Effects Of Covered With Colored And Biodegradable Films On The Soil Condition And Yield Formation In Peanut Field

Field experiments were conducted from 2012 to 2014 at the experimental station of Shandong Institute of Peanuts, Laixi, Shandong Province, China. Taking the Arachis hypogaea cv.‘huayu 22’ as test material, a field experiment was conducted to study the effects of three kinds of color film(BCF: black-clear-black 3-band film, SF: sliver grey film, BF:black film) and four types of biodegradable film(T1: 100% PBAT, 0% starch; T2: 90%PBAT, 10% starch; T3: 85% PBAT, 15% starch; T4: 80% PBAT, 20% starch) on the the soil condition and the growth of peanut. The main results were as follows:The colored PE films were effective in controlling weeds compared with CK, while the BF had the optimal weeds control effect. Compared with CK, the colored PE films were not sensitive to the air temperature, and had the smaller temperature variations in the whole day.The soil moisture with the colored PE films at the 0-40 cm depth were higher than CK, and the highest moisture occurred in BF. The soil moisture under BCF and SF showed no significant difference. The more favorable soil environment under the colored mulches resulted in the higher soil enzyme and microbial activity, compared with CK, the soil enzyme and microbial biomass C, N under the colored mulches were all higher, and the difference all reached significant. Peanut covered colored PE films could promote the growth of peanut,increased chlorophyll content at different degrees, improved photosynthetic efficiency of functional leaves significantly, fluorescence parameters also increased to varying degrees,especially in the late growth stage. And the pod yield with BCF, SF and BF were significantly increased by 6.10%, 11.58%, and 4.13% in 2012, and 13.73%, 8.15%, and 3.59% in 2013,respectively. And the seed kernel protein and crude fat content under BCF, SF were all higher than that of CK. Accordingly, SF and BCF may be better field-management options for weeds control and high yield in peanut field.With the increase of the proportion of starch, the degradation rate of biodegradable plastic films become faster. The degradation cycle of the PBAT biodegradable film that contained 15% starch was coincided with peanut growth period. The water holding effects ofmulching treatments were better than that of no mulching treatments, the length of bough and side-bough, photosynthetic, fluorescence, dry weight and peanut yield were all higher for film covering. In the early growth stage of peanut, the effect of the biodegradable film on soil temperature and moisture were same as those of plastic film. Peanut covered biodegradable films remained higher chlorophyll content, net photosynthetic rate and fluorescence properties in the late growth stage. The effects of the PBAT biodegradable film that contained 15%starch was better than the other three biodegradable films, and it got the third degradable degree in the peanut pod setting stage, crack on the surface of the film increased the water infiltration, maintained a high soil temperature, increased the soil enzyme and microbe activity, improved photosynthesis, fluorescence properties and the accumulation of dry matter,so as to increase the yield and quality of peanuts. The pod yield with the PBAT biodegradable film that contained 15% starch were 4421.57 kg/ha in 2013, and 5231.32 kg/ha in 2014, no significant difference were found, when compared with ordinary film. The seed kernel protein and soluble sugar content were all higher than that of the no mulching treatment and the plastic mulching treatment. But the PBAT biodegradable film that contained 20% starch had the higher degradable degree, and it got the fifth degradable degree before the harvest of peanut, that was not conducive to improving the soil temperature, moisture and peanut yield.Those PBAT biodegradable films that contained 0% and 10% starch had slower degradable rate, with the third and fourth degradable degree gotten at the harvest of peanut. This result in much residual plastic film in the soil, and it inhibited the growth of the crop, it also not conducive to the protection of farmland soil environment. Based on these results, it can be concluded that the PBAT biodegradable film that contained 15% starch can be used as the substituting article of ordinary plastic film for peanut growth.