增密对旱区春玉米光合特性及产量构成的影响

Effects of Increasing Density on Photosynthetic Characteristics and Yield Increasing Potential of Maize

【目的】为了研究增密对旱区玉米光合特性及产量构成的影响,揭示不同玉米品种对种植密度响应的生理机制。【方法】本试验于2016和2017年连续两年在宁南山区开展田间试验,以半紧凑型先玉698和紧凑型大丰30两种春玉米为供试品种,采取完全随机设计,设置5.25、6.0、6.75、7.50和8.25万株/hm25个不同的密度,分析增密对玉米不同生育时期叶面积指数、叶绿素含量、荧光参数、光合参数及产量构成的影响。【结果】随着生育进程的推进,玉米叶面积指数(LAI)、叶绿素含量(SPAD)、荧光特性(PI)、最大光化学效率(Fv/Fm),热耗散量子比率(F0/Fm)、净光合速率(Pn)、气孔导度(Gs)、胞间CO2浓度(Ci)、蒸腾速率(Tr)及产量构成随密度变化显著。其中叶面积指数、叶绿素含量及净光合速率在不同生育时期内呈现单峰曲线,且均在灌浆初期出现较高值。同一生育时期不同密度处理指标出现显著性差异,2016和2017年灌浆初期先玉698净光合速率在6.00万株/hm2处理时达到最大,分别为43.24和37.83μmol(m2s)-1,大丰30在6.75万株/hm2处理时的净光合速率最大,分别为41.85和36.94μmol(m2s)-1。两年数据显示,先玉698和大丰30在密度为6.75万株/hm2时产量均达到最大值,其中先玉698分别为14.50和16.06 t/hm2,大丰30为14.23和14.50 t/hm2。在T1基础上密度每增加0.75万株/hm2,先玉698两年平均产量分别增加18.16%、25.59%、3.33%、-0.82%,大丰30两年平均产量分别增加22.64%、34.50%、11.73%、13.11%,但在6.75万株/hm2密度下,先玉698的两年平均产量比大丰30分别高出11.99%、8.66%、5.76%、3.10%、-0.37%。【结论】综上所述,在本试验条件下,半紧凑型玉米先玉698和紧凑型玉米大丰30的适宜密度均为6.75万株/hm2,此密度条件下可有效发挥玉米增产潜力,提高该地区玉米产量。

【Objective】The present paper aimed to study the effect of increasing density on the photosynthetic characteristics and yield of the maize in the southern mountain area of the Ningxia Hui autonomous region.【Method】The physiological mechanism of the response of different maize varieties to the planting density was revealed,and the field experiments were conducted for two years in 2016 and 2017.Based on the semi-compact Xianyu 698 and the compact Dafeng 30 two-spring corn variety as the test material,5.25,6.00,6.75,7.50 and 8.25 million plants of hm-2 were set for five different densities.【Result】Study on the effects of density on leaf area index(LAI),chlorophyll content(SPAD),fluorescence characteristics(PI),maximum photochemical efficiency(Fv/Fm),heat dissipation quantum ratio(F0/Fm),net photosynthetic rate(Pn),stomatal conductivity(Gs),intercellular CO2 concentration(Ci),transpiration rate(Tr)and yield composition.The results showed that with the development of growth process,the leaf area index,SPAD value and fluorescence characteristics of corn showed a single peak curve,and there were significant differences in different density treatment indexes during the same growth period.The net photosynthetic rate of Xianyu 698 reached the maximum at 6.00 million hm-2,43.24 and 37.83μmol(m2s)-1 in 2016 and 2017,respectively,while that of Dafeng 30 was 41.85 and 36.94μmol(m2s)-1 in 6.75 million hm-2,respectively,the net photosynthetic rate of Xianyu 698 was 41.85 and 36.94μmol(m2s)-1 in 2016 and 2017,respectively.Reasonable close planting can increase the yield of different corn varieties.During two years,Xianyu 698 and Dafeng 30 reached the maximum yield when the density was 67500 plants/hm2.The values of Xianyu 698 were 14.50 and 16.06 t/hm2,and those of Dafeng 30 were 14.23 and 14.50 t/hm2,respectively.On the basis of T1,the average yield per 6.75 million plants per hectare increased by 18.16%,25.59%,3.33%,0.82%and 22.64%,34.50%,11.7%,respectively.At the same density,the yield of Xianyu 698 was 11.99%higher than that of Dafeng 30,8.66%,5.76%,3.10%,-0.37%,respectively.【Conclusion】To sum up,under the experimental conditions,the selection of Xianyu 698 at a density of 6.75 million plants per hectare could effectively increase the maize yield in this area.