Construction of index to characterize degree of wheat waterlogging impact by soil moisture
[Objective]To address the problem of limitations of using characteristic parameters,such as groundwater depth and meteorological elements for assessing wheat waterlogging,a wheat waterlogging index(WI)was developed.The index offered a scientific basis for forecas-ting wheat yield,as well as for mitigating disasters and enhancing resilience.[Method]The study utilized wheat varieties of'Yangmail 1'and'Zhengmai7698'as materials,which were prevalent in the middle and lower reaches of the Yangtze River Plain.Pot experiments were conducted on these different wheat varieties subjected to waterlogging treatment.The APSIM model was utilized,and the characteristic im-pact of soil water and oxygen stress on wheat roots was used as the daily index of wheat waterlogging.This approach combined soil volumetric moisture content to establish the relationship between soil moisture hypoxic stress,waterlogging degree and wheat yield.[Result](i)The du-ration of waterlogging showed a negative correlation with the rate of increase or decrease in wheat yield.This meant that the longer the dura-tion of waterlogging,the lower the rate of increase or decrease in wheat yield.Moreover,when comparing the rate of increase or decrease in wheat yield at different waterlogging stages,it was found that waterlogging treatment from the flowering to maturity stage had a significant effect on wheat yield;(ii)The cumulative WI showed a significant negative linear relationship with SPAD of wheat leaves,that was,the more serious of waterlogging,the lower the chlorophyll content and activity in wheat leaves;(iii)When WI was less than 5.3('Yangmai1 1')or 6.0('Zhengmai7698'),it showed a positive correlation with the rate of increase or decrease in wheat yield,indicating that a higher WI corresponded to a higher rate of increase or decrease in wheat yield;Conversely,When the WI exceeded 5.3('Yangmai1 1')or 6.0('Zhengmai7698'),the WI displayed a negative correlation with the rate of increase or decrease in wheat yield,in line with the sub-surface waterlogging wheat mechanism.[Conclusion]The WI constructed based on soil moisture provides a valid quantitative measure of the degree and its impact on wheat yield,demonstrating universality.The WI can provide a quantifiable calculation method for as-sessing the damage of sub-surface waterlogging in wheat.It is valuable for early warning and damage assessment of wheat waterlogging.
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