ﺑﺮرﺳﻲ ﺗﻐﻴﻴﺮات رﻧﮕﻴﺰهﻫﺎی ﻓﺘﻮﺳﻨﺘﺰی ﮔﻴﺎه ﻟﻮﺑﻴﺎ ﺳﺒﺰ (.Phaseoluse vulgaris L) در ﭘﺎﺳﺦ ﺑﻪ ﺗﻠﻘﻴﺢ ﻗﺎرچ Piriformospora indica و ﻣﺤﻠﻮلﭘﺎﺷﻲ ﭘﺎﻛﻠﻮﺑﻮﺗﺮازول

To study the effect of Piriformospora indica and Paclobutrazol (PBZ) as a plant growth regulator for inducing cold stress tolerance in green beans (Phaseolus vulgaris L.) plant, a greenhouse experiment was performed as a factorial arrangement based completely randomized design with three replications. Treatments consisted of three cold stress levels (control, three and six days cold stress at 5°C), two levels of fungi inoculation (non-inoculated and inoculated with P. indica) and three levels of PBZ (0, 40 and 80 ppm). Eight weeks after planting, green bean plants exposur to cold stress and some morphological and physiological growth characteristics were measured. The results showed that the six days of cold stress particularly reduced aboveground dry weight, the amount of chlorophyll a, b and carotenoids (respectively about 19, 18 and 8%). Generally, in all cold stress levels, the inoculation of P. indica increased the plant dry weight that the largest increase was in six days of cold stress 65%. Spraying of PBZ, particularly 40 ppm, enhanced chlorophyll a and carotenoid as the rate of 5 and 9, respectively. While, PBZ application on inoculated plants significantly reduced dry weight of green beans that the concentration of 40 ppm PBZ reduced to about 17 percent. The results of this study confirmed the positive role of the P. indica and PBZ on growth and improving plant resistance to cold stress in green beans.