PHYSIOLOGICAL STUDIES ON THE EFFECT OF SOME BENEFICIAL MICROORGANISMS ON LETTUCE PLANTS POLLUTED BY LEAD | ||||
| Journal of Plant Protection and Pathology | ||||
| Article 11, Volume 32, Issue 5, May 2007, Page 3823-3848 PDF (741.37 K) | ||||
| Document Type: Original Article | ||||
| DOI: 10.21608/jppp.2007.219536 | ||||
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| Authors | ||||
| Fatma El-Ghinbihi; Wafaa H. Mahmoud | ||||
| Agric. Botany Dept., Faculty of Agric., Minufiya University | ||||
| Abstract | ||||
| The present investigation was conducted during the two winter seasons of 2004/2005 and 2005/2006 to study the responses of growth characters, leaf water relations, chemical components, yield and its attributes to lead pollution treatments, the inoculation with different effective microorganisms and their interaction. Two pot experiments were carried out to investigate the effect of lead (Pb) pollution in different concentrations (0, 100, 250 and 500 mg/l) and the application of beneficial microorganisms [Halex 2 or EM (biofertilizers)] or lead bioremediator Bacillus subtilis strain in order to overcome the harmful effect of lead treatments on lettuce (Lactuca sativa L.) plants. The obtained results revealed that growth characters of lettuce plants expressed as plant height, root length, number of leaves, leaf length and width, leaf area as well as dry weight of roots and shoots were markedly decreased in response to lead pollution treatments. The highest significant reduction in these characters was more pronounced at higher lead rate (500 mg/l). RWC (%), photosynthetic pigments (chl. a, chl. b, chl. a+b and carotenoids), total soluble sugars, total carbohydrates concentrations and phenoloxidase activity were significantly decreased following the increase in lead levels in the growth medium. On the other hand, Pb treatments increased LWD (%), chl. a/b ratio, total free amino acids and proline accumulation in lettuce leaves compared with unpolluted plants. The concentration of minerals (N, P and K+) was sharply reduced by Pb treatments, especially at higher lead levels. The concentration of lead in lettuce leaves and roots was positively correlated with Pb concentration in root medium. The increase in lead concentration was more pronounced in lettuce leaves than in roots. Yield and its components represented by average head weight, head length, head diameter, dry matter content % and TSS % were significantly decreased as a result of increasing Pb concentrations. The application of biofertilizers (Halex 2 or EM) or lead bioremediator Bacillus subtilis strain exhibited significant increases in most studied characters, but decreased LWD (%), chl. a/b ratio, proline accumulation in leaves and the concentration of lead in lettuce leaves and roots. The interaction between lead pollution treatments and the inoculation with different effective microorganisms mitigated the harmful effects exerted by lead pollution stress on lettuce plants and enhanced growth characters, leaf water relations, chemical parameters, yield and its components of lettuce plants. | ||||
| Keywords | ||||
| Lettuce plants; lead; Halex 2; EM; plant height; leaf area; photosynthetic pigments; minerals; yield; TSS % | ||||
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