Evaluation of Argemone mexicana for Control of Root‐Infecting Fungi in Tomato

Abstract

Argemone mexicana L. (Papaveraceae), a tropical annual weed, is known to be phytotoxic to many crop species. This study was designed to examine the possible impact of A. mexicana on root‐infecting fungi, changes in fungal community structure and the growth of tomato. A. mexicana decaying shoots in soil provided a marked decrease in the infectivity of Fusarium solani and Rhizoctonia solani but Macrophomina phaseolina remained unaffected. Plant height and shoot growth of tomato plants increased markedly though high concentration of A. mexicana (5% w/w) was deleterious to tomato plants. General species diversity of soil fungal communities increased in the amended soils over the controls and greater increase in diversity occurred at higher concentrations of decaying A. mexicana. Likewise, equitability and richness components of diversity increased in treatments compared to controls but declined with increasing sampling period. Aspergillus nidulans, Cephaliophora irregularis, Drechslera halodes, Paecilomyces lilacinus and Trichoderma viride were isolated exclusively from the amended soils. Aqueous extract of A. mexicana when applied in soil greatly suppressed all three of the above root‐infecting fungi, and at lower concentration actually enhanced plant growth. The influence of different levels of N‐fertilization with NH4NO3 on the modification of the effect of decaying A. mexicana on root‐infecting fungi was also investigated. N‐fertilization to some extent alleviated the phytotoxicity to tomato plants while suppressing the root‐infecting fungi. A. mexicana in conjunction with Pseudomonas aeruginosa, a plant growth‐promoting rhizobacterium, significantly suppressed root‐infecting fungi with concomitant increase in plant growth. Whereas P. aeruginosa was reisolated from the rhizosphere and inner root tissues of tomato, its population slightly declined in the amended soil but not to an extent that could reduce the biocontrol and growth promoting potential of the bacterium.

Allelopathic Effect of Aqueous Extract of Argemone mexicana L on Germination and Growth of Brachiaria dictyoneura L and Clitoria ternatea L

“…Argemone mexicana (Mexican poppy) is amongst the ecologically and economically destructive exotic invasive plant species in Tanzania affecting both natural and agricultural ecosystems [19]. A. mexicana is a herb plant with branches, which has naturalized widely in many tropical and subtropical regions although it is a native of tropical American [20]. It is a widespread annual weed primarily associated with agricultural crops and wastelands.…”

Evaluation of antifungal activity of food additives against soilborne phytopathogenic fungi

“…The soilborne fungal pathogens play a major role in the development of root-rot disease complexes on many important field and horticultural crops that often results in the death of plants and important yield losses (Siddiqui et al 2002). Fusarium, Rhizoctonia, Macrophomina, and Sclerotinia are major pathogen genus that cause rots and damping on roots and foots of plants (Agrios 1988).…”

Evaluation of the Allelopathic Effect of Aqueous Extract of <i>Zygophyllum simplex</i> L. on <i>Vicia faba</i> L. Plants

“…To some extent this indicates the toxic effect level on Vicia faba at this concentration. A number of previous studies support this hypothesis (Siddiqui et al 2002, Laosinwattana et al 2009, Siddiqui 2007, Han et al 2008, Haroun and Al Shehri 2001, Hassan et al 2013, Teerarak et al 2010, Batish et al 2006.…”