Within-Row Spacing Influences on Diverse Sorghum Genotypes: II. Dry Matter Yield and Foratge Quality
- G. J. Caravetta,
- J. H. Cherney and
- K. D. Johnson
Research was conducted to determine changes in dry matter yield, cell wall composition, and digestibility of four diverse sorghum [Sorghum bicolor (L.) Moench.] genotypes as influenced by withinrow spacing. Genotypes (IS-0469, IS-0865, P-954063, and IS-2952) were selected to represent a range in morphology and cell wall composition, and were sown at five within-row spacings of 5,10, 15, 30, and 60 cm at two field locations in 1986 and 1987. Harvested herbage was separated into stem, leaf sheath, and leaf blade components for main-shoot and tillers. Forage dry matter yield declined linearly from 10.9 to 8.1 Mg ha−1 as within-row spacing increased from 5 to 60 cm. Total forage neutral detergent fiber and permanganate lignin concentrations declined linearly from 717 to 700 g kg−1 and 79.5 to 71.5 g kg−1, respectively, as within-row spacing increased from 5 to 60 cm. Main-shoot permanganate lignin concentration in the stem component declined 15.3%, while leaf sheath and leaf blade components were relatively unchanged in lignin concentration with increased within-row spacing. Total forage in vitro dry matter digestibility and N content increased 8.7 and 16.1%, respectively, as within-row spacing increased. Reduced plant populations, through increased within-row spacing, improved forage quality and increased digestibility and protein content, however, dry matter yield was significantly reduced. Within-row spacing may significantly influence genotype selection for dry matter yield. Genotypic selection for improved forage quality in a breeding nursery should not be greatly affected by within-row plant spacings of 15 cm or less.
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