Evaluation Of Suitable Regions For Rain-fed Potato With Plastic Mulching And Research Of Its Potential To Increase Production In China

China’s food security has always been highly concerned by governments at all levels.In recent years,the potato has been proposed as the fourth major staple food crop,following rice,wheat,and maize by the Ministry of Agriculture and Rural Affairs to further improve China’s food security.Potato has high yield,high production potential,low demand on soil quality,water and fertilizer,and is widely distributed in cool climate zones/seasons.Plastic film mulching（PM）can significantly increase potato yield and has been widely used in potato production.In this study,on the national scale,using a process-based model-the DNDC model to simulate the potato yield with PM and without plastic film mulching（CK）under rainfed conditions.We determined the suitable regions of rain-fed potato with PM by cost-benefit analysis,analyzed the change of potato tuber yield,water use efficiency（WUE）,food energy by PM and evaluated the potential change in food energy supply of potato,compared to traditional staple foods（rice,wheat and maize）.The main results are as follows:1.Model could accurately simulate the potato tuber yield:the adjusted coefficient of determination of potato tuber yield is 0.81 between field experiment observation and model simulation.We identified the areas where net economic benefit of improvement by PM is greater than 0 and the net economic benefit in PM reaches the national average level as the suitable regions of rain-fed potato with PM,considering the cost of plastic film recycling.2.The suitable regions of rain-fed potato with PM were mainly distributed in Northeast China（including Heilongjiang,Jilin and Liaoning）,Northwest China（including Inner Mongolia,Shaanxi,Ningxia,Gansu,Qinghai and Xingjiang）and Southwest China（including Guizhou,Chongqing,Yunnan,Sichuan and Xizang）and the suitable regions of rain-fed potato with PM were mainly concentrated in areas with a drought index of 0.22-0.49.3.PM increased the dry mass of potato tuber from 4358 kg ha^-1 to 6373 kg ha^-1,reduced the coefficient of variation for tuber yield from 24%to 15%and increased WUE from 12.5 kg ha^-1mm^-1to 19.3 kg ha^-1mm^-1,compared to CK across the regions where growing rain-fed potato with PM is appropriate.4.The total production of potato was 3.29×10¹⁰kg for CK in regions where growing rain-fed potato with PM is appropriate,and increased to 4.76×10¹⁰ kg after PM,an increase of 44.7%.5.In regions where growing rain-fed potato with PM is appropriate,potato in CK provided food energy for Chinese of 60.4 kcal per person per day,which increased to86.2 kcal after PM,an increase of 42.7%.6.In South China（Guangxi,Guangdong,Fujian,Hainan,Macao,Hong Kong and Taiwan）,potato is mainly grown on idle fields in winter.The potato yield in CK was already higher(averaging 4613 kg ha^-1).The economic,yield and energy benefits of potato with PM planting were not much higher than those in CK.Therefore,it is possible to develop winter potato planting in CK in South China.7.In the suitable regions of rain-fed potato with PM,if the local wheat areas are converted to potato production with PM,about 64%terrestrial land areas showed significant food energy increases,6%terrestrial land areas showed significant food energy decreases and 30%terrestrial land areas showed no significant food energy changes;if the local maize areas are converted to potato production with PM,about 40%terrestrial land areas showed significant food energy increases,10%terrestrial land areas showed significant food energy decreases and 50%terrestrial land areas showed no significant food energy changes;if the local rice areas are converted to potato production with PM,about 20%terrestrial land areas showed significant food energy increases,32%terrestrial land areas showed significant food energy decreases and 48%terrestrial land areas showed no significant food energy changes.In general,PM will greatly improve the yield level and water use efficiency of rain-fed potato,reduce the interannual variation of potato tuber yield,and benefit the regional food energy production and stability in China.