Physiological and Molecular Evaluation of Positive and Negative Heterotic Rice Hybrids for Grain Yield

Abstract

Exploitation of hybrids is of greater importance to increase the productivity of rice, as it is a staple food around the world. Hybrid rice is developed by exploiting the phenomenon of heterosis. To evaluate the phenomenon of heterosis, a pot culture experiment was conducted at ICAR-Indian Institute of Rice Research, Hyderabad, during Kharif 2014. The experiment was laid out in completely randomized design with seven rice hybrids (DRRH3, DRRH2, KRH2, APMS6A X C20R, APMS6A X BCW56, APMS6A X AjayaR, PUSA5A X BR 827-35) along with their parents to evaluate whether these hybrids are positively heterotic or negatively heterotic for grain yield. Data was recorded on different parameters like SVI, root length, root volume, total biomass, stomatal conductance (gs), transpiration rate (T), panicles plant-1 , grain number panicle-1 and yield plant-1 . For molecular characterization 14 hyper-variable polymorphic Expressed Sequence Tag derived Simple Sequence Repeats (EST-SSRs) primer pairs were used for PCR amplification. Of the 14 primers amplified in the hybrids, 6 are monomorphic and the rest are polymorphic. These hybrids were also analyzed for parental polymorphism wherein the coefficient of marker polymorphism was calculated and correlated to standard heterosis % with respect to grain yield. The parental combinations exhibiting CMP values of ≥ 0.7 exhibited positive heterosis and others are negatively heterotic for grain yield. It is concluded that the hybrids DRRH3, DRRH2, KRH2, APMS6A X C20R, APMS6A X BCW56 are positively heterotic and the hybrids APMS6A X AjayaR, PUSA5A X BR 827-35 are negatively heterotic.