Soil application of <I>Pseudomonas fluorescens</I> and <I>Trichoderma harzianum</I> reduces root-knot nematode, <I>Meloidogyne incognita</I>, on tobacco

Abstract

The effects of Pseudomonas fluorescens and Trichoderma harzianum, on the control of the rootknot nematode, Meloidogyne incognita, were investigated in three tobacco cultivars (RK-18 P8, RK-26 P3 and RK-12 P3). Soil application of the biocontrol agents was compared with two nematicides, Phorate and Furadan. Greatest reduction in the numbers of second-stage juveniles in soil, host root galls and egg mass indices were recorded with Furadan and P. fluorescens compared with experimental controls. The greatest increase in the plant growth and biomass of tobacco was obtained in cv. RK-18 P8 with P. fluorescens (16-32%) followed by Furadan (15-30 %) compared with experimental controls. Increases in total phenol (TP) and salicylic acid (SA) were negatively correlated with numbers of root galls and egg masses/root system. Greatest increases in the leaf contents of SA (20%) and TP (31%) were recorded in cv. RK-12 P3, whereas least increases were detected in cv. RK-18 P8 (17% TP and 10% SA). The study has revealed that cv. RK-12 P3 may be exploited commercially for nematode resistance to M. incognita, and P. fluorescens may be used as an alternative to nematicides in nematode infested field, to obtain higher productivity of tobacco.