| Field experiment was conducted in Flood river irrigation district in Minle Gansu in April-September 2009, study on deficit irrigation technology about straw mulching potato cultivation without tillage. Experiment was composed of six treatments at different growth stages and different levels of deficit conditions, mild deficit Y1(LDYM)treatment in Seedling stage , mild deficit Y2(LDJS)treatment tuber initiation period, severe deficit Y3(SDYM)treatment in Seedling stage, severe deficit Y4(SDJS)treatment tuber initiation period, straw mulching sufficient irrigation control CK1 treatment, conventional planting sufficient irrigation control CK2 treatment. The results showed that:1. Potato's no-tillage mulching cultivation is a new type of technique, it has changed the traditional potato cultivation methods.2. Soil moisture content of maturity and germination stage is higher in the whole growth period roughly changes. Higher soil water content in germination stage related to crop growth conditions and straw mulching agronomic water saving measures, the relatively small plants group, plant transpiration is not yet strong, at the same time straw mulching also suppress evaporation, total water consumption in small, the higher soil water content in maturity was mainly due to more rainfall in September. In addition, soil moisture content of the conventional without cover mulching control CK2 treatment is lower than the rest of processing overall.3. Crops'evaporation characteristics quite different in Straw mulching cultivation without tillage and conventional ridge planting two cropping patterns, the curve of soil evaporation of conventional cropping amplitude changes relatively large with the rainfall and irrigation, Overall amplitude is much larger than no-tillage cultivation of straw cover model, the daily average evaporation is about the 3.53mm, The no-tillage cultivation of straw covering curve is more stable, with a minor change in rainfall, the cropping patterns of the daily average evaporation is about keeping in 0.85mm. Soil evaporation accounts for the proportion of the total field evapotranspiration are quite different in two cropping patterns, straw mulching no-tillage cropping patterns evaporation accounts for 29% of total evapotranspiration in whole growth period, conventional cropping patterns accounted for 64%, Straw plant model can effectively reduce the crop evaporation, use the limited water to the crop transpiration.4. Water use efficiency of potato of Y1 (slight seedling) treatments with Y3, Y4, CK2 treatment were very significant different (P <0.01), its value reaches the maximum 7.41 kg/m3, And water use efficiency of Y3, Y4 treatment only 7.15 and 7.10 kg/m3 under deficit irrigation, show mild water stress can get a higher water use efficiency. In addition, CK2 treatment's water use efficiency was significantly (P <0.01) lower than other treatment, only 6.07 kg/m3, and lower than CK1 by 19.60%.5. Y1, Y2 mild water deficit treatment, plant height has significant rehydration and suddenly growth phenomenon after given drought, but the extent of water recovery is certain. Y3, Y4 severe stress treatments have had a negative effect on plant growth.The stem diameter of plants of each treatment showing some rehydration phenomenon after the drought stress, but mild treatment recovery better than severe treatment in the effect. Y1 is the best water rehydration treatment, the final diameter as same as the treatment CK1 basicly, the body can better promote the plant material transport.Leaf area index rewater compensation effect good after light deficit in seedlings stage. LAI changes of different treatment at all growth stages show single peak curve, LAI peak appears in the tuber initiation period, Afterwards leaves began to decline, leaf area index began to decline, and leaf area index largest differences between treatments appears in the tubers initiation period. Throughout the growth period severe water stress Y4 treatment dry matter accumulation overall lower than the other treatment, CK1 and Y1 treatments overall level higher than the rest of treatment. Seedlings mild water stress Y1 as same level as Y2, Y3, CK2 treatment on dry matter accumulation in the early days, but the treatment compensate the rehydration obtained good results later, the final dry matter accumulation higher than the rest of the standard treatment, but seedling severe stress of Y3 treatment failed to achieve a good compensation effect.6. 5-15cm soil temperature showed a single peak-shaped curve throughout the day of no-cover conventional cropping patterns, while the cover treatment was slowly increasing curve shape, the treatment day changes relatively slow, amplitude of diurnal variation significantly smaller, and subjected influence of atmospheric temperature from the surface to the deep getting smaller and smaller, conventional non-cover changes sharply, large amplitude, the highest point appearances at 2-3 o'clock in the afternoon, no-covering treatment's 5cm average ground temperature high 5℃than covering treatment in the whole growth period. This reflects the role of a straw-covered thermostat, if outside air temperature higher, inhibit soil temperature increased, while at night under low ambient temperature, maintaining the temperature does not drop.7. Potato production in Y1 and CK1 treatments had no significant difference (P> 0.05), and both were showed significant differences (P <0.01) with CK2, Y2, Y3, Y4 treatments, and Y3treatment obtain the lowest yield. Seedlings mild water stress Y1 treatment production did not decreased significantly with fully irrigated CK1 treatment, while water consumption was reduced compared with CK1.8. CK1 treatment obtain the highest net income for 14404 yuan ? hm-2, Y1 second, Y1 and CK1 treatment were significantly different with the other treatments, Y3 get the lowest net income. Full irrigation CK1 treatment receive 263 yuan ? hm-2 more than Y1, but more irrigation 150 m3 ? hm-2. Conventional cropping CK2 not only consume more water, but also receive lower net income.9. Potato dry matter content of Y1 treatment was significantly (P <0.01) higher than Y3, Y4 and CK2 treatment, reached 22.41%; starch content was significantly (P <0.01) higher than Y3 and CK2 treatment, significantly (P <0.05 ) higher than the Y4 treatment, value reached 15.44%; Vc content was significantly higher than other treatments, reaching 14.56 mg/100g tuber. Show mild water deficit in seedling stage can improve the quality of potatoes.Starch content of conventional no-tillage CK2 treatment was significantly (P <0.01) lower than the straw coverage treatment CK1, Vc content was significantly lower than CK1.10. Straw coverage no-tillage cultivation pattern of potato has obvious inhibiting and steamed soil moisture effects, while changed the status of straw burning in Hexi area, reducing greenhouse gases CO2 emissions, has a certain effect for straw returning, fertility soil, control Hexi region dust.
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