Effects of soil moisture on water utilization characteristics of rice (Oryza sativa).

A pot experiment was conducted to study the effect of soil moisture on water utilization characteristics of rice. Results showed that the cumulative water consumption of rice during the whole growth period under conventional flooding cultivation was significantly more than that under non-flooding cultivation with plastic film mulching,but slightly less than that under flooding cultivation with plastic film mulching. Compared to conventional flooding cultivation,the rice grain yield was not decreased or even increased with the increased water productivity under light and no water stress treatments with plastic film mulching. The cumulative water consumption of rice,the water consumption at each growth stage and its consumption intensity were decreased gradually with the decreasing soil moisture. And a significantly quadratic correlation was found between the field water-holding capacity and the cumulative water consumption of rice. The highest water consumption at each stage and the highest periodic consumption ratio were found at the elongation and booting stages under no water-stress treatments with plastic film mulching,and at the milky ripeness stage under the other treatments. With the decreasing soil water content,the periodic consumption ratio gradually reduced before heading and flowering,whereas increased after heading and flowering,in addition,the consumption intensity decreased. The number of effective panicles and the number of grains per panicle decreased with reducing water moisture,resulting in the declined rice yield. However,the water productivity increased gradually first and then decreased with the decreasing soil moisture. Quadratic correlation was also observed between the yield and the water productivity of rice.