Morphological studies in safflower (carthamus tinctorius linn.) with special reference to the effect of 2,4-D and gamma rays—I. Vegetative shoot apex

The effects of 2,4-D (10, 50 and 100 ppm) and gamma rays (10, 20 and 30 kR), both individually and in combination, were studied on the vegetative shoot apex of safflower. While 2,4-D had no effect on the shoot apex organization, gamma rays caused much injury. The extent of injury was, however, much less in the shoot tips treated with 10 ppm 2,4-D plus gamma ray exposures than in the apices treated with gamma rays alone. Occurrence of multinucleate cells and abnormally positioned tracheidal cells was observed in the apices treated with gamma rays and 2,4-D plus gamma ray combinations.