Influences Of Different Low Limit Of Soil Moisture On Growth And Yield Of Spring Wheat Under Permanent Raised Bed

Conservation tillage technology is a new type of farming system which fixed Conservation tillage,ridge tillage,furrow irrigation and less technologies,zero tillage and straw mulching.Permanent Raised Bed(PRB)can improve the soil environment between soil and crop growth,which is conducive to coordinate the contradiction between individual and group of wheat and play the maximum advantage of the boundary line of wheat,It Makes the individual robust,per ear,grain weight,grain,more conducive to increase wheat yield.Lower limit of soil water refers to the lowest soil moisture content,It decided start time and times of irrigation and will affect the determination of irrigation amount frequency.Controlling suitable soil moisture can make its reach a quality site scope,it will improve yield and water use efficiency.The project’s aim was to analyze the effects of different soil water thresholds on the growth and yield of spring wheat(Triticum aestivum L.)under permanent raised bed tillage(PRB).A field investigation was carried out to assess effects of different soil water thresholds under PRB and conventional farming systems(CF)on leaf area index(LAI),dry matter,yield,water use efficiency(WUE)and consumption characteristics of spring wheat.The experiment followed a completely randomized split-plot design,taking soil water thresholds(T1:40%of the field capacity,T2:55%of the field capacity,T3:70%of the field capacity,CK:85%of the field capacity)as main plot treatments,and tillage systems(PRB and CF)the sub-plot treatments.The results show that:(1)Permanent raised bed tillage(PRB)is beneficial to the accumulation of dry matter,the accumulation of ear,grain weight and allocation proportion arrive the maximum when thelow limit of soil water is 70%.It is beneficial to accumulation of dry grain matter.As the lower level of soil moisture increases,the leaf dry weight of wheat,dry weight and dry weight of the stalk are increasing.In the mature period,the lower limit of soil water in 85%,wheat leaf,leaf sheath and stem dry weight and distribution proportion is highest,the allocation amount and the proportion of wheat kernels in the lower limit of soil water under the condition of 70%,the largest grain allocation proportion accounted for about 50.8%to53.49%(2)Permanent raised bed tillage(PRB)can obviously increase the content of chlorophyll of wheat and raise the photosynthetic rate,when the lower limit of soil water was 70%,the photosynthetic rate of wheat arrive the maximum,it is beneficial to the growth of wheat.With the lower limit of soil moisture increased,the amount of chlorophyll in wheat increased,representing 85%>70%>55%>40%.The wheat of Permanent raised bed tillage(PRB)processing net photosynthetic rate,transpiration rate and stomatal conductance(Gs)was the highest than other various processing,it is beneficial to the formation of wheat photosynthetic product.(3)Permanent raised bed tillage(PRB)greatly reduces the amount of water consumed of the each reproductive stag and the whole growth period.It Increase the proportion of the total water consumption of wheat on rainfall and the amount of water stored in the soil and reducing the proportion of the total water consumption.The Change rule of Water consumption and the water consumption intensity under different treatment is the same.Heading-Middle Filling>Jointing-Heading>Seeding-Jointing>Middle Filling-Maturity.The maximum period of water consumption and the intensity of water consumption is Jointing-Middle Filling,Water consumption component of wheat proportion is:the irrigation water>rainfall>soil water consumption.With the lower limit of soil moisture increases,the total consumption of wheat and the amount of irrigation water is increasing gradually,and the consumption of soil water storage decreases gradually.(4)The lower limits of soil water have a significant impact on yield and water use efficiency,Permanent raised bed tillage(PRB)is beneficial to the increase of wheat yield and the efficiency of water use.The yield and water efficiency of wheat is highest when the low limit of soil water is 70%.In traditional farming,the yield and water use efficiency is 7233kg/hm~2 and 10.57 kg/hm~2/mm,in Permanent raised bed tillage(PRB),The yield and water utilization efficiency of the fixed track is 7733kg/hm2 and 14.3 kg/hm2/mm.Compared with traditional farming,the yield increased by7%,5%,7%and 1%and water use efficiency increased by 4%.Based on the growth,photosynthetic properties,water use efficiency and yield,In the irrigation district of hexi oasis,Permanent raised bed tillage(PRB)Can improve the wheat leaf area and dry matter accumulation,it is beneficial to wheat growth.It also can improve the yield and water use efficiency of spring wheat.In the lower limit of soil water was 70%,two kinds of cultivation mode of spring wheat spike grain number and grain weight and water use efficiency,yield reached the maximum value,so the 70%field capacity would be the most appropriate soil water thresholds for the growth and yield of spring wheat.