Study on heterosis for yield and physiological characters in rice hybrids

摘要

Moderate to high heterosis was indicated for grain yield and ten morpho-physiological characters viz., days to 50% flowering (DF), plant height (PH), leaf area index (LAI) at 45 days after sowing (DAS), at 60 DAS and at flowering, leaf thickness (LT)at 60 DAS, dry weight (DW) at 60 DAS, crop growth rate (CGR), total dry matter (TDM), harvest index (HI) and grain yield plant~(-1) (GY) from study with 72 hybrids evolved from 36 improved WA-CMS maintainer lines with eui gene and two adapted restorers crossed in line x tester fashion and evaluated in replicated experiment under two (E_1- optimum and E, -high) fertility environments. Expression of heterosis was higher in the E_1 than E_2 environment. The maximum estimates of standard heterosis (%) forgrain yield were 211.0 in E^ and 155.7 in Higher heterosis in grain yield was also accompanied by higher heterosis in some key physiological components like TDM, CGR, DW at 60 DAS and LAI at flowering. Most estimates of standard heterosis for days to 50%flowering were negative, indicating earliness in hybrids. A wide range of standard heterosis for plant height across environment (-5.40 to 69.04) was recorded. Hybrids L_(16)T_2- UPR 2911-271-8-4B/Pant Dhan-4, L_(15)/T_2, - UPR 2911-271-8-3B/Pant Dhan-4and L_(19)/T_1 - UPR 2911-271-12-2B/UPR193-287 outperformed in both the environments and with better per se performance could be exploited through conventional breeding to isolate physiologically efficient maintainers in segregating generations. The lines L_(15) and L_(19) could directly be exploited for their conversion into CMS by back crossing.