Interactive Effect of Phosphorus and Nitrogen on Leaf Anthocyanins, Tissue Nutrient Concentrations, and Dry‐Matter Yield of Floralta Limpograss during Short Day Length

Abstract

Abstract A field trial was conducted during the short‐day period of 2004–2005 at Ona, Fl., to study the factorial effect of nitrogen (67, 90, and 134 kg N ha−1) and phosphorus (0, 5, 10, 20, and 40 kg P ha−1) rates on forage dry‐matter yield, quality, nutrient uptake, and leaf pigment concentration of limpograss (Hemarthria altissima). The N and P fertilizers were applied 45 days before each of two harvests. There was no interaction between N and P rates on any of the measured variables. Cool‐season forage yield increased curvilinearly from 137 to 350 kg ha−1 in winter and 237 to 1389 kg ha−1 in early spring, whereas crude protein (CP) concentration increased from 145 to 158 g kg−1, as P was increased from 0 to 40 kg ha−1, but yield and CP were not affected by N rate. There was a decreasing linear relationship between leaf concentration of anthocyanins and P rate of application such that forage obtained with 0 kg P ha−1 had 61% more leaf anthocyanins and purple pigmentation than with 40 kg P ha−1. There was no effect of N on anthocyanins content. It was concluded that increased level of leaf anthocyanins was due to the cumulative stress from cool weather and lower plant‐tissue P levels, which resulted in reduced growth and yield of limpograss. In cool weather, P played a critical role in controlling leaf purple pigmentation and forage yield.