The effect of Iraqi probiotics interacted with some bio- agents in controlling Okra root-rot caused by Rhizoctonia solani, and its effect on growth and yield parameters

Abstract

The aim of this study was to evaluate the efficacy of Iraqi probiotics and the bio-agents, Trichoderma harzianum and Pseudomonas fluorescence addition to organic fertilizer (compost) against the pathogenic fungus Rhizoctonia solani that causes okra root-rot.The results of field trials showed significant efficacy of the Iraqi probiotics (IPB) + P. floursecens treatment leading to the highest percentage of okra seeds germination, 97.75%, compared to treatments of the pesticide, T. harzianum , P. fluorescence , IPB alone, IPB+ T. harzianum, IPB + P. fluorescence and the T. Trichoderma + P. fluorescence where it gave 89.50 , 88.25 , 86.25 , 91.50 , 93.33 , 97.75 , 92.13%, respectively, in addition to the control treatment, which amounted which gave a 59.42%. IPB had the best results compared to other treat ments separately which gave a germination rate of 91.50% compared with the treatment of T.h and P.f that gave 88.28 % and 86.25 %, respectively. While organic fertilized soil had germination percentage of 88.96% compared with the non-fertilized treatment which gave 85.04%.Treatment of the IPB + Pf also gave highest chlorophyll content, reaching 2.45%, which significantly varied from all other treatments except treatments of IPB + Th and IPB that resulted in 2.36% and 2.33%, respectively, compared to the control treatment which gave 0.71%. The chlorophyll content also was the highest in the treatment of IPB compared with other treat ments separately wiich gave 2.36% compared with the P. floursecens treatment and of the T. harzianum 2.03% and 1.92%, respectively. But, for the organic fertilizer, the fertilized soil resulted in chlorophyll content of 2.09% compared to 1.67% from the non-fertilized soil. As for yield, the treatment of IPB + P. floursecens had the highest pod weight which significantly differed from the control treatment , 30.83 g and 8.38 g, respectively. The IPB treatment alone was the best treatment in pod weight (19.29 g) compared to 15.88 g and 16.00 g for treatments of T.h and Pf, respectively. Pod weight in the fertilized soil was also better than that in the non-fertilized soil which gave 22.26 and 13.07 g / plant, respectively.