| The unit yield of Inner Mongolia, which was the main producing region of potato inChina, was dramatically low. The shortage of water during the growth period was themain factor limting the yield in the producing region of potato in Inner Mongolia whichwas mostly in arid and semi-arid. Drip irrigation under mulch, as one of the newwater-saving irrigation techniques, was widely applied in potato production in InnerMongolia. However, the advantages of drip irrigation under mulch was canceled out byover-irrigation or non-timing irrigation during the past years. Field experiment wasconducted to evaluate the potato response to water and the rules of growth and nutrientuptake, water consumption characteristics, water use efficiency of potato drip irrigationunder mulch and irrigation techniques. The main results were as follows:There was a significantly negative linear relationship between soil water content andthe rate of seed tuber dry matter and positive linear relationship with plant fresh weightplant root length, root number, root dry matter and, stem height respectively. When thesoil water content ranged from82%to91%, plants showed a rapid emergence, and ithappened19-23days after planting and the emergence rate was100%, also the plant rootfresh weight, the root total length, the number of root, the fresh weight of per plant andthe stem height showed greater growth value than other treatments. When the soil watercontent was higher than91%, it stimulated potato plant emergence earlier but theemergence rate just had30%due to much soil water induced much more rot seed tubers.When the soil water content was lower than75%, plant emergence later, and it happened26-67days after planting plant and growth rate slower.It was benefit for plant growth when the soil water content ranged from85%to91%,plant height, stem diameter, leaf number were higher, root fresh weight and root activityand photosynthesis were highest, plant dry matter accumulation and tuber dry mattercontent were triggered. In this soil condition, the leaf Pro content and MDA content keeplower than other treatment plants, as so as SOD activity. Higher soil water condition hadhigher plant leaf water content, and its benefit for plant physiological metabolism, sogood for tuberization. Water controlling happened after20DAS （days after sowing） had adisadvantage on plant growth, there was no significant difference between25DAS and 30DAS, above-ground dry matter accumulation was significant higher under30DASwater controlling than20DAS or25DAS, and fund no difference of tuber dry matteraccumulation.When the soil water content ranged from85%to91%, the timing of tuberizationwas advanced around5days. In general, the content of IAA、ZR、GA、ABA and thevalues of ABA/IAA, ABA/ZR, ABA/GA of soil water content below85%were higherthan that above85%before tuberization. At tuberization stage, changes of the content ofIAA、ABA and changes of the values of ABA/IAA, ABA/ZR, ABA/GA with the soilwater content increasing and the content of ZR of soil water content ranging from CK to91%were similar to that before, the values of ABA/IAA, ABA/ZR, ABA/GA increasedexcept the values of ABA/GA when soil water content is91%, while changes of thecontent of GA was contrary to that before. After tuberization, with soil water contentincreasing, the values of ABA/IAA, ABA/ZR, ABA/GA just decreased when the soilwater content ranged from66%to78%.The relationship of soil water content and tuber yield, soil water content and wateruse efficiency were in accordance with quadratic model, and the peak values of the yieldand WUE（water use efficiency） were1590.3kg·667m-2and7.98kg·mm-1presentedwhen the soil water content were91%in the pot experiment, and had significantdifference with treatments except78%soil water content. In the field experiment, tuberyield got the highest value when soil water content ranged from85%to100%, and wateruse efficiency was highest from70%to85%. Date of water controlling had no effect ontuber yield, but affected water use efficiency, later date water controlling and higherwater use efficiency.Soil water content of each soil layer was higher in drip irrigation under mulch thanunder mulch without dip irrigation during the growth stages. The average soil watercontent was20%and0-40cm depth was the layer of main water consumption in dripirrigation under mulch and below15%and0-60cm in mulch without dip irrigation.Compared with mulch without dip irrigation, plants growth well and the plant height,stem diameter, leaf area were increased by47.66%,17.86%,113.38%,165.71%,112.21%and287.04%in drip irrigation under mulch.To compare mulch without drip irrigation, the content of N, P, K in various organs ofdrip irrigation under mulch were no obvious difference. The average absorption amountof N, P, K in stem and leaf of drip irrigation under mulch were higher, and the averageabsorption rate of N, P, K in various organs of drip irrigation under mulch were significant higher.The stage of top water consumption amount and water consumption intensity wastuber bulking stage, and followed by tuberization stage, sprout stage and starchaccumulation stage. Compared with mulch without drip irrigation, drip irrigation undermulch was extremely significant on water consumption amount and the average waterconsumption intensity of each plant growth stages and the whole plant growth periodrespectively. Tuber yield was3706.4kg·667m-2, significantly higher in drip irrigationunder mulch than much without drip irrigation. The WUE of potato drip irrigation undermulch was11.36kg·mm-1, which was higher than that without drip irrigation, but thedifferences were not significant.Irrigated every8days benefited for potato plant growth, this can be contributed tocongenial soil water content at0-40cm depth for soil layer of high root concentrationdistributing, and the average plants heights, dry matter accumulation, tuber starch contentand water use efficiency was40.8cm,578.87kg·667m-2,13.9%,11.2kg·mm-1respectively, which was higher by3.1%,4.1%,8.9%and10.1%than irrigated every4days and by37.2%,9.3%,26.3%and33.3%than irrigated every12days, respectively.The peak tuber yield was obtained from plants irrigated every4days, and the tuber yieldwas2359.9kg·667m-2, which was higher by12.1%and15.4%when compared withyield from plants irrigated every8days and12days, respectively. Tuber yield of irrigatedevery4days was significantly higher that of irrigated every8days.The bigger per irrigation amount and total irrigation amount the higher soil watercontent and yield, while the water use efficiency presented a single peak curve with theincreasing of irrigation amount. Two years experiments showed that the yield and WUEof drip irrigation under mulch were3395.92kg·667m-2and16.89kg·mm-1in2010,whichwere significantly increased by41.3%and69.1%than furrow irrigation methods. Theyield and WUE of drip irrigation under mulch were2175.79kg·667m-2and8.23kg·mm-1in2011，the former was no significant difference, but the latter was increased by6.8%as comparing with furrow irrigation methods. |
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