SYMBIOTIC NITROGEN FIXATION PROCESS IN FABA BEAN AND CHICKPEA AS AFFECTED BY BIOLOGICAL AND CHEMICAL CONTROL OF ROOT-ROT

Abstract

Three biocontrol agents Trichoderma harzianum, Gliocladium virens and Bacillus subtilis were evaluated in controlling of damping — off caused by Rhizoctonia solani under laboratory and greenhouse conditions as well as their biocontrol agents effect on both nodulation, growth and nitrogen content of faba bean and chickpea plants. Results showed that all tested biocontrol agents significant reduction in mycelial radial growth of R. solani in all different agar media. The obtained results showed that all tested biocontrol agents significantly reduced pre and post emergence damping-off and increased survival plants when combined with Rhizobium strain (ICARDA 441) for faba bean or Rhizobium strain (ICARDA 1148) for chickpea. The maximum protection of faba bean and chickpea plants were achieved when faba bean seed treatment with Trichoderma harzianum combined with Rhizobium and chickpea seed treatment with Bacillus subtilis combined with Rhizobium. Concerning the effect of different biocontrol agents on riodulation, growth and N-content of faba bean and chickpea plants, the results indicated that the combined inoculation with T. harzianum and Rhizobium strain (ICARDA 441 for faba bean) gave the best results in terms of number, dry weight of nodules, shoots, roots dry weight, and their N- content with faba bean in case of non-infested or infested soil. While, Bacillus subtilis gave the best results in terms of number of nodules, dry weight of nodules, shoots dry weight, roots dry weight and their N-contents with chickpea in case of non•infested or infested soil when combined inoculation with Rhizobium strain(ICARDA 1148 for chickpea) at the first and the second season. Taken together with evidence of obtained data it is clear that the beneficial effects exerted by symbiotic N2-fixation in combination with disease protection afforded by biocontrol agent, had more compensated the loss occurred in N2-fixation parameters caused by R. solani in both legume crops under investigation. Generally, it is clear that favorite results were obtained in case of combined inoculation by three bioagent in combination with two Rhizobium strains in reducing damping — off, enhancing nodulation status, growth and N- content of faba bean and chickpea plants at the first and the second seasons.