Effect of cultivar, cold and paclobutrazol on growth, chlorophyll content and cell membrane injury in Phaseolus vulgaris plantlet

Abstract

The paclobutrazol is one of plant growth regulators from triazoles group that is able to protect plants against environmental stress conditions. This experiment was carried out to investigate paclobutrazol (0, 25 and 50 mg/L) effects on reduction of injuries caused by low temperature (5±1ºC) stress in two cultivars of Phaseolus vulgaris [Daneshkadeh cv. (white bean) and Sayyad cv. (red bean)]. The results showed that low temperature stress, reduced fresh weight and dry matter and also reduced length of shoots and roots and leaf chlorophyll contents but increased electrolyte leakage percentage. Paclobutrazol treatment reduced fresh weight and dry matter and length of shoots but increased root dry weight and root development. Moreover, paclobutrazol-treated plants, when exposed to the cold stress condition, showed electrolyte leakage percentage less than control plants. Treatment of seedlings with paclobutrazol led to an increase in chlorophyll contents, either in stress or non stress conditions. White bean was more sensitive to cold than red bean and paclobutrazol affected white bean more than red bean. Therefore, it could be concluded that paclobutrazol treatment improved ability of plant responses to the cold stress and this effect was more remarkable in cold sensitive cultivars.

Keywords

• Paclobutrazol
• Cold stress
• growth
• Chlorophyll content
• Phaseolus vulgaris
• Electrolyte leakage