Development and Research Status of New Environmental Films

The development and utilization of new environmental film is an important measure to tackle the residual film pollution, protect the ecological environment and promote the sustainable development of agriculture. The types of new environmental film and their development status were reviewed from the aspects of photodegradable film, biodegradable film, photo-biodegradable film, liquid film, paper film and bast fiber film. In terms of the experimental research status of environmental films in China, analysis and comparisons were made from three aspects including the different types, the same type and imported environment-friendly film. Suggestions were proposed for the research and development prospect of environmental film.

Top-grain filling characteristics at an early stage of maize(Zea mays L.) with different nitrogen use efficiencies

Maize genotypes vary significantly in their nitrogen use efficiencies（NUEs）.Better understanding of early grain filling characteristics of maize is important,especially for maize with different NUEs.The objectives of this research were（i）to investigate the difference in apical kernel development of maize with different NUEs,（ii）to determine the reaction of apical kernel development to N application levels,and（iii）to evaluate the relationship between apical kernel development and grain yield（GY）for different genotypes of maize.Three maize hybrid varieties with different NUEs were cultivated in a field with different levels of N fertilizer arranged during two growing seasons.Kernel fresh weight（KFW）,volume（KV）and dry weight（KDW）of apical kernel were evaluated at an early grain filling stage.Ear characteristics,GY and its components were determined at maturity stage.Apical kernel of the high N and high efficiency（HN-HE）type（under low N,the yield is lower,and under higher N,the yield is higher）developed better under high N（N210 and N240,pure N of 210 and 240 kg ha^–1）than at low N（N120 and N140,pure N of 120 and 140 kg ha^–1）.The low N and high efficiency（LN-HE）type（under low N,the yield is higher,while under higher N,the yield is not significantly higher）developed better under low N than at high N.The double high efficiency（D-HE）type（for both low and high N,the yield is higher）performed well under both high and low N.Apical kernel reacted differently to the N supply.Apical kernel developed well at an early grain filling stage and resulted in a higher kernel number（KN）,kernel weight（KW）and GY with better ear characteristics at maturity.

Effects of degradable films with different degradation cycles on soil temperature,moisture and maize yield

Photo biodegradable film is an ideal degradable mulch film with synergistic effect of photo-degradability and biodegradability.To examine the covering effects of different films,maize was cultivated in the field with three kinds of degradable films(DF)mulching which had different degradation cycles(DF No.1,No.2 and No.3),with common plastic film mulching and no filming mulching(open ground)as comparison.The degradation rates and degrees of degradable films were examined,and the effects of different films on soil temperature,soil moisture,maize yield and relevant characteristics in each treatment were analyzed.The results indicated that the degradable films had good degradability,and the weight loss rate in 100 d for DF No.1,No.2,and No.3 were 22.31%,19.46%,and 15.63%,which were 4.16,3.63,and 2.92 times of the plastic film,respectively.In the early period of maize growth,the degradable films had good warming effects on soil,which were similar with the plastic film.The effect of DF No.2 on soil water conservation was slightly better than that of DF No.1 or No.3,similar with that of the plastic film.The soil water contents in 0-140 cm depths were significantly higher for DF No.2 than that for the open ground(p<0.05).The degradable films could significantly promote the ear development of maize,improve the ear characteristics,shorten the bald tip,and increase kernel number per plant(KNP)and 1000-kernel weight(TKW).The grain yields(GYs)for DF No.2,No.1,and No.3 were significantly improved,with 35.15%,31.35%,and 30.07%higher than that the open ground respectively(p<0.05).With no significant difference between DF and the plastic film,the GY was increased more for DF No.2 than that for DF No.1 and No.3.The degradable films fulfilled successfully all the functions of the plastic film,thus they were recommended as viable option to the plastic film due to their good degradability.

Effects of alternate moistube-irrigation on soil water infiltration

Alternate moistube-irrigation is a new type of water-saving irrigation,and research on water infiltration with alternate moistube-irrigation is important for the design of irrigation schemes and helpful to understand and apply this technology.The effects of the pressure head(1.0 m and 1.5 m)and tube spacing(10 cm,20 cm,and 30 cm between two moistubes respectively)on soil water infiltration in alternate moistube-irrigation were studied in laboratory experiments,and the cumulative infiltration,discharge of the moistube,and shape and water distribution of the cross-section of the wetting front were determined.The cumulative infiltration increased quickly and linearly with the infiltration time at 0-96 h(R^(2)>0.99),and changed smoothly at 96-192 h with a basically steady infiltration rate.The discharge of the moistube increased rapidly at the beginning of irrigation,then decreased before stabilizing.The cumulative infiltrations and discharges of moistube under the 1.5 m pressure head were more than those under the 1.0 m pressure head.The shape of the cross-section of the wetting front for a single moistube was similar to a concentric circle.With the increase of tube spacing,the interaction between water infiltrations of two moistubes decreased.The soil water distributions around two moistubes were similar to each other under the 1.0 m pressure head and large tube spacing.When the tube spacing was 20 cm,the soil water distribution was more uniform around two moistubes.