种植密度对旱地不同株型春玉米品种光合特性与产量的影响

【目的】研究种植密度对渭北旱塬不同株型春玉米品种光合特性与产量差异的影响,旨在揭示旱地不同株型玉米品种对种植密度的响应规律,确定与降水资源相适应的适宜种植密度。【方法】于2015—2016年以豫玉22、郑单958和先玉335为供试品种,设置D1(5.25万株/hm~2)、D2(6.75万株/hm~2)、D3(8.25万株/hm~2)和D4(9.75万株/hm~2)4个种植密度处理,研究玉米各生育时期光合特性、叶面积指数(LAI)、干物质量和产量相关性状的变化规律。【结果】(1)随着种植密度增加,光合速率(Pn)、蒸腾速率(Tr)均降低,而LAI增加,密度每增加1万株/hm~2,Pn降低1.32μmol CO2·m-2·s-1,Tr降低0.297 mmol·m-2·s-1,LAI增加0.181。(2)有效穗数随种植密度增加而显著增加,但穗粒数和千粒重显著降低(P0.05),密度每增加1万株/hm~2,穗粒数平均减少45粒,千粒重平均减小12 g。3个品种籽粒产量均以D2密度最高,2015年豫玉22、郑单958、先玉335产量分别为10.52、9.59、9.14 t·hm-2,2016年分别为11.37、9.73、9.77 t·hm-2。密度从5.25万株/hm~2增加到6.75万株/hm~2,两年内平均籽粒产量分别提高了21.9%、19.5%和7.5%;密度从6.75万株/hm~2增加加到9.75万株/hm~2,籽粒产量分别降低了19.8%、15.4%和7.7%。(3)春玉米基部茎粗、穗长随种植密度增加而逐渐减小。密度每增加1万株/hm~2,穗长平均降低0.86 cm,基部茎粗平均减小0.09 cm,豫玉22和郑单958倒伏率随之增高,但先玉335各密度下均未出现倒伏。(4)收获指数在两年间差异较大,平均表现为2015年高于2016年,品种间表现为先玉335郑单958豫玉22。水分利用效率和光能利用率均随着种植密度增加而先增大后降低。【结论】渭北旱塬旱地豫玉22、郑单958和先玉335最适种植密度分别为7.25、7.40、7.32万株/hm~2,其中豫玉22稳产性和丰产性较高,不同类型玉米品种最适种植密度范围为7.26—7.40万株/hm~2,稀植型品种宜采用较低密度,密植型品种宜采用较高密度。

Effects of Different Planting Densities on Photosynthetic Characteristics and Yield of Different Variety Types of Spring Maize on Dryland

【Objective】Effects of different planting densities and different variety types of spring maize on physiological characteristics and yield in Weibei highland were investigated. The aim of this study was to determine the suitable maize varieties and their planting densities in dryland. 【Method】Field experiments were carried out by using spring maize cultivar Yuyu22, Zhengdan958, Xianyu335, and four planting density treatments including D1(52 500 plants/hm²), D2(67 500 plants/hm²), D3(82 500 plants/hm²) and D4(97 500 plants/hm²) were designed. The changes of photosynthetic characteristics, leaf area index(LAI), biomass yield and yield related traits of spring maize at different growth stages were observed.【Result】(1)Photosynthetic rate (Pn) and transpiration rate (Tr) decreased with the increase of planting density, while LAI increased. Pn decreased by 1.32 μmol CO₂·m^-2·s^-1, Tr decreased by 0.297 mmol·m^-2·s^-1 and LAI increased by 0.181 for each increase in density of 10 000 plants/hm². (2)The number of productive ear was remarkably increased with the increase of planting density, but the kernels per ear and 1 000-kernel weight were significantly decreased(P＜0.05). The kernels per ear decreased by 45 and the 1 000-kernel weight decreased by 12 g for each increase in density of 10 000 plants/hm². The yield of three maize varieties was the highest at D2 density. In treatment D2, the yield of Yuyu 22, Zhengdan 958, and Xianyu 335 were 10.52, 9.59, and 9.14 t·hm^-2 in 2015, and 11.37, 9.73, and 9.77 t·hm^-2 in 2016, respectively. The average yield of three maize varieties was increased by 21.9%, 19.5%, and 7.5%, respectively, within two years, when the density was increased from 52 500 plants/hm² to 67 500 plants/hm². The average yield of three maize varieties was decreased by 19.8%, 15.4%, and 7.7%, respectively, within two years, when the density was increased from 67 500 plants/hm² to 97 500 plants/hm². (3) The stem diameter, and ear length of spring maize decreased with the increase of planting density. The ear length decreased by 0.86 cm, the stem diameter decreased by 0.09 cm for each increase in density of 10 000 plants/hm². The lodging rate of Yuyu 22 and Zhengdan 958 rather than Xianyu 335 increased with the decrease of stem diameter. (4)The harvest index varied greatly in two years, the average performance was 2015＞2016, and the varieties showed that Xianyu 335＞Zhengdan 958＞Yuyu 22. Water use efficiency (WUE) and radiation use efficiency (RUE) were increased with the increase of planting density and then decreased.【Conclusion】The optimum planting density of different variety types of spring maize in Weibei dryland was different. Yuyu 22 was 72 500 plants/hm², Zhengdan 958 was 74 000 plants/hm², and Xianyu 335 was 73 200 plants/hm². Yuyu 22 had high stability and high yield. The optimum planting density of different variety types of spring maize was 72 600-74 000 plants/hm². Low density was recommended for thin planting varieties, and high density was recommended for close planting varieties.