SOME STUDIES ON THE EFFECT OF GROWTH1RETA DANT (UNICONAZOLE) ON SOYBEAN AND HELIANTHUS PLANTS

Abstract

the present investigation soy bean and sunflower seeds were soaked in, or the plants were foliar-sprayed with the growth retardant uniconazole. The effects of uniconazole at concentrations 0, 5, 10, 20, 40 and 80 ppm. on the growth, endogenous growth regulating substances, photosynthetic pigments, carbohydrates, nitrogenous constituents, nucleic acids, some minerals, protein, oil and enzymes were studied.

The results showed that the concentration 20 ppm. of uniconazole caused significant increases in most of the growth parameters and the higher concentration (80 ppm.) resulted in a decrease in these parameters. All concentrations of uniconazole induced decrease in auxin, gibberellin and cytokinins contents and increased the inhibitor contents. The used concentrations of uniconazole increased chlorophyll a, b and carotenoid contents in soy bean and sunflower leaves.

All concentrations of the growth retardant increased reducing sugars, sucrose, polysaccharides and total sugars. The lower concentrations of uniconazole caused highly significant increases in DNA and RNA contents, while the higher concentration induced highly significant decreases. High significant increases were observed in the total-N and total soluble-N contents of the shoots at lower concentration, highly significant decreases were observed at the higher concentration. The concentrations 5,10 and 20 ppm ofuniconazole induced increases in soybean-seed protein content while the higher concentration induced a decrease. All concentrations used of growth retardant increased oil contents and some mineral ions in sunflower seeds. Uniconazole induced high significant decreases in a-amylase, 13-amylase and protease activities. However, high significant increases were observed in RNase and IAA oxidase in shoots of both plants studied.