Combining ability and heterosis in maize (Zea mays L.)

The present investigations were carried out in the Economic Botany Section of Agriculture Research Institute, Sariab, Quetta, during 1998-99. Twenty eight single crosses were obtained by crossing eight elite maize inbred lines in all possible combination excluding reciprocals. The F, hybrids seed along with the parental inbred lines was sown in n replicated trail according to Randomized Complete Block Design. So far GCA effects are concerned, four inbred lines viz.; OHJ.14-3B, BN-105, N-158 and Antigua-11 displayed positive GCA for number of ears per plant. Three inbred lines viz.; A-141, Antigua-I1 and Q-- 143 showed positive GCA effects for grain rows per ear, grains per. row, and 100 grain weight, while five inbred lines viz.; 13N-105, N-1-58, Antigua-II, S11- 131 and Q- 143 manifested positive GCA effects for spike length and grain yield per plant. These findings conclude that the parent BN-105 with maximum positive GCA effects in all the characters except grain rows per ear can be assorted for use in the improvement of maize crop. Twenty seven single crosses exhibited positive heterosis over mid parental values for whereas, twenty six hybrids positive heterosis, for this number of kernel rows per ear were recorded to have shown character, relative to better parents. The maximum heterosis manifested for number of kernel rows per ear was recorded to be 46.80% over the better parent. Twenty seven hybrids were superior to their mid as well as better parents for number of kernels per row with the maximum increase being 98.09% relative to the better parent. For the ear length twenty seven crosses expressed positive heterosis comparative to mid parents and twenty four hybrids were found superior as compared to their better parents. The maximum increase of ear, length was recorded as 58.730 relative to the better parent. Twenty six single crosses manifested positive heterosis over their mid parents for 100 grain weight whereas twenty one hybrids showed increase over their better parents. The best cross combination for 100 grain weight was estimated to be 39.65% superior to its better parent. For the grain yield per plant all. the single crosses presented superiority over their mid and better parents with the maximum increase of 121.73% relative to the better parent. These results conclude that the Antigua Sh-31, A-1.41, BN-105 and N-133, Q-193 can be selected with high Yielding potential and promising source character material for the improvement of hybrid maize.