种植密度对川中丘陵夏玉米茎秆性状及产量的影响

以玉米品种‘正红505’为材料,设置4.50万株·hm~(-2)、5.25万株·hm~(-2)、6.00万株·hm~(-2)、6.75万株·hm~(-2)、7.50万株·hm~(-2) 5个密度处理,研究种植密度对川中丘陵夏玉米茎秆性状及产量的影响。结果表明:随种植密度的增加,株高、穗位高、节间长、茎节长粗比逐渐增加,茎粗、茎粗系数、节间干重、单位茎长干物质重、茎秆压碎强度和外皮穿刺强度逐渐减小,除穗位高外,其余各性状均存在显著性差异;其中,当种植密度增加到7.50万株·hm~(-2)时,第1、3、5茎节的外皮穿刺强度分别较4.50万株·hm~(-2)显著降低27.10%、22.78%和30.80%。在本试验设置的密度范围内,玉米产量随密度的增加而先增后减,在6.00万株·hm~(-2)处获得最大值,与4.50万株·hm~(-2)相比,6.00万株·hm~(-2)显著增产12.02%。随种植密度增加,玉米穗长、穗粗、成穗率、穗粒数和千粒重显著降低,有效穗数和秃尖长显著增加。相关分析表明,茎秆压碎强度与外皮穿刺强度呈极显著正相关(r=0.93**),且茎秆压碎强度和外皮穿刺强度分别与茎粗、茎粗系数、节间粗、节间干重和单位茎长干物质重呈显著或极显著正相关,而与株高、节间长和茎节长粗比呈负相关或极显著负相关。其中,茎秆农艺性状与茎秆压碎强度的相关性更好。单株产量与茎粗、茎粗系数、节间粗、节间干重、单位茎长干物质重、茎秆压碎强度和外皮穿刺强度呈显著或极显著正相关,与节间长和茎节长粗比呈显著负相关。逐步回归分析表明,茎粗系数和单位茎长干物质重对茎秆压碎强度的影响最大。综上所述,种植密度是影响玉米茎秆性状和产量的重要因素,适当增加种植密度可以显著增加玉米群体产量,茎粗系数和单位茎长干物质重可以作为评价玉米茎秆抗倒伏能力的重要农艺指标。

Effect of planting density on stem characteristics and yield of summer maize in the Hilly Central Sichuan Basin, China

Increasing planting density has been one of the most common ways of increasing maize yield. In order to determine the proper planting density of maize in Hilly Central Sichuan Basin (HCSB) in China, an experiment involving 5 planting densities (4.50×104, 5.25×104, 6.00×104, 6.75×104 and 7.50×104 plant·hm-2) of maize were conducted. The effects of planting density on stalk characteristics and yield of summer maize cultivar 'Zhenghong-505' were investigated. The results showed that plant height, ear height, internode length, length-to-diameter ratio of internode increased with increasing planting density. Also stem diameter, stem diameter coefficient, internode dry weight, internode dry matter weight to length ratio, stalk crushing strength (SCS) and rind penetration strength (RPS) decreased with increasing planting density. There were significant differences the traits except ear height among different planting densities. Compared with planting density of 4.50×104 plant·hm-2, RPS of the 1st, 3rd and 5th internodes reduced significantly respectively by 27.10%, 22.78% and 30.80% under planting density of 7.50×104 plant·hm-2. Maize yield increased at first and then decreased with increasing planting density, with a maximum yield under 6.00×104 plant·hm-2. There was a significant increase in yield (12.02%) under planting density of 6.00×104 plant·hm-2 compared with yield under planting density of 4.50×104 plant·hm-2. Corncob length, corncob diameter, spike rate, kernel per spike and 1000-seed weight significantly (P < 0.05) decreased with increasing planting density, while the effective panicle and barren tip length significantly increased. Correlation analysis indicated that SCS was significantly positively correlated with RPS (r= 0.93**). Moreover, SCS and RPS had significantly or extremely significant positive correlation with stem diameter, stem diameter coefficient, internode diameter, internode dry weight and internode dry matter weight to length ratio. SCS and RPS had significantly or extremely significant negative correlation with plant height, internode length and length to diameter ratio. A stronger correlation was found between stalk agronomic trait and SCS. Yield per plant had significant or extremely significant positive correlation with stem diameter, stem diameter coefficient, internode diameter, internode dry weight, internode dry matter weight to length ratio, SCS and RPS. It then had significant negative correlation with internode length and length to diameter ratio. Stepwise regression analysis suggested that stem diameter coefficient and internode dry matter weight to length ratio had the most significant influence on SCS. It was concluded that planting density was the primary factor influencing maize stalk characteristics and yield. An appropriate increase in planting density significantly increased maize yield. Then stem diameter coefficient and internode dry matter weight to length ratio were important agronomic indexes for evaluating lodging resistance of maize stalk.