| Mulched drip irrigation under water deficit regulation(WDR) potato trials were launched in 2015 from April to September in the public Zhangye in Gansu Province Minle County Yimin Irrigation Experimental Station. Depending on the different water stress level and WDR growth period, this study designed five WDR processes(WD1 ~ WD5) and a full irrigation control check(CK). The five WDR processes were divided into mild(55% to 65% of field capacity) and moderate(45% to 55% of field capacity) of water stress in the tuber initiation, tuber bulking and potato starch accumulation period. The field experiment was conducted to test the potato periodic evapotranspiration, yield, water use efficiency(WUE), and dynamic growth influencing factors of mulched drip irrigation under WDR. Besides, crop water production function based on Jensen model was established, and the optimal irrigation schedule for potato was determined in this study. The results showed that:1. Mulched drip irrigation under WDR test on influence depth of potato soil moisture is approximately 0 ~ 40 cm soil layer, while the influence of soil moisture in 40 ~ 60 cm soil layer is not obvious. Potato tuber bulking of water consumption is the largest growth period, followed by seedling and tuber initiation period, the minimum water consumption is potato starch accumulation period. And the large degree of water stress have large impact on water consumption of each potato growth.2. Potato yield was not decreased in low WDR plots during tuber initiation(p> 0.05), but was significantly decreased in the medium WDR plots during tuber initiation and low and medium WDR plots during tuber bulking(p <0.05). The WUE was maintained in low WDR potato during tuber initiation, which significantly improved by 6.2%, 8.3% and 6.7% than WUE in medium WDR plots during tuber initiation, low WDR plots during tuber bulking and CK, respectively. With the increasing of water consumption, the potato bulb yield increased, while the WUE decreased. The higher potato bulb yield and lower WUE in CK than medium WDR plots during tuber bulking. And water consumption increased by 22.4%, the potato bulb yield increased by 20.4% and the WUE decreased by 14.0%. WDR have no significant effect on tuber number, but have significant influence on tuber weight per plant, and the greater degree of water stress also have greater impact on reducing tuber weight per plant. Moreover, different levels of water stress did not cause a significant effect on tuber diameter and longitudinal diameter among treatments, and that cause a high consistency among treatments.3. Soil moisture environment have a great impact on potato plant height, but have no effect on the primary stem diameter. Leaf area growth rate of potato starch accumulation under low WDR treatment is large in tuber initiation and bulking stage than other periods, and leaf photosynthesis is also more obvious. The result could indicate that soil moisture meet the crop needs have a significant effect on enhancing crop LAI and LAD. In addition, the relative growth rate(RGR) during the potato tuber initiation to bulking period is higher than other growth stages.4. The largest sensitive index was found at the tuber bulking stage, followed by the tuber initiation stage and relatively small at the seeding and potato starch accumulation stages. The optimal irrigation system was established by genetic algorithm with crop water production function show that the highest potato bulb yield(43.86t/hm2) can be obtained when the growth period irrigation quota was up to 225 mm, and irrigation WUE is 19.5kg/m2. The recommended amount of irrigation is 20-30, 70-75, 100-115 mm and 20-25 mm for the periods of seeding, tuber initiation, tuber bulking and potato starch accumulation, and the irrigation interval is 7 days.Therefore, mulched drip irrigation under WDR could reduce potato water consumption, in same time, it could enhance the WUE. The low WDR does not affect the potato yield during tuber initiation, and it could reach the water-saving purposes. |
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