Interactive Effects of Salinity and Phosphorus Nutrition of the Concentrations of Phosphate and Phosphate Esters in Mature Photosynthesizing Corn Leaves 1

AUTOR(ES)

Nieman, Richard H.

RESUMO

The effects of salinity on corn plants (Zea mays L.) are influenced by the concentration of nutrient orthophosphate. Salinity (−2 bars each of NaCl and CaCl2) was more injurious in combination with a high concentration of orthophosphate (2 mm) (that gave optimum yields in the absence of salinity) than it was with a lower concentration (0.1 mm). With 2 mm orthophosphate, salinity seemed to damage the plant mechanisms that normally regulate the internal concentration of orthophosphate resulting in excessive accumulation and P toxicity. On the other hand, with 0.1 mm orthophosphate, salinity decreased orthophosphate concentration in mature leaves. This effect was paralleled by decreases in the concentration of adenosine 5′-triphosphate and in the energy charge of the adenylate system, indicating an orthophosphate deficit. Even so, plants survived salinity better under these conditions than in the presence of 2 mm orthophosphate. The data indicated that salinity affected the phosphorylated state of the adenine nucleotides only indirectly through its effect on the concentration of orthophosphate in the cells.

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