One year-old uniform and well-rooted plants (45 cm height) of mandarin orange (raised in sand bed nursery), were transplanted in earthen pots (12″ diameter) filled with well-sieved acid-washed sand. Plants were supplied with 1/10 strength of MS solution (pH 5.6) every alternative day. Seven weeks after transplanting, the stress treatment was applied for 14 weeks until pronounced visual structural indications of stress (e.g., chlorosis of leaves, growth impairment etc.) appeared. On every alternate day, each pot was fed with 500 ml of 1/10 strength MS solution (pH 5.6) together with ZnSO₄ solutions containing 1 mM, 2 mM, 3 mM, 4 mM, 5 mM, 10 mM, 15 mM and 20 mM of Zn. Without Zn (0 mM Zn) was served as the control.

Zn stress reduced the photosynthetic rate, stomatal conductance, and transpiration along with reduction of chlorophyll a, chlorophyll b, and carotenoids content in leaf.