EFFECT OF SOME GROWTH RETARDANTS ON THE PHYSIOLOGICAL AND GROWTH BEHAVIOR OF RICE PLANTS

Abstract

This investigation was conducted during 1993 and 1994 seasons, to study the effect of some new growth retardants i.e. MLU 208, RSW 0411 and uniconazole in addition to CCC as foliar application on the lodging, growth, chemical characters and stem anatomical structure as well as yield components of rice plants. The main results of this work can be summarized in the following points:

1) All concentrations cfMLU 208, RSW 0411 and uniconazole decreased markedly the heights of plants.

2) The CCC treatment did not cause any significant effect on any growth character studied in this work.

3) Treating rice plants with different concentrations ofMLU 208, RSW 0411 and uniconazole led to an increase in the number of tillers per/m2

4) All growth retarding substances increased the flag leaf area as compared to untreated plants.

5) The highest concentration ofMLU 208, RSW 0411 and uniconazole caused an increase.in the dry weights of roots and shoots duiing the growth period.

6) The application of MLU 208, RSW 0411 and uniconazole increased the culm diameter and increased the ability of plants to resist the lodging. 7) All growth retardants increased the concentration of chlorophyll a, chlorophyll b in rice leaves, while the carotenoid concentration was decreased.