Effects of Tall and Short Isogenic Lines among Grain Sorghum Varieties on Dry Matter Production and Yield Performance at Different Planting Densities

[摘要] It is very important to determine the optimum planting density giving the highest yield and also to understand the effect of plant height on growth and yield. This experiment was conducted to investigate the effect of the planting density and the plant height on dry matter production and yield performance under three different planting densities with three grain sorghum varieties in 1977. The tall and short line in each variety used for this experiment were isogenic having a common genetic background. The main results obtained are summarized as follows. 1. There were statistically significant differences in tiller number, dry matter weight and leaf area per unit area among planting densities. These characters were larger in high density than in low desnity. No significant differences were shown in tiller number and leaf area between tall and short isogenic line. 2. There were significant differences in NAR and CGR among varieties in t2 (29, June-11, July) and t3 (11, July-25, July). The tall lines exceeded significantly the short ones in NAR and CGR (Table 1). 3. With the increase of LAI, NAR decreased, while CGR increased (Figure 1). The best fitting regression of NAR on LAI was curvilinear while that of CGR on LAI was straight. This relationship was common among varieties and lines. But the tall lines showed higher value of NAR and CGR than that of the short ones at the same LAI level. 4. As the grain yield was closely related with CGR and LAI at t1 (16, June-29, June), t2 and t3 (Table 3), the higher yield will be attainable when both CGR and LAI are higher from early growth stage. 5. The positive significant correlation between grain yield and LAI at heading stage was observed. The optimum LAI may occur over higher level obtained in this experiment. 6. The grain yield of tall lines significantly exceeded that of short ones and the grain yield of tall and short lines increased with the increase of planting density (Table 1, 4). The optimum may occur outside the range of density used in the experiment. 7. It has been said that the taller the plant height, the better the distribution of light within a plant population. It may be concluded that the tall line is more advantageous in the efficiency of dry matter production and in getting higher yield than short line, whereas lodging must be noted.

[学科分类] 农业科学（综合）