Study On Water Productivity Of Potato(Solanum Tuberosum L.) Under Mulched Drip Irrigation In Desert Oasis Region

The field experiment was carried out in Yimin Irrigation Experimental Station the Administration of Hongshui River in Minle County,Zhangye City,Gansu Province northwest China from April to September,2016.The effects of water stress on water consumption,potato yield,water use efficiency(WUE),irrigation water use efficiency(IWUE),tuber starch content,soil nutrient change and growth dynamics during different growth stages and different water deficit levels were analyzed in this experiment.This study were designed with eight regulated deficit irrigation treatments(WD1-WD8)with different water deficit degree during different growth stages and one control group(CK)with full irrigation all the growth time,which were slight regulated deficit irrigation treatment during seedling stage WD6(soil water content was maintaining at 55% to 65% of FC,Field Capacity is referred to as FC),medium regulated deficit irrigation(45% to 55% of FC)treatment during seedling stage WD7,slight regulated deficit irrigation(55% to 65% of FC)during tuber formation stage WD1,medium regulated deficit irrigation(45% to 55% of FC)during tuber formation stage WD4,slight regulated deficit irrigation(55% to 65% of FC)during tuber bulking stage WD2,medium regulated deficit irrigation(45% to 55% of FC)during tuber bulking stage WD5,slight regulated deficit irrigation(55% to 65% of FC)during starch accumulation stage WD3,medium regulated deficit irrigation(45% to 55% of FC)during starch accumulation stage WD8,and one full irrigation(65% to 75% of FC)treatment during all the growth stage CK control group.The field experimental results showed that:1.The water productivity of potato under mulched drip irrigation was significantly affected by water deficit irrigation.The potato yield,biomass and harvest index(HI)of potato were significantly decreased(P <0.05)during the tuber formation stage with slight water deficit.The potato yield,biomass and harvest index of the water treatment WD1 were significantly increased by 70.82%,20.65% and 52.38%,respectively,compared with the water treatment WD4 with medium water deficit irrigation during the tuber formation stage.2.Compared with the control group CK,the water use efficiency(WUE)and irrigation water use efficiency(IWUE)of the slight regulated deficit irrigation during tuber formation stage WD1 were increased by 29.04% and 35.61%,respectively.The yield of the control group CK with full soil water all the time was higher than that of other water treatments,but the water use efficiency and irrigation water use efficiency of CK control were significantly reduced.At the same time,the medium water deficit treatment of tuber formation stage was also beneficial to improve the potato production,edible value and economic benefit of starch tuber starch content,potato dry matter content and so on.There was no significant difference in dry matter content between treatments and control group CK.The starch content of water deficit treatment WD1 was significantly increased by 49.18% compared with CK control,which was 6.26% higher than that of WD4 with medium water deficit irrigation during the tuber formation stage.3.The daily water consumption and water consumption modulus of mulched drip irrigation were as follows: tuber bulking stage > tuber formation stage > starch accumulation stage > seedling stage.The CK control was maintained at a high water content level and the total water consumption was the highest,which was significantly higher than that of other water treatments about 13.15% to 43.84%.The total water consumption of WD4 was 34.48% lower than CK control which consumed the most soil water during the whole growth period.The water consumption modulus and daily water consumption of potato were significantly decreased with the increase of water deficit level(P <0.05).Potato tuber bulking stage was the most critical period of water demand,and the sensitivity to water deficit was the highest,and the water deficit of tuber bulking period will lead to the serious decrease of potato yield and starch content.The degree of water sensitivity of tubers formation stage was the second,and the sensitivity to water deficit was smaller during the seedling stage and starch accumulation stage.4.Only during the seedling stage,the plant height and stem diameter of potato were affected by soil water deficit.The results of the experiment showed that the higher the degree of water deficit,the more affected by water.However,plant height and stem diameter were not significantly affected by water deficit in other growth stages(P> 0.05).The trend and direction of leaf area index(LAI)and leaf area duration(LAD)of potato during the whole growth period were all the same,which were short and slow growth in the early growth stage,rapid increase in the middle stages and slow or stop in the later growth stages.In the key stage of potato growth and development,maintaining the soil water content to meet the normal water demand of crop has significant effect on improving the index of crop leaf area index and leaf area duration.Therefore,the root area soil of potato field could be always kept moist state with the mulched drip irrigation,which also might reduce the leakage losses and the loss of evaporation between plants of potato.Water deficit during tuber formation stage can further improve crop water use efficiency,irrigation water use efficiency and potato starch content,especially the water treatment with slight water deficit during the tubers formation stage.