Effect of Pretreatment with Indole-3-Butyric Acid on Germination Characteristics of Pinto Bean Seed under Salt Stress

In order to study the effect of seed priming by indole-3-butyric acid (IBA) on germination characteristics of pinto bean under salinity stress, a factorial laboratory experiment, based on completely randomized design with three replications, was carried out at the Faculty of Agricultural Sciences, University of Guilan, Rasht, Iran, in 2011-2012. Three levels of pretreatment (0, 10 and 20 mg/L IBA) and five levels of salinity stress due to NaCl (0, 1, 2, 3 and 4 dS/m) were considered. Results represented the significant effect of IBA on shoot length, root dry matter as well as allometric coefficient. Salinity had significant effect on shoot and root length, shoot dry weight, vigor index and allometric coefficient. While, interaction effect of IBA and salinity was significant only for allometric coefficient. In this experiment, the rate and percentage of germination were not affected by any of the treatments. Comparison of means showed that increasing IBA concentration resulted in an increase in shoot length (1.9 to 2.1 cm), shoot dry weight (0.03 to 0.05 gm) and allometric coefficient (0.71 to 1.06 cm), while increased salinity resulted in a decrease in root length (2.6 to 2 cm), vigor index (202.8 to 147.7) as well as allometric coefficient (1.1 to 0.78 cm). Increasing salinity increased shoot length first, and then reduced it. Overall, it appears that application of IBA for pretreatment of pinto been seeds could enhance seedling establishment under saline conditions through the improvement of root length.