THE ABILITY OF SOME SELECTED ISOLATES OF Trichoderma spp. TO IMPROVE SEED VIABILITY AND PLANT HEALTH THROUGH SEED TREATMENTS

Abstract

Among ninety eight Trichoderma isolates obtained from plant rhizosphere soil of sixteen governorates in Egypt, and conserved seeds. Nine isolates were highly performed against high temperature, salinity and drought stresses under in vitro conditions and pot experiments. Also, they showed their ability as biological control agents against the phytopathogenic fungi Fusarium oxysporum and Rhizoctonia solani through the dual culture technique with more than 85% inhibition. The nine isolates were phenotypically characterized and identified by specific species primers which confirmed their species as five isolates of Trichoderma harzianum, three isolates of Trichoderma viride, and one isolate of Trichoderma virens. The isolates NGB-T14, NGB-T20 and NGB-T33 were able to grow at ±45ºC in in vitro, and the NGB-T14, NGB-T16, NGB-T17 and NGB-T18 isolates showed a significant salinity tolerance up to 2M. While the NGB-T59, NGB-T86 and NGB-T90 were grown in 30% PEG for drought tolerance. The ex vivo pot treatments under abiotic stresses with selected isolates were tested individually and showed an enhancement in morphological and biochemical traits compared with the untreated seeds. In determination of the biochemical traits, proline and chlorophyll were significantly increased under severe abiotic stresses. T. harzianum (NGB T14) alleviated the heat stress on plants to survive under ±40°C. Moreover, T. harzianum (NGB-T14) gave the best profile in high salinity levels that can reach 12 dSm-1. The isolate T. viride (NGB-T59) was the best in drought tolerance. These observations may be of use to phytosanitary services for growers and agricultural researchers under the arid land for sustainable utilization.