Predicting green leaf proportion in ungrazed kleingrass ( Panicum coloratum L.) in the semiarid Pampas Region of Argentina

摘要

Green leaf proportion is an important factor affecting nutritive value, ingestive behavior and forage intake. Determination of green leaf proportion by hand separation of plant samples is time consuming and expensive. The aim of this work was to establish whether a stable relationship exists between the proportion of green leaf blade and total mass of harvestable forage in ungrazed kleingrass ( Panicum coloratum L.) cv. Verde. The study was carried out during four consecutive growing seasons in an established pasture of kleingrass. During two growing seasons, 90 kg N ha-1 was applied. Forage samples were collected at biweekly intervals and separated into leaf blades, stems (inclusive of leaf sheaths), and senescent material. Regression analysis indicated a consistent relationship (y = 0.70x-0.41, R2 = 0.84, P< 0.001, n = 180) between the proportion of green leaf blade and total mass of harvestable forage in ungrazed kleingrass, even under varying environmental conditions of rainfall and N availability. Thus, total harvestable forage might be used to predict the green leaf proportion of kleingrass in contrasting environments, and used as an easy-to-measure indicator of green leaf proportion that would permit a balance of forage quality and quantity in kleingrass.