关键词: 玉米, 茎秆性状, 种植密度, 植物生长调节剂

Abstract:

【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.

Key words: maize, stem characters, planting density, plant growth regulator