Study On Mulched Drip Irrigation Under Water Deficit Regulation Of Potato (Solanum Tuberosum L.) In Hexi Oasis Region

The experiment about mulched drip irrigation under water deficit regulation ofpotato was conducted in Zhangye Water Authority Irrigation Experiment in Gansu duringApril to November in2012. According to the different growth stages at different waterdeficit levels of potato, the experiment was composed of five water deficit regulationtreatments and one control CK treatment, low water deficit treatment WD1，WD2andWD3in tuber initiation stage, tuber bulking stage and in starch accumulation stage (soilmoisture content was maintaining at55%to65%of field capacity, FC, Field Capacity),medium water deficit treatment WD4and WD5in tuber initiation stage and tuber bulkingstage (soil moisture content was maintaining at45%to55%of FC), fully irrigatedtreatment CK during growth stages of potato (soil moisture content was maintaing at65%to75%of FC). The main studies were about the growth, water consumptioncharacteristics, photosynthetic physiological indexes, tuber yield of potato and theinterrelation with soil moisture. The main results were as follows:1. The effect of mulched drip irrigation under water deficit regulation on the changeof0~40cm layer soil moisture content was graeter than40~60cm. Water consumptionperformance in various potato growth stages indicated that water consumption duringtuber initiation valued the highest, followed by that during tuber expansion, seedling, andstarch accumulation sequentially. Periodic water consumption of potato was greatlyaffected by WDR, and the higher water deficit in soil water, the less potato periodic waterconsumption.2. The maximum yield was found in the fully irrigated potato (CK) with soilmoisture maintaining at65%to75%of field capacity (FC, Field Capacity), while theminimum yield was in the medium WDR plots with soil moisture maintaining at45%to55%of FC during tuber bulking of potato. Difference was not significant（p＞0.05）intuber yield between CK and low WDR potato with soil water content maintaining at55%to65%of FC during tuber initiation, but tuber yield was significantly （p＜0.05） lowerby22.9%～39.8%in the other four WDR treatments than that in CK. Therefore, potatoyield was not decreased by low WDR during tuber initiation, but was significantlydecreased in the medium WDR plots during tuber initiation and low and medium WDRplots during tuber expansion. Mulched drip irrigation under WDR had significant effecton potato tuber number and tuber weight per plant, but no significant effect was found ontuber lengthwise and lateral diameter. The highest WUE was maintained in low WDRpotato during tuber initiation, significantly improved by36.2%and32.4%respectivelythan that in medium WDR plots during tuber bulking and low WDR plots during potatostarch accumulation. The lowest WUE and IWUE both occurred in medium WDR plotsduring potato tuber expansion, and14.2%of WUE and9.4%of IWUE was respectivelyimproved in low WDR plots than in CK. Although WUE and IWUE were both higher in low WDR potato during tuber bulking and medium WDR plots during tuber initiationthan in CK, their tuber yields were significantly reduced.3. WRD in tuber initiation stages and tuber bulking stages had no significant effecton plant height, stem diameter and LAI. LAI, LAD and RGR were reduced by WDRduring tuber bulking and starch accumulation stage. It was concluded that the soil waterof tuber bulking and starch accumulation stage played an important role in the growthand development of stems and leaves of potato.4. The results showed that Pn and Tr were reduced by WDR during different potatogrowth stages, and their reduction levels were determined by WDR levels. No differencewas found in Pn before and after re-watering of potato, but Tr and Gs were obviouslyimproved. At the tuber initiation stage of potato, Pn varied as double-peak curves, and Trin low water deficit potato (WD1) and full water application (CK) both varied assingle-peak curves, with the trend in medium water deficit (WD4) being not obvious.Photosynthetic available radiation (PAR), air temperature (Ta), and leaf temperature (Tl)are three dominant elements affecting Tr under full water application or low water deficit,but effect of PAR was lower than Ta and Tl under medium water deficit.Therefore, the use of drip irrigation under plastic film for potato can always keepgood soil moisture around root, reduce leakage losses. The light water deficit can furtherimprove water use efficiency (WUE) during periods of tuber initiation, but does notreduce tuber yield.