Abstract
A study on uptake of 14C-urea by vanilla was conducted at the Radio Tracer Laboratory, Kerala Agricultural University, Thrissur, India with the objective of finding the factors affecting uptake. The experiment was conducted on young and old leaves of one year old vanilla plants raised in polythene bags. Radioactivity present in plant samples and also in the washings were recorded. The radioactivity was determined by liquid scintillation counting technique in a micro-processor controlled liquid scintillation system. Plant factors namely leaf surface, age of leaf, cuticle thickness and stomatal index as well as duration allowed for uptake were found to influence the absorption of foliar applied urea. It was found that in order to get greater efficiency of foliar applied nutrient uptake, spraying should be done to the lower surface of younger leaves and allowing a minimum absorption time of two days. It was also observed that aerial roots of vanilla are the major nutrient uptake plant part, and absorbing about 80- 90% of the applied nutrients. Foliar nutrition can therefore be recommended in vanilla and spraying on aerial roots and younger leaves would be more effective.
