RESPONSE OF CANOLA FORAGE TO PLANT DENSITY

Abstract

Increasing plant density in canola forage (Brassica napus L. var. oleifera) may improve dry matter (DM) and nutrient yields. Two experiments were conducted to evaluate the effect of plant density on forage chemical composition and yields of DM, crude protein (CP) and net energy for lactation (NE_L) in canola. The trials were carried out during the 2011-2012 and 2012-2013 cycles in Matamoros, Coahuila, Mexico. Plant densities at harvest varied from 19.1 to 248 plants m^-2. The association between plant density and the response variables were analyzed using simple linear regression (P ≤ 0.05). The increase in plant density enhanced the concentration of CP and NE_L in the first cycle, whereas in the second cycle chemical composition was not affected. At low plant densities, the plasticity of canola did not compensate DM, CP and NE_L yields, as these variables showed a positive linear relationship (P ≤ 0.05) with plant density. Dry matter yield ranged from 6067 to 9356 kg ha^-1. Yields of CP and NE_L were fitted to a linear function (P ≤ 0.05). Yields of CP (1398 to 2260 kg ha^-1) and NEL (29,248 to 54,487 MJ ha^-1) in the second year were higher than those observed in the first year, with 842 to 2159 kg ha^-1 of CP and 17,533 to 44,617 MJ ha^-1 of NE_L. Results indicate that DM and nutrient yields in canola forage increased as plant density increased, without affecting forage chemical composition.