Yield, Crude Protein, and Chemical Composition of Five Napier Grass Cultivars on the Northwestern Coastal Plains of Puerto Rico

Abstract

Five Napier grass cultivars (Pennisetum purpureum Schum.) were evaluated under cutting management on a Bayamón sandy loam soil on the northwestern coastal plains of Puerto Rico for a period of 2.05 years without irrigation. Grasses received a high input of fertilizer (4,484 kg/ha/yr) and were harvested every 5') days. Mean dry forage yield for cultivars PRPI 13079, 7350, Merker, 13078, and 532 were 46755, 45449, 39439, 38816, and 37581 kg/ha/yr, respectively. Cultivars 13079 and 7350 had similar dry forage yields, which were significantly (P < .05) higher than those of the remaining cultivars. Cultivar 7350 was the highest crude protein yielder, with 5413 kg/ ha/yr. Mean crude protein, P, K, Ca, and Mg contents for the 5 cultivars were 11.44, .37, 2.56, .31, and .34%, respectively. Leaf/stem ratios for all cultivars ranged from a maximum of 60 to a minimum of 52%. Cultivars 13079 and 7350 are the most outstanding grasses for this region of Puerto Rico. Cultivars 13078 and 532 are recommended as substitutes for the Merker cultivar. However, cultivar 13078 yields can be adversely affected by prolonged droughts.