Sprinkling-induced foliar injury to pepper plants: Effects of irrigation frequency, duration and water composition

Summary

This study was conducted to determine the conditions and causes of foliar salt absorption and injury from sprinkler irrigation with saline water. Bell pepper plants (Capsicum annuum L. cv. Yolo Wonder B) grown in covered nutrient solution cultures in the greenhouse were sprinkled daily with NaCl and CaCl₂ waters for up to 10 weeks. Unsprinkled plants grown in nonsaline, and in one experiment, saline cultures were compared with plants sprinkled with waters containing different concentrations of NaCl and/or CaCl₂. Both the frequency and duration of sprinkling (up to 32 min each day) were tested.

The results showed that Ca²⁺, Na⁺, and Cl⁻ were readily absorbed through the leaves at rates that were essentially linear functions of salt concentration and duration of sprinkling. Increasing frequency of sprinkling increased salt uptake and injury more than increasing duration. Sprinkling with either NaCl or CaCl₂ waters was more toxic to pepper than mixtures of the two salts. Although CaCl₂ was more toxic than NaCl, low concentrations of Ca²⁺ ameliorated the detrimental effects of NaCl waters. Foliar analyses indicated that leaf injury was not correlated with Cl⁻ accumulation. It appeared that it was caused directly by excessive cation accumulation or indirectly by the resultant ionic imbalance.