EFFECT OF AMMONIUM NITRATE AND LIME ON GERMINATION AND EARLY GROWTH OF PINUS CARIBAEA

Abstract

Depressive effects of nitrogen (N) salts on germination and survival of Caribbean pine (Pinus caribaea Mor.) were investigated in the glasshouse by following changes in mineral soil N after the application of lime and fertilizers. The effect of partial soil sterilization was also studied. Immobilization and subsequent nitrification of ammonium nitrate was greatly stimulated by liming. Germination and survival declined as the soil nitrate level was raised, apparently because of increased pre—and post-emergence damping-off by Fusarium spp. Seedling yield at 20 weeks was reduced by high soil nitrate levels, but this effect was reversed at 31 weeks except for the highest level of nitrate. The percentage of total N in seedling tissues was closely correlated with the concentration of soil nitrate. The effects of partial soil sterilization on plant behaviour were slight compared to those of ammonium nitrate and lime.