Abstract:

Upland rice and dry-cultivated paddy rice have been attracted more and more attention because of limited water resources in China, however, there is little information available on effect of cultivation methods on grain quality of upland rice and paddy rice. The objective of this study was to evaluate the difference between upland rice cultivar Zhonghan 3 (japonica) and paddy rice cultivar Wuxiangjing 99-8 (japonica) under three cultivation methods of moist cultivation (MC, control), plastic film mulching cultivation (PFMC) and bare cultivation (BC). The results showed that, compared with the MC, the grain yield was significantly lower under PFMC for upland rice, but no significant difference between PFMC and MC for paddy rice, and significantly reduced under BC for both upland and paddy rice. The chalkiness, the ratio of kernel length to kernel width, amylose content, gel consistency and peak viscosity were lower, whereas protein content and pasting temperature were higher for PFMC and BC rice compared with those of MC rice. The percentage of chalky grains was significantly decreased under PFMC and BC for upland rice and under BC for paddy rice, but no significant difference between PFMC and MC for paddy rice. Chalkiness, amylose content, gel consistency, breakdown viscosity and the declining amount of nitrogen content in plants from heading to maturing stages were the least and protein content and setback viscosity were the most and Q-enzyme average activity remained the highest level for PFMC among the three cultivation methods. Compared with paddy rice, upland rice showed lower percentage of chalky grains and gel consistency, no difference in chalkiness, and higher levels in ratio of kernel length to kernel width, amylose content, protein content and pasting temperature. The relationship between Q-enzyme activity and grain quality was similar to that between the grain-filling parameters from Richards equation. The results suggest that the dry cultivation can improve appearance quality and nutrient quality, whereas has negative effects on cooking quality.

Key words: Upland rice, Paddy rice, Dry cultivation, Rice quality, Q-enzyme, Grain-filling