Effects Of Different Plastic Film Mulching On Soil Hydrothermal Dynamics And Potato Growth In Sandy Area Of Northern Shaanxi

The sand area of northern Shaanxi is the suitable area of potato.Drip irrigation under film is the main measure of high yield and efficient cultivation of potato in this area.In recent years,the use area of degraded mulch and black mulch in potato production has been increasing,but its effect on potato growth remains unclear.In the research,five treatments,including white degradable mulching film（TDM）,black degradable mulching film（BDM）,white polyethylene mulching film（TPM）,black polyethylene mulching film（BPM）and bare land（CK）were set up through field experiments to systematically study the effects of different mulch materials on soil water and temperature conditions,agronomic characteristics,physiological characteristics and yield of potato.The purpose of this study was to screen the suitable coating material for green high-yield cultivation of potato.The results show that:（1）Different mulching film materials affect soil water and temperature in potato fields.In the whole growth period,the 0-25 cm soil temperature of the four mulching treatments was higher than CK treatment.In the early stage of potato growth（from seedling stage to tuber formation stage）,compared with CK treatment,TPM treatment had the largest temperature increase,enhancing 0-20 cm soil layer temperature by 1.10℃-3.60℃,and TDM treatment had the second temperature increase effect.The soil temperature of TPM and BPM treatment was higher than that of TDM and BDM treatment in the middle and late stage of potato growth（from tuber swelling stage to maturity stage）.Compared with CK treatment,BDM treatment reduced 0-5 cm,15-20 cm and 20-25 cm soil layer soil temperature,and BPM treatment reduced 20-25 cm soil layer soil temperature;In the whole growth period,the soil water content of 0-100 cm soil layer under different mulching films was higher than CK.At the seedling stage,the soil water content of 0-20 cm layer was BPM>BDM>TPM>TDM>CK,and the soil water content of the four mulching treatments was 16.28%-56.98%higher than that of the CK treatment.In the tuber formation stage,the soil water content of 0-20 cm soil layer was BPM>TPM>BDM>TDM>CK.The difference of soil water content increased between TPM and BPM treatments and TDM and BDM treatments during tuber swelling stage to maturity stage.In 0-100 cm soil layer,the soil water content under TPM treatment was significantly higher than that under TDM treatment with increasing soil depth by 10.53%-51.43%（P<0.05）,and the soil water content under BPM treatment was 2.91%-66.22%higher than that under BDM treatment with increasing soil depth,respectively.In addition,the effects of different mulching treatments on soil water potential of 0-40 cm soil layer at each growth stage of potato were different.The absolute value of soil water potential treated by CK was the highest during the whole growth period.The absolute value of soil water potential under BDM treatment was the lowest in seeding stage to tuber swelling stage,while the absolute value of soil water potential under BPM treatment during starch accumulation stage to maturity stage was the lowest.（2）The variation trends of potato growth indexes were different under different film mulching materials.The plant height and stem diameter of potato increased first and then decreased during the whole growing period.From tuber formation stage to tuber swelling stage,the plant height under BPM treatment was the highest,followed by BDM treatment,and the stem diameter under BDM treatment was the largest,followed by BPM treatment.At the mature stage,the plant height of potatoes treated with BDM was significantly higher than that treated with BPM,TPM and CK by 4.67%-6.21%（P<0.05）,and the stem diameter was significantly higher than that treated with TDM and CK by 5.79%-8.96%（P<0.05）;The Chlorophyll content（SPAD value）of potato leaves treated with BDM was the highest during tuber formation stage to maturity stage;From tuber swelling stage to maturity stage,the net photosynthetic rate（Pn）,intercellular CO₂ concentration（Ci）,stomatal conductance（Gs）and leaf water use efficiency（WUE_L）of BDM treatment were higher than those of other treatments,but the transpiration rate（Tr）was lower than those of other treatments;During tuber formation stage to starch accumulation stage,the root,stem,the leaf and whole plant dry weight of potato treated with BDM were the highest,and the tuber dry weight and whole plant dry weight of potato treated with BDM were significantly higher than those treated with other treatments by 7.61%to 130.06%（P<0.05）.At the maturity stage,the dry weight of all organs treated with BDM was significantly higher than that treated with other treatments by 8.02%-58.20%（P<0.05）.（3）The potato yield of the four film mulching treatments was higher than that of CK treatment.The effect of black film mulching on potato yield was greater than that of white film mulching.The tuber weight per plant,the big potato rate and the yield of each treatment were as follows:BDM>TDM>BPM>TPM>CK.Compared with CK treatment,the potato yield of four kinds of film mulching treatments was increased by 5.00%-19.00%,and BDM treatment had the best yield increase effect.The water use efficiency of BPM treatment was the highest,and the value of BDM treatment was slightly lower than that of BPM treatment by 3.14%,but there was no significant difference.In conclusion,the surface soil mulched by black degradable film has higher water content,suitable soil temperature,best potato plant height,stem diameter,chlorophyll content and photosynthetic index,highest dry weight of potato organs,higher yield and large potato rate than other treatments,and higher water use efficiency of potato,which is a suitable film mulching material in northern Shaanxi sandy area.The results of this study could provide theoretical and data support for the sustainable development of potato industry in the sandy area of northern Shaanxi.