Studies On The Effects Of Waterlogging Stresses On Quality Traits And Regulation Of Two Winter Wheat Cultivars With Different Glutens

Under pot-culture conditions,two winter wheat cultivars,Yumai 34(a strong-gluten wheat)and Yumai 50(a weak gluten wheat),were used to evaluate effects of post-anthesis waterlogging on activity of key enzymes involved in starch synthesis and quality traits of grains from 2003 to 2005.Exogenous regulators(6-BA and epi-BR)were also sprayed after waterlogging to test the alleviative effect on grain quality.The results were as follows::1.Compared with control plants(in normal growing conditions),Under after anthesis waterlogging conditions,contents of albumin,globulin,glutenin and total protein content in grains decreased while gliadin content increased.With the stress enhanced,the effects became stronger,especially the protein content and the ratio of content of amylase to amylopectin.2.The activity of UDPG-PPase,ADPG-PPase,SSS and SBE in grains reduced under post-anthesis waterlogging conditions,and its effects became stronger with the increase of stress degrees and the development of grain filling.Obvious different in behavior of these enzymes was observed between the two cultivars,indicating that the strong-gluten cultivar Yumai34 was more sensitive to waterlogging than Yumai50.Starch and its components changed under waterlogging conditions.As for strong gluten wheat of Yumai 34,the content of amylase decreased while amylopectin increased.However,contents of alymose and alymopectin increased equally in weak gluten wheat of Yumai 50.Finally it was represented that the contents of total starch and the ratio of alymose/alymopectin decreased in strong gluten wheat Yumai 34 but increased in weak gluten wheat of Yumai 50. Comparison the effects between different periods,waterlogging effect in early stage was greater than that of later stage. 3.For both wheat cultivars,break down increased while setback decreased in waterlogging conditions.Starch parameters,such as peak viscosity,final viscosity and hold-through decreased in strong gluten wheat Yumai 34.But in weak gluten wheat Yumai 50,peak viscosity and hold-through increased while final viscosity decreased.This showed that different effects of waterlogging on starch viscosity parameters existed between two wheat cultivars.4.Under post-anthesis waterlogging conditions,epi-BR and 6-BA could delay the decrease of photosynthesis rate,chlorophyll content and senescence of flag leaves,and increase1000-kernel grain weight,yields and starch biomass.Spraying of 6-BA after waterlogging stress increased peak viscosity and final viscosity and hold-through in both cultivars.But difference effects of epi-BR on starch properties existed between Yumai 34 and Yumai 50.Most starch viscosities increased in strong gluten wheat Yumai 34 while decreased in weak gluten wheat Yumai 50.This indicated 6-BA had positive effects on starch properties for both wheat cultivars.But epi-BR had positive effects only on strong gluten wheat,while negtive effects on weak gluten wheat.Above results implicated that 1)Post-anthesis waterlogging had obvious effects on protein and starch quality the two kinds of genotypes.Experiments with more wheat cultivaes should be carried out.2)Some exogenous materials could decrease the effect of waterlogging,but further study need be done on its physiological mechanism.