HETEROSIS AND COMBINING ABILITY IN 7×7 DIALLEL POPULATIONS OF WHITE MAIZE (Zea mays L.)

Abstract

The study was conducted to evaluate the forty-two F 1 lines derived from 7×7 full diallel cross of white maize for yield and yield components. Seven(7) inbred lines of white maizewere mated using complete 7×7 diallel fashion during rabi season 2017-18 and then evaluated their combining ability and heterosis of forty-two hybrids over two checkvarieties BARI hybrid maize-12 and BARI hybrid maize-13 at research farm of Sher-eBangla

Agricultural University, Dhaka-1207 during rabi season 2018-19. The variancesfor general combining ability (GCA) were found significant for all the characters except ear diameter, while specific combining ability (SCA) was significant for all the characters except ear height and plant height suggesting that non-additive gene action was importantfor inheritance of yield and yield related characters in the hybrid progeny. GCA varianceswere much higher in magnitude than SCA for all the characters except number of row per ear and ear diameter indicating the superiority of additive gene effects for the inheritanceof these traits. The analysis of GCA revealed that parents P7 and P4 were the best general combiner for yield related character, while parents P7 and P3 for earliness and dwarf plant ype. The analysis of SCA showed that crosses P7×P1, P1×P3, P7×P4, P6×P3, P3×P5, P4×P6, P6×P7, P5×P7, P3×P7 and P4×P5 exhibited maximum positive SCA effects for yield related character viz. ear length, ear diameter, number of row per ear, number kernel per row and hundred kernel weight and kernel yield per plant. The heterosis showed that percent heterosis for grain yield varied from -9.412% to 40.421% and -16.304 to 38.361%, considering BARI hybrid maize-12 and BARI maize hybrid-13 as check varieties respectively. Twenty crosses exhibited significant and positive heterosis over the check varieties. The highest positive heterosis showed by cross P5×P7 (40.421% and 38.361%), P3×P7 (39.50% and 37.45%), P1×P3 (37.99% and 35.97%), P5×P4 (37.81% and 35.79%), P4×P7 (36.26% and 34.26%), P6×P7 (33.10 and 31.15%), P6×P4 (32.28 and 30.34%),P1×P7 (32.19% and 30.25%) ,P4×P6 (26.39% and 24.54%) and P4×P5 (21.86 and 20.07%)over the checks BARI hybrid maize 12 and BARI hybrid maize 13, respectively. Considering the performance of SCA effects and heterosis, the crosses P5×P7, P3×P7,