Field evaluation of chlorophyll meter for screening groundnut (Arachis hypogaea L.) genotypes tolerant to iron-deficiency chlorosis.

Visual diagnosis, using visual chlorotic rating (VCR), and chlorophyll content determination are widely used for selecting groundnut genotypes tolerant of iron-deficiency chlorosis in the field. The possibility of using a chlorophyll meter (SPAD) for rapid and in situ screening of genotypes for chlorosis tolerance was investigated. The study showed that the correlation between SPAD readings and chlorophyll content was positive and highly significant, with r = 0.94 for chlorophyll a, 0.90 for chlorophyll b and 0.93 for total chlorophyll content. This clearly indicated a close relationship of these traits with SPAD readings, i.e., the higher the SPAD reading, the higher the content of chlorophyll pigments. Regression analysis showed that these variables have a linear relationship with each other. On the basis of the linear relationship, regression equations were developed from which it is possible to predict the chlorophyll content and VCR of the leaves. Thus, the chlorophyll meter is an efficient and speedy tool for screening genotypes for tolerance of iron-deficiency chlorosis.