Studies On Lodging-resistance Performance Of Maize Varieties Under Different Plant Density Conditions

Experiment was conducted at Gongzhuling experimental station of Institute of Crop Sciences, Chinese Academy of Agricultural Sciences, Jilin Province during 2010-2011. Six representative varieties of maize (Baihe in 1950s, Jidan101 in 1960s-1970s, Zhongdan2 in 1970s-1980s, Yedan13 in 1990s, Zhengdan958 and Xianyu335 in 1990s-2000s) were used. Split-plot design was used with density (3.75, 5.25, 6.75 and 8.25×104 plants/hm2) as main plots and variety as sub-plots, three replicates. The stem mechanical strength, ear character, yield components and yield potential of different populations were studied using morphology, physiology and biomechanics research methods.The results were showed as follows:1. As the density increase, maize lodging rate was gradually increased, and the early varieties were significantly higher than the modern varieties in lodging rate, especially under high-density conditions.2. Maize plant height gradually decreased with the increase of density, but the difference did not reach significant level (P<0.05); ear height and ear height coefficient gradually increased with the density, both showed a significant positive correlation. Ear height contributed much than plant height to ear height coefficient. Maize lodging rate had a close relation with ear height. Among all the varieties used, Xianyu335 and Baihe had higher plant height, Baihe and Zheng958 had higher ear height, and Zhengdan958 had higher ear height coefficient, compared with other varieties.3. Lodging resistance performance was affected by stem diameter, and the thicker of the stem the better of lodging resistance performance. Stem mechanical characters decreased with the increase of plant density, and had no significant correlation with lodging rate. For the varieties with the similar plant character, the lodging resistance performance was close related to stem mechanical characters. There were significant differences exist in stem mechanical characters of the varieties, as they mainly used in different eras. Zhongdan2 witch used in 1970s-1980s has the strangest stem mechanical characters, but the lodging resistance performance is poor. So, it is necessary to take account the variety characters in the study of lodging resistance performance.4、Maize lodging rate and ear morphology is closely related. With the increase of density, ear diameter, cob diameter, ear length, rows per ear and grain number are all gradually reduced, resulting in lower yield per plant. With the replacement of maize varieties, modern maize yield per plant is higher than that the early varieties. With the increase of plant density, the bare plant rate showed an increasing trend, and the yield per plant decreased. Variety of different types has different reaction to density; the bare plant rates of Xianyu335 and Zhengdan958 were low, and there were no significant changed with the increase of density, so the higher yield reached. For varieties of Baihe and Zhongdan2 the bare plant rates increased with the density, and the significant differences appeared at density of 82500plant/ha. Yield per plant increased with the replacement of varieties, and modern maize varieties are significantly higher than that of the early varieties.5. Maize yield is affected by lodging. The effect of lodging on yield components in an order: bare plant rate > grain yield per plant >the actual yield > grain number > ear row number> kernel numbers per row. Lodging caused the increased bare plant rate, and lowered the yield component of grain number, ear row number and kernel numbers per row, so the plant and population yield decreased.