Study on effect of lead toxicity on generative organ's structure in Matricaria chamomilla L.

Matricaria chamomilla L. is one of the most important medicinal plants which it grows among 50-80 cm hight. It has the yellow and ray flowers in central of florescence and the white and disk flowers in margin. Heavy metal is an important contamination in environment that they are very toxic، although، their concentration is low. The present study was undertaken to determine the effects of lead on structural characteristics and inflorescence development in M. chamomilla. Plants in vegetative stage treated with contaminated hydroponic in 5 treatments (0، 60،120،180،240 µM) with 3 repeat in per treatment for 21 days. Anatomical characteristics of pollen grains affected by lead contamination، also optical microscope studies indicated structural changes in natural shape of pollen grains. Decreased the size of them and decreased the diameter of wall in pollen sac. Also the results of study of pistil in cross section did not show any changes in diameter of ovule but diameter of ovum is different in terminal stage. Results indicated that in terminal stages of flower development، anatomical characters changes of pollen grains and flowers have increased with Pb concentration increasing to 240 µM.