Effect of salicylic acid on drought stress through improving some morphological, physiological and yield components traits of mustard plant (Brassica compestris var. parkland)

Salicylic acid reduces the effects of oxidative stress as a secondary stress in dry condition. In order to study mitigation effects of salicylic acid (SA) on drought stress conditions in mustard plant، a factorial experiment was conducted based on completely randomized design with three replications at the Research Greenhouse of Ferdowsi University of Mashhad Iran، in 2012. The first factor was three levels (0، 100 and 200 ppm) of salicylic acid (SA) and the second factor was three levels of drought stress (%25، %50 and %75 of field capacity (FC)). Foliar spraying of salicylic acid started one week before the initiation of drought stress and continued in seven- day intervals until three weeks after drought stress The results showed that the effects of salicylic acid (SA) and drought stress on all morphophysiological، seed weight per plant and its components were significant. The greatest plant height was obtained from application of 200 ppm SA and %75 FC drought stress treatment. The maximum photosynthetic amount and membrane stability index (MSI) were observed where 100 ppm of SA was applied at %75 FC drought stress. The highest seed weight per plant with 1. 43 g was also acquired with application of 100 ppm SA and %75 FC drought stress treatment. The results of the correlation coefficients showed that the greatest significant positive correlations were observed between seed weight per plant and number of seeds per pod (r=0. 93**)، number of pod per plant (r=0. 84**) and 100-seed weight (r=0. 84**). Amongst physiological traits the greatest significant positive correlation was observed between seeds per plant and photosynthesis (r=0. 53**). Overall، it seems that application of 100 ppm SA may reduce harmful effects of water deficit and enhance growth and production of mustard plant through improving some physiolological traits.