| In this study,a total of six treatment groups were designed to investigate the effects of straw strip mulching on flag leaf water potential,flag leaf relative water content,soil water content,yield,and water use efficiency(WUE) of winter wheat after flowering in dryland farming area of western Loess Plateau,including straw strip mulching treatments SM3(straw mulching coverage 59%),SM4(straw mulching coverage 50%),SM5(straw mulching coverage 42%),SM6(straw mulching coverage 37%),with plastic film mulching(PM) and open field(CK) as controls.The results showed that compared with CK,the straw strip mulching improved the flag leaf water potential,flag leaf relative water content,flag leaf water content and surface layer soil water content by 9.2%,6.6%,3.6% and 30.0%,respectively;while plastic film mulching decreased the flag leaf water potential,flag leaf relative water content,flag leaf water content by 6.0%,4.2% and 3.2%,respectively,but increased surface soil moisture by 15.1%. The diurnal variation of flag leaf water potential of winter wheat showed a V shaped trend of higher in the morning and afternoon but lower at noon during 7-28 days after flowering. Flag leaf water potential under straw strip mulching treatments in the morning,noon and afternoon was increased by 10.6%,9.8% and 7.7% compared with that under CK,while that under plastic film mulching was reduced by 4.6%,7.9% and 4.8%,respectively. Compared with CK,the yield and WUE of winter wheat under SM was increased by 3.0%-6.5% and 6.4%-17.5%,and there are significant difference between SM and CK. SM5 treatment had the highest yield(3 866.6 kg·hm-2) and WUE(15.7 kg·hm-2·mm-1) among all straw strip mulching treatments.Grain yield has positive correlation with the spike number per unit area(r=0.693**)and WUE(r=0.615**); the spike number per unit area has a positive correlation with WUE(r=0.690**) and surface soil water content(r=0.570*).Overall,increasing surface water content improved the water supply of flag leaf of winter wheat by mulching in arid years,and thus enhanced spike number per unit area and WUE. Straw strip mulching with 42% coverage has the best yield increase effect in dry years,which is suitable for the green and sustainable development of dry farming in Northwest of China. |