Interaction And Regulation Mechanism Of Soil Water And Gases In Potato Field Under Drip Irrigation

Potato ranks as the fourth largest global food crop.The suitable environments for potato growth include stable and high soil moisture,good soil aeration and suitable soil temperature in the root zone.Potato is an important crop in Northwest China,where rainfall is little and evapotranspiration is large,water shortage is the key factor limiting local potato production.Therefore,regulating soil temperature and aeration by regulating soil moisture,so as to realize water saving,high quality and high yield of potatoes is of great scientific and practical significance.In this study,two years of field experiments from 2014 to 2015 were conducted to study the effects of different proportions of wetted soil volume and different plastic film mulching methods on temporal and spatial dynamics of soil water content,soil temperature,soil aeration and their effects on the growth,yields,evapotranspiration and qualities of potatoes.The effects of different soil compactions on soil moisture,soil aeration and potato growth were studied by pot experiments.The main results are as follows:(1)Soil temperature in the treatment wetting 55 percent of the soil volume under drip irrigation with black plastic mulch was 15.3?18.4 ? during tuber initiation and bulking stage,which was lower than other treatments and was beneficial to tuber growth.Two hours after irrigation,soil CO2 content increased,while soil O2 content and water vapor content decreased,and the decreased extent of the water vapor content increased with the decrease of the soil wetting proportion.The evapotranspiration and the accumulation of aboveground biomass increased with the increase of soil wetting proportion.Both the aboveground dry matter content and the biomass accumulation of potato tubers were not significantly different under different proportions of wetted soil volume.Both yield and water use efficiency(WUE)were higher in the treatment wetting 55 percent of the soil volume than in other treatments.(2)The warming effect of plastic film mulching was obvious at the stage of early vegetative growth.The average temperature in the root zone was 1.6?5.4 ? higher in plastic film mulched treatments than in non-mulched treatments.Soil temperature in the root zone under black plastic film mulch were 2.4 ? and 0.8 ? lower than that in treatments with transparent plastic film mulch and without mulch during the middle stage of potato growth,respectively,which was beneficial to tuber initiation and tuber bulking.Plastic film mulching reduced soil aeration,but the decreased extent of soil aeration under black plastic film was small,which had no adverse impact on potato growth.Two hours after irrigation,the soil water vapor content was reduced in treatments with plastic film mulch,but it was increased in treatments withthout mulch.Both plant height and biomass accumulation were higher in treatments with plastic film mulch than in treatments without mulch.LAI in plastic film mulched treatments was 2?3 times of that in non-mulched treatments.Treatments with black plastic film mulch had higher WUE and larger amount of tuber biomass than other treatments.(3)Soi aeration was decreased with the increase of soil compaction,leading to low potato tuber yield,high rate of malformed tubers and low vitamin C content in the tubers.(4)Under the conditions of bare soil,pot and field with sandy loam soil,the same relationship of soil moisture and soil aeration were found.Soil water-filled pore space(WFPS)was negatively correlated with soil O2 concentration and positively correlated with soil CO2 concentration.There was a negative correlation between soil O2 and CO2 concentration.Potato tuber yield,WUE and quality indexes were not significantly correlated with average WFPS,soil CO2 and O2 concentrations during the whole potato growing season.(5)Treatments wetting 55 percent of soil volume under black plastic mulch could increase soil temperature in the root zone at the stage of early vegetative growth and decerease soil temperature in the root zone at tuber initiation and bulking stage without defective aeration,which was benificial for potato growth and could enhance tuber yield,suggesting that these practices were favorable for potato production in arid areas of Northwest China.