Synergy Effect And Yield Formation Mechanism Of Plastic Film Mulching Of Rice Fields In A Saline-sodic Soil In Songnen Plain, China

The main problems of saline-sodic land in the western Jilin province are soilsalinization and water shortage in the agricultural production, resulting in low yieldand poor quality of rice. Due to plastic film mulching can increase soil temperature,save water, inhabit salt, improve yield, it is important scientific and practicalmeaning for exploiting, controlling and using highly the saline-sodic soil in thewestern Jilin province. The trail was carried out on the Da'an sodic landexperimental station of China (N45°35′58″-45°36′28″, E123°50′27″-123°51′31″)in2010and2011. The experiment was set up two treatments: FM and CK. Theexperimental plots were filmed before rice was transplanted, uncovered beforetransplanted in the following year, and coated plastic film again. The synergy effectand yield of rice plastic film mulching in the saline-sodic soil was researched for twoconsecutive years. The primary research findings were as follows:1The warming effect of plastic film mulching embodied mainly at the earlygrowth stage of rice. As growing period advanced, warming effect weakenedgradually. The warming effect on the soil surface layer was the most obvious,making the temperature increase more than2oC. Along with the soil layer depthraised, warming effect declined gradually.2The water saving effect of plastic film mulching chiefly reflected in inhibitingevaporation, promoting transpiration, reducing irrigation amount and improveirrigation water use efficiency. Compared to CK, irrigation amount and evaporationin FM decreased by7.1%and17.6%, and transpiration and irrigation water useefficiency in FM increased by64.7%and30.7%in2010. In2011irrigation amountand evaporation in FM decreased by14.1%and25.7%, transpiration and irrigationwater use efficiency increased by86.5%and75.4%.3The salt suppressing effect of plastic film mulching primarily reflected inlowering the soil salt in the rice root zone (0~20cm). Plastic film mulching cansignificantly declined the electrical conductivity of the soil surface layer (0~5cm).The electrical conductivity of the soil surface layer was declined by7.75%and 19.86%respectively in2010and2011. The reducing extent of electrical conductivitylessened gradually as soil layer depth increased.4Plastic film mulching can significantly improve number of rice tillering in thetillering stage, enhancing respectively by43.7%and42.6%in2010and2011. Plasticfilm mulching may significantly increase the aboveground biomass in the headingstage, elevating by36.4%in2011. Plastic film mulching can significantly enhanceleaf area index in the jointing and booting stage, improving by21.0%and38.4%respectively in2010and2011.5Plastic film mulching can significantly increase rice yield, enhancingrespectively by21.4%and50.7%in2010and2011. It was founded throughanalyzing yield components that seed weight per panicle (SWP) had the greatestcontribution to yield. It was detected through further analyzing seed weight perpanicle (SWP) that spikelets per panicle (SP) had the greatest contribution to seedweight per panicle (SWP). Improving yield mechanism of plastic film mulching wasthe increase of spikelets per panicle (SP) and seed weight per panicle (SWP). Netrevenue in FM enhanced respectively by34.1%and87.7%in2010and2011.It can be seen that yield increase mechanism of plastic film mulching is improvesoil hydrothermal conditions, inhibit soil salts in the root zone, and save water whileincrease yield, achieving the purposes of yield increase and water saving. Plasticfilm mulching can provide new ways and methods of increasing yield for solving thefood problems in the western region of Jilin province.