EFFECT OF CERTAIN NUTRIENT DEFICIENCIES ON STOMATAL BEHAVIOR

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Abstract
Several methods of measuring stomatal aperture were tested; Lloyd''s strip method, slightly modified, and direct observational methods were most used, the former to the greatest extent. Studies with Zea, Pisum, Phaseolus, Nicotiana, and Tradescantia, demonstrated that when these plants showed symptoms of deficiency for any one of the elements, N, P, or K, the stomates were correspondingly more sluggish in their responses to the environmental factors, light and water supply. The degree of sluggishness induced by these deficiencies was also in the order named. In cultures supplied with a full nutrient solution the stomates were more responsive to changing environmental conditions, opening and closing more completely and more rapidly, than when one of these elements was deficient. The subnormal stomatal behavior in the deficient cultures was accompanied by increased water requirement, decreased yield of fruit, decreased size of plants, and decreased top-root ratio. That the stomatal mechanism itself was not altered in the deficient cultures was indicated by the fact that when placed in NH4OH soln. the stomata in all cultures responded similarly.