Advances in the use and application of plant analysis

Abstract

Abstract In the past, there have been problems associated with the use of the critical value approach as a foliar diagnostic tool such as the variation in tissue composition on a dry matter basis with age and the wide range in critical values for the same crop published by various workers. In addition, there has been controversy in the literature concerning the use of nutrient concentrations and ratios. These problems are reviewed and investigated in the context of the Diagnosis and Recommendation Integrated System (DRIS) which is the latest approach to foliar diagnosis to appear in the literature. Using data from various sources and for various crops, the case is made that this approach leads to the reduction or elimination of many of the above problems allowing one to make diagnoses over a wide variation in age of crop which rank the nutrients in their order of limiting importance on yield.