PRESENT STATUS OF DIAGNOSIS OF MINERAL REQUIREMENTS OF PLANTS BY MEANS OF LEAF ANALYSIS

Abstract

Procedures by different workers are examined with respect to 1) selection of material and sampling technique, 2) prepn. of samples for analysis, 3) methods of chemical analysis, 4) treatment of analytical data, and 5) interpretation of results. The validity of some of the methods of procedure is questioned and among others the need for greater uniformity is emphasized. The views of 2 schools of thought are discussed. The use of minimum or limiting values of a nutrient element is restricted principally to investigations of the survey type, particularly to the diagnosis of deficiencies resulting in physiological diseases. In field plot expts. in which the objective is to relate leaf composition to yields, the most effective procedure is one that will give not only a quantitative measure of the fertilizer elements present in the leaf at the moment of sampling, but will give, in addition. an index of the qualitative relations resulting from their interactions. Citations are made to 80 papers.