Study on High-yield Potential for Maize Varieties in Mountain Area of Yunnan-Guizhou Plateau

JunjiaoGUAN,PengZHANG,QingmeiHUANG,HuiZHANG,YunfengZHANG,Yanlin WANG,Baoshu WANG,Jianhua ZHANG*

1.Quanlity Standard and Testing Technology Research Institute,Yunnan Academy of Agriculture Sciences,Kunming 650223,China;2.Chuxiong State Research and Extension Institute of Agricultural Science,Chuxiong 675000,China;3.Huizhe State Agricultural Technology Promotion Center,Qujing 675000,China;4.Economic Crops Workstation of Dayao County,Chuxiong 675000,China

Contributed by improved cultivation technology and updated field management,the yield of maize per unit area went up dramatically.It is notable that to enhance planting density is a key technology[1-2]and to increase N fertilizer is a crucial way for improving maize yield[3].However,the increasingly applied N fertilizer would always result in environment pollution and eco-condition deterioration.Therefore,it has become a great concern for plant nutritionists and plant breeders to raise use rate of N fertilizer,improve eco-environment and boost economic development[4-6].

Crop yield is a result of interplay between gene and environment and tends to be volatile upon crop variety,environment and cultivation[7-10].Yunnan is situated in a mountainous area,characterized by complicated environment and diversified soil type and resulting from elevation and landform differences,climate tends to be diversified,affecting maize growth and development.Maize developmentis confronted by how to achieve highyield,high-quality and low-consumption and environment-friendly production by integrating cultivation measures,crop character and fertilizer application[11].

The research investigated the effects of planting density (52 500,67 500 and 82 500 plant/hm2)and nitrogen rate (four rates)on yields of Yunrui No.8,Yunrui No.6 and Yunrui No.88 in different eco-conditions,providing theoretical references and guidance for promotion of new varieties.

Materials and Methods

Test materials

Yunrui No.8,Yunrui No.6 and Yunrui No.88 were provided by Yun-nan Academy of Agricultural Sciences.

Test design

The test was conducted in Zhehai Town(Huize County),Yaozhanjie Village (Chuxiong City),Xiaojie Town(Chongming County),Malong County(Qujing City)and Dayao County(Chuxiong Yi Autonomous Prefecture)simultaneously,based on local major cultivars were selected as control.The climate condition was shown in Table 1 and the test was by uniform design with three replications.Besides,planting density included 52 500,67 500 and 82 500 plant/hm2,and N fertilizers,containing 46.6% nitrogen,were applied at 600 and 900 kg/hm2as per local methodand controlled in time.Specifically,fertilization with time and space controlled involved three stages,as follows:during the 4th-6thleaf stage,maize was applied with soils added with 10 kg maize specific compound fertilizers in the depth of 5-10 cm;during small bell stage,maize was applied with soils and 10 kg maize specific compound fertilizers with depth of 8-10 cm;during large bell stage,maize was applied with soils and 15 kg maize specific compound fertilizers with depth of 15-20 cm.Othercultivationandmanagement were the same as local method.

During tasseling stage,10 plants were selected from every test plot randomly to explore indices,such as leaf length,leaf width,stem diameter of the 2ndinternode,ear height and plant height,as well as ear height coefficient.After maize ripeness,10 plants were surveyed in terms of ear length,ear thickness,the number of ear row,the number of seed per row,the weight per ear,the weight of seed per ear,the rate of seed,and thousandseed weight.

Results and Analysis

Comparisons of major economic traits of maize in different eco-conditions

As shown in Table 2,neither same maize variety in different ecoconditions nor different varieties in the same eco-condition performed diversified.Forexample,YunruiNo.88 reached the highest in yield in Xiaojie Town(Chongming County),increasing by 15.51% than that of local dominant varieties.Besides,Yunrui No.8 and Yunrui No.6 also proved high in yield,but decreased by 4.33% and 2.96%.What’s more,Yunrui No.88 performed better also in Zhehai Town and Dayao County,which indicated that Yunrui grows well in the areas from middle to high elevations.

Effects of densities on plant shape,ear character and yield

In the treatment with high planting density,plant height,ear height and earposition coefficeintmaintained stable,but leaf width and stem thickness changed dramatically(Table 3).Besides,of the three varieties,stem thickness and leaf area were decreasing upon planting density.Additionally,plant height and ear position were significantly lower than those of the other two varieties,and ear position height showed insignificant differencesamong the three varieties.

In the treatment with planting density of 82 500 plant/hm2,ear length,the number of seed per row,and thousand-seed weight all declined considerably,but the number of ear per row and seed rate were less affected(Table 4).Besides,yields of the three varieties were all increasing dramatically upon planting density.These incorporated that high density has adverse effects on ear characters,compensated by yield-increasing effects.Of the three varieties,Yunrui No.88achieved the highest yield,especially in the treatment with high density,which demonstrated that Yunrui No.88 is tolerant to high density,enjoying high yield potential.

Table 1 Eco-conditions of test sites

Table 2 Comparisons of economic characters in different ecological conditions

Table 3 Effects of planting density on maize plant

Table 4 Effects of planting density on maize yield and yield components

Effects of fertilizer quantities on plant shape,ear character and yield

The treatments with urea quantities of 600 and 900 kg/hm2had insignificant effects on plant shape,ear characters and yield.However,provided that fertilization with time and space controlled,a high yield can be reached only with applied fertilizer at 600 kg/hm2.These suggested that to increase N fertilizer is an important way for improving maize yield,but excessive N fertilizer would result in environment pollution.It is recommended to N fertilizer should be applied with a rational way.

Discussion

The growth of maize requires different eco-conditions upon varieties.Yunnan owns diversified eco-environment,which should be taken into consideration in variety cultivation and promotion.For instance,yield of Yunrui No.88 grew more in Zhehai Town,Xiajie Town and Dayao County;yield of Yunrui No.8 reached the highest in Yaozhanjie Village and of Yunrui No.6 the highest in Malong County.In general,yield of Yunrui No.88 kept increasing from low-elevation to high-elevation areas.

The yield of maize per plant is decided by the number of seed per ear and seed weight,and the improvement of planting density would lead to ear character deterioration[13].According to the test results,ear length,the number ofseed per ear,thousand-seed weight,stalk diameter and leaf area were decreasing upon planting density,which coincided with previous researches.Although seed yield was declining upon density,the yields of the three varieties all grew,indicating that high density had adverse effects on ear characters,but compensated by yield-increasing effects from high density.Besides,the three varieties enjoy the potential of yield increasing provided planting density of 82 500 plant/hm2.

Either local fertilization method or fertilization quantities of 600 and 900 kg/hm2have insignificant effects on plant shape,ear characters and yield.In contrast,the fertilization method with time and space controlled reduced N fertilizers,butincreased maize yield.

Yunrui No.88,with the highest potential,can be widely promoted due to good plant shape,optimal plant height and ear height,as well as high tolerance to high density.

Table 5 Effects of fertilizations on maize plants

Table 6 Effects of fertilizations on maize yield and yield components

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