Response of sandal (Santalum album Linn.) seedlings to shade and mycorrhizal association

Abstract

The occurrence of sandal- Arbuscular Mycorrhizal Fungi (AMF) associations in natural sandal growing forests and the response of sandal seedlings to inoculation with commonly available cultures of AMF, shade levels and nature of hosts were investigated in a pot culture experiment at the College of Forestry, Kerala Agricultural University, Vellanikkara. Two important sandal growing regions in the state, Marayoor (ldukki district) and Wadakancherry (Thrissur district) were selected for this study and a non-sandal growing area in Thrissur district was selected as a control for the soil studies . The result showed that characters like height, number of leaves, leaf area and shoot weight of sandal seedlings increased due to the Arbuscular Mycorrhizal Fungi inoculation and maximum response was observed for seedlings grown in soils inoculated with Glomus mosseae. The characters like collar girth, root weight did not show any significant difference for the mycorrhizal inoculation. It was further observed that the interactions between shade and mycorrhizae were the best under 50 per cent shade level especially for those seedlings inoculated with Glomus mosseae. During the initial seedling phase, high shade (75 per cent) is needed for sandal, but during the later stages of seedling growth, medium shade (50 per cent) resulted in best growth of seedlings. Growth of sandal seedlings with two host species, casuarina and redgram was on par. The relative water content and plant water potential were higher in seedlings inoculated with AMF. The N, P, K content of the shoot of sandal seedlings were maximum for seedlings inoculated with Glomus mosseae.

Sandal seedlings collected from natural sandal growmg regions investigated for the presence of sandal-AMF association revealed that the roots of sandal seedlings from Wadakancherry forest showed 33 per cent of colonization, while the seedlings from Marayoor forest showed no colonization. Sandal seedlings grown for four months in the soils collected from these two regions showed superior growth when compared to those seedlings grown in soils from the agricultural lands of Thrissur, but no AMF colonization was observed in the roots of the sandal seedlings .