Variation In Pentosan Accumulation In Wheat Grains With Genotype And Environment And Its Regulatory Approaches

Pentosan is one of the major components in wheat grains, which mainly presents in cell-wall of grain coat. Both foreign and native scientists paid much attention on wheat pentosan because of lots special functions pentosan owned. The structure, functional mechanism and properties had been widely studied. To date, however, knowledge involved in pentosan is limited, besides impacts of environmental factors and cultivation practices on content and accumuation of pentosan. In the present study, different wheat varieties were grown at different ecological environments with different cultivation practices (water stresses, fertilizer, sowing dates , soure and sink) to study the regulatory efforts of genotype, environment and cultivation practices on content and accumulation of pentosan. The results should help clarify pentosan accumulation mechanism and provide regulatory approaches for super quality wheat. Total three experiments were established as:Experiment 1: Six wheat varieties of Wanmai 38, Huaimai 18, Yangmai 9, Xuzhou 26, Yangmai 10, Ningmai 10 were grown at six representative ecological sites in Jiangshu as Ganyu, Hai'an, Jiangyan, Jintan, Yandu, Wujiang in the 2000 ~ 2001 season. The aim of this experiment was to study genotypic and ecological effects on pentosan content.Experiment 2: Three wheat varieties of Xuzhou 26, Wanmai 38, Xuzhou 25 were grown at three ecological environments in China as Baoding (115.4°E, 38.8°N), Xuzhou (117.2°E, 34.4°N) and Jiangyan (120.1°E, 32.5°N) in the 2001 ~ 2002 season. Two sowing dates as optimal and late sowing were designed at each site to study variation in pentosan content with sowing date and ecological environment.Experiment 3: Effects of different cultivation practices on pentosan content and accumulation in wheat grains were studied. No1: Two wheat varieties as Xuzhou 26 and Yangmai 9 were grown in cement boxes in Nanjing Agricultural University in the 2002 ~ 2003 season. Treatments of ear-removal (one-third head was cut) and flag leaf-removal (the whole flagleaf was cut) were designed for each variety. The aim of this experiment was to investigate changes in pentosan content under varied conditions of sink and source. No2: Two wheat varieties, Xuzhou 26 and Yangmai 9 were sown in cement boxes in NAU. Three water treatments were established, i.e. RSWC (relative soil water content) was maintained at 70 ~ 80% as control, at 45 ~ 50% as drought and maintained a water layer of 1 ~ 2 cm above ground as waterlogging. For each water treatment, two nitrogen rates were set, i.e. 120 kg N ·hm-2 and 240 kg ·hm-2. the aim of this study was to evaluate effect of nitrogen on content of pentosan in grain of wheat grown under water stresses of drought or waterlogging.No3: Low protein content wheat varieties of Yangmai 9 and Ningmai 9 were grown in Kunshan, Suzhou City Jiangsu Province in 2002 ~ 2003. Six nitrogen rates were used for each variety, as 0, 60, 120, 180, 240 and 300kg N · hm-2. At N rate of 180 kg N · hm-2, five ratios of basal to topdressing N were designed as 8:2, 7:3, 7:2:1, 6:4 and 5:5. The aim of this experiment was to study response of pentosan accumulation pattern to nitrogen application methods. Ningmai 9 and Yangmai 10 were planted in cement boxes in NAU in the growth season of 2003 ~ 2004. Four phosphorus rates as 0, 60, 120and 180 kg P2O5· hm-2 and four potassium rates of 0, 75, 150 and 225 kg K2O · hm-2 were use for each variety. The aim of this experiment was to study response of pentosan content and accumulation to phosphorus and potassium rates.The main results were as follows:Effect of genotype and ecological environment on pentosan content in wheat grains Pentosan content in wheat grain was not only dependent on genotype but also on environmental factors. Contents of total N and available P showed insignificant positive effects, while contents of organic matter and available K showed insignificant negative effects on pentosan content. Close relationship between pentosan content and weather conditions after anthesis was observed. The correlations be...