| Elucidating the physiological mechanism and regulation principles for grain quality formation in wheat is of important significance for understanding grain quality physiology and guiding cultural management in wheat. With controlled water experiments, the present study characterized the photosynthesis, C/N assimilate translocation and regulatory enzyme activities in relation to formation of grain quality in different wheat varieties under varied soil water status, explored the regulation mechanisms of endogenous and exogenous hormones on wheat grain quality, and established the technical approaches to regulation of the wheat grain quality with plant growth regulators under soil drought and waterlogging.Four winter wheat (Triticum aestivum L.) genotypes differing in grain protein contents, Heixiaomai76, Wanmai38, YangmailO and Yangmai9, were used in pot culture experiment in greenhouse to investigate the effects of post-anthesis drought (SRWC=45%~50%), waterlogging and moderate soil water status (SRWC=75%~80%) on protein and starch contents and relative quality characters in wheat grains. The results indicated that grain protein content, glutenin content, ratio of Glu/Gli, dry gluten and wet gluten contents were increased significantly under drought. Glutenin content and ratio of Glu/Gli were reduced significantly under waterlogging. Under both drought and waterlogging, grain starch yields were reduced significantly, and amylose contents were elevated while amylpectin contents were lowered. So the ratios of amylose/amylpectin were depressed under both drought and waterlogging. Drought and waterlogging had differential effects on grain gluten index, sedimentation value and falling number in different varieties. Compared with CK, correlations among grain quality characters in different wheat varieties under drought and waterlogging were reduced. Thus, the distinct differences in grain quality characters between extreme and moderate soil water status would have impact on grain quality and utilization values of specialty wheats.With the four winter wheat varieties in the same experiment, investigations were made on the effects of post-anthesis drought, waterlogging and moderate soil water status on net photosynthesis and chlorophyll contents of flag leaves, remobilization of assimilates stored before anthesis, transportation of post-anthesis assimilates, and contents and yields of starch and protein in grain at maturity. It was found that the PAD and RSP of flag leaves in four wheat genotypes were shortened by both drought and waterlogging. As compared to CK, the values of PAD and RSP declined under waterlogging and drought. Theremobilization rate of pre-anthesis stored assimilates was the highest for CK, while the lowest for waterlogging. The amounts of post-anthesis assimilates and nitrogen transferred into grains were declined with CK>\vaterlogging>drought and CK>drought>waterlogging, respectively. The yield of grain protein significantly decreased at 5% level with the order of CK> drought > waterlogging in four wheat genotypes. The contents of grain protein increased significantly under drought, but had no significant differences between CK and waterlogging. Compared with CK, starch yield significantly decreased under drought and waterlogging in four wheat genotypes, but starch content varied among four wheat genotypes.In the same experiment, two winter wheat varieties, Wanmai 38 and Yangmai 9, were chosed to investigate the effects of drought, waterlogging and moderate water supply on the activities of key enzymes for grain starch and protein accumulation. The results showed that the changing patterns in the activities of enzymes in both leaves and grains were similar in the two varieties. Compared with CK, sucrose content and SPS activity declined more markedly than amino acid content and GS activity under drought and waterlogging. Both drought and waterlogging resulted in decreases in the activities of SS and GBSS, and especially in that of SSS. More marked decreases in the activity of SS occurred...
|
PDF Full Text Request