A key role of penconazole in biomass production and responses to different soil moisture levels in Satureja sahendica Bornm

Drought stress is a significant environmental factor retarding plant growth as well as productivity. Plants adapt to environmental stress via numerous strategies such as changes in plant height, biomass, carbohydrate content and phytohomnonal levels. Therefore, a split plot experiment based on randomized complete block design with three replications was carried out to determine possible drought tolerance mechanisms in Satureja sahendica Bornm. induced by penconazole (PEN). The determined water (100, 60 and 30% FC) and PEN (0, 10 and 20 mg.l-1) levels were applied. Result showed that drought stress significantly decreased plant height, fresh and dry weight, indoleacetic acid (IAA), gibberellic acid (GA) and induced accumulation of carbohydrates, glucose, sucrose, fructose and abscisic acid (ABA). PEN treatment even decreased further plant height, IAA, GA and increased fresh and dry weight, carbohydrate content, glucose, sucrose, fructose and ABA. PEN increased fructose and ABA up to 2.5 folds and 3.5 to 4.5 folds, respectively compared to the control, especially at the second harvest. The significant decrease in growth hormones along with significant increase of the inhibitor hormone by elevating drought stress and PEN application led to significant augmentation in (GA+IAA)/ABA ratio (~70% at 30% FC and 20 mg.l-1 PEN) compared to the control. Altogether, the application of 20 mg.l-1 PEN together with 60% FC seems an appropriate treatment for planting Satureja sahendica in dry regions. Furthermore, the improved fructose production and ABA level induced by PEN had outstanding role on drought tolerance of this plant.