Growth and yield of rice cultivars under sprinkler irrigation in south-eastern Queensland. 2. Comparison with maize and grain sorghum under wet and dry conditions

Abstract

The performance of non-flooded rice was compared with that of the 2 major cereal crops grown in south-eastern Queensland. Three cultivars of rice and 1 cultivar each of sorghum and maize were grown either under weekly sprinkler irrigation or under non-irrigated conditions after establishment. Grain yield, total dry matter and light interception were measured to determine the responses of the cereal species to soil water deficits. Under weekly irrigation, the low grain yield (ovendry) of rice (680 g m-2 in the highest yielding cultivar compared with 1240 g m-2 for sorghum and 1060 g m-2 for maize) was mostly due to inefficient conversion of solar radiation to dry matter. Both total radiation interception and harvest index were similar among the 3 species. Under dry conditions, rice intercepted less radiation than did the 2 cereals. There was also a larger reduction in the efficiency of conversion of solar radiation to dry matter in rice, and hence total dry matter production was severely reduced. Grain yields under dry conditions were 52, 58 and < 10% of the corresponding yields in the wet trial in maize, sorghum and the 3 rice cultivars, respectively. In rice, dry conditions delayed heading, and consequently grain set was severely affected in the 2 quick maturing cultivars, while the long season cultivar (IR43) failed to head during the experimental period of 163 days. At maturity, the rice cultivar, Shinhakaburi, bred for upland conditions, produced a significantly higher biomass than the lowland cultivar, Labelle, or the upland cultivar IR43.