African Journal of
Plant Science

  • Abbreviation: Afr. J. Plant Sci.
  • Language: English
  • ISSN: 1996-0824
  • DOI: 10.5897/AJPS
  • Start Year: 2007
  • Published Articles: 718

Full Length Research Paper

Effects of crude extracts on some selected physiological parameters of French beans (Phaseolus vulgaris) infected with rust (Uromyces appendiculatus)

Menge D. M. S.*
  • Menge D. M. S.*
  • Department of Botany, Faculty of Science, Jomo Kenyatta University of Agriculture and Technology, P.O Box 62000-00200, Nairobi, Kenya.
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Makobe M.
  • Makobe M.
  • Department of Botany, Faculty of Science, Jomo Kenyatta University of Agriculture and Technology, P.O Box 62000-00200, Nairobi, Kenya.
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Monda E. O.
  • Monda E. O.
  • Department of Plant and Microbial Sciences, School of Pure and Applied Sciences, Kenyatta University, Nairobi, Kenya.
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Okemo P. O.
  • Okemo P. O.
  • Department of Plant and Microbial Sciences, School of Pure and Applied Sciences, Kenyatta University, Nairobi, Kenya.
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  •  Received: 07 February 2012
  •  Accepted: 12 June 2014
  •  Published: 31 July 2014

Abstract

Rust (Uromyces appendiculatus) is a major foliar disease that reduces yield and pod quality in beans. The field trial of French beans was established at Jomo Kenyatta University of Agriculture and Technology (JKUAT). Single plant extracts and combinations of Boscia angustifolia, Zanthoxylum chalybeum and Melea volkensii were used to evaluate their effect on U. appendiculatus in the field. During the growing period, beans were infected with rust from natural inoculum at the field. Physiological responses such as carbon dioxide assimilation, transpiration (E), stomatal conductance (gs), and photosynthetic rate (Pn) of French beans treatments were examined after extracts of three antifungal plants were sprayed. B. angustifolia - Z. chalybeum combination and single plant treatment M. volkensii had positive effects on enhancing the rate of photosynthesis in bean plants. The high regressions between stomatal conductance and rate of transpiration in the treatments indicated that stomatal conductance and rate of transpiration were interdependent and it was interpreted to mean that stomatal conductance enhanced rate of transpiration at different times of the day. These plant extracts however caused an increase in the rate of transpiration of the bean plants, which resulted in loss of water. Results reveal bioactive potential of the flora from M. volkensii and a combination of B. angustifolia and Z. chalybeum to produce metabolites with potential applications as botanical pesticides.

 

Key words: Antifungal, beans, physiological responses, rust.

Abbreviation

PAR, Photosynthetic active radiation; C3, carbon parameters; JKUAT, Jomo Kenyatta University of Agriculture and Technology; Pn, photosynthetic rate; IRGA, infrared gas analyzer; E, transpiration; gs, stomatal conductance; Cu2+, copper; kg/ha, kilograms per hectare.