密度对川中丘陵区春玉米籽粒灌浆及脱水特性的影响

Effects of density on grain filling and dehydration characteristics of spring maize in hilly region of central Sichuan

[目的]本文旨在为四川丘陵区密植高产宜机收春玉米栽培提供理论依据。[方法]于2017和2018年,在川中丘陵区中江县开展田间试验,以全国耐密品种‘郑单958’(ZD958)和西南耐密宜机收品种‘仲玉3号’(ZY3)为试验材料,2017年设置5.25、6.00、6.75、7.50、8.25万株·hm^-25个密度处理,2018年设置4.50、6.00、7.50、9.00万株·hm^-24个密度处理,测定籽粒灌浆和含水量动态变化。[结果]籽粒平均灌浆速率和收获期百粒重均随种植密度的增加呈降低趋势,密度每增加0.75万株·hm^-2,ZD958和ZY3籽粒灌浆速率平均减少1.66%和3.36%,百粒重分别减少1.66%和3.32%;密植对玉米籽粒灌浆中后期的干物质积累影响较大。ZD958和ZY3从吐丝到生理成熟时所需有效积温分别为1133.0和1074.7℃,到收获期所需有效积温分别为1316.0和1279.5℃。ZD958和ZY3生理成熟时籽粒含水量均在30%以上;达到适宜机收条件(籽粒含水量28%和25%)时所需有效积温因密度增加而增加,密度每增加0.75万株·hm^-2,ZD958有效积温平均增加26.98和35.95℃,ZY3有效积温平均增加5.35和19.65℃;ZY3籽粒总脱水速率较ZD958大,到达适宜机收的时间较ZD958短。收获期百粒重、籽粒总脱水速率、生理成熟后籽粒脱水速率均与有效积温显著或者极显著正相关,而生理成熟期和收获期籽粒含水量与有效积温极显著负相关。[结论]种植密度增加会导致玉米籽粒灌浆性能及脱水速率降低,适宜密植可获高产。ZY3籽粒灌浆及脱水速率受密度影响小,到达生理成熟及适宜机收条件所需灌浆期有效积温低,总脱水速率快,更适合作为川中丘陵区密植宜机收推广品种。

[Objectives]This article aimed to provide a theoretical basis for analyzing the high-yield and suitable mechanized harvesting of spring maize densely planted in hilly region of central Sichuan.[Methods]Field trials were arranged in Zhongjiang County,a large agricultural county in hilly region of central Sichuan,in 2017 and 2018.‘Zhongyu 3’(ZY3),the dense-tolerant variety and suitable for mechanized harvesting in southwest China,and‘Zhengdan 958’(ZD958),the national dense-tolerant variety,were used as test materials.In 2017,5 density treatments were 5.25×10^4,6.00×10^4,6.75×10^4,7.50×10^4 and 8.25×10^4 plants·hm^-2.In 2018,we set 4 density treatments,which were 4.50×10^4,6.00×10^4,7.50×10^4,and 9.00×10^4plants·hm^-2.Dynamic changes in grain filling and water content were measured.[Results]The average grain filling rate and the dry matter weight per hundred grains showed a decreasing trend with the increase of sowing density.For every increase in the density of 0.75×10^4 plants·hm^-2,the grain filling rate of ZD958 and ZY3 decreased by 1.66%and 3.36%respectively,and the dry matter mass per hundred grains reduced by 1.66%and 3.32%respectively.The dense planting had a greater influence on the dry matter accumulation in the middle and late stages of maize grain filling.The effective accumulated temperature required for ZD958 and ZY3 from spinning to physiological maturity was 1133.0 and 1074.7℃respectively,and from spinning to harvest was 1316.0 and 1279.5℃respectively.When ZD958 and ZY3 were physiologically mature,the grain moisture content was above 30%;the effective accumulated temperature increased due to the increase in density,if the moisture content of grains reached 28%and 25%suitable for the mechanized harvesting condition,for each increase of density of 0.75×10^4plants·hm^-2,the effective accumulated temperature of ZD958 increases by 26.98 and 35.95℃on average,and that of ZY3 was 5.35 and 19.65℃respectively.Compared with ZD958,the total dehydration rate of ZY3 was greater,while the time to reach the suitable machine was shorter.The correlation coefficients among the hundred-grain weight at harvest,the total dehydration rate of grains,and the dehydration rate of grains after physiological maturity with the effective accumulated temperature were significant or extremely significant,while the moisture content of grains at physiological maturity and harvest period was extremely negatively correlated with the effective accumulated temperature.[Conclusions]Increasing planting density might reduce the grain filling performance and the dehydration rate of maize.Suitable planting density could achieve high yield.ZY3 was more suitable for popularization as a densely planted variety in the hilly areas of central Sichuan,due to the less affection of the grain filling and dehydration rate by the density,and the lower effective accumulated temperature to reach physiological maturity and suitable mechanical harvest conditions,and the faster total dehydration speed.