| With the global shortage of water resources and the increasingly acute contradiction between supply and demand,water-saving agriculture has been vigorously promoted at home and abroad nowadays.As an effective and feasible water-saving irrigation method,Alternate Partial Root-Zone Irrigation(APRI)has attracted wide attention since it was proposed.However,there are few studies on the water-saving benefits of APRI,which is a combination of spatial deficit and water deficit in different growth stages.In order to give full play to the water-saving benefits of APRI,it is of great significance to improve the water-saving irrigation system for typical crops in arid regions.A pot experiment was conducted during May to October in 2017 at large-scale movable canopy of China Institute of Agricultural Water Conservation in Dry Areas,Northwest Agriculture and Forestry University using "Zhengdan 958" as experimental material.The effects of water deficit on the physiological growth index,water use efficiency(WUE)and water migration and distribution dynamics in soil-crop system of summer maize at different growth stages under APRI were studied.Sixteen treatments were set up in the experiment: Irrigation methods included conventional irrigation(CI,watered both sides),alternate partial root-zone irrigation(APRI,watering was alternated to both sides)and fixed root-zone irrigation(PRD,watering was fixed to one side);Irrigation levels included full irrigation(W0:(70%-85%)FC),mild deficit(W1:(55%-70%)FC)and severe deficit(W2:(40%-55%)FC);Deficit stages included seedling stage(S)and milk stage(M).The irrigation level of deficit stage was corresponding deficit irrigation level,in other reproductive periods,the irrigation level was full irrigation.In addition,full irrigation during the whole growth stage under conventional irrigation was set as the control.The main results are as follows:(1)For the same irrigation method and irrigation level,the plant height,leaf area,the accumulation of dry matter,ET and leaf content of malondialdehyde,proline,soluble sugar under water deficit in seedling stage are significantly lower than those under water deficit in milk stage and the whole growth stage,and rewatering after water deficit treatment at seedling stage,compensation effect of the plant height and leaf area under APRI are stronger than those under CI,but the grain yield,WUE and leaf catalase activity under water deficit in seedling stage are significantly higher than those under water deficit in milk stage and the whole growth stage.There is no significant difference between physiological indexes for different irrigation methods and levels during seedling stage,but there are significant difference between water deficit treatment during milk stage and the whole growth stage.(2)For the same irrigation method and deficit stage,with the decrease of irrigation level,the root weight,aboveground and the total dry matter,grain yield,ET,the content of leaf chlorophyll a,b,chlorophyll and carotenoids are significantly lower,and the decreasing trend of the content of leaf chlorophyll under APRI is significantly higher than that under CI.WUE and IWUE of moderate water deficit treatment are higher than those of severe water deficit,but the difference between them are not significant.(3)For the same irrigation level and deficit stage,the root weight under APRI is significantly lower than that under CI,leaf catalase activity of moderate water deficit under CI is higher than that under APRI,severe water deficit under APRI and CI are significantly higher than that under PRD under water deficit in milk stage and the whole growth stage.Under water deficit in the whole growth stage,leaf catalase activity under CI is higher than that under APRI and PRD,but the difference is not significant,but leaf catalase activity under water deficit in seedling stage under APRI and CI are significantly higher than under PRD,leaf catalase activity of moderate water deficit in seedling under APRI is significantly higher than CI,the difference between severe water deficit under APRI and CI is not significant.(4)For the same irrigation level and deficit stage,compared with CI,the total water consumption and the total irrigation volume under APRI are significantly lower,and APRI increases the grain yield,the total dry matter,IWUE,WUEb and WUEy increase by 22.11%,23.72% and 37.25%.Compared with CI,the content of leaf malondialdehyde,proline and soluble sugar under APRI and PRD are increased under water deficit in seedling stage,but the differences are not significant.The content of leaf malondialdehyde,proline and soluble sugar under water deficit in milk stage under different irrigation methods are PRD>APRI>CI,and the differences are significant.(5)Grain yield is positively correlated with root weight in 0~40 cm soil profile and negatively correlated with root dry weight in 40~50 cm soil profile.The root weight of 0~20cm soil profile in late stage of maize is more closely related to grain yield and increasing root dry weight of 0-20 cm soil profile is beneficial to increase grain yield.APRI not only promotes the growth of roots in surface soil layer,but also benefits the growth of roots in deep soil layer.(6)The different irrigation methods,irrigation levels and deficit periods do not change the accumulation trend of the aboveground dry matter and the total of root weight of maize,but there are significant differences in the aboveground dry matter and the total of root weight of all treatments in different sampling periods.That is,the aboveground dry matter and the total of root weight of different treatments show "S" and "V" curves with the advance of growth period.Based on the analysis of the above indexes of maize,it is found that moderate water deficit(55%-70% FC)treatment in APRI seedling stage is the best treatment for this experiment. |
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