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Pak. J. Bot., 47(6): 2421-2426, 2015.

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EFFECT OF ENDOPHYTIC PSEUDOMONAS AERUGINOSA AND TRICHODERMA HARZIANUM ON SOIL-BORNE DISEASES, MYCORRHIZAE AND INDUCTION OF SYSTEMIC RESISTANCE IN OKRA GROWN IN SOIL AMENDED WITH VERNONIA ANTHELMINTICA (L.) SEED’S POWDER

HAFIZA ASMA SHAFIQUE ¹, RUBINA NOREEN¹, VIQAR SULTANA ², JEHAN ARA³ AND SYED EHTESHAMUL-HAQUE ¹

¹Agricultural Biotechnology and Phytopathology Laboratory, Department of Botany, University of Karachi, Karachi-75270, Pakistan, ²Biotechnology and Drug Development Laboratory, Department of Biochemistry, University of Karachi, Karachi-75270, Pakistan, ³Post Harvest Technology and Food Biochemistry Laboratory, Department of Food Science and Technology, University of Karachi, Karachi-75270, Pakistan.

^*Corresponding author e-mail: ehtesham12@hotmail.com

Abstract: Biostimulants are used in agricultural practices for plant growth improvement. These fertilizers improve microbial activity and cause a negative impact on soil-borne pathogens. In recent years, stimulating plant’s natural defense is considered as most promising alternative strategy for crop productivity. The present study was carried out to examine the effect of endophytic Pseudomonas aeruginosa and Trichoderma harzianum in soil amendment with Vernonia anthelmintica seed’s powder, on root rotting fungi, plant growth,  mycorrhizal population around roots, phosphorous uptake and stimulation of plant defense markers  like poylphenol and antioxidant status in okra. Combine application of Vernonia with Pseudomonas aeruginosa and Trichoderma harzianum significantly (p<0.05) suppressed Rhizoctonia solani and Fusarium oxysporum with complete reduction of Macrophomina phaseolina and Fusarium solani. Pseudomonas aeruginosa and T. harzianum alone or in Vernonia amended soil significantly reduced  nematode’s galls on roots. Organic amendment also improved plant resistance against root diseases as evident from enhanced DPPH radical scavenging capacity and polyphenol content in treated plants as compare to control. VA Mycorrhizal spores were found significantly (p<0.05) higher in number around roots received Pseudomonas aeruginosa or T. harzianum alone or in Vernonia amended soil. Whereas, higher concentrations of phosphorus in okra shoots were found in plants received biocontrol agents in amended soil. Mixed application of PGPR and T.harzianum  in amended soil produced tallest plants than other treatments. Soil amendment with Vernonia seed’s powder  alone or with biocontrol agents offer a non-chemical means of plant disease control.

Key words: Vernonia anthelmintica, Pseudomonas aeruginosa, Trichoderma, Systemic resistance, Mycorrhizae, Okra.