effect of salinity stress and foliar application of methyl jasmonate on photosynthetic rate, stomatal conductance, water use efficiency and yield of german chamomile

jasmonate is new plant growth regulator that plays an essential role at increasing plants resistance to the environmental stresses like salinity stress. hence, in this research the effect of foliar application of methyl jasmonate on some physiological indices and yield of german chamomile under salinity conditions was studied. a factorial experiment was laid out based on randomized complete block design (rcbd) with three replications in the greenhouse condition. foliar application of methyl jasmonate was five levels (mj1; 0, mj2; 75, mj3; 150, mj4; 225 and mj5; 300 μm) and salinity stress was four levels (s1; 2, s2; 6, s3; 10, s4; 14 ds m-1). the effect of methyl jasmonate, salinity condition treatments and their interaction was significant for traits of photosynthesis rate, stomata conductance, transpiration rate, carboxylation efficiency, intercellular co2 concentration and yield of flower. the highest values of photosynthetic rate, stomata conductance, transpiration rate, carboxylation efficiency and yield of flower (3.76 g pot-1) and the lowest intercellular co2 concentration were achieved at mj×s treatment. maximum value of photosynthetic water use efficiency was revealed at mj5×s2 treatment. with decreasing stomata conductance, photosynthetic water use efficiency and intercellular co2 concentration were increased. in general, it seems that application of methyl jasmonate by lower dose (mj2) under salinity conditions especially mild salinity stress (s2) can improve physiological indices and yield of chamomile.