Germplasm Screening and Genetic Analyses for Drought Tolerance Improvement in Maize (Zea mays L.)
Loading...
Date
2016-08
Authors
Journal Title
Journal ISSN
Volume Title
Publisher
University of Agricultural Science, Dharwad
Abstract
Drought is one of the major abiotic challenges to maize production in India and in the world. This study focused on identification and development of drought tolerant germplasm and understanding the genetics of drought tolerance in maize.
Hundred inbred lines were screened for drought tolerance and the following were selected: DMR-M-81, M4, FA6, DMR-M-83, GPM36, DMR-M-88, DMR-M-84, M39, M53, FA3, GPM43, and M53. Lines DMR-M-88, FA6, GPM36, M39, and M53 were stable across environments.
The twelve drought tolerant lines were involved in half diallel analysis. Pooled (across traits) general combining ability effect (gca) of lines and pooled specific combining ability effect (sca) of crosses were estimated. Good general combiners under drought were: DMR-M-88, M39, FA3, and GPM43. Five among best crosses under drought, namely [FA3 / M39], [GPM43 / DMR-M-88], [DMR-M-84 / DMR-M-83], [FA3 / DMR-M-81], and [DMR-M-83 / FA6], had positive sca effects both under drought and well-watered conditions. Two crosses, [FA3 / M39] and [GPM36 / M4] were high yielding and stable across diverse environments.
Genetic distances (GD) among the twelve lines were estimated using microsatellite (SSR) marker data. The correlation coefficient between GD and mid-parent heterosis in respect of grain yield under drought was significant and negative, but low and unreliable for predictive purposes. The correlation coefficients between GD and per se performance and sca were not significant.
Lines GPM36, DMR-M-88 and FA6 were good general combiners in a study involving the twelve tolerant lines and two adapted hybrid testers. The testers, BIO-9681 and ARBMH-1 differed in terms of mean testcross grain yields, implying differences in gene frequencies at loci governing grain yield.
Regarding interrelationship among traits under drought, grain yield (t ha-1) (GY) was highly and positively correlated with ears per plant, ear length, ear diameter, number of kernels per ear row, number of kernels per ear, and grain yield per plant. Conversely, GY was highly and negatively correlated with drought susceptibility index.
In generation mean analysis under drought, additive gene effects were important for inheritance of anthesis-silking interval. For grain yield and its component traits, non-additive gene effects were more important.