Effects of shading, irrigation and mycorrhizal inoculation on growth and development of oil palm Elaeis guineensis Jacq. (Magnoliophyta: Arecaceae) seedlings in the nursery

Experiments were conducted to examine the growth and development of oil palm Elaeis guineensis Jacq. (Magnoliophyta: Arecaceae) seedlings subjected to shading, irrigation regimes and mycorrhizal inoculation in the dry season. Treatments were 2 x 2 x 2 factorial combination consisting of shade and no-shade (open sun), 7 and 14 day irrigation intervals and mycorrhizal inoculation or non-inoculation. Seedlings that were grown under shade and irrigated weekly produced highest number and length of fronds, and shoot, leaf and frond weights in addition to taller plants compared to open sun (unshaded) seedlings. Across irrigation treatments, unshaded seedlings had lower weights of leaf, frond and shoot biomass. The effects of shade treatments were significant on plant height and frond length from 2 to 20 weeks after planting. The seedlings irrigated fortnightly produced longer roots compared with the unshaded and weekly irrigated. Fortnight irrigation enhanced root development compared with weekly irrigation. Shading and weekly irrigation significantly enhanced soil moisture contents and seedling water use efficiency compared with the unshaded. Shaded seedlings irrigated weekly used larger amount of water compared with fortnight irrigation. Significant interactions were obtained between shade and irrigation regimes for most of the growth parameters measured. Mycorrhizal inoculation, shaded and weekly irrigated seedlings were more vigorous compared with the unshaded and non-inoculated.