Response of NIILs with Single and Multiple Qtls for Root Length on Grain Yield and Water use Efficiency in Rice (Oryza sativa L) Under Aerobic Condition

Drought is a major cause of yield loss in rain-fed rice (Oryza sativa L.), grown on over 40 million ha in Asia. The objective of this study was to evaluate the effectiveness of the root QTLs on grain yield and water use efficiency in a set of 116 near isogenic lines (NILs) derived from cross IR64 and Azucena populations which were screened for grain yield and water use efficiency under severe reproductive-stage drought stress. Among NILs with single QTL, the NIL with QTL on chromosome 9 exerted its effect significantly on both grain yield and water use efficiency. Where as none of two or three QTL combination could not make it significantly which may be attributed to pleotropic effect of QTLs. However the two roots QTL on chromosome 2 and 7 and three QTL combinations on chromosome 1, 2, and 7 had comparable water use efficiency as that of Azucena which is a donor of root QTLs. The experimental findings indicate that deeper root may increase grain yield but more number of QTLs may have their effect on putting up root length rather than grain yield.

NILs having 1, 2 and 3 QTLs for root traits developed through MAS were screened under severe reproductive stage drought condition.

Study was to assess the effect of QTLs on grain yield and WUE through carbon isotope discrimination method.

QTL on chromosome 9 had significant effect on grain yield and water use efficiency rather than pyramided QTLs.