Multivariable control strategy for the photosynthetic cultures of microalgae

In this paper, the problem of dissolved inorganic carbon monitoring and control in a photobioreactor has been addressed. This represents a key variable in the photosynthesis rate. Based on measurements obtained with a dissolved inorganic probe in a lab-scale photobioreactor it is shown that, in batch cultures especially, pH control by CO 2 gas injection is not sufficient to guarantee non-limiting growth conditions and may lead to failure. A control strategy based on the dissolved inorganic carbon measurement has been implemented in simulation, using a dynamic model able to describe the observed behavior. Simulations show promising results of the proposed control solution

Physiological traits and Mn transporter genes expression in ryegrass genotypes under increasing Mn at short-term

We studied physiological traits and Mn transporter genes expression in ryegrass genotypes (One -50, Banquet -II, Halo-AR1 and Nui) under increasing Mn (2.4-750 M) at short-term (8-24 h) in nutrient solution. An increment in Mn concentration occurred early in roots of all genotypes at increased Mn doses relative to control. Banquet -II and Nui roots showed the greatest Mn concentration at the highest Mn supply. Net photosynthesis (Pn) of Banquet -II and Halo-AR1 were not perturbed by Mn doses, whereas One -50 and Nui, decayed strongly at the highest Mn dose, concomitant with reduced total chlorophyll concentration. A high accumulation of Mn in roots together the maintained Pn under increased Mn doses in Banquet -II and Halo-AR1 suggest a higher Mn resistance of these genotypes. Stomatal conductance (gs) of all genotypes did not vary in presence of Mn. In roots of Banquet -II an augment of lipid peroxidation (LP) by Mn excess was observed earlier decreasing afterwards, being attenuated by the augment of the radical scavenging activity (RSA) and total phenols (TP) of this genotype. Mn concentration and LP in tissues of One -50 and Nui genotypes rose together, may be due to its Mn sensitivity. Differential expression of Mn transporter genes were found in the studied genotypes grown under increasing supplies of Mn, being MTP8.1 expressed' in shoots and NRAMP2-like in roots, We concluded that Banquet -II showed greater Mn concentration associated to high roots NRAMP2-like gene expression, without changes in photosynthetic performance. Despite, this genotype showed an increase of LP at the first hours of Mn-excess, it was decreased by the RSA and TP. Halo-AR1 appears to be Mnresistant in the short-term due to its photosynthetic performance was unchanged by Mn-toxicity, whilst One -50 and Nui were Mn-sensitive. (C) 2017 'Elsevier Masson SAS. All rights reserved

Physiological and biochemical responses to manganese toxicity in ryegrass (Lolium perenne L.) genotypes

We studied resistance to manganese (Mn) toxicity under acidic conditions and its relationship with nutrients such as calcium (Ca) and magnesium (Mg) in new perennial ryegrass (Lolium perenne L.) genotypes (One-50, Banquet-II and Halo-AR1) introduced in southern Chile, using the Nui genotype as the reference. Plants were grown in nutrient solution at increased Mn concentrations (0-750 mu M) at pH 4.8, and physiological and biochemical features were determined. Under higher Mn concentration, the One 50 genotype had a significantly lower relative growth rate (RGR) of shoots and roots, whereas in the other cultivars this parameter did not change under variable Mn treatments. Increasing the Mn concentration led to an increased Mn concentration in roots and shoots, with Banquet-II and Halo-AR1 having higher Mn in roots than shoots. Shoot Mg and Ca concentrations in all genotypes (except Banquet-II) decreased concomitantly with increasing Mn applications. In contrast to the other genotypes, Banquet-II and Halo-AR1 maintained their net CO2 assimilation rate regardless of Mn treatment, whereas the chlorophyll concentration decreased in all genotypes with the exception of Banquet-II. In addition, lipid peroxidation in Banquet-II roots increased at 150 mu M Mn, but decreased at higher Mn concentrations. This decrease was associated with an increase in antioxidant capacity as well as total phenol concentration. Banquet-II and Halo-AR1 appear to be the most Mn-resistant genotypes based on RGR and CO2 assimilation rate. In addition, Mn excess provoked a strong decrease in Ca and Mg concentrations in shoots of the Mn-sensitive genotype, whereas only slight variations in the Mn-resistant genotype were noted. When other evaluated parameters were taken into account, we concluded that among the perennial ryegrass genotypes introduced recently into southern Chile Banquet-II appears to be the most Mn-resistant, followed by Halo-AR1, with One-50 being the most sensitive. (C) 2017 Elsevier Masson SAS. All rights reserved

Physiological and biochemical responses to manganese toxicity in ryegrass (Lolium perenne L.) genotypes

We studied resistance to manganese (Mn) toxicity under acidic conditions and its relationship with nutrients such as calcium (Ca) and magnesium (Mg) in new perennial ryegrass (Lolium perenne L.) genotypes (One-50, Banquet-II and Halo-AR1) introduced in southern Chile, using the Nui genotype as the reference. Plants were grown in nutrient solution at increased Mn concentrations (0–750 μM) at pH 4.8, and physiological and biochemical features were determined. Under higher Mn concentration, the One-50 genotype had a significantly lower relative growth rate (RGR) of shoots and roots, whereas in the other cultivars this parameter did not change under variable Mn treatments. Increasing the Mn concentration led to an increased Mn concentration in roots and shoots, with Banquet-II and Halo-AR1 having higher Mn in roots than shoots. Shoot Mg and Ca concentrations in all genotypes (except Banquet-II) decreased concomitantly with increasing Mn applications. In contrast to the other genotypes, Banquet-II and Halo-AR1 maintained their net CO2 assimilation rate regardless of Mn treatment, whereas the chlorophyll concentration decreased in all genotypes with the exception of Banquet-II. In addition, lipid peroxidation in Banquet-II roots increased at 150 μM Mn, but decreased at higher Mn concentrations. This decrease was associated with an increase in antioxidant capacity as well as total phenol concentration. Banquet-II and Halo-AR1 appear to be the most Mn-resistant genotypes based on RGR and CO2 assimilation rate. In addition, Mn excess provoked a strong decrease in Ca and Mg concentrations in shoots of the Mn-sensitive genotype, whereas only slight variations in the Mn-resistant genotype were noted. When other evaluated parameters were taken into account, we concluded that among the perennial ryegrass genotypes introduced recently into southern Chile Banquet-II appears to be the most Mn-resistant, followed by Halo-AR1, with One-50 being the most sensitive