| Maize(Zea mays L.)has become one of the main crops cultivated in the dry farming areas of central Gansu,China due to the large application of completely mulched ridge-furrow plastic films.But maize increases soil nutrient consumption while achieving high yield under this planting technique.To maintain the sustainable improvement of maize yield,reasonable soil amendments are important.This research aimed to determine the maize yield as affected by soil amendment treatments.Under different soil amendment treatments,we discuss the main mechanism regarding the impact on maize yield dependent on photosynthesis and sucrose metabolism.The study relied on a soil amendment field experiment in central Gansu,China,developed in 2012 in dry farming areas.The experimental treatments consisted of a no nitrogen fertilizer(NA)and four fertilizer treatments with the same nitrogen level: chemical nitrogen fertilizer(CF),chemical nitrogen fertilizer +organic fertilizer(SC),organic fertilizer(SM)and maize straw(MS).The main results are as follows:1.Compared to NA,the four soil amedment treatments all increased leaf area index and dry matter accumulation at each maize growth stage and reduced the transportation rate of assimilates stored in maize vegetative organs prior to flowering,of which CF and SC treatments increased most,while CF and SC leaf area index and dry matter accumulation increased by 61.4%、65.1%和 145.8%、142.3% on average compared to NA treatmens.2.The four soil amendment treatments all improved the photosynthesis of maize.With the development of the growth cycle period,the photosynthesis of maize decreased.Compared with NA,the average photosynthetic levels of CF,SC,SM and MS increased by 58.7%,48.7%,17.7% and 7.8%,respectively.Ru BPC and PEPC under CF and SC were significantly higher than NA,which increased by 31.3%,34.4%,25.0%,and 31.2% on average compared to NA treatments.3.While the growth cycle progressed,the content of sucrose in the ear leaf slowly decreased,and changes in SS and SPS activity were consistent with sucrose content.At the same time,SS and SPS activity were substantially associated with sucrose content.Soil amendment treatments have increased the content of sucrose,sucrose synthase(SS)and sucrose phosphoric acid synthase(SPS)in the ear leaf,of which CF and SC treatments increased the most.Compared with NA,the content of sucrose,sucrose synthase(SS)and sucrose phosphoric acid synthase(SPS)in ear leaf under CF and SC increased by 35.6%、27.6%、32.8%和 32.3%、24.8%、28.1%.4.The four soil amendment treatments all improved maize yield,full-growth water consumption,and water use efficiency,of which CF and SC treatments had the most evident synergies.Grain yields under CF and SC increased by 146.2% and 115.8% compared with NA,biological yield increased by 108.1% and 94.2%,and water consumption increased by 18.4% and 15.9%.The water use efficiency of each treatment was CF > SC > SM > MS > NA,and the water use efficiency of CF and SC was significantly higher than that of other treatments.5.Maize grain yield was positively associated with ear number(m-2),kernel number per ear,biomass,grain yield WUE,photosynthetic synthesis factor,primary photosynthetic enzyme synthesis factor,and sucrose metabolism synthesis factor.To sum up,in this analysis,four soil amendment treatments boost maize carbon metabolism,increase dry matter accumulation and maize yield by adding leaf chlorophyll content,leaf area index,Rubp and PEP activity,and enhance sucrose content and main enzyme activity such as sucrose metabolism.The application of chemical fertilizer and chemical fertilizer + organic fertilizer has had the strongest effect on carbon metabolism improvement and increased maize yield,and the effect of both on yield has been close.Chemical nitrogen fertilizer + organic fertilizer was therefore an effective soil amendment in the rainfed maize field,with plastic film completely mulched ridge-furrow. |
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