Introduction. Many desirable properties make cloudy fruit juice widely produced according to consumer acceptance. The pulp of mango (Mangifera indica L.), a good source of carbohydrates and water, has many uses including the production of juice. Nowadays, the use of food enzymes has become widespread in the juice industry for various reasons. However, the application of enzymes has not yet been tested in the context of the production of cloudy mango juice, except for the stabilization of nectars. Thus, the aim of our study was to examine and optimize some parameters involved in the enzymatic production of cloudy mango juice. Materials and methods. To achieve our objective, we used Response Surface Methodology (RSM) by combining five factors: time (30–50 min), temperature (35–55 °C), pH 4–5.5, Pectinexr Ultra SP-L (20–40 μL·L-1) and Cellubrixr L (15–25 μL· L-1). Results and discussion. The study of juice yield, cloud stability and the browning index showed that the coefficients of determination (R2 values) of these traits with the studied parameters were greater than 0.900. The optimized juice yield, cloud stability and browning index varied with specific values chosen for the five parameters mentioned above. Conclusions. Finally, the use of 30 μ L·L-1 Pectinexr Ultra SP-L and 22 μL·L-1 Cellubrix at 45 °C, for 43 min, at pH 5.5, was found to be the optimum set of conditions for processing cloudy mango juice.

Introduction. Bacterial canker, caused by Pseudomonas syringae pv. syringae, is a devastating disease of stone fruit worldwide. The effects of mineral nutrients and freezing-thawing on bacterial canker susceptibility were evaluated using potted peach trees in an attempt to understand predisposing factors in bacterial canker of stone fruit. Materials and methods. A split-plot experimental design with randomized complete block main plots (i.e., inoculations associated with freezing-thawing or nonfrozen pretreatments) and subplots of trees with the seven treatments (i.e., solutions deficient in N, P, K, Ca, Mg or Fe, respectively, and a full nutrient control) was adopted to study the effect of mineral deficiency and freezing-thawing on peach susceptibility to bacterial canker. Results and discussion. Phosphorus deficiency was the only treatment to significantly decrease lesion length that developed after inoculation with P. syringae pv. syringae, compared with the control trees that received full nutrients. Nitrogen and potassium deficiency treatments significantly decreased bark nitrogen and potassium concentrations accordingly, but had no clear effect on lesion sizes. Inoculation during freezing-thawing cycles significantly increased lesion length. In another independent experiment, nitrogen deficiency significantly increased the number of P. syringae pv. syringae leaf scar infections, but the subsequent infection was limited to a few millimeters. Nitrogen-deficient trees, which had higher [carbon / nitrogen] ratios, developed lesion sizes equivalent to trees provided with full nutrients. Collectively, these data suggest that, in the absence of other major predisposing factors (i.e., low soil pH or ring nematodes), mineral nutrients may play a minor role in the susceptibility of peach to bacterial canker.

Introduction In Morocco the olive growers rely totally on pesticides to control the black scale Saissetia oleae, although this technique has adverse effects on natural enemies, on product quality and on the environment. However, the pesticides are not used efficiently because of ignorance of the developmental cycle of the insect, and of the periods of vulnerable instar presence. We studied these two parameters. Next, we tested the efficacy of the pesticide and we studied the effect of pruning on the scales as an alternative to chemicals. Materials and methods The seasonal trend of the black scale was studied in two olive orchards near Essaouira, in the west of Morocco, during 2005 and 2006. One of these orchards was subject to chemical treatment in 2007, while two new orchards were selected to study the effect of pruning on the scales. The evolution of crawler and nymph density on different olive tree organs was followed in order to discover their preferences for these different organs. Results and discussion The seasonal trend study showed the presence of one generation of S. oleae per year and the tendency to colonise young organs rather than old ones. The optimum of mobile instar population coincided with the beginning and the end of July. On the organs of the chemically-treated samples, numbers of crawlers and nymphs were highly reduced. The results showed a small-scale infestation in pruned trees compared with the unpruned trees (control). Conclusion. Though the chemical control has good results, pruning remains very efficient and can help improve the control of the black scale populations without harming the environment

Des Progrès considérables ont été réalisés dans certains domaines de la Photosynthèse au cours des toutes dernières années. Ces progrès ont non seulement permis d’éclaircir le mécanisme de certaines réactions de la Photosynthèse, mais encore ils nous obligent à modifier la conception même que nous avions de cette fonction physiologique capitale. Cela est si vrai qu’on hésiterait maintenant à définir la Photosynthèse comme la biosynthèse de substances carbonées au moyen de l’énergie lumineuse à partir du gaz carbonique de l’air!

L’un des buts de cet article sera de montrer que la Photosynthèse, au sens strict du mot, est davantage une assimilation de phosphate inorganique que de gaz carbonique. Nous nous attacherons moins au mécanisme détaillé des diverses réactions qu’à la place qu’elles occupent dans le concept actuel de la Photosynthèse.