Vegetative water stress alters grain-filling behaviour improving grain quality in rice

Drought and competition from the environment, cotton and nut crops have seen a reduction in the availability of irrigated water for rice production in south-eastern Australia. The need to maintain yields with less water has led to the development of a water saving technique referred to as delayed permanent water (DPW). Conventional practices have rice permanently flooded throughout most of its life cycle whereas in DPW, the crop is intermittently irrigated during the vegetative stage and permanent water applied until just before the crop reaches the reproductive stage. Removing permanent water post flowering with intermitted irrigation until maturity, known as DPW with post flower flushing (DPW+PFF), can provide further water savings. DPW improves nitrogen and water use efficiency of rice without a substantial reduction in grain yield. Although yield is important in rice production, Australia competes in the global rice market by producing high-quality grain for premium markets with financial penalties applied to growers who do not meet these high-quality standards. Consequently, even with high yields, grower’s returns can be negatively impacted by poor grain quality. Currently, the impact of DPW and DPW+PFF on grain quality of rice grown in south-eastern Australia is unknown. We compared the effect of DPW and DPW+PFF with conventional drill irrigation on grain-filling behaviour and quality parameters of two commercial Australian rice varieties (Medium grain varieties Sherpa and Reiziq).