BIOCONTROL OF Meloidogyne incognita ATTACKING POTATO PLANTS USING THE EXTRACT OF A NEW ISOLATE OF Chlorella vulgaris AND MOLECULAR CHARACTERIZATION

Root-knot nematodes are dangerous pests that cause losses of many crops and its management generally by using chemical nematicides which caused contamination and have serious effects on all living organisms and environment. Consequently, this study was conducted to control Meloidogyne incognita in potato plants, cultivated in root-knot nematode infested soil, by using bioactive compounds extracted from Chlorella vulgaris against Meloidogyne incognita under greenhouse conditions. The algal isolate was identified using morphological and molecular characterization by using ITS rDNA. The content of Nitrogen (N), phosphorus(P), Calcium (Ca), Potassium (K), Sodium (Na), Heavy metal, Protein and Carbohydrate in extract of the Chlorella vulgaris biomass was determined. The results indicated that the C. vulgaris extract had significant increments in growth parameters and significant decreases of nematode galls and egg masses. In contrast, the control plants had the lowest values in all criteria. As well as, data indicated that C. vulgaris was more effective in controlling nematode or in enhancing plant resistance against nematode as shown at most nematode parameters, especially the nematode galls, which resulted in 71.4 and 61.3% decreases in both treatments of potato plants treated with C. vulgaris alone or with potato plants infected by M. incognita, respectively. It had insignificant differences compared the nematicide. The chemical analysis of C. vulgaris extract revealed the presence of high amount of nitrogen, phosphorus, calcium, carbohydrates and proteins with 4.02, 3.24, 3.23, 39.7, and 19.7%, respectively. Therefore, using C. vulgaris extract as a bioagent against root-knot nematodes is recommended, especially in sustainable agriculture. Additionally, the algal could increase soil maintaining and improves its fertility a combined with strengthens resistance against nematode invasion. In collectively, C. vulgaris extract it could be considered safe and eco-friendly alternative to chemical pesticides.