FORAGE YIELD AND COMPOSITION OF BLACK OATS AT DIFFERENT HARVEST FREQUENCIES AND INTENSITIES

Abstract

The frequency and intensity of defoliation are the main harvest management criteria, and their alternatives affect the production and nutritional composition of forage. The objectives were to evaluate forage production, morphological components and nutritional composition of black oats (Avena strigosa Schreb) cv. Saia, managed at three canopy heights (40, 50 and 60 cm) as an expression of harvest frequency in combination with three harvest intensities (8, 14 and 20 cm residual forage height). Total forage production and the production of leaf blade, stem plus pseudostem, inflorescence, dead material and weeds were evaluated. Likewise, the contents of crude protein (CP), neutral detergent fiber (NDF) and acid detergent fiber (ADF) were measured. Forage production increased linearly (P = 0.007) with the rise in canopy height (average 35 kg DM cm^-1, R2 = 0.91). Leaf blade production decreased (average -33 kg DM cm^-1, R2 = 0.99, P = 0.001) and that of stem plus pseudostem augmented (46 kg DM cm-1, R2 = 0.98, P = 0.001) with the increase in canopy height (CH). Harvest intensity (HI) did not affect forage production (P> 0.05). However, leaf blade production was greater with 8 cm HI (P <0.05). The CP content decreased linearly (P = 0.001) with the increase in CH (on average -0.22% cm^-1, R² = 0.99) and that of NDF was highest (51.2%) in 60-14 and lowest (41.9%) in 40-8. It is concluded that the increase in CH favored forage production but affected leaf quantity and hence nutritional composition (CP, NDF). At 40 cm CH in combination with 8 and 14 cm residual forage height, forage with more leaves and lower NDF content was harvested.