from 11 to 15 were promising for their sustainable cultivation under rainfed conditions with >2 tonnes ha-1. Under irrigated conditions, in general, both the early and medium/late flowering hybrids had better seed yield, test weight and oil content (%) and the differences depended on the nature of parental combinations rather than on PNN and DF50%. Analysis of results further indicated that the performance of hybrids was highly influenced by the environment and is significantly influenced by the type of castor genetic resources to be utilized, breeding, selection and evaluation strategies to be adopted in castor improvement programmes for rainfed and irrigated conditions.