[Effects of irrigation on the water soluble carbohydrate contents in different wheat cultivars stem and sheath and the grain yield].

Taking two wheat (Triticum aestivum L.) cultivars Jimai 20 and Taishan 22 as test objects, this paper studied the effects of different irrigation treatments on the water soluble carbohydrate contents in penult stem internode and sheath and the grain yield. Four irrigation treatments were installed, i. e. , no irrigation (W0), irrigation at overwintering and jointing stages (W1), irrigation at overwintering, jointing and anthesis stages (W2), and irrigation at overwintering, jointing, anthesis and filling stages (W3). In treatment W0, the contents of total soluble sugar and of fructan with the degree of polymerization (DP) > or = 4 and = 3 in the penult stem internode and sheath of the two cultivars at early filling stage and the fructose content at later filling stage were the highest, indicating that the accumulation and degradation of water soluble carbohydrate in the penult stem internode and sheath were promoted under no irrigation, which in turn increased the 1000-grain weight. In treatment W1, the contents of fructan with DP > or = 4 and DP = 3 in the penult stem internode and sheath of Jimai 20 at early filling stage, the total soluble sugar and fructose contents at middle and later filling stages, and the grain yield were the highest. In treatment W2, Taishan 22 had the highest contents of fructan with DP > or = 4 and DP=3 in the penult stem internode and sheath at early filling stage, lower fructose content at higher filling stage than in treatment W1, and the highest grain yield. Comparing with Jimai 20, Taishan 22 had higher contents of total soluble sugar and of fructan with DP > or = 4 in the penult stem internode and sheath at early filling stage and higher content of fructose at later filling stage, and lower grain yield in treatments W0 and W1 but higher grain yield in treatments W2 and W3. In this study, treatments W1 and W2 promoted the accumulation and degradation of water soluble carbohydrate in the penult stem internode and sheath of Jimai 20 and Taishan 22, and gained the highest grain yields of the two cultivars, respectively, being most appropriate irrigation treatments for Jimai 20 and Taishan 22, respectively.