Studies on The Rhizosphere Mycoflora of Celosia Argentea and Hibiscus Esculentus

Abstract

Rhizosphere studies of two local green vegetables, Celpsia argentea Linn and Hibiscus esculentus. Linn (new name Abelmoschus esculentus) were studied from vegetative stage to senescence.

The viable seeds of both vegetables were collected and planted on garden beds made from sandy loam soil. Samples were collected at two-week intervals at 9.00 hrs in the the morning. Morphologically, A. esculentus (okra) had 3 leaves with more dense rooting system at 2 weeks than C.argentea (solo) with 6 leaves. Both plants appeared to reach maturity at the 14th week after planting. Both plants encouraged the growth of fungi and bacteria in the vicinity of their roots due to their secretions into the soil. In the 14th and 16th weeks of growth however, when the plant fruits were fully developed, fungal and bacterial populations were repressed.

Twenty species of fungi belonging to 9 genera were isolated from non-rhizosphere and rhizoplane of okra while 12 and 9 were obtained from the rhizosphere of solo. Aspergillus was the dominant genus isolated. Other genera included Penicillium, Trichoderma, Fusarium, Curvularia, Rhizoctonia, Gliocladium, Myrothecium Scolecobasidium, Botryodiplodia and sterile mycelia.

Biochemical studies revealed that no sugars were detected chromatographically from any of the root exudates. Okra exudate was however found to contain alanine and glycine while 'soko' exudate contained aspartic acid, glutamine and an unidentified amino acid.

Most of the isolated fungi were found to grow together in Petri dishes without any inhibitions. Trichoderma harzianum Rifai however was found to be antagonistic to Rhizoctonia spp.

Studies on the activities of some fungicides showed that thirst (arisen) which was most effective in reducing microbial population in the soil persisted in the garden soil for 35 days after application.

A few of the isolated fungi were found in nutritional experiments to utilise carboxylate metal cellulose as the sole carbon source.