| Plastic-film mulch is an agricultural technology widely used for maize?Zea mays L.?production in agricultural areas of loess plateau in China.However,currently maize breeding in China has not targeted the plastic-film mulch ridge-furrow systems widely used in northern China,but the effects of the interaction between cultivar and plastic-film mulch on the grain yield,root characteristics,root/shoot,nutrient absorption and transport were less.It is very important to select the suitable cultivar for improve the yield and quality of grain in a cold semiarid environment.Five maize hybrids,Jiusui 4?JS?;Jixiang 1?JX?;Pingyu 8?PY?;Xianyu 335?XY?and Yuyuan 5?YY?,were assessed by field experiment in 2014 and 2015 in plastic-film mulched?M?and non mulched ridge-furrow?NM?plots in yuzhong county,Gansu province?35°54?N,104°05?E?.On the basis,exploring differences among treatments on grain yield,yield components,water use efficiency,root biomass,root length density,root/shoot,nitrogen?phosphorus?absorption and translocation.Whether the effects of plastic-film mulch on these items of maize varies among cultivars.In order to illuminate the effects of plastic film mulch on maize yield,root distribution and nutrient absorption of different varieties,choose the judge index of high yield and quality maize,select suitable cultivars to grow to maximize maize production in the plastic-film mulched ridge-furrow technology is an objective of both breeders and agronomists,further,to provide important scientific basis for improving the yield and quality of breed new varieties.The main results as below:1.In 2014,the grain yield of the five cultivars varied from 685 to 898 g m-22 with no mulch,and from 966 to 1228 g m-22 under mulch.In 2015?drier than in 2014?,the grain yield varied from 179 to 353 g m-22 without mulch,and from 548 to 1021 g m-2with mulch.By incorporating the variation in grain yield over cultivars,mulch treatments and cropping years,Jixiang 1 was the highest yielding cultivar.Compared with no mulch,plastic film mulch doubled grain yield in Pingyu 8,Jinsui 4 and Xianyu 335 and tripled in Yuyuan 5 and Jixiang 1.There was a significant two-way interaction between cultivar and mulch on maize grain yield.A moderate aboveground biomass and high harvest index may give satisfactory grain yield in plastic-film mulched or non-mulched fields in hydrothermally-limited areas.2.Mulch generally increased the length of the spike,kernel number?per cob or area?,kernel weight and reduced the length of the bare length,the present study showed that the mulch effect on the length of the spike,kernel number and kernel weight varied with cultivar.The key to stable grain yield is to ensure cob number in the field.And larger grain morphology?hundred grain weight?suit to get higher grain yield,especially in hydrothermally-limited areas.Increasing the number of ears,grain number and grain weight is the key to breeding and screening cultivars for high yield.3.Each year,the WUE in Jixiang 1 were 1.8 and 3.2 g m-2mm-22 with or without mulch respectively,which were higher than Yuyuan 2,Jinsui 4 and Xianyu 335.Differences in maize water use efficiency?grain yield per unit of evapotranspiration?as affected by mulch and cultivar paralleled those of grain yield due to minor effects of mulch and cultivar on growing-season evapotranspiration.Plastic-film mulch increased the maize soil water use efficiency?WUE?,and resolved the contradiction between the large amount of precipitation and the inconsistency of maize development in the early spring maize in arid region.4.Averaging years and mulch treatments,Yuyuan 5 had the highest root biomass(123 g m-2)while Jixiang 1 had the smallest root biomass(88.5 g m-2)in the upper 60cm soil layer,and mulch increased the root length of Pingyu 8 and Xianyu 335.Plastic-film mulch improved maize root biomass and root length density in the upper60 cm soil profile,the effects of plastic-film mulch on maize root biomass and root length density varied with cultivar.Plastic-film mulch promotes the accumulation and changes the soil water condition on the ground,not only elevating the soil water from the deep layer to the surface soil layer,but also enlarged the distribution proportion of root biomass and root length density in soil layer 0–20 cm.The change of root biomass and root length is not consistent with the grain yield,so it is hard to say larger root system is favorable for grain yield accumulation.5.With regard to cultivars,in 2014 the mulch increased root/shoot ratio in Xianyu 335,had no effect in Jinsui 4,Jixiang 1 and Yuyuan 5,and decreased the root/shoot ratio in Pingyu 8,compared to no mulch.In 2015,the mulch significantly increased the root/shoot ratio in Jinsui 4 and Xianyu 335,had no effect in Yuyuan 5,and decreased the root/shoot ratio in Jixiang 1 and Pingyu 8,compared to no mulch.A wide variation of root/shoot ratio with maize cultivar and cropping year indicated that using a fixed root/shoot ratio to estimate the root carbon input to the soil would induce large uncertainty.6.The effect of plastic-film mulch on absorbing ability of nitrogen and phosphorus vary with cultivar.Jinsui 4 and Yuyuan 5 had higher nitrogen and phosphorus concentration than other three cultivars,however,the grain yield of Jinsui4 and Yuyuan 5 were lower than Jixiang 1.It was negatively correlated between grain nitrogen concentration and yield.It was exist that the contradiction between high yield and high quality.7.The plastic-film mulch increased the nitrogen and phosphorus content of corn stalk and leaves on the ground,so mulch promoted the transfer of nitrogen and phosphorus from stalk and leaves to grain.Mulch enhances the adaptability of maize to the growth environment,which is not only reflected in the stability of grain yield increase,but also in the aspect of nutrient absorption.To sum up,there was interactive between mulch and cultivars on maize yield,root biomass and root length density.In semi-arid area,the farmers plant maize with plastic-film mulching should select the appropriate cultivars according to the characteristics of the planting area.In order to increase yield and utilize the limited precipitation and soil nutrients efficiently. |
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