Forage yield, rate of CO₂ assimilation, and quality of temperate annual forage species grown under artificial shading conditions

Produção de forragem, taxa de assimilação de CO ₂ e qualidade de espécies forrageiras hibernais cultivadas sob níveis de sombreamento artificial

ABSTRACT:

In this study, it was evaluated the effect of shade on forage yield, rate of CO₂ assimilation, and the quality of annual ryegrass (Lolium multiflorum L.) cv. 'BRS Ponteio' and black oat (Avena strigosa Schreb) cv. 'IAPAR 61', grown under three shading conditions (0%, 25%, and 50% shade) using slatted wooden structures. The experimental design was completely randomized with four replications. Slatted structures were efficient in simulating the proposed shading conditions. Shading plants significantly decreased forage yield and CO₂ assimilation by both species. Ryegrass cv. 'BRS Ponteio' performed better under shade, with higher forage production under all shading conditions. Rate of CO₂ assimilation was reduced by 13 and 22 percentage points compared to the same species grown in the open field (0% shade), under 25% and 50% shade, respectively. These shading conditions did not affect crude protein (CP) content, neutral detergent fiber (NDF) concentration, or the leaf:stem (L:S) ratio compared to those grown in the open field. Between the species evaluated, ryegrass had the greatest potential for use as forage in a silvopastoral system.

Key words:
grass; light restriction; photosynthesis; silvopastoral system