No abstract

To investigate the influence of arbuscular mycorrhizal fungi (AMF) on biomass and root morphology, a greenhouse experiment was conducted using three elite strawberry (Fragaria × ananassa Duch.) cultivars ('Kent', 'Jewel', and 'Saint-Pierre'). They were subjected to three NaCl levels (0, 30, and 60 mmol/L) and were inoculated and noninoculated (control) with AMF Glomus irregulare. The presence of AMF significantly changed root morphology and increased rootlength percentages of medium (0.5 mm < root diameter 4 ≤ 1.5 mm) and coarse (4 > 1.5 mm) roots, shoot and root tissue biomass, root to shoot ratio (R/S ratio), and specific root length (SRL), regardless of cultivar and salinity. In contrast, salt alone changed root morphology and decreased shoot and root tissue biomass, R/S ratio, and SRL. The AMF colonization rates were reduced linearly and significantly with increasing salinity levels. Cultivars responded differently to AMF than to salt stress. 'Saint-Pierre' seemed to be the most tolerant cultivar to salinity, while 'Kent' was the most sensitive. Consequently, AMF symbiosis highly enhanced salt tolerance of strawberry plants, which confirmed the potential use of mycorrhizal biotechnology in sustainable horticulture in arid areas.Résumé : Afin d'examiner l'influence des champignons mycorhiziens arbusculaires (CMA) sur la biomasse et la morphologie des racines, les auteurs ont conduit une expérience en serres, en utilisant trois cultivars élites de fraisier (Fragaria × ananassa Duch.) ('Kent', 'Jewel', et 'St-Pierre'). Ils les ont soumis à trois concentrations de NaCl (0, 30, et 60 mmol/L), avec ou sans (témoin) inoculation, avec le CMA Glomus irregulare. La présence du CMA a modifié significativement la morphologie racinaire et a augmenté les pourcentages des longueurs des racines moyennes (0,5 mm < diamètre racinaire 4 ≤ 1,5 mm) et grosses (4 >1,5 mm), la biomasse des tissus caulinaires et racinaires, le rapport racine tige (rapport R/S) et la longueur spécifique des racines (LSR), indépendamment du cultivar ou de la salinité. Au contraire, le sel pris isolément a également modifié la morphologie racinaire et diminué la biomasse des tissus caulinaires et racinaires, le rapport R/S et la LSR. L'augmentation de la salinité a réduit linéairement et significativement la colonisation par le CMA. Le cultivar 'StPierre' apparaît comme le plus tolérant à la salinité et le cv 'Kent' comme le plus sensible. On conclut que la symbiose CMA augmente fortement la tolérance à la salinité chez les plants de fraisiers, ce qui confirme le potentiel de la biotechnologie mycorhizienne pour l'horticulture en régions arides.

Fan, L., Yu, C., Fang, C., Zhang, M., Ranieri, M., Dubé, C. and Khanizadeh, S. 2011. The effect of three production systems on the postharvest quality and phytochemical composition of Orléans strawberry. Can. J. Plant Sci. 91: 403–409. The effects of two production systems, plastic mulch (PM) and plastic mulch with row covers (PMRC) versus the commonly used matted-row system (MRS) on postharvest fruit quality, including shelf life, fruit weight loss and juice leakage, fruit glossiness, postharvest disease caused by grey mould (Botrytis cinerea Pers.), and chemical composition of Orléans strawberry were evaluated during 2008 and 2009. Plastic mulch with row covers accelerated fruit maturity by 7 to 10 d and produced larger fruits compared with the MRS. Production systems significantly changed the total phenolic content (TPC) and total antioxidant content (TAC), but the effect varied during the harvest season. Total phenolic content was significantly higher for PMRC than MRS and PM at early harvest, but the effect was similar to PM at mid and late harvest. Total antioxidant content was significantly higher for PMRC compared with MRS and PM at all stages of fruit production, especially at late harvest. Fruit weight loss and juice leakage and the presence of grey mould during storage were lower and fruit glossiness was higher for those harvested under PMRC compared with those from MRS. No significant differences were observed for firmness, pH, titratable acidity (TA) and soluble solids content (SSC) between the three production systems. Titratable acidity and SSC of PMRC were slightly higher than those from MRS and PM, but the differences were not significant. It seems that PMRC not only accelerates ripening, but also has a significant effect on pre- and postharvest fruit quality and chemical composition of the harvested fruits.