Dry Matter Partitioning and Forage Nutritive Value of Soybean Plant Components
- Rodney W. Hintz and
- Kenneth A. Albrecht
Soybean [Glycine max ( L.) Merr.] can be a high-quality alternative forage, but little is known about the influence of management practices on partitioning and composition of soybean plant components, and therefore on whole-plant forage quality. Cultivar, row spacing, planting rate, and harvest maturity effects on the dry matte prartitioning and nutritive value of soybean plant parts were determined in a 2-yr field study.The cultivars Corsoy 79, Pella, and Williams 82 were grown in 20- and 76-cm row spacings at planting rates of 280 000 and 890 000 seeds ha−1. Plants were harvested at R1, R3,R5, and R7 stages of development harvest maturity had the greatest effect on dry matter partitioning and nutritive value of soybean plant parts. The leaf dry matter fraction decreased continually as plants were harvested at later reproductive growth stages, declining from 708 g kg−1 at R1 to 168 g kg−1 at R7. The stem fraction of total plant mass increased from 292 g kg−1 at R1 to 383 g kg−1 at R5 and then declined to 283 g kg−1 at R7. The pod fraction increased from 105 g kg−1 at R5 to 549 g kg−1 at R7. As plants matured, neutral-detergent fiber (NDF), acid-detergent fiber (ADF), and acid-detergent lignin (ADL) concentrations increased; crude protein (CP) concentration decreased for leaf and stem components. The greatest change occurred as plants matured from Stage R5 to R7. The pod component showed an opposite trend, with NDF, ADF, and ADL concentrations decreasing and CP concentration increasing between Stages R5 and R7. Row spacing, planting rate, and cultivar had little effect on dry matter partitioning and nutritive value of soybean plant parts.
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