Responses Of Growing Stages And Growth Characteristics Of Spring Maize To Drought At Jointing Stage And Rewatering

Plant growing stages reflect the interrelationship between plants?including crops?and cyclically varying environmental conditions?climate,hydrology,and soil conditions?.In the context of climate change,crop growing stages have changed significantly and had important effects on crop planting systems,yields and quality.However,most studies have focused on the relationship between growing stages and environmental factors,while few studies have focused on explaining the response mechanism of growing stages from the perspective of plant physiological processes.Crop growing stages are affected by light,temperature,water and other environmental conditions.Especially in the context of climate change,drought and rewatering caused by precipitation change have seriously affected the growing stages of crops.In order to increase the cognition of crop growing stages response to drought and rewatering,this study was based on the data of growing stages,growth characteristics and corresponding ecophysiological characteristics of spring maize,which obtained from field simulation experiment that controlled water at jointing stage and rewatering at tasseling or silking stage,respectively.We analyzed the effects of drought and rewatering on growing stages and ecophysiological characteristics of spring maize,clarified the relationship between relative soil water content,growing stages,growth characteristics and ecophysiological characteristics,and revealed the ecophysiological mechanisms of growing stages changes in spring maize.The main conclusions are listed as follows:?1?The growing stages of spring maize had memory to drought stress in early stage.Drought at jointing stage had significant effect on the reproductive stages of spring maize.The grouting time was prolonged and the milking stage was delayed?about 9 days?.The growing stages of spring maize were still affected by drought at jointing stage after rewatering at tasseling stage or silking stage.?2?Drought at the jointing stage affected the growth characteristics of spring maize and could not return to normal levels even after rewatering.The root dry weight,stem dry weight,leaf dry weight,total dry weight and leaf area of spring maize were significantly reduced by drought treatment at jointing stage.The leaf dry weight,stem dry weight,total dry weight and leaf area could not return to normal levels after rewatering at tasseling stage or silking stage.?3?Drought reduced the yield of spring maize,and the later the rewatering time,the lower the yield.Drought at jointing stage and rewatering at tasseling stage reduced 100-grain weight,grain weight per plant and theoretic yield by 12.34%,26.42%and 26.42%respectively,while drought at jointing stage and rewatering at silking stage reduced 100-grain weight,grain weight per plant and theoretic yield by 20.33%,54.27%and 54.27%respectively.?4?Drought and rewatering significantly changed the ecophysiological characteristics of spring maize.The leaf net photosynthetic rate?Pn?,transpiration rate?Tr?,stomatal conductance?Gs?,and relative chlorophyll content?SPAD?of spring maize showed a trend of decrease–increase–decrease with time.The Pn,Tr,Gs,and SPAD reached the local minimum at tasseling stage under the water control.The Pn,Tr,and Gs reached the local maximum at silking stage and SPAD reached the local maximum at filling stage after rewatering at tasseling or silking stage.The leaf water potential?LWP?presented a downward trend over time.Rewatering had a temporary compensation effect on ecophysiological characteristics of spring maize.?5?The response mode of growth characteristics and ecophysiological factors of spring maize to drought at jointing stage was that relative soil water content?RSWC?first affected LWP,leading to changes in Pn,and then affected leaf area and total dry weight.?6?Pn was the most important ecophysiological factor affecting the growing stages of spring maize.The order of decision coefficients?R²?of ecophysiological factors affecting the growing stages of spring maize were,R²?Pn?>R²(_LWP)in the control treatment,R²?Pn?>R²(_LWP)in the T1treatment and R²?Pn?>R²?LWP?>R²?RSWC?in the T2 treatment.Pn was the main decision variable and the soil water content was the main limiting variable in the growing stages of spring maize.