PHYSIOLOGICAL RESPONSE OF STRAWBERRY GROWN IN ROOT- KNOT NEMATODE INFESTED SOIL UNDER DIFFERENT SAFETY CONTROL APPLICATIONS

Two successive field experiments during two seasons of 2008 and 2009, were carried out to evaluate some safety treatments including: mulching, tunnels, natural yeast extract, antioxidant and two rhizobacteria Serratia marcescens and Pseudomonas fluorescens towards root-knot nematode Meloidogyne spp. on strawberry plant grown in naturally infested soil and consequently their probable effects on growth parameters, chemical components and yield of strawberry compared to untreated control. Results of this study confirmed that all used treatments, significantly reduced all related nematode parameters i.e. number of galls/root system; number of egg masses/root system as well as number of juveniles/250 g soil ﴾either after 2 or 4 months﴿ when compared to plants grown in the naturally infested soil only. The highest percentage of reduction in all related nematode parameters were noticed after 4 months. Mulching, S. marcescens, P. fluorescens and tunnels, played an important role in reducing the percentage of nematode parameters. Mulching and S. marcescens reduced the percentage of gall numbers/root system by 77%, followed by tunnels by 75% and P. fluorescens by 70%. S. marcescens reduced the percentage of egg masses/root system by 80% followed by P. fluorescens by 78% and mulching by 76%. Results indicated that the soil treated with mulching, also significantly reduced the percentage of juvenile numbers/250 g soil by 79% followed by S. marcescens by 73%. Results confirmed also that all used treatments significantly increased all related plant growth characters viz. leaves, stems, root fresh and dry weight; plant height, leaves number, root length as well as false stem length. Moreover, these treatments significantly increased the activity of some oxidative enzymes e.g. peroxidase and phenoloxidase as well as some other chemical components i.e. total soluble solids (T.S.S %) and vitamin C (V.C). Results revealed that all previous treatments significantly increased the early and total yield. Our results confirmed that, the rhizobacterium S. marcescens came in the first rank as a promoter of all related plant growth characters, followed by tunnels and mulching treatments. Results confirmed that also the antioxidants, are considered the effective one in enhancing the activities of peroxidase and phenoloxidase as well as T.S.S% and V.C followed by the natural yeast extract