Screening of salinity and temperature tolerant Trichoderma isolates, and its effect on Zea mays growth at in vitro condition
Many of biocontrol isolates of Trichoderma by increasing plant tolerance to environmental stress improves plant growth and yields.In order to evaluate salinity stress on 10 isolates from seven strains of Trichoderma, an experiment carried out as randomized design with three replications. The treatments included five levels of salinity (7, 9, 13, 30 and60dS/m) from NaCl, CaCl2, MgCl2 sources and 10 isolates of Trichoderma. Salt stress effect on isolates growth was done on PDA medium (1/4-Strenghth PDA) containing different concentration of salts to get desired salinity level. Also, the isolates were screened from temperature tolerance at 30, 35 and 40 ̊C. The results demonstrated inhibitory effect of salinity on growth of isolates and showed significant difference among isolates. More tolerant and the most sensitive isolates against salinity (60dS/m) with respectively 12 and 100percent growth inhibition were T.virens Ham65 and T.capillare Isf-7. None of isolates are able to growth at 40 ̊C and at 35 ̊C and just 4 isolates could be grown. Temperature increase from 30 to 35 ̊C causes to decrease growth of 3 isolates and increase growth of T.virens Ham65. The results of zea mys inoculation with tolerant isolate to salinity and temperature (T.virens Ham65) indicated significant effect of this fungus to increase wet and dry weight and height of root and shoot of plants grown under both saline and non-saline condition.