A mathematical approach for evaluating iron chlorosis inducing factors

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Abstract
Factors inducing Fe‐chlorosis in grape vines had been studied during a 2 years field review. Based on soil and leaf samples, taken consecutively every two weeks over the whole vegetation period, the variable parameters were determined. The comparison was achieved between chlorotic and nonchlorotic stands of grape vines, differing in rootstocks but grafted with the same cultivar. By means of different statistical methods, the influence of the sole parameters were tested. Chlorosis in its different intensities was'neither induced by an absolut Fe‐deficiency (in leaf or soil) nor by a relative Fe‐deficiency in the soil, as shown by the amounts of DTPA‐extractable Fe. In spite of this fact, the concentration of water and citrate buffer‐extractable Fe in leaves was in most cases lower, while the 0,5 n HCl‐ and 1,0 n HCl‐extractable Fe was higher in chlorotic leaves compared with green ones. All of the applied statistical methods proved in accordance the important influence of water soluble phosphate in the soil layer between 20 and 60 cm. The comparison with additional results from field surveys primarily points to a complex acting through HCO3‐ ‐Pw on and energy status during the development of the physiologically induced iron‐chlorosis.