适当增加种植密度是提高玉米产量的重要途径之一，而倒伏是玉米增加群体密度的主要限制因素。2005—2006年以茎秆抗倒伏性不同的3个品种（稀植大穗型品种京科519、耐密抗倒型品种登海3719和当地主栽品种农大108）为材料，设3.0、5.25、7.5、9.25、12.0万株 hm-2 5个密度处理，研究了种植密度对茎秆的抗倒力学和农艺性状的影响。结果表明，随着群体密度的增加，茎秆的压碎强度（SCS）和外皮穿刺强度（RPS）以及节间直径、干重（DW）、干物质百分比、单位茎长干物质重(RDWL)显著降低，而节间长度有所增加，以上这些变化在供试品种间存在着明显的差异；茎秆抗倒力学性状随群体密度呈指数曲线（y = aebx）变化。茎秆抗倒力学性状与农艺性状密切相关。节间伸长慢且节间变细可能是耐密品种在高密度群体下的适应性表现，而节间干物质积累、尤其高位节间的干物质积累较高的品种抗倒伏能力强。在玉米抽雄前1周茎秆第4节间以上干物质百分比大于7.5%，单位茎长干物质重（RDWL）高于0.2 g cm-1时较为抗倒。逐步回归分析表明，单位茎长干物质对茎秆压碎强度（SCS）和外皮穿刺强度（RPS）的正向影响最大，可以作为玉米抗倒伏品种选择的重要农艺指标。
Lodging is a major constraint to limit grain yield under increased planting density in modern maize (Zea mays L.) production. Effects of planting density on stalk mechanical and agronomic characteristics were investigated using three maize cultivars differing in lodging resistant ability,i.e. Jingke 519 (with a large spike under thinned planting density), Denghai 3719 (tolerant to high density) and Nongda 108 (a main local cultivar). Five levels of density treatment were imposed, 3.0, 5.25, 7.5, 9.25 and 12.0×104 plants ha-1. Experiments were arranged in a split plot design with four replicates. The irrigation and fertilizer management in the experiment plot was consistent with typical agronomic practices in the local high-yield field. The results indicated that the increase of planting density would cause significant decreases in stalk crushing strength (SCS), rind penetration strength (RPS), internode diameter and dry weight (DW), percentage of dry matter and ratio of dry matter weight to length of internode (RDWL), and dramatic increase in internode length. The relationship between stalk mechanical characteristics and planting density fitted a exponential curve (y = aebx) significantly. The stalk mechanical characteristics were highly correlated with the agronomic characteristics. These characteristics of Jingke 519 were susceptive of the increasing planting density above 75 000 plant ha-1, especially for these above the 4th internode was. The whole plant would have high lodging resistant ability if the dry matter accumulation was high in the 4th and above 4th internods. That the internod length enlarged slowly and diameter of internode decreased significantly with increasing plant density was an adaptability to high planting density for the resistant cultivar. When the percentage of DW of the 4th and above 4th internods was more than 7.5%, and its RDWL was more than 0.2 g cm-1 at a week prior to anthesis, the plants would be resistant to lodging .The stepwise regression analysis revealed that the RDWL contributed positively the most to SCS and RPS. RDWL was definite as an agronomic indicator of maize stalk lodging resistant ability.
全 文 ：