Abstract

POLANIA, Joséé A.; RAO, Idupulapati M.; BEEBE, Steve  and  GARCIA, Ramiro. Root development and distribution under drought stress in common bean (Phaseolus vulgaris L.) in a soil tube system  . Agron. colomb. [online]. 2009, vol.27, n.1, pp.25-32. ISSN 0120-9965.

Phenotypic differences in root development and distribution of 16 common bean genotypes grown under drought stress were analyzed. We developed a method using transparent plastic tubes (inserted in PVC tubes), filled with a soil-sand mix (2:1, weight: weight), to capture differences in root growth under greenhouse conditions. Ten days after emergence, two water supply treatments were imposed: 80% of field capacity (without stress) and withholding of water (to induce drought stress). Total leaf chlorophyll content and transpiration rate were measured during the trial. At harvest (32 days after planting), leaf area, shoot biomass, leaf and stem total nonstructural carbohydrates content (TNC) were determined. The soil in the tubes was divided into five layers from the top to the bottom of the tube (0-5, 5-10, 10-20, 20-30 and 30-45 cm). Roots were washed from each soil layer to determine their length, diameter and dry biomass. A randomized complete block design was used with three replications. The method was suitable for determining phenotypic differences in total root length, specific root length and root distribution by soil depth. Three lines (BAT 477, SEA 5 and SER 16) were superior in their root development under drought stress.

Keywords : total leaf chlorophyll content; root diameter; deep rooting; root length; transpiration rate.

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