The influence of temperatures on germination and seedling growth of pyrethrum (Tanacetum cineraiifolium) under drought stress

Pyrethrum is a perennial daisy grown commercially for the insecticide that is extracted from its flowers. In order to evaluate germination and seedling growth of pyrethrum under different temperature and drought stress treatments, an experiment was conducted in seed technology laboratory of Faculty of Agriculture of Islamic Azad University of Isfahan branch in 2018. During this experiment, polyethylene glycol (PEG) at 6 levels (0, -0.2, -0.4, -0.6, -0.8, -1.0 MP) and two temperature treatments (10oC and 15oC) were used. Two separate factorial trials, on the basis of absolute randomized design with three replications were used. Drought stress impact on germination percentage, mean time germination, shoot and root length, abnormal germination, germination uniformity, plumule dry and fresh weight, root dry and fresh weight and seed stamina index was significant. The influence of temperature was meaningful on germination percentage, mean time germination, shoot and root length, plumule dry weight, plumule fresh weight, root dry weight and root fresh weight. The rate of germination, germination percentage, as well as seedling growth and establishment were significantly lowered with the rise of stress levels using PEG. Control treatment and 15oC had obtained the highest germination percentage, mean time germination, shoot and root length, germination uniformity, plumule dry and fresh weight, root dry and fresh weight, and seed stamina index. Taking all traits into account, a clear understanding of the germination responses of seeds is useful in screening for tolerance of species to extreme temperatures.