Improvement in selfed and random-mated generations of four subtropical maize populations through S3 recurrent selection

Summary

In maize (Zea mays L.) source germplasm having tolerance to inbreeding is needed for the derivation of productive inbred lines. The germplasm with non-temperature adaptation, generally suffer from large inbreeding depression (ID). the objective of the present study was to improve four white subtropical populations for tolerance to ID through S3 recurrent selection. Two cycles of selection were conducted and the effect of selection was evaluated in the first selfed (S1) and random0mated (Synthetic-2=Syn-2) generations. To complete each cycle. 200 to 250 S3 progenies were evaluated and 15 to 20 superior ones selected for recombination in each population. Selection was practiced for high grain yield, vigour and other agronomie traits. The S1 and Syn-2 generations of the original (C0) and improved (C1, C2) populations were evaluated in a split-split plot design, with populations in main plots, generations in subplots and cycles in sub-subplots. In all populations, S1 and Syn-2 generations of C2 were significantly higher yielding than the C0 and the linear gain per cycle varied from 16.3 to 28.8% in S1 generation and 5.5 to 10.7% in Syn-2 generation. Selection reduced the anthesis-silking interval but slightly increased plant height, grain moisture and days to silk. An increase in plant height was expected because of emphasis on vigour during selection. For grain yield. ID decreased from 48.4% in C0 populations to 37.9% in C2, indicating an improved tolerance to inbreeding. Further, the selection accumulated favourable alleles; and Pop. 42 seemed to be the best source populations for deriving high yielding inbred lines. It may be concluded that S3 recurrent selection was effective in improving grain yield and the improved populations would provide better germplasm sources for the derivation of productive inbred lines.