Morphology, productivity and forage quality of Leucaena leucocephala as influenced by irrigation under field conditions

摘要

A field study was conducted to investigate the effect of water deficit on the morphology, productivity, and quality of Leucaena leucocephala (Lam.) De Wit. Five main irrigation levels were applied based on actual evapotranspiration (AET): 0.25, 0.50, 0.75, 1.00, and 1.25 of the AET. Plant height, number of leaves and branches, and root length and diameter were measured. Fresh and dry weights were recorded at harvest, and crude protein was analyzed in leaves and roots. The results showed that morphological and yield characteristics were affected by the amount of water applied. The number of leaves remaining at the end of 21 weeks of growth was 65, 84, 93, 87 and 102 at 0.25, 0.50, 0.75, 1.00, and 1.25 AET. Root length and diameter increased with increasing irrigation. The greatest root length (66.5 cm) at 1.00 AET did not differ significantly from that at 1.25 AET (58.8 cm). The dry yield at 0.50, 0.75 and 1.00 AET showed an increased trend per plant in each treatment. Similarly, leaf crude protein showed a trend of increase with increasing irrigation although values were not significantly different between the levels of irrigation. The moisture content ranged from 60 to 63 % in leaves and 32–35 % in branches across the five treatments. The analysis of water use efficiency showed that the 0.50 AET plants produced 2.6 kg ha−1 mm−1 of dry forage compared to 1.8 kg ha−1 mm−1 at 0.75 AET. The results showed that 0.50 or 0.75 AET represents the best irrigation level for L. leucocephala cultivation, producing a total dry yield of 0.68 and 0.72 t ha−1, respectively, in our study.