Head rice yield of rice varieties in response to water deficit during reproductive stage and aerobic conditions

Head rice yield (HRY) is an important criterion to determine milling quality of rice. Traditionally rice is grown under flooded condition however with water scarcity aerobic production has been considered a water saving option. The impacts of an aerobic system or one, which suffers mild water deficit at reproductive stage on HRY has not been determined. A series of experiments were sown across two years to investigate the stability and G×E interaction on HRY of 20 diverse rice genotypes grown under well-watered aerobic conditions (WW) as well as various water deficit (WD). Genotype and G×E were highly significant in all environments. Based on HRY, cluster analysis grouped environments into EG1: poor (48.9%), EG2: favourable (64.3%) and EG3: average (57.6%). Of 6 genotype groups, medium maturity genotypes groups: GG3 and GG5 including Lemont, Jefferson, Amaroo, Sherpa and Calrose had good adaptability under WD at grain filling as well as flowering time. IR 64 (GG1) had poor adaptability across environments and is considered as a susceptible genotype. Genotypes with low amylose achieved high HRY under aerobic condition where there is no water shortage but no relationship with grain yield in any environmental group. The stable and consistent genotypes with high HRY under aerobic and WD conditions will be beneficial for farmers and rice industry in Australia and still needs improving.