Effects of paclobutrazol on physiological characteristics of two sesame genotypes (Sesamum indicum L.) under water stress conditions

Sesame (Sesamum indicum L) is a flowering plant in the genus Sesamum. It is widely naturalized in tropical regions around the world and is cultivated for its edible seeds, which grow in pods (Monayem Miah et al., 2015). Drought is one of the most important abiotic stresses which affect almost every aspect of plant growth. The arid and semi-arid regions where sesame is grown are specified by high temperatures, high evaporation demand and occurrence of unpredictable drought (Oscar Rojas et al., 2014). This plant is relatively drought tolerant. Resistance to water stress in sesame is important in many countries with low rainfall.
Material and In order to evaluation effects of Paclubutrazul on two Sesamum indicum genotypes under drought stress and study physiology, yield and yield component responses of genotypes, these experiment was done using factorial arrangement based on Randomized Complete Block with three replications in 1393-94 in greenhouse of educational department of Kordkoy. Treatments included Sesamum indicum genotypes (Yellow- white and Oltan), three levels of watering (20, 50 and 80% FC) and three concentrations of paclubutrazul application (0, 7.5 and 15 mgL-1). Data were analyzed with SAS software.
Finally results showed that genotype, water treatment and paclubutrazul on thousand seed weight, yield, proline, epicuticular wax of leaf, catalase activity of leaf and root, starch and carbohydrate soluble was significant. Although proline, EWL, catalase enzyme activity in leaf and root were declined, but Starch and carbohydrate solution content of leaf was elevated in Yellow- white against 20% FC. Application of paclubutrazul on starch, proline and catalase enzyme activity in both genotypes were not significant, but catalase enzyme activity in root, carbohydrate solution and EWL in leaves, thousand seed weight and yield were different significantly. Oltan in waterless stress had maximum proline content, EWL and catalase enzyme activity than yellow white, albeit, yellow white had highest carbohydrate solution than Oltan. Also EWL in leaves of Oltan was increased in 15mgL-1 paclubutrazul. EWL accumulation leaves protect them from addition water evaporation (Gonzalez et al., 2010). Also concentration of EWL accumulation leaves against severs waterless stress and highest paclubutrazul content, was highest 4 times than well water and without paclubutrazul usage. Catalase enzyme activity in root and leaves and proline content of leaves in 15 mg paclubutrazuland severe waterless stress were 9, 0.2 and 0.4 times more than without paclubutrazul and well water treatment. Carbohydrate solution in leaves under severe water stress and highest paclubutrazul content was 0.6 times more than control. In well water with 15 mg paclubutrazul, average yield per plant 13.3 g with thousand seed weight, 3.61g than control was highest in comparison control. Also, Oltan genotype than Yellow white to highest concentration paclubutrazul usage in case of effect on Osmolites and Catalase activity enzyme showed positive reaction.