Study On The Overcompensation Response Of Wheat Yield-related Traits

Food production is facing severe challenges with the impact of climate change,environmental pollution,reduced arable land,and biological and abiotic stresses.As one of three most important main crops in the world,common wheat(Triticum aestivum L.,2n=6x=42,AABBDD)provides nutrients and energy to more than 20 percent of the world’s population.However,conventional genetic improvement of wheat has limited yield increase.Therefore,it is of great significance for food security to explore new ways to increase wheat yield.Plants have a certain compensation ability after the damage.They can quickly resume the growth,compensate for the loss,and even overcompensate the yield,which may be a new way to increase food production.However,overcompensation is affected by many factors and is very complex,especially in wheat.Therefore,it is still controversial that whether overcompensation can lead to yield increase.In this study,25 wheat varieties/lines were artificially cut at seedling stage.The changes of growth period and the compensation responses of 8 yield-related traits including plant height,tillering number,panicle length,spikelet number,effective panicle,flag leaf length,flag leaf width and 1000-grain weight after defoliation were studied.The following results were obtained through two years research of three planting places:(1)All the materials had a certain degree of delay in heading,flowering and maturity compared with the control after defoliation.There were differences among different materials,but there was no statistically significant difference in delay,indicating that the plants of common wheat could quickly resume the growth after defoliation.(2)Some regularity have been showed in the compensation response of defoliation to plant height: among the 15 materials with planting density gradient in2018,plant height of 3 materials with plant height less than 90 cm increased significantly or highly significantly after defoliation,while plant height of most materials with plant height more than 90 cm decreased significantly or highly significantly.In addition,7 of the 10 non-density gradient materials had significant or highly significant reduction in plant height,and the other 3 had no significant difference in plant height.Similarly,the plant heights of 12 materials planted in different places were decreased in 2019,indicating that defoliation may lead to lodging resistance.(3)The compensation response of length and width of flag leaves to the defoliation also showed a certain rule: under the ecological conditions with good soil and water fertilizer conditions,the length and width of flag leaves showed a significant trend of increase.Under clay and arid ecological conditions,the length and width of flag leaves decreased significantly.(4)There was no obvious pattern in the compensation response of cutting seedlings in tillering number,panicle length,spikelet number,effective panicle and1000-grain weight of the materials.Different materials had different compensation responses,but there were overcompensation types,and a few materials were sensitive to planting density.Several yield related traits of SM1668 and SM1710 response positively to defoliation in different years,planting places and planting densities,and these two materials might be the overcompensation type to the wheat yield.This provides a material basis for the subsequent genetic and molecular biology research.(5)Most wheat varieties have no significant difference on plot yield after defoliation in two different places.Some materials tended to decrease in yield while most materials have no significant change after defoliation.Our study preliminarily shows that there is an overcompensation response to yield traits in defoliation treatment of common wheat,which can provide reference for further use of overcompensation to increase wheat yield.