Seed yield and quality enhancement of pollarded subabul (Leucaena leucocephala) by nutrient supplementation

Agroforestry species Leucaena leucocephala (subabul), a multipurpose leguminous tree, is one of the most suitable species for silvipasture system. Its seeds, a good protein source to livestock, also have lot of industrial application. Subabul responds well to pollarding, a practice that helps growth of understory crops but reduces seed yield of main tree species. The aim of this study was to evaluate the effect of nutrient application on fruit and seed characters, seed yield, germination and vigour of pollarded subabul trees. The study was conducted on three important salvodar type subabul varieties (K8, K636 and S24) with different fruit and seed characters. Three nutrient mixtures (SSP @ 150 kg/ha + ZnSO4 @ 20 kg/ha; CuSO4 @ 0.25 % + Borax @ 0.15 % + KNO3 @ 1 % in 500 l spray volume per ha and KNO3 @ 4 kg/ha) were applied before anthesis. The nutrient treatments have enhanced fruit length and weight without affecting the fruit width. Similarly, seed characters responded positively to nutrient applications resulting in enhanced mean yield across varieties and years. The seed viability measured as germination percentage varied among varieties with maximum viability in small-seeded K 636. The application of nutrients enhanced the germination and vigour in all three varieties irrespective of the seed size. Among the nutrient mixtures, potassium nitrate @ 4 kg/ha has better effect on seed yield and its attributing characters as well as on seed quality across the varieties over the years.