EFFECT OF SEASON OF THE YEAR ON FORAGE YIELD AND PROTEIN CONCENTRATION OF TAIWAN GRASS

Abstract

In Taiwan grass (Cenchrus purpureus var. Taiwan) there is limited information on variations in dry matter yield and protein concentration with plant age and environmental conditions (season of the year and fertilization). The objective of this research was to evaluate the effect of season of the year, plant age, and fertilization on the yield of aerial dry matter (YADM), roots (YRDM), protein, nitrogen demand (ND), growth rate (GR) and relative growth rate (RGR) on Taiwan grass. The YADM increased with age, from 1481.47 kg ha-1 at 40 days of age in unfertilized plants in the dry season, to 11,775.2 kg ha-1 at 80 days in plants fertilized in rainy season. The highest YRDM at 40 (432.74 kg) and 60 days (475.28 kg ha-1) occur in ‘nortes’ (rain in winter) in fertilized plants. The highest YRDM (610.21 kg ha-1) was at 80 days after
cutting in rainy season in fertilized plants. Protein decreased from 40 days (153.99 g kg-1MS) in plants fertilized in nortes to 80 days (73.99 g kg-1MS) in unfertilized plants in rainy season. The season of the year of nortes maintained the highest protein concentrations in the plant. DN was correlated (R2 = 0.959, P < 0.0001) with RMSA; thus, the highest DN (178.97 kg ha-1) was in plants fertilized at 80 days of age and in rainy season. GR increased with age and fertilization in both, the dry season and rainy season; conversely, RGR decreased from 40 days (0.190 g g-1MS d-1) to 80 days after cutting (0.024 g g-1 MS d-1), with no differences detected in nortes between fertilized and unfertilized plants in the three ages. Fertilization improved the aerial and root RMS, protein, GR and RGR in the three seasons of the year.