Simulated insect defoliation on soybean: influence of row width.

Area of Science:

• Agronomy
• Entomology
• Crop Physiology

Background:

• Soybean production is increasingly adopting reduced row spacing for improved canopy closure and higher yields.
• Yield response to insect defoliation is linked to changes in light interception, suggesting row width could influence this relationship.

Purpose of the Study:

• To determine if the relationship between insect injury and yield loss in soybeans varies with row spacing.
• To assess the applicability of existing insect injury models across different row widths.

Main Methods:

• Soybean was grown across four states with consistent methodologies.
• Simulated insect defoliation was applied using a model, followed by plant growth measurements.
• Key variables like light interception, leaf area index, and defoliation percentage were measured.
• Analyses of covariance were used to test for interactions between insect injury variables and row width on yield.

Main Results:

• Few significant interactions were found between insect injury variables and row width concerning yield.
• The impact of light interception and leaf area index on soybean yield was consistent across tested row spacings.
• The insect-injury-yield-loss relationship appears independent of row width.

Conclusions:

• Established insect-injury-yield-loss relationships are applicable across various soybean row widths.
• Management decisions for insect pests, based on light interception and leaf area indices, can be consistently applied regardless of row spacing.
• Reduced row spacing in soybean production does not fundamentally alter the crop's response to insect defoliation in terms of yield loss.