Northeast Corn Material Production And Root Water Absorption Study On The Response Of Water Stress

Strengthening the water-absorbing process of typical vegetation roots and its response to water stress has an important role in understanding the process of land-water cycle and improving the simulation of water-heat flux by the land surface process model.In order to find out the effects of drought in different periods on the growth and yield of maize,the differences in root water uptake under different water stress conditions,and the shortage of root water uptake schemes in existing land surface process models.For the research object,based on the field observation station of Jinzhou corn farmland ecosystem,large-scale farmland soil moisture control test site,large root system observation system,combined with micro-root tube and stem flow observation technology,root distribution of different development stages of maize under different soil moisture conditions.Dynamic observations of biomass and root water-related parameters were carried out to analyze the effects of different degrees of drought on maize growth and yield at different developmental stages.Combined with the measured data,the response of root water uptake to water stress was revealed and the crop model was optimized.Through the quantitative evaluation model to improve the impact on land-fluid flux simulation,reveal the reasons for the influence of root water absorption on land-water heat exchange,and provide reference for understanding the land-sea interaction law,improving the land surface process model and even the climate model simulation capability.The main findings are as follows:1.With the prolongation of drought duration in the jointing stage of maize,the reduction of various parameters increased,and the recovery ability after rewatering decreased.The same duration of drought in different developmental stages,the reduction of each parameter showed that the tasseling period was greater than the jointing stage,but the resilience after rehydration showed that the tasseling period was less than the jointing stage.The effects of different stages of drought on the yield of maize were different.The 30-day water control at jointing stage affected the number of ears per panicle by affecting the length of panicle and bald tip,while the water control in the jointing period was 40 days and the water control in the tasseling period was 40 days.By reducing the length of the ear and the thickness of the ear,the number of grains per ear is small,and at the same time,the yield is affected by reducing the weight of 100 grains.2.The net photosynthetic rate(P_n)and transpiration rate(T_r)of leaves had obvious hysteresis in response to drought,and the tasseling period responded faster than the jointing stage.After water treatment for 30 days at jointing stage,P_n and T_r can be restored to normal levels;after water treatment for 40 days at jointing stage,rehydration after treatment,P_n and T_r first increase and then decrease,can not return to normal level;After 40 days of treatment,the water was rehydrated,and P_n and T_r could not be recovered.Different drought treatments reduced the stem flow rate(SF),and the original exponential relationship between day stem flow(DSF)and photosynthetically active radiation(PAR)disappeared.The water control during the jointing period was 40 days and the water control during the jointing period was 30days.Linear relationship;After the rehydration,the original relationship of each treatment is restored.3.There is a good space-time correspondence between corn root length density(RLD)and soil moisture(W_r).The root growth of plants moves to deep soil due to drought.In the initial stage of drought,the roots of water-stressed plants were more than normal plants.As the degree of drought increased,the aging rate of the roots of the plants increased,and the deep roots began to increase.The drought in the tasseling period caused the dry matter of the roots to rapidly shift to the position of the ear,and the aging rate of the upper roots was faster than that during the jointing stage.Root water uptake(RWU)is significantly affected by soil moisture(W_r)and radiation.Root water uptake(RWU)has a significant logarithmic relationship with radiation in the normal state of water other than the end of plant growth,and this relationship is weakened with the persistence of drought.After rehydration,the logarithmic relationship between the two will also recover.4.In the root water absorption optimization function,it is almost no effect on the heat flux simulation to determine whether the root system absorbs water in a certain layer of soil.The cumulative root efficiency lower limit parameter that determines the maximum transpiration rate has a significant impact on the land surface process simulation.The heat flux simulation accuracy increases as the parameter decreases.After optimization of the root water absorption function,the simulation performance of soil moisture and temperature,sensible heat and latent heat in the precipitation-preferred land surface model was significantly improved,especially in the most vigorous and continuous no-water period of corn water,which proved that the root water absorption process was carried out for the model.The optimization has a good adaptability to the simulation of water and heat flux in corn farmland under drought conditions.