Abstract
Twenty hybrids were developed from crossing four environmental genic male sterile (EGMS) lines with five testers in line × tester mating design to magnitude of heterosis over better parent for grain yield and contributing traits in rice (Oryza sativa L.). Five hybrids ‘WTSC9059’ × ‘Sakha101’, ‘WTSC9039’ × ‘Sakha102’, ‘WTSC9059’ × ‘Sakha108’, ‘WTSC9039’ × ‘Sakha108’ and ‘WTSC9039’ × ‘Sakha101’ express superior value for number of panicles, fertility percentage, 100-grain mass, grain yield, apparent heterosis and phenotypic acceptance. The top three heterotic combinations identified for grain yield/ha were ‘WTSC9059’ × ‘Sakha101’, ‘WTSC9039’ × ‘Sakha102’ and ‘Longping’ × ‘Sakha105’ which exhibited 100.00, 71.51 and 66.61 % heterobeltiosis, respectively. The lines ‘WTSC9059’ and ‘‘Longping’’ and testers ‘Sakha101’, ‘Sakha102’ and ‘Sakha108’ was found to be good general combiner for most of the characteristics and could be extensively used in future hybrid rice breeding program. The grain yield was correlated highly significant and positive with panicle exertion, panicle mass, fertility percentage and appearance of heterosis, otherwise the negative correlation and significant was found with flag leaf area.
Highlights
Rice (Oryza sativa L.) is one of the world’s three major food crops and represents an important component of the world’s food supply
Environment-sensitive genic male sterility is controlled by nuclear gene expression, which is influenced by environmental factors such as temperature, day length, or both (Chang et al, 2016)
Agronomic characteristics that are useful for rice breeding, such as large panicles and flowering habit have good panicle uniformity, concentrated flowering periods and good panicle exertion rates, which would be more conducive to hybrid seed production (El-namaky, 2018)
Summary
Rice (Oryza sativa L.) is one of the world’s three major food crops and represents an important component of the world’s food supply. The two-line hybrid system is based on environmentally sensitive genetic male sterility (Yu et al, 2020)” and it usually uses photoperiod- and thermo-sensitive genic male sterile (PTGMS) lines as maternal parents to produce hybrid seeds. Environment-sensitive genic male sterility is controlled by nuclear gene expression, which is influenced by environmental factors such as temperature, day length, or both (Chang et al, 2016). In the two-line system, certain lines, referred to S lines, can be either male sterile (functionally female) or male (produces viable pollen) depending upon temperature and day length. Under temperature / day length combined condition, the S lines are crossed as females to fertile inbred lines to produce hybrid seed, while under separate temperature/day length combination, the same lines are allowed to self-pollinate and produce viable seeds to maintain a source. The success of hybrid rice technology primarily depends on genetic purity, timely availability and the affordability of hybrid seed costs to the farmers (Singh and Ram, 2012)
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