الفهرس 
Biocontrol of Rhizoctonia solani and Meloidogyne incognita attacking potato plants using the microalga, Chlorella sp.Only 14 pages are availabe for public view
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Abstract
Potato crop is a strategic crop in the most countries of the world. There are many diseases that affect potato plantations, the most important diseases are the black scurf caused by the fungus, Rhizoctonia solani and the root-knot caused by Meloidogyne incognita. Controlling plant diseases through using resources of biological origin, is a good alternative tactic as well as utilizing its elements (natural source) to prevent or minimize the damage produced from using chemical fertilizers is an extra additional target. Therefore, the purpose of this research study aimed to use the green alga, Chlorella vulgaris as a biological agent against R. solani and M. incognita infection and to stimulate potato growth through applying potato plants with minerals, hormones and vitamins. The main findings of the present study could be summarized as follows:
1- An isolate of the green microalga, Chlorella sp. was obtained from soil and fresh water samples collected from Abees area in Alexandria city. The morphological characteristics of the algal isolate showed that its cells were unicellular, spherical in shape with size of 2 to 10 μm in diameter. Algal cells shown single or forming colonies, contained a single chloroplast, pyrenoid present and without flagella.
2- The PCR amplification of ITS region of the isolated alga was carried out using the universal primers ITS1 and ITS4. The PCR amplification produced a single specific band of approximately 760 bp molecular length.
3- Sequence analysis of the amplified regions; ITS region for the isolated alga confirmed the morphological identification of the isolated algal species, Chlorella vulgaris. According to the percentage of identity imported data obtained from GenBank using Blast search, the algal isolate has identity of 99 %. Our isolated algal species have been registered in European Nucleotide Archive (ENA) under accession number MK283687.
4- The phylogenetic tree showed that the tested algal species were divided into two main clusters. Cluster I contained two sub-clusters, sub-cluster I and sub-cluster II. Sub-cluster I included two groups; group I contained C. sorokiniana KT818713.1 and C. sorokiniana KT818712.1. While, group II contained C. variabilis JN865973.1. Sub-cluster II contained two groups; group I contained our Chlorella isolate (Chlorella vulgaris) which had the accession number MK283687 in Gene Bank and group II represented by the C. vulgaris the accession number D26374. 1. Cluster II included C. vulgaris with accession number AB096693.1.
5- The analysis of chemical components of the C. vulgaris extract indicated the existence of nitrogen, phosphorus, potassium, calcium and sodium with 4.02, 3.24, 1.72, 3.23 and 1.02 %, respectively.
6- Determination of heavy metals existing in the dry weight of algal extract revealed the presence of the 7 elements; Zinc, Copper, Cobalt, Cadmium, Nickel, Lead and Iron with 28.30, 1.20, 0.87, 0.34, 0.96, 1.58 and 10.81 μg g-1 algal dry weight, respectively.
7- Determination of carbohydrate and total protein existing in the algal extracts of C. vulgaris isolate indicated occurred with 39.7 and 19.7 %, respectively.
8- The efficiency assessment, in vitro, of four methanolic-based C. vulgaris extract concentrations compared with the fungicide, Rizolex-T against the plant pathogenic.