Influence of Intra-Row Spacing and Cutting Regimes on the Growth and Yield of Leucaena1
- A. B. Guevarra,
- A. S. Whitney and
- J. R. Thompson2
Leucaena (Leucaena leucocephala (Lam.) de Wit) has proven to be a very productive tropical legume, but the factors which control production under intensive management have not been well defined. Thus three harvest frequencies (based on attained plant height), three population densities, and two plant types of leucaena were evaluated at North Kohala, Hawaii (120-m elevation, Typic Ustropept). Plants of K341 (a shrubby “Hawaiian” type) and K8 (an arboreal “Salvador” type) were grown at spacings of 15 ✕ 50, 30 ✕ 50, and 45 ✕ 50 cm, and harvested when plants attained average heights of 55, 105, or 155 cm. Stem elongation rates and yields were highest during periods of high solar radiation and high night temperature. Selection K341 tended to flower at an early stage, especially at the lower planting densities, with consequent reduction in vegetative growth. Selection K8 increased in height more rapidly than K341 and thereby intercepted more sunlight until about 14 weeks when light interception values were similar at 96%.
Yields increased with less frequent cutting. Total dry matter yields when cut at attained heights of 55, 105, and 155 cm (about 2 1/2, 3, and 4 months growth duration) were 11.9, 16.9, and 20.8 metric tons/ha, respectively. However, the percentage forage fraction was higher under more frequent cutting; averaging 79, 68, and 59% for the same three treatments. Percentage forage fraction also tended to be slightly higher at the highest plant density, since leucaena was unable to compensate for wide spacing by producing more shoots. Plant type, spacing, and cutting treatments did not affect the levels of N or mimosine in the forage fraction (4.3 and 6.7% respectively) or in the stem fraction (1.5 and 0.9%, respectively. K341 yielded nearly 600 kg N ha−lyear−1 in the forage fraction while K8 yielded about 500 kg N ha−lyear−l.
Dense planting (15 ✕ 50 cm) and cutting when the plants were approximately 1 m in height were desirable management practices considering forage yield, percentage forage fraction, forage quality, flowering behavior, and average cutting frequency (3 months).Please view the pdf by using the Full Text (PDF) link under 'View' to the left.
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