Permeability of root membranes in wild and domesticated bean (phaseolus vulgaris L.) seedlings under water déficit [Permeabilidad de las membranas radicales de plántulas de frijol (phaseolus vulgaris L.) silvestre y domesticado bajo déficit de humedad]
Article
Overview
Research
Additional Document Info
View All
Overview
abstract
Wild and domesticated common bean root membrane permeability was evaluated in its response to water deficit. Wild common bean from Chihuahua (SCH) and Durango (SD) and the cv. Bayomex were used; 72h old seedlings of 3-4cm root length were maintained for 24h in vermiculite with water potentials (Ψ W) of -0.03, -0.65, -1.48 and -2.35MPa. Roots collected were maintained in deionized water for 3h and then relative water content (CRA), and K%2b and Na%2b concentrations in the media were quantified; electrical conductivity and pH of the medium were measured every 30min. CRA sharply decreased (46%25) in the cultivar and SD with water deficit, but diminished slightly in SCH (15%25). Electrolyte leakage showed two phases in all treatments, in the initial 30min it went from 0.8 to 3.2S·cm -1·g-1 of dry tissue in the cultivar, from 1.4 to 3.1 in SCH and from 2.2 to 6.4 in SD; but, after the next 2.5h the increments were not significant. The significant interaction showed that although SCH was not damaged (0.84%25) with any ΨW tested, SD and the cultivar were drastically damaged (>50%25) with -2.35MPa. In contrast with electrical conductivity, media pH continued increasing during the first 3h. The lower ΨW promoted a significant pH increase for the domesticated common bean root (from 4.59 to 4.91) and SD (from 4.86 to 5.16). High Ψ W produced significantly similar (P≤0.75) K%2b leakage (5.9mg·g-1 in average) in all three variants, but the water deficit caused increase of K%2b leakage (up to 2.5 times), while Na%2b leakage was not detected. Based on CRA, electrical conductivity, damage index and stress recovery data, it seems that low ΨW affected root membranes of SCH less than those of SD and the domesticated common bean.
