Temporal Importance of Greater Light Interception to Increased Yield in Narrow-Row Soybean
- J. E. Board ,
- M. Kamal and
- B. G. Harville
Increased light interception is considered the main factor explaining greater yield in narrow- compared to wide-row spacing in soybean [Glycine max (L.) Merr.]. Controversy exists, as to when during the growth cycle the greater light interception of the narrow rows has an enhancing effect on yield. The objectives of this study were to analyze crop growth rate and yield components to determine the importance of greater light interception during vegetative (E-Rl), early reproductive (Rl-R5), and late reproductive (R5-R7) periods to increased yield in narrow-row culture. Field studies were Conducted during 1989 and 1990 at a late (July) planting date with ‘Centennial’ soybean (determinate, Maturity Group VI) at row spacings of 100, 75, 50, and 25 cm. The test was conducted at Baton Rouge, LA on a Mhoon silty clay soil (fine-silty, mixed, nonacid, thermic, Typic Fluvaquents). Yield increased with greater light interception as row spacing was reduced from 100 to 75 and 50 cm. Although greater light interception occurred throughout the growing season in narrow compared to wide rows, increased crop growth rate occurred only during vegetative and early reproductive periods. The main factors responsible for increased yield in narrow rows were greater fertile node production and increased pod per fertile node. These yield components are primarily determined during the vegetative and early reproductive periods. In conclusion, analyses of crop growth rate and yield components revealed that greater light interception during the vegetative and early reproductive periods was responsible for increased yield in narrow-row culture.
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