Analysis of leaves and petioles for nutritional diagnosis of potato

This article deals with the preliminary phases of a study aimed at adapting the technique of foliar analysis for diagnosing the mineral nutrition of potatoes. In a pot experiment, analytical results for petioles and leaflets were obtained at three sampling dates and yields of tubers were measured. There were three series of fertilizer treatments with graded amounts of N, P, or K in the presence of the highest level of the other two elements. Yield responses were obtained to nitrogen and phosphorus, the plants showing typical deficiency symptoms when either of these elements was omitted. For both N and P the nutritional status of the plants was clearly reflected in the results of foliar analysis. The omission of potassium had no significant effect on yield, and differences in leaf composition were found only at the last sampling date. It appears that for greatest sensitivity and simplification of sampling, analyses should be made for soluble nitrogen (NO3-N), soluble phosphorus (PO4-P) and total potassium in petioles of the third leaf front the apical bud.