Differential responses of iron, magnesium, and zinc deficiency on pigment composition, nutrient content, and photosynthetic activity in tropical fruit crops

Fe, Mn, and Zn affected the chlorophyll (Chl) content whereas Fe deficiency caused larger reduction of total chlorophyll content than Mg and Zn defici encies. Mg deficient mango had a higher Chl a/b ratio than the respective h ealthy plants. The foliar contents of Fe, Zn, and Mg in the deficient leave s were lower than the critical level. Nutrient deficiency significantly aff ected the F-v/F-m ratios as observed from the CN fluorescence induction cur ves. Fe deficiency resulted in larger reduction of variable fluorescence th an Mg and Zn deficiency.