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Abstract
The identification of mineral element deficiencies by enzymatic methods was introduced by the late A. Bar‐Akiva with citrus leaves. The level of specific enzyme activities was found to provide a rapid and sensitive indicator for deficiencies of the micronutrients iron (Fe), manganese (Mn), zinc (Zn), copper (Cu), and molybdenum (Mo) as well as the macronutrients nitrogen (N) and phosphorus (P). Infiltration of the missing element into deficient leaf material reactivated the respective enzyme. The extent of reactivation of the enzyme was negatively correlated with the level of the element in the deficient leaves. The enzyme indicator concept has recently been extended to the characterization of potassium (K), magnesium (Mg), and calcium (Ca) deficiencies. Pyruvate kinase activity was found to reflect the K, Mg, and Ca balance. Amylase activity was inversely correlated with citrus leaf K levels. The level of RuBP carboxylase was reduced under Ca deficiency conditions. The significance of enzymatic methods for study of citrus mineral element nutrition is discussed.
Notes
Contribution from the Agricultural Research Organization, Institute of Horticulture, Bet Dagan, Israel, No. 210/98.
