Relationship of foliar analysis to applied levels of nutrients on potatoes and radishes
The diagnosis of mineral deficiencies of crops is an important problem in agricultural and horticultural practice. Although the appearance of mineral deficiency symptoms may be of use, they usually appear when the deficiencies are already severe. Sometimes the symptoms are not characteristic, or else they may be masked when there are multiple deficiencies. Leaf analysis of perennial crops has been successfully employed for diagnostic purposes, particularly in the tropics. It is possible to standardize the sampling techniques as regards to time of year, morphological position of the leaves and physiological age. Under these conditions, analysis can be used as a diagnostic tool and it affords a useful check on any fertilizer policy adopted. Where annual crops are concerned, the possibilities of leaf analysis are much more restricted. Sampling and diagnosis has to be done at a stage of development which is early enough to enable nutritional disorders to be corrected. The chemical composition of annual crops may change during the growing season as a result of climatic conditions, fluctuations in the composition of the soil solution and the stage of development of the crop. In making leaf analyses of annual crops we are therefore faced with the problem of obtaining comparable samples of rapidly growing crops. Potato plants, in particular, in the production of tubers remove substantial amounts of nitrogen, phosphorus and potassium from the soil. In Saskatchewan nitrogen and phosphorus often must be increased in the soil by addition of these fertilizers. The objectives of this study were to relate foliar nutrient levels to the levels of applied fertilizer, as well as to such parameters as yield and quality.