Fusaria in the Rhizosphere and Rhizoplane of Groundnut (Arachis hypogaea)

Abstract

Fusarium species were isolated from the rhizosphere soil, non-rhizosphere soil and rhizoplane of groundnut (Arachis hypogaea) grown in sandy soil. The experimental soil had pH 7.9 and 8.1% moisture content prior to seed planting. Although the pH of the rhizosphere soil and non-rhizosphere soil in the pots and field varied as the plants aged, it was in the neighbourhood of 7.0 throughout the sampling period. The soil diluting plate method was used to isolate Fusarium species from the rhizosphere soil and non-rhizosphere soil. The Fusarium species isolated from the rhizosphere soil, rhizoplane and non-rhizosphere soil in the pots and field were Fusarium oxysporum, F. semitectum, F. poae, F. solani, F. minoliforme, F. dimerum and F. avenaceum. The last three species were not isolated from the non-rhizosphere soil in the pot and field. The most predominant species both in the field and pot soils as well as the rhizoplane was F. oxysporum. The numbers of F. oxysporum  ranged from 1.4  x 10² TO 2.4 X 10² cfu per g of soil or per g of roots. The rhizosphere was highest when the plants aged 10 weeks in the pots and the field, being ratio 1:3 and 1: 2.5 respectively. In the rhizosphere soils in the pots and the field, the numbers of Fusaria increased progressively with the age of plants from the 6^th week until the 10^th week, and then declined progressively until the 14^th week.

JARD Vol. 5 (2) 2006: pp. 153-164