Root System Architecture And Re-watering Compensatory Effects Under Drought Stress In Spring Wheat

China’s water resources are relatively scarce and drought occurs frequently in various regions,resulting in poor production conditions of agriculture.To increase crop water use efficiency,we should understand the relation between water stress and recovery compensation mechanism in crops.In this study,i use half the amount of rehydration and Total rehydration,the two different drought rehydration way,to measure changes in crop yields,water use efficiency and growth parameters,to compared compensation effect,reveal the physiological and ecological mechanism of compensative effect and the optimization of rehydration strategy.Root system architecture of crops under drought stress designed different containers(horizontal,and vertical equalization)pot experiment,sufficient water WW and alternate root rehydration group(APRI),by controlling the architecture and alternate partial root zone irrigation,measured root space configuration features,water use and yield indicators and root partition rehydration compensation effect.In another experiment,two varieties,an ancient variety HST with big roots and modern variety L8275 with small roots and higher drought resistance were used in the present study.Water treatments on wheat were at different times three days,six days,nine days and twelve days(D3,D6,D9,and D12),with moderate water stress,the soil moisture content was 55% of field water capacity.There were three kinds of water recovering compensation mechanisms: Physiological compensation,growth compensation and yield compensation.The aim of the present study was to find the optimum moisture stress time to provide a biological basis for the theoretical biological water conservation.The experimental results were as follows:(1)Under water stress,photosynthesis and transpiration rate decreased significantly,osmotic adjustment substances contents and protection activity increased rapidly,after rehydration recovery,short-term stress treatment group recovered rapidly,and can be restored to the control level,longtime stress recovered in lag.Photosynthetic rate and transpiration rate under water deficit conditions were significantly reduced,but the influence of water stress on photosynthesis was less than on transpiration.Rapid recovery after compensation occurred both in photosynthetic rate and transpiration rate,exhibiting hysteresis effects.D9 and D12 were undergoing tougher stress,with decreased ability to compensate.D3 and D6 were the only treatments that exhibit equal or higher value compared with control.According to osmosis content it can be judged that under water stress,osmotic adjustment mechanisms play an important role in rapid after recovery compensation effect.But if the stress level exceeds a certain threshold,poor or no compensation effect occurred.Three to six days stress is the best stress treatment duration.As can be seen from the law change three kinds of substance penetration,when modern varieties to withstand stress,in physiological activity parity stable,and coordinated with each other through a variety of physiological processes,maintain the normal growth of the system,better compensation after recovery.(2)L8275 of D3 and D6 appear better compensation effect,aboveground biomass,plant height,leaf area did not fall,cause the same amount of compensation,but short-term drought stress group has higher biomass,the order trends for four treatment is to increase first and decrease then.six days L8275 treatment groups height of 79.6cm,control group(ck)74.3cm generated obvious compensatory growth.After rehydration,accelerate plant assimilates accumulation rate.3 and 9 days of drought treatment group lower than the control,but the difference was not significant,produce the same amount of compensation.L8275 leaf area are greater than or identical to the control,better compensation.HST treatments did not significant changes in height,the six days of drought produce the same amount of compensation and other water treatments function time of leaves is shorter,leaf area of 12 days group is small.12 days treatment aboveground biomass of L8275 is lower than the control group,prolonged water stress aboveground biomass decreased.3 days,6 days and 9 days treatment group was higher in aboveground biomass.Four treatment of HST are lower than the control group,D6 is higher,D3 decrease significantly.(3)In yield and water use efficiency,four treatment groups of HST were generating the same amount of compensation or super compensation,where six days treatment groups cause super compensation.Four treatment groups of L8275,yield and water use efficiency cause equal amount of compensation,compensation of D3 and D6 group are better.IN yield and water use efficiency of various water treatments two species appeared first increase and then decrease,short-term stress compensative effect better than long-term stress group.In yield HST 6 days treatment group was 2.68 g / plant,control group(ck)of 2.06 g / plant,super compensation.3 days,9 days,12 days the same amount of compensation.In yield,treatment group of L8275 were for the equivalent compensation,three days of drought treatment groups for 2.07 g / plant,better,control was 1.67 g / plant.Indicating that moderate water stress can contribute increasing production.In yield water use efficiency,six days of HST has WUE of 0.37 g.kg-1,significantly increased,super compensation,ck is 0.3g.kg-1.,The same amount of compensation for the other treatment groups.Short-term drought stress group of 3 and 6 days stress referred WUE were increased,long-term water stress group 9 and 12 days is flat with CK.Filling connection,filling rate and effective filling time of 6 days treatment group of two varieties higher than the control.In addition to the six days treatment group,filling rate and effective filling time of other treatments by drought stress,are lower than the control.Yield components factors,especially the long drought stress water stress significantly increased invalid spike,this phenomenon is more pronounced in the HST.Spike weight and grain number in the short-term stress is higher or unchanged with CK.(4)Efficient irrigation group(APRI)yield trends and full irrigation group(WW)are consistent.Yield of WW group longitudinal group was 12.17 g / pot.Control 27.97 g / pot yield and lateral group 21.53 g / pot,and showed no significant differences,but lower than the balance group,APRI group lateral group,a balanced group and longitudinal group were 21.2 g / pot,22.41 g / pot and 9.41 g / pot,WW group is higher than APRI group,hemi-alternate root rehydration is not conducive to improved yields.Transverse yield WUE group was 0.83 g / kg was significantly lower than 1.29 g / kg.Longitudinal water consumption was significantly reduced,WUE balanced group with a higher flat,APRI group lateral group,a balanced group and longitudinal group was 0.89 g / kg,1.49 g / kg and 1.24 g / kg,WW group were lower than the APRI group,hemi-alternate root rehydration beneficial water use efficiency.Root longitudinal configuration yield components were lower,down effective small panicles,grain number and grain weight decreased with the decrease of production,is not conducive to reproductive output yield.Growth aspect,height APRI group lateral group is high,higher leaf area WW group lateral group.Each longitudinal section of the aboveground biomass were lower.Final lateral group and no significant differences in aboveground biomass balancing group,significantly lower than the other two longitudinal groups.APRI group root configuration greater impact on the shoot and root biomass ratio,WW group significantly decreased longitudinal group root biomass and aboveground biomass,root longitudinal configuration is not conducive to root growth inhibition greater than the above-ground.By the unilateral roots alternately rehydration experiment shows that the longitudinal group yield and biomass decreased significantly,WUE significantly increased yield and biomass and balancing group differences lateral groups was not significant,but lower than the balancing group,significantly lower WUE,so root Architecture compensation effect balancing group of the best and most efficient in favor of high-yielding crops.In summary,yield,growth parameters,water use efficiency are two varieties of wheat,etc produce better compensation or an equivalent amount in compensation after 3-6 days of water stress water and recovery.Other groups were generating the same amount of compensation.Modern hexaploid varieties exhibit higher drought tolerance.Root configuration of lengthways is not conducive to crop growth and yield formation,less water using,high water use efficiency,tillering capacity and assimilates accumulation decreased significantly.The growth of influence of the lateral root configuration of wheat was not significant.Alternative root zone irrigation under severe stress conditions compared with sufficient water to make lower production,higher WUE,not significant,indicating that less irrigation under conditions of alternate partial root zone unilateral rehydration can still produce the same amount of compensation,which will help crops with yield stable and water-saving.