Effects of Shading on the Internode Critical for Soybean (Glycine Max) Lodging

Abstract

Increasing planting density is among the most effective ways to increase soybean yield, but high planting density increases lodging risks in soybean plants. To examine the effects of shading on soybean plant lodging, the tall cultivar Heinong 48 (HN48) and dwarf cultivar Henong 60 (HN60), two soybean cultivars with large plant height differences (approximately 40 cm), were selected, and their internode lengths were measured under different planting densities in 2019 to determine the key internode influencing lodging. In 2020, we treated soybean plants with different shading treatments to examine the morphology, anatomical structure and stem fiber composition of the fifth internode, changes in the GA3 (gibberellic acid) content, and relative expression of GA3-related enzyme genes in the stem under different shading conditions. The results showed that as the planting density increased, the lengths of the internodes changed significantly, starting from the fifth internode. Under different shading conditions, the length of the fifth internode increased for both cultivars, but the diameter and the diameter-to-length ratio decreased; the area of the xylem decreased, and the pith cells stretched more longitudinally and were more orderly; the lignin, cellulose, and hemicellulose contents decreased; the GA3 content in the stem increased, and the expression levels of GmGA3ox6, GmGA20ox1-D, and GmGA2ox4 enzyme genes were all upregulated; and the change in PSN treatment was more significant than other treatments. Therefore, the fifth internode was the key internode that affected lodging in soybean plants, shading could increase the GA3 content significantly in soybean stems, and the increase in GA3 content was positively correlated with the shaded area. This study provides a new direction for future research on lodging resistance in densely planted or intercropped soybean plants.

Effect of Different Sowing Seasons, Growth Stages, Leaf Positions, and Soybean Varieties on the Growth of Clanis bilineata tsingtauica Mell Larvae

“…The light intensity in summer and autumn was different, and it is an important factor affecting maize lodging at high plant density [47]. The high density and low light intensity of summer-sown soybeans can lead to plant elongation and even lodging [48], which affects larval survival. Therefore, adjusting the period to inoculate CBT eggs appropriately and the reasonable number of eggs and plant density according to the characteristics of different sowing seasons is necessary [36].…”

Positive Correlation of Lodging Resistance and Soybean Yield under the Influence of Uniconazole

“…The weight of the stem The length of the stem At the same time, three soybeans were randomly selected from each plot, and the second internode of the stem base was conserved at −80 • C in a refrigerator. The content of cellulose, hemicellulose, and lignin in soybean stems was determined by an ELISA [36].…”

Effects of narrow-wide row planting pattern on canopy photosynthetic characteristics, bending resistance and yield of soybean in maize-soybean intercropping

“…Many studies have revealed that stems' morphological and biological characteristics, particularly bending resistance, play critical roles in soybean lodging. Furthermore, cellulose and lignin concentrations are directly related to the formation of soybean stems and the lodging of soybeans 21,22 . Maize shading reduced soybean cellulose accumulation, signi cantly positively correlated with stem bending resistance.…”