Effect of Planting Density on the Stalk Characteristics and Mechanical Properties of Spring Maize in Hilly Region of Central Sichuan

ProposeIn order to provide a theoretical basis for the analysis of the lodging resistant mechanism of spring maize with high density planting in the hills region of Central Sichuan, effects of planting density on the stalk characteristics and mechanical properties of spring maize were explored.

MethodWe set two maize cultivars Zhengdan 958 (ZD958), the national high density-tolerance cultivar, and Zhongyu3 (ZY3), the local main cultivar and 4 density treatments (4.50×10⁴, 6.00×10⁴, 7.50×10⁴, and 9.00×10⁴ plants/hm²) to investigate effects of different planting densities on lodging and stalk characteristics and mechanical properties of maize.

ResultWith increase of planting density, plant height, ear height, ear height coefficient, internode length, and lodging percentage of maize increased significantly. Internode diameter, ratio of dry weight to length of internode, stalk crushing strength, anti-fracture, and rind penetration strength decreased significantly (P>0.05). With increasing 0.75×10⁴ plants/hm², the stalk crushing strength, anti-fracture, and rind penetration strength in the third internode of ZD958 reduced 5.48%, 8.54%, and 4.74%, respectively, and those of ZY3 reduced 5.70%, 6.55%, and 3.09%, respectively. Among the cultivars, the plant height, ear height, ratio of internode diameter to length, ratio of dry weight to length of internode, stalk mechanical properties and root lodging percentage of ZY3 were significantly higher than those of ZD958 (P<0.05). The ear height coefficient and stalk breaking percentage of ZY3 were significantly lower than ZD958 (P<0.05). Correlation analysis showed that the lodging percentage was significantly negative correlation with stalk crushing strength, rind penetration strength, and anti-fracture (P<0.05). Stepwise regression analysis showed mechanical properties of maize stalk, the stalk breaking percentage, and the root lodging percentage were mainly affected by the ratio of dry weight to length of internode, the ear height coefficient, and the plant height, respectively.

ConclusionPlanting density significantly affects the stalk characteristics, mechanical properties, and lodging percentage of maize. With better lodging resistance than ZD958, ZY3 (recommended planting density 6.00×10⁴ plants/hm²) is a better choice for high density planting in hilly region of central Sichuan.