Effects Of Different Plastic Film Mulching On Soil Temperature And Crop Growth In A Ground Cover Rice Production System

The technology of ground cover rice production with plastic film mulch means the use of film mulching,dry farming and dry management,the use of rainfall and supplemented irrigation.It can reduce evaporation and deep leakage,improve water use efficiency.There are few studies on the law of soil heat transfer and the mechanism of its effect on rice physiological growth under film mulching,especially the regulation of rice soil thermal environment and rice growth by different film materials.In order to study the effects of different plastic film mulching treatments on soil temperature and rice growth,a field experiment was conducted in the agricultural,hydrological and hydroecological experimental base of Yangzhou University.Five treatments were set,including conventional flooding(CK),non plastic film mulching(NM),transparent film mulching(TM),black film mulching(BM)and two-color film mulching(silver on the front and black on the back,BWM).Soil temperature at the depth of 5cm,10cm,15cm,20cm and 25cm in different growth stages were monitors.Transpiration rate,photosynthetic rate,inter-cellular CO2 concentration,leaf water use efficiency,plant height,stem diameter,yield,irrigation water use efficiency and rice quality were measured.Soil temperature at 0-25cm depth and rice yield were simulated with swap model.The main conclusions are as follows:(1)The diurnal variation of soil temperature in film mulching treatment was 0.33-6.33℃ higher than NM treatment.Film mulching treatment could increase soil temperature at the depth of 0-25 cm in the whole growth period,and Its warming effect was most obvious in the shallow soil and during the middle and late tillering stages.The warming effect of TM was better than BM and BWM(2)Compared with CK,the transpiration rate decreased by 1.9%-28.6%,but the photosynthetic rate(except BM treatment at panicle differentiation stage)increased by 8.1%-65.6%.Dry farming inhibited plant height and dry matter of rice than CK treatment.The plant height in the whole growth period was as follows:conventional flooding treatment>dry planting without plastic film mulching treatment>plastic film mulching treatment.(3)Comprehensive two year experiments showed that film mulching could improve rice yield,and TM and BM had the best effect.Compared with conventional flooding,dry farming can significantly improve irrigation water use efficiency by 273%-1024%.Without considering heat stress,the irrigation water use efficiency of TM was better than that of BM and BWM.Ground cover rice production with plastic film mulch can improve the milled rice rate,head rice rate,chalky grain rate,chalkiness degree and amylose content of rice to a certain extent.(4)After calibration and verification,the swap model can simulate the variation of soil temperature with time in the depth of 0-25cm under the condition of dry rice cultivation in the study area.