Relationships of external osmotic potentials with water saturation deficit and some N compounds in two maize cultivars

الملخص EN

The percentage water saturation deficit (WSD) and the content of nitrogenous compounds free amino acids, proline and soluble proteins were studied in two Egyptian cultivars (Composite 5 and Giza 2) of maize (Zea mays, L) under varying osmotic potentials (0, -I, -2, -4, -6, -8 and -10 MPa) and varying times (from 1 to 7 days of exposure to 0.0, -2.02 and -4.04 MPa osmotic potentials.

The obtained relationships were linear and showed significantly different rates of increase in WSD of the two cultivars with the decrease in external water potential or increase in time of stress.

Composite 5 cultivar exhibited greater WSD than Giza 2, and the two cultivars showed dissimilar rates of daily increase in WSD under osmotic stress.

Free amino acids, proline and soluble proteins accumulated but with greater rates from 0.0 to -2.02 than under from -2.02 to -4.04 MPa in both cultivars.

Free proline and amino acids continued to accumulate with time of stress.

Proteins accumulation was inhibited after the third day of stress.

Proline and amino acids accumulated by greater rates with the increase in WSD in Giza 2.

The increase in proline was by about 15 and 8 mg/g D.

wt.

per MPa decrease in osmotic potential in Composite 5 and Giza 2 cultivar respectively.