| Potato is one of the main food crops on the Loess Plateau.Due to the shortage of water resources and the backward cultivation techniques,the yield of dryland potato is relatively low and fluctuates greatly between years.In recent years,the trend of global warming has become more and more obvious,which poses a severe challenge to agricultural production in fragile ecological areas.Therefore,under the background of climate change,to optimize potato cultivation and management measures on the Loess Plateau is of great significance to ensure regional food security and to realize the sustainable development of ecological environment.Based on the historical yield and meteorological data,the relationship between potato yield and climate change in Northwest China was explored.At the same time,the effects of different mulching methods on yield and water use efficiency of potato were evaluated via meta-analysis.Three years field experiment was carried out in Guyuan of Ningxia in typical loess hilly area.The high yield and high efficiency cultivation technology of dryland potato was established by exploring the suitable planting density,phosphorus fertilizer application rate and the cultivation mode.The main results are as follows:?1?Based on the long-term data of yield and meteorology,this study analyzed the variation trend of potato yield and meteorological factors in Northwest China,and explored the relationship between potato yield and climatic factors.The results showed that the daily mean air temperature,daily maximum temperature and daily minimum temperature of potato growing period in Northwest China were significantly increased,but the precipitation did not change significantly from 1981to 2015.The diurnal temperature range and solar radiation only show significant changes in some provinces.The change of potato yield in Gansu,Ningxia,Shaanxi and Xinjiang has a significant negative correlation with the change of daily maximum temperature.Potato yield of Gansu,Ningxia,Shaanxi and Xinjiang decreased by 123,195,291 and 339 kg ha-1 for every 1°C increase in daily maximum temperature,respectively.There was also a significant negative correlation between potato yield and daily minimum temperature in Xinjiang.The yield of potato in Xinjiang decreased by 582 kg ha-1 with the increase of 1°C in daily minimum temperature.At the same time,the change of potato yield in Gansu,Ningxia and Qinghai had a significant positive correlation with the change of precipitation during the growth period.For every 100 mm increase in precipitation,potato yields in Gansu,Ningxia and Qinghai increased by 252,182 and 378kg ha-1,respectively.The comprehensive effects of different climatic factors on potato yield in different provinces are different.The variation of potato yield in Gansu and Ningxia is influenced by rainfall and daily maximum temperature.The daily maximum temperature was the key climatic factor affecting potato yield in Xinjiang and Shaanxi,and precipitation was the key climatic factor affecting potato yield in Qinghai.Appropriate measures to adapt to climate change in different regions will help to ensure potato production in Northwest China.?2?The results indicated that relative to no mulching,plastic mulching significantly increased the yield and WUE by 29.2%and 31.7%,respectively.The effects on yield under different mulching methods were ranked as follows:ridge-furrow mulching?RFM?>flat mulching?FM?,and the effects on yield with different mulching extents were ranked full-area mulching?FAM?>partial-area mulching?PAM?.The effects of plastic mulching on the yield using different colors of film were ranked as transparent plastic mulching?TPM?>black plastic mulching?BPM?and under different rainfall levels as?precipitation<400 mm?>?precipitation>400 mm?.The rankings of the effects of plastic mulching on WUE were the same as for potato yield.The yield-evapotranspiration?ET?relationship could be described using a quadratic polynomial,and the yield response curve to ET under plastic mulching fell above the no-mulching curve,indicating that plastic mulching can result in higher yields than no mulching when ET is equal.The yield-ET relationship indicated that potatoes required an ET of 334 mm and 360 mm to achieve the highest yield under plastic mulching and no mulching,respectively,and potato WUE increased linearly with yield under both plastic mulching and no mulching.This study indicated that RFM,FAM and TPM are better potato management measures and that there is potential to improve the yield and WUE on the Loess Plateau.?3?The results showed that plastic mulching and straw mulching increased potato yield in average by 24.3%and 16.0%,respectively.The effects of mulching on the WUE of potato were also improved by 28.7%?plastic mulching?and 5.6%?straw mulching?.At regional scale,plastic mulching performed better in Northeast China and Northwest China,while straw mulching performed better in Southwest China and South China.The yield and WUE of potato in response to mulching were affected by the mean growing season air temperature,water input,soil basic fertility and fertilizer applications.When compared to non-mulching control,the improvements of yield and WUE in potato were higher at mean air temperatures of15-20°C than at temperatures below 15°C or above 20°C during the growing season for both mulching practices.Increase in potato yield under black film was significantly higher than that under transparent film when air temperature was over20°C.Potato yield and WUE increases in mulching treatments were greater in areas with a water input of<400 mm than in areas with a water input of>400 mm.The mean effects of mulching on the yield of potato were greater at relatively low(<100kg ha-1)or moderate(100-200 kg ha-1)N rates than at high(>200 kg ha-1)N rates.Similar trends were observed for P and K rates.In conclusion,this meta-analysis demonstrated that mulching increases the yield and WUE of potato in China and that the adoption of mulching practices should be site specific.?4?Field experiments in 2015-2017 showed that the planting density of 60000plant ha-1 improved plant growth and development of potato.Compared with low planting density(45000 plant ha-1),yield and water use efficiency of potato in planting density of 60000 plant ha-1 increased by 26.1%and 23.5%,respectively.In addition,the number and mass percentages of big tuber were increased in planting density of 60000 plant ha-1.Therefore,planting density of 60000 plant ha-1 is the suitable potato planting density in Guyuan.Three years field experiments showed that P application rate of 90 kg ha-1 improved plant height,leaf area index and aboveground biomass per plant in the middle and late potato growing stage.Compared with control(0 kg P ha-1),yield and water use efficiency of potato under P application rate of 90 kg ha-1 increased by 16.2%and 14.3%,respectively.In addition,the number and mass percentages of big tuber were increased under P application rate of 90 kg ha-1.Therefore,P application rate of 90 kg ha-1 is the suitable potato P application rate in Guyuan.The optimized cultivation modes improved plant height,leaf area index and aboveground biomass per plant during potato growing season.Compared with the traditional cultivation mode,yield and water use efficiency of potato in high yield and high efficiency cultivation mode increased by 54.7%and 62.2%,respectively.In addition,the number and mass percentages of big tuber were increased in high yield and high efficiency cultivation mode.Therefore,high yield and high efficiency cultivation mode is the suitable potato cultivation mode in Guyuan. |
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