Abstract

Lolium perenne L. (Lp) and Agrostis capillaris L. (Ac) are perennial grasses and there is a lack of information regarding their growth strategies when incident light becomes limited. The objective was to evaluate morpho-physiological and productive responses of Lp and Ac with incident light diminishment. Three incident light regimes were imposed regarding photosynthetic active radiation (PAR): 60.7, 140.5 and 199.9 µmol m-2 s-1, named Heavy Shading (HSh), Medium Shading (MSh) and Full Sunlight (FS), respectively. The pasture used was a humid temperate naturalized pasture, with (FP) and without (NFP) fertilizer addition, being Lp and Ac targeted. Metal rings were placed in the pastures under each shading condition and Lp and Ac growth evaluated. The experimental design was a randomized complete block with factorial arrangement of the treatments: three levels of shading (HSh, MSh and FS), two levels of fertilization (NFP, FP) and two species (ring class: 100% Lp tillers and 100% Ac tillers); in 3 blocks. It was concluded that in a restricted soil nutrient condition (NFP), Lp DM accumulation and tiller density were greater in MSH and HSh than FS, whereas in contrast Ac DM yield and tiller density were greatest in FS. Crude protein, chlorophyll content index, leaf area and leaf length for Lp were greatest in FP-HSh and for Ac lowest in NFP-FS. MSh and HSh created an environmental condition with enough WC, N and PAR to favor pasture production, a fact that implies the mitigation of the drought stress effects in the future climate change scenario.