灌浆期低温对夏玉米光合性能及产量的影响

以郑单958为供试品种,设置了6月15日(对照)、6月25日和7月5日3个播期,研究灌浆期低温对夏玉米光合性能、干物质生产转运及产量的影响,以期为华北平原夏玉米充分利用热量资源、指导生产实践和实现高产稳产提供理论依据。结果表明:6月25日和7月5日播期的夏玉米在灌浆期均遭遇不同程度的低温胁迫,且随着播期的推迟受胁迫程度随之加剧,这2个播期的玉米光合性能、干物质积累量与转运量、群体生长率均较对照呈逐渐降低趋势。3个播期的单位面积总粒数之间差异不显著,但千粒重在不同播期间差异显著,最终6月25日和7月5日播种的玉米产量较对照分别显著下降了17%和31%。因此,应该选择适宜的夏玉米播种时间,降低玉米在灌浆后期遭遇低温逆境的几率,进而保障玉米生育后期的正常灌浆,最终实现玉米抗逆高产的目标。

Effects of low temperature during grain filling stage on photosynthetic characteristics and yield of summer maize

A field experiment was conducted in order to analysis the impacts of low-temperature during grain filling stage on photosynthetic characteristics,dry matter translocation and yield of summer maize.The experiment was set up at Shangzhuang Experimental Station of China Agricultural University (Beijing) in 2013.Three sowing dates were arranged with randomized block design:June 15(CK),June 25,and July 5 with 3 replicates.Leaf area index,dry matter accumulation,net photosynthesis rate,SPAD values,Fv/Fm,and grain yield were measured.The results showed:Delayed sowing date (June 25 and July 5) caused low temperature stress to maize during grain filling stage and sowing on July 5 significantly limited maize growth;Photosynthesis,dry matter accumulation and translocation,crop growth rate of delayed sowing treatments were all significantly decreased compared with CK.Among yield components,total amount of grains were similar across treatments,while thousand-grain weight of delayed sowing treatments were significantly less than CK.Hence,grain yield reduced by 17% and 31% of maize sowed on June 25 and July 5 respectively compared to CK.Therefore,selection of proper sowing date of summer maize would reduce the risk of low-temperature during the late filling period of maize,and improve maize resistance to cold stress and yield production.