Abstract
The potentials of Bio-arc (a commercial formulation of the Bacillus megaterium) at the rate of 5, 10, 15 and 20 ml and Nemastrol (a commercial formulation of active ingredients) at the rate of 0.25 ml, for induction of systemic resistance to sugar-beet var. Negma infected with M. incognita were conducted in two soil types. Results revealed that all treatments with tested rates were found to have nematicidal activity against nematode infection and improved plant growth parameters of sugar-beet with various levels of success. The dual application of Bio-arc+Nemastrol at the rate of 20 ml +0.25 ml proved to be the best and showed significant improvement in plant growth parameters in terms of shoot length (92.6,127.5%) and total plant fresh weight (91.7, 370.4) of sugar-beet grown either in clayey or sandy soil, respectively. Among all treatments Nemastrol ranked next to oxamyl and performed the best and significantly suppressed total nematode population (Rf=1.9, 2.2), root galling (RGI=3.0, 3.0), number of egg masses (EI=3.0, 3.0) and number of eggs / egg mass (Red. %=76.5, 74.5) in clayey and sandy soil, respectively. However, concomitant treatment showed better results than did Bio-arc alone at four tested rates. The greatest suppression in total nematode population was recorded with clayey and sandy soil receiving the dual application of Nemastrol (0.25 ml) and Bio-arc (20 ml) with reproduction factor 2.2, 2.6 and reduction percentages reached 92.8, 92.6% respectively. Leaves of sugar-beet were assayed for their biochemical profiles with respect to NPK, total cholorophyll, total carbohydrates, proteins, and phenols. Moreover, remarkable induction in such chemical constituents except phenol content was recorded with the application of Bio- arc+Nemastrol (20 ml+0.25 ml). On the other hand, activities of related enzymes i.e. Peroxidase (PO) and Polyphenol Oxidase (PPO) were evaluated in roots of sugar-beet infected with M. incognita. The enzymes accumulation was much greatest in Bio-arc+Nemastrol (20+0.25 ml) treated plants compared to control as they reached their peak at day 9th from nematode inoculation
Highlights
Sugar-beet (Beta vulgaris L.) is considered an important root crop, which is ranked second to sugar-cane for supporting the expansion of Egyptian sugar industry
Two greenhouse experiments were conducted at Nematological Research Unit (NERU), using sandy and clayey soil in order to evaluate the nematicidal properties of the commercial formulation of rhizobacterium, Bacillus megaterium (Bio-arc), the commercial biocide, Nemastrol against the root-knot nematode, M. incognita
Negma infected with M. incognita and grown in two soil types i.e. clayey and sandy is summarized Table 1
Summary
Sugar-beet (Beta vulgaris L.) is considered an important root crop, which is ranked second to sugar-cane for supporting the expansion of Egyptian sugar industry. Root-knot nematodes (RKNs) Meloidogyne spp. are among the most deleterious plant pathogens since these organisms play a detectable role in limiting the productivity of such economic agriculture crop. The root –knot nematode Meloidogyne incognita (Kofoid & White) Chitwood is among the most important nematode infesting sugar-beet. Because of the lack of plant resistance to most species of root-knot nematode as well as the environmental restrictions on nematicidal use for controlling plant parasitic nematodes, biological control and other eco-friendly disease control measures have gained recently increasing interest. The activation of the plant's own defense system through biotic and abiotic agents, called elicitors, has been considered as a focus of research only in recent years for the control of plant pathogens. The resulting elevated resistance due to an inducing agent upon infection by a pathogen is called induced systemic resistance (ISR) or systemic acquired resistance (SAR) [1]
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