Does salinity inhibit maize leaf growth by reducing tissue concentrations of essential mineral nutrients?

Abstract

Excessive salinity can reduce growth of crop plants in many regions of the world but the underlying mechanisms are largely unknown. We investigated the possibility that inhibition of maize (Zea mays L.) leaf growth by salinity might be associated with loss of capacity to maintain adequate mineral nutrient concentrations in the leaf tissues. Maize plants were grown for 20d in a controlled environment on expanded vermiculite and irrigated daily with nutrient solution containing additional Ca. The effects of salinization with 100 mM NaCl and 20‐fold differences in the strength of the external nutrient solution on root growth, leaf growth, and ion concentrations in leaf tissues were determined. Salinity caused reductions in root and leaf growth. Increasing external nutrient supply to the roots increased growth of control plants but did not increase growth of salinized plants. Moreover, N and P concentrations in the leaf tissues were increased by salinity and Mg concentrations were unaffected. The small salinity induced reductions in concentrations of K and Ca ions, or lowered K/Na ratios, did not appear to be large enough to inhibit growth. Thus reduced leaf nutrient concentrations did not appear to be a primary cause of inhibited leaf growth under saline conditions.

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