Impact of zinc fertilization on gas exchange characteristics and water use efficiency of cotton crop under arid environment.

Abstract

Gas exchange characteristics play an important role in the growth and development of cotton plants .Therefore, field experiments were conducted for consecutive two years during 2004 and 2005 to study the effects of Zn fertilization @ 0 (control), 5.0, 7.5, 10.0 and 12.5 kg Zn ha -1 on gas exchange characteristics of cotton cv. CIM-473. The soil of the experimental site was alkaline in nature, moderately calcareous, silt loam with low Zn (DTPA -extractable Zn, 0.5 mg kg -1 soil). The net photosynthetic rate (PN), transpiration rate (E) and stomatal conductance (gs) increased while intercellular CO2 (Ci) decreased with the increasing Zn levels during both years of study. The water use efficiency (PN /E) was improved by 32% under the highest Zn dose compared to control. There were positive correlations between Zn doses and PN (0.98**), E (0.97**), g s (0.88**), WUE (0.94**), while a negative correlation was observed with Ci (-0.95**). The addition of Zn fertilizer caused beneficial influence on cotton plant by enhancing its water use efficiency and gas exchange parameters.