Biophysical and interaction effect of uv-b radiation and water stress on cucurbita pepo l.

الملخص EN

UV-B radiation substantially reduced the growth criteria of 22- days old squash (Cucurbit pepo L) seedlings This reduction increased by the exposure time to UV-B radiation.

The inhibition of shoot growth was accompanied by reduction in levels of carbohydrate and phosphorus fractions, as well as in nitrate reductase activity.

The activities of alkaline and acid phosphates slightly increased.

The sensitivity of squash to UV-B irradiation decreased by subsequent exposure to visible light.

Moreover, irradiation of water - stressed plants for short time with UV-B followed by exposure to visible light induced a great recovery in squash growth and all of measured metabolic parameters as compared with the drastic effects induced by prolonged exposure to UV-B radiation.

These results emphasize the usefulness of photo reactivation by realistic level of visible light that can minimize the harmful effect of prolonged UV-B irradiation time.