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Data on climate and nutrient composition of water of commercial cultivation of four different rose varieties were analysed statistically. The calculated mineral uptake was related to nutrient supply, plant growth and glasshouse climate. The data were derived from a production period of 3 to 7 years and consisted of weekly averages of the production (g m-2 wk-1 fresh weight), climate, climate control and fertigation variables. The latter included volumes applied and drained, EC ‘in and out’ (providing estimates of total ion uptake) and concentrations of macro and micro elements ‘in and out’. The roses were grown on rockwool substrate and two glasshouses were equipped with mobile growth systems. The installed assimilation light ranged from 65-165 μmol m-2 s-1 between systems. Regression models were calculated by means of forward stepwise regression, the models describe the total ion uptake and the uptake of the individual elements. The total ion uptake of the crop varied and depended on glasshouse climate, climate regulation of the glasshouse, drain water percentage and drain water pH, season, and production. The uptake of the individual nutrient element was explained for 33% to 99% by the ensemble of nutrient concentrations in the fertigation solution, depending on the element and cultivar. Across the four cultures, the 3-7 year average uptake concentration of the elements showed little variation. Within each culture the uptake of the individual elements varied most of the time parallel with each other and with the production. The regression model gives insights in the supply and demand of nutrients by roses, ultimately leading to a high production and good quality combined with a more sustainable fertilizer management.

International audience; Collaborative research was conducted at the INRA Research Centers to assess the microbial control potential of Beauveria bassiana- and Lecanicillium lecanii-based formulations against whiteflies in protected crops under Mediterranean conditions. Four series of small-scale glasshouse trials were performed in 1999 and 2000 in southern France. Two applications at 4-5 day intervals of Naturalis-L and Mycotal were conducted on young larvae of the greenhouse whitefly, Trialeurodes vaporariorum, at rate's recommended by the manufacturers. Because of the expectation that environmental conditions prevailing in Mediterranean greenhouse crops may lead to greater climatic constraints for mycoinsecticide efficacy than in more temperate areas, manipulation of the greenhouse climate has been used to aim at optimizing mycoinsecticide efficacy. The climatic management strategy was mainly based on closing the ridge vents 2 h more at night-time in so-called "humid" glasshouse compartment than in a "dry" one. Thus, the daily period at high humidity (>90% RH) was two or three times longer in the "humid" compartment than in the "dry" one. In spite of this differential, mycoinsecticide treatments reduced numbers of surviving whitefly larvae by >85% in the "humid" compartment as expected as favorable, as well as in the "dry" compartment, expected as unfavorable. The results indicated clearly that both B. bassiana- and L. lecanii-based mycoinsecticides have a strong potential for microbial control of whitefly larvae infesting tomato crops at moderate ambient humidity in Mediterranean glasshouses. Our investigations provided strong arguments for explaining these unexpected results. The RH conditions prevailing in the targeted insect habitat should be greatly disconnected from that of the ambient glasshouse air. We suggest that strategies of mycoinsecticide optimization against phyllophagous insects in protected crops have to take into account factors acting on the leaf transpiration activity. (C) 2003 Elsevier Science (USA). All rights reserved.