Abstract

Sequential leaf senescence is defined as a kind of programmed death events which is an important process in growth of plant. This study aimed to explore the sequential leaf senescence rate due to indoleacetic acid and lack of zinc (-Zn). Therefore, the effect of zinc and indole-3-acetic acid on senescence which occurs in Helianthus annuus (sunflower) cotyledons was analyzed. It was found that in cotyledons of seedlings grown in Hoagland solution which was prepared without addition of zinc senescence is delayed. It was recognised that in case of ¹⁴C indoleacetic acid (IAA) which was given from apical tip not reaching the root and cotyledons, senescence does not occur in cotyledons. It was studied to get more information about physiological system of sequential leaf senescence.

Key words: Sequential leaf senescence, cotyledon, zinc, ¹⁴C indole-acetic acid (IAA), Helianthus annuus (sunflower).