Differential responses of iron, magnesium, and zinc deficiency on pigment composition, nutrient content, and photosynthetic activity in tropical fruit crops.
Balakrishnan K., Rajendran C., Kulandaivelu G.
Author Affiliation: School of Biological Sciences, Madurai Kamaraj University, Madurai, India.
Photosynthetica 38 : 477-479
Abstract : The effects of Fe, Zn, and Mg deficiencies on pigment composition, nutrient content and photosynthetic activity in field grown fruit trees of sapota (Achras zapota [Manilkara zapota]) cv. PKM-1, mango (Mangifera indica) cv. Neelam, jamun (Eugenia jambolana [Syzygium cumini]) cv. Local and sweet orange (Citrus sinensis) cv. Sathgudi were studied. The deficiency of Fe in sapota and jamun, of Mg in Mango, and of Zn in sweet orange were identified based on the visible symptoms in 15-year-old trees in Tamil Nadu, India. Fe, Mn and Zn affected the chlorophyll (Chl) content whereas Fe deficiency caused a larger reduction of total Chl content than Mg and Zn deficiences. Mg deficient mango had a higher Chl a/b ratio than the respective healthy plants. The foliar contents of Fe, Zn, and Mg in the deficient leaves were lower than the critical level. Nutrient deficiency significantly affected the ratio of variable to maximum flourescence as observed from the Chl fluorescence induction curves. Fe deficiency resulted in larger reduction of variable fluorescence than Mg and Zn deficiency.