以紧凑型玉米品种郑单958为材料,使用金得乐(EC)化控试剂,在不同密度条件下对紧凑型玉米的群体结构进一步优化,以挖掘夏玉米的增产潜力。试验设3个密度,每个密度设4个EC试剂叶面喷施处理, 不喷施为对照(CK)。结果表明,不同化控处理下,6叶展期叶面喷施EC试剂2.25 mL/L与对照差异不明显;6叶展期喷施2.25 mL/L、12叶展期喷施1.5 mL/L夏玉米株高、穗位高降低,叶茎夹角增大,穗位层叶间距缩小,株型趋向平展型;6、8叶展期分别叶面喷施1.5 mL/L夏玉米株高降低不明显,穗位高降低,单株叶面积、叶茎夹角缩小,株型更为紧凑。分析结果表明,在高密度条件下调整株型是解决群体结构郁闭突破点,确认整体紧凑、穗位低、穗下层叶间距小、穗位层及穗上层叶茎夹角小、叶间距大、群体结构持续时间长为理想株型。

Canopy structure has strong effects on photosynthesis and grain yield in maize.Chemical regulator is one of the most important factors that can regulate canopy structure. The aim of this study conducted in 2009 was to improve canopy structure of compact maize under high plant population density condition, and explore summer maize yield potential, using compact maize hybrid zhengdan958, and plant growth regulator JinDeLe. The same four treatments were conducted within three planting densities which were spraying 2.25 mL/L JinDeLe(EC) at the 6^th-leaf stage named T1, spraying 2.25 mL/L EC at the 6^th-leaf stage and spraying 1.5 mL/L EC at 12^th-leaf stage named T2, spraying 1.5 mL/L EC at the 6^th-leaf stage and 8^th-leaf stage, respectively, named T3, no spraying as contrast named CK. The results showed that there were different plant types under different chemical regulations. There was no significant difference between T1 and CK. Plant type T2 was a flat type with bigger leaf angles, smaller leaf spacing of ear layer, and shortened plant height and ear height. Plant type T3 was a small compact type with reduced leaf area, smaller leaf angles, and shortened ear height, but plant height was not reduced significantly. The results of path analysis among yield, rate of canopy light interception, and yield components indicated that overcrowded canopy was one of the limiting factors to yield improvement under high density. The preliminary conclusion is that ideal compact plant type should contain low ear height, small leaf spacing below ear layer, small leaf angle and large leaf spacing at ear layer and above ear layer, and a perfect sustained performance.

国家“973”项目(2009CB118602)、国家玉米产业技术体系(CARS-02)