Abstract:

Rice is one of the main staple food crops in the world, but rice production almost occupies 70 percent of the total water consumption of agriculture in China. To save water resources, improving rice drought resistance is a major goal in rice breeding, and water-saving rice culture (dry-cultivation) is also with a great potential. Most of the rice quality characteristics are controlled by quantitative genes and also affected by environment. Rice grain quality is different under water- and dry-cultivation environments on which comparative studies are very important for rice breeding and cultivation.
A doubled haploid (DH) population consisting of 116 DH lines developed through anther culture of the F1 hybrid between an upland rice cultivar ‘IRAT109’ and a lowland rice cultivar ‘Yuefu’ was used in this study. The parents and the 116 DH lines were planted in water- and dry-cultivation systems, on the experiment farm of China Agricultural University in 2002. Seeds of parents and 116 DH lines were harvested at maturity, and used to measure the content of crude protein, brown rice percentage, milled rice percentage, head milled rice percentage, amylose content, gel consistency, alkali value, chalkiness, grain length, grain width, and grain length/grain width. All data were analyzed by SPSS software.
The correlation analyses were conducted between quality characteristics in the two cultivated systems. The results indicated that the content of crude protein, head milled rice percentage, gel consistency and alkali value were higher, and chalkiness, grain length and grain width lower in dry-cultivation than in water-cultivation (Table 1). In general, most of characters of rice grain quality were improved in dry-cultivation compared with that in water-cultivation. The content of crude protein, head milled rice percentage, gel consistency and alkali value were more sensitive to water-stress, as compared with amylose content, grain length, grain width and chalkiness. Especially, the content of crude protein was increased by 37.9% or 3.02 percentile in dry-cultivation than in water-cultivation (Fig.1). But brown rice percentage, milled rice percentage and the ratio of grain length/grain width were not influenced by cultural environment. In addition, milling quality characters were affected by the interaction of gene and environment (culture system), but the appearance, cooking and nutrition quality characters mainly controlled by genetic factor. Therefore, the grain quality of the lowland or upland rice cultivars with drought-resistance could be improved under upland condition or dry-cultivation by the cross between lowland rice cultivar with elite grain quality and drought-resistant upland rice cultivar.

Key words: Rice, Water- and Dry-cultivation, Quality characteristics, Doubled haploid (DH) population, Correlation analysis