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Seeds of Pinus caribaea were sown in plastic pots containing nursery soil with or without a basidiospore inoculum of Scleroderma dictyosporum. After seedling establishment, five fertilizer treatments involving 0, 250, 500, 750 and 1000 g NPK per m3 of nursery soil were administered. The ratio of N:P:K in NPK was 3:3:1.Basidiospores of S. dictyosporum were an effective inoculum for P. caribaea seedlings. Inoculated seedlings showed superior growth in height, root collar area, length of stem with needles and dry matter production. Inoculation also increased the concentration of P in the plant tissues but had no effect on other nutrients studied.Fertilizer response was evident, but there were generally no benefits of using fertilizer levels above 250 g NPK per m3 soil. In fact, mycorrhizal development was progressively reduced with each increase in the level of NPK fertilizer. Tissue Mg concentrations were also deficient, a reflection of nutrient uptake imbalance due to high concentrations of ammonium sulphate and potassium chloride in the soil. Basidiospores of S. dictyosporum can therefore be used for routine inoculation of P. caribaea seedlings in nursery soils at low levels of NPK. Coincidentally such a reduction in the amount of NPK applied in nursery soil will have both biological as well as economic benefits |
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