Study On Dynamics Of Soil Moisture Content And Its Relationship With Root Growth And Physiological Functions In Wheat (Triticum Aestivum L.) Under Conditions Of Returning Corn Stalks To Field

Water resources is the main restrict factors for the agricultural production as well as an important constraint for the effect of stalks returning to field.A 2-year micro-plot experiment was conducted under rain-proof shelter to investigate the influence of returning corn stalks to field under different soil moisture on wheatgrowth,grain yield,stalkdecomposition regularity and water use efficiency of winter wheat.Research was carried out with corn stalks returning,which was powdered and plowed into soil,with non-stalks returning as control(CK),and three water treatments,which were subjected to 50%~55%(Drought),60%~65%(Slight Drought)and 70%~75%(Normal)of field moisture capacity,respectively.The main results are as follows:1.Under drought condition,population,leaf area per plant and dry matter accumulationwere all dramatically reduced(P<0.05),the number of nodal roots per plant at maturity as well as root activity and root dry weight density within 0~25 cm soil layer of winter wheat during different growing stages was dramatically reduced(P<0.05).Compared with those in CK,the maximum population in RS treatment was increased.Under drought soil moisture content,leaf area per plant as well as dry matter accumulation above-ground parts in RS treatment was dramatically decreased,both root vigor and drop rate of root dry weight density within 25~50cm soil layer were significantly higher than those in CK;Under slight drought and normal water supply conditions,the maximum population,leaf area per plant and dry matter accumulation above-ground parts in RS treatment was increased,the decrement of both root vigor and root dry weight density within25~50cm soil layer were lower in RS treatments.2.Under drought condition,spike number as well as grain yield of winter wheat was dramatically reduced(P<0.05),irrigation amount and total water consumption were also dramatically decreased,consumption of soil water storage and water use efficiency were dramatically increased.Compared with those in CK,grain yield and water use efficiency were significantly decreased;Under slight drought and normal water supply conditions,corn stalks returning would increase consumption of soil water storage significantly,decrease total water consumption amount,increase spike number,grain number per plant and improve grain yield and water use efficiency dramatically by conserving soil water storageduring the whole growing period.In addition,the present study showed a significant interaction of yield and water use efficiency between corn stalks returning and soil moisture condition.3.After 130 days of decomposition,straw decomposition rate and nitrogen release rate were dramatically reduced under drought condition(P<0.05),while reached to a same level after 220 days under different soil water content,each of them reached to69.5%,68.4%,66.5% and 75.9%,76.3%,77.3%.Compared to pre-sowing,soil organic content were all present a decrement trend,but the drop rate of RS treatments was lower than those in CK.Compared to CK,soil organic content in RS treatment was dramatically increased to 17.22% and 13.47% at pre-sowing and maturity stage.Under the same soil moisture content,soil alkaline hydrolytic nitrogen content was also dramatically increased in RS treatment at different growing stages.In addition,wheat grain protein content in RS treatments tend to be decrease,grain yield dramatically decreased 20.36% under drought condition in RS treatment.