Chlorine—A Micronutrient Element for Higher Plants

Abstract

A severe nutritional deficiency disease was observed in tomato plants when the known halide supply was limited. The nutritional deficiency is visibly characterized in its early stages, by a wilting of leaflet blade tips; progressively,by chlorosis, bronzing and necrosis basipetally in areas proximal to the wilting. Severely diseased plants failed to produce fruit. Growth was correlated with chlorine supply in the culture solution. Adequate additions of chlorine as chloride to culture media entirely prevented the disease; severely deficient plants resumed staisfactory growth after chlorine was applied to the culture solution or through injection into stems. Bromine appears to complement chlorine when supplied at about ten times the required chlorine levels. Possible effects of iodine are difficult to assess because of its toxicity. It is concluded that chlorine is a nutrient element, certainly the naturally occurring essential halide.