Solarization of nursery soil induces production of fruit bodies of mushrooms and enhances growth of tropical forest tree seedlings

The aim of this work was to find out the effect of soil solarization on microbial population and its effect on growth of two species of tropical forest trees. For this purpose, solar heating of nursery seedbeds (1 x 5m) was done during April- May 2009 for one month, by application of a thin clear sheet of polyethylene. The top soil (5 inches) consists of a mix of loam soil, sand and farm yard manure in 2:1:0.5 ratios (v/v). Temperature variations were recorded daily for a period of one month, at 2 depths, (5 cm and 10 cm). Maximum differences in temperature between solar treatment and control was recorded as high as 12.1° C at 5 cm and 9.1° C at 10 cm depth. After one month, population of Aspergillus, Fusarium, Penicillium, Rhizopus and nematodes were completely eliminated from upper 5 cm depth, although population of AM fungi, bacteria and Trichoderma were reduced, but not completely eliminated. Seedlings of Gmelina arborea Roxb. and Tectona grandis Linn.f. were raised through seeds on treated and control beds. After three months, the production of fruit bodies of mushrooms, namely Amanita populiphila Tullos & E. Moses, Lepiota longicauda Henn. and Scleroderma sp. were observed. It was noticed that these mushrooms only appeared on treated soil with white mycelial growth in rhizosphere under fruit bodies. Lepiota longicauda produced the maximum number of fruit bodies on teak seedbeds followed by Scleroderma sp. on G. arborea seedbeds. Due to solar heating there was 23.9% increase in plant height and 22.1% increase in collar diameter of G. arborea seedlings, where as 17.4% increase in plant height and 9.8% increase in collar diameter in case of T. grandis, as compared to control seedlings.