种植密度和植物生长调节剂对玉米茎秆性状的影响及调控

【目的】研究并明确种植密度和植物生长调节剂对玉米茎秆性状的影响,可为合理密植、构建适宜群体结构、实现玉米高产抗逆栽培提供理论依据和技术支撑。【方法】以JK968为试验材料,设置6.0×10 ⁴株/hm ²（D1）、7.5×10 ⁴株/hm ²（D2）和9.0×10 ⁴株/hm ²（D3）3个密度水平,以及乙烯利矮壮素复配剂（EC）和喷施清水为对照（CK）2个处理,研究种植密度对玉米茎秆性状的影响以及茎秆性状对化学调控的响应。 【结果】（1）倒伏率随种植密度增加呈升高趋势,其中在D1密度条件下,JK968的倒伏率分别比D2和D3低69.1%和83.4%;EC处理可显著降低倒伏率,在D1、D2和D3密度条件下分别比对照降低了5.0%、19.8%和41.0%。（2）株高、穗位高、穗位系数和重心高度在不同种植密度和化控处理间均存在极显著差异,具体表现为随种植密度增加呈升高趋势;EC处理后显著降低了地上部第6节以下的节间长度,增加了地上部第7节以上的节间长度,株高和穗位系数略降低,而穗位高和重心高度显著降低。（3）茎秆抗折力和茎秆外皮穿刺强度在不同处理间均存在极显著差异。大喇叭口期至成熟期呈先升高后降低趋势,在乳熟期达最大值。随种植密度增加,地上部第3、4和5节茎秆抗折力和茎秆外皮穿刺强度呈降低趋势;不同节间茎秆抗折力和茎秆外皮穿刺强度表现为地上部第3节>第4节>第5节;EC处理后显著增加了地上部第3、4和5节茎秆抗折力和茎秆外皮穿刺强度。（4）穗粒数和百粒重随种植密度增加呈降低趋势;EC处理后,穗粒数、百粒重和产量均较对照增加。在D1、D2和D3密度条件下,EC处理后产量分别较对照高438.8 kg·hm ^-2、1041.3 kg·hm ^-2和3376.5 kg·hm ^-2,增幅分别为3.6%、8.2%和27.8%。 【结论】随种植密度增加,玉米株高增加、重心高度上移、基部节间伸长、基部节间充实度和抗折力下降。EC处理显著降低了地上部第6节以下的节间长度,显著增加了地上部第7节以上的节间长度,株高略降低,重心高度和穗位高显著降低,基部节间长度缩短、基部节间充实度提高,从而提高了茎秆的抗倒伏能力。由此可见,在风灾倒伏频发地区以及种植密度过大等倒伏风险较大条件下,喷施植物生长调节剂可显著增加玉米茎秆的抗折力和茎秆外皮穿刺强度,显著降低穗位高、重心高度和倒伏率,有利于玉米高产稳产。

Effects of Plant Density and Plant Growth Regulator on Stalk Traits of Maize and Their Regulation

【Objective】Studying and defining the effects of planting density and plant growth regulator on maize stalk traits can provide theoretical basis and technical support for rational close planting, optimizing suitable population structure and realizing high yield of maize. 【Method】 JK968 was used as material. The experiment was conducted to study the effects of planting density and plant growth regulator on maize stalk traits with three planting density treatments, 6.0×10 ⁴ plant/hm ² (D1), 7.5×10 ⁴plant/hm ² (D2) and 9.0×10 ⁴plant/hm ² (D3), and plant growth regulator treatment (ethylene and chloramphenicol compounds, CK). 【Result】 (1) With the increase of planting density, the lodging rate was increased. In the condition of D1 density, the lodging rate of JK968 was 69.1% and 83.4% lower than that of D2 and D3 treatments, respectively. Among them, the lodging rate in D3 was 22.6% and 47.8% higher than D2 and D1, respectively. The ethylene and chloramphenicol (EC) treatment significantly reduced the lodging rate, and the lodging rate D1, D2 and D3 after EC treatment decreased 5.0%, 19.8% and 41.0% than that of the control, respectively. (2) Plant height, ear height, ear position coefficient and center of gravity height were significant different among three plant densities and EC treatment, which showed an increasing trend with the increase of planting density. EC treatment significantly reduced the internodes length below the 6th node of the shoot, increased the internodes length above the 7th node of the shoot. Compared with the control, the height and the ear position coefficient were decreased slightly after EC treatment, while the ear height and gravity center height were significantly decreased. (3) There were significant differences in the bending strength and puncture strength of stem epidermis between different treatments. The stem bending force and rind penetration strength were first increased and then decreased from booting stage to mature stage and reached the maximum value in milk stage. The stem bending force and rind penetration strength of 3rd, 4th and 5th internodes aboveground were significantly different with the increase of planting density and significantly increased after EC treatment. The stem bending force and rind penetration strength of different internodes showed that 3rd > 4th > 5th. (4) The number of grains per panicle and 100-grain weight was significantly decreased with the increase of planting density. After EC treatment, the number of grains per panicle, 100-grain weight and yield increased compared with the control. Under the D1, D2 and D3, the yield of EC treated were 438.8 kg·hm ^-2, 1 041.3 kg·hm ^-2 and 3 376.5 kg·hm ^-2 higher than those of CK, with an increase of 3.6%, 8.2% and 27.8%, respectively. 【Conclusion】 With the increase of planting density, the plant height and height of center of gravity were increased, the basal internodes were belonged, the basal internodes fullness and bending resistance were decreased. EC treatment significantly reduced the internodes length below the 6th node of shoot, significantly increased the internodes length above the 7th node of shoot, slightly reduced plant height, significantly reduced the height of center of gravity and ear height, shortened the length of base internodes and increased the filling degree of base internodes, thus improving the lodging resistance of stem. Therefore, spraying plant growth regulators can significantly increase the bending resistance of maize stalks and the puncture strength of stalk epidermis, significantly reduce ear height, height of center of gravity and lodging rate, which is beneficial to high and stable yield of maize under the conditions of high lodging risk such as frequent wind disasters and high planting density.