Effects Of Ridge And Furrow Mulching With Plastic Film On Yield And Water Use Efficiency Of Potato In Semi-arid Agroecosystem (Dingxi)

In the circumstances of low air temperature and low precipitation during the early growing season, coupled with higher air temperature during the later growing season in semi-arid Loess Plateau region, two experiments of different cropping patterns (various plastic mulching methods) combinated plastic film mulching for varying durations in potato production had been investigated in2009-2010in Dingxi with three aims of improving potato yield, rainwater use efficiency and prevent the high temperature during later growth stage.The first experiment comprised four different treatments in2009:(1) flat field and non-mulched control (CK);(2) soil ridges non-mulched and potato planted in the furrow between the two ridges (SR);(3) only ridges mulched with plastic film and potato planted in the furrow between the two ridges (MR);(4) ridges and furrows were all mulched with plastic film and potato planted in the furrow between the two same ridges (MFR). An additional treatment was tested in2010:(5) two ridges (one wide ridge and one narrow ridge) and furrows mulched by plastic film and potato planted in the furrow between the two ridges (DMFR). The second experiment was based on MFR and DMFR in the first experiment and comprised four mulched treatments:(1)M50;(2)M65;(3)M80/85;(4)Mw, indicating plastic film mulching for50,65, and80/85days after sowing, and whole growth season, respectively-after which mulch in furrows was removed. The study had analysed the phenology, plant height, leaf area index, and biomass accumulation, root/shoot, soil temperatures and moisture under different plastic film mulching methods and various durations of film mulching, discussed the effect of ridges and furrows mulching and removal film from furrow in different stages on potato in semi-arid region. The main results are shown as follows:(1) Ridges and furrows mulching (MFR,DMFR) than other traditional cultivation methods (SR,MR,CK) collected more precipitation, rainwater harvesting efficiency (RHE) reached89.5%. In2009, RHE of MFR,MR,SR were85.1%,82.8%,20.2% respectively. In2010, RHE of DMFR,MFR,MR,SR were89.5%,88.7%,85.5%23.6%respectively. Which retained the natural precipitation and provided for the early growth of crop, significantly improved the soil moisture and water shortage in this area.(2) During the sowing-emergence, mulched plots MFR and DMFR significantly reduced the actual evapotranspiration of potato, increased topsoil temperature and humidity. The soil water content in MFR and DMFR was13.28-21.79%higher than that in controls during the early growing season (sowing-emergence). The daily mean topsoil temperature in MFR and DMFR was2.48-3.49℃higher than that in controls during the early growing season, the difference became less as the plant canopy grew; on some days later in the season, the difference was even negative (the difference were0.24-1.38℃and0.13-0.82℃during middle and last growing season). There was no significant difference between MR or SR and CK in increasing topsoil temperature and soil water content.(3) Seedlings under mulching emerged8.1-11.7days earlier than those in controls due to the increased topsoil temperature and moisture in the early season, and emergence rate reached98.7%by an increase of9.3-14.4%. Mulching also prolonged the duration from seedling to maturity by4.0-12.9days, especially tuber bulking was prolonged by2.3-4.1days, which is benefit to the vegetative growth and reproductive growth after emergence, and to the formation and expansion of tubers. MR had also little increase and SR had almost no increase in temperature and moisture during the early growing season.(4) Mulching significantly increased the plant height, LAI of potato plants, higher leaf area used to photosynthesis can assimilated more carbohydrates and transport to underground. The dry matter of leaves, roots increased by mulching prolonged the duration of the potato from seedling to harvest, which may help the tuber bulking in the longer time. At harvest, the root/shoot of MFR, DMFR were higher59.79%,66.21%than that of CK respectively, the difference was significant. Tthe root/shoot of SR, MR were higher14.11%,55.15%than that of CK respectively, the difference was not significant.(5) Plastic film mulching significantly influenced tuber bulking, yield and WUE, especially increased the number and weight of Grade1tuber. Consequently yield and WUE improved largely. In2009, the yield and WUE in MFR, increased57.4%,70.3%than that of CK; followed by the MR, an increase of33.1%,31.9%; in SR an increase of10.4%,8.4%, CK is the lowest in yield. In2010, the yield in DMFR, MFR, MR, SR increased by78.2%,69.7%,32.7%,11.6%than that of CK, respectively. The WUE in DMFR, MFR, MR, SR increased62.2%,56.8%,30.6%,3.2%than CK. The difference between DMFR and MFR was not significant.(6) However, film mulching throughout the entire growing season harmed the tuber bulking due to higher temperatures in the middle and late June or early July, although mulching can increase the yield. Therefore, mulching should be removed early in order to reduce the negative influence on tuber yield and WUE. Removing the plastic mulch at65DAS can effectively utilize soil water and harvesting rain, thereby increasing the tuber yield and WUE, they decreased gradually as the mulching period increased. Increase in yield as follows:in2009, the M65, M85increased92.5%,45.7%than CK, increased43.8%,8.9%than Mw. In2010, the M65, M50, M85increased77.8,70.0,68.2%than CK, increased9.2%.4.4%,3.3%than Mw. Increase in WUE as follows:in2009, the M65, M85increased112.6%.58.4%than CK, increased50.3%.11.8%than Mw. In2010, the M65, M50, M85increased70.6.60.3.45.9%than CK, increased13.0%,6.2%,-3.1%than Mw. The difference between M65and CK was not significant. The difference was significant in2009and not significant in2010between M65and Mw.(7) M65significantly improved crop yields, M65got the highest economic benefits and input/output ratio. Both two-year experiment, the order of the economic benefits and the input/output ratio was M65> M50> M80/85> Mw> CK. In2009, for economic benefits, the M65was3.18times as the Mw,3.22times as the CK, M85was1.62times as Mw and1.64times as CK. For input/output ratio, the M65increased60.51%than Mw and increased43.65%than CK. M85increased17.19%than Mw and4.87%than CK. In2010, for economic benefits, the M65was1.28times as the Mw,2.14times as the CK, M50was1.12times as Mw and1.86times as CK, M80is1.08times as Mw and1.80times as CK. For input/output ratio, the M65increased50.25%than Mw and increased26.52%than CK. M50increased40.13%than Mw and15.58%than CK. M80increased38.09%than Mw and13.37%than CK.(8) At harvest, there was more soil water in the M65in depth of61-100cm soil. The soil water content were86.9.80.7.81.2mm in M65.M85.Mw in2009, M65significantly higher than M85and Mw. It was proved highly conducive to later growth of the crop.(9) Plastic film mulching65days increased temperature and moisture during the early growing season but lowered temperature during the later growing season, ensuring a favourable coupling of temperature and moisture to improve WUE and yield of potato, thereby improved economic benefits. Removing the film early can also decrease environmental pollution and reduce recovery or reprocessing costs, a distinct but small advantage. In addition, after harvest, higher soil water content was benefical in drier years. Thus, short-term mulching is a promising farming practice for potato production and an excellent adaptation measure to climate warmer and drier in the semi-arid rainfed region of the Loess Plateau in north-western China.