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Water restrictions management for fruit rosaceous during slowdown periods of fruit growth can increase water use efficiency and improve fruit quality without reducing significantly their yield. In this context, two water restriction levels were tested during four consecutive seasons (2007-2011) in peach, plum and almond trees during slowdown periods of fruit growth corresponding to stage II for peach and plum and to stages II and III for almond. Water was applied by drip irrigation to produce different water-application treatments of 50% ETc (T₅₀) and 75% ETc (T₇₅) of non-stressed trees irrigated at 100% ETc (T₁₀₀). The response of trees is presented only for the last season of the experiment (2010-2011) where the effect of the applied water stress is more pronounced. Results show that the effect of water restrictions varied depending on the species. Yield and fruit size were reduced significantly for peach only under treatment T₅₀. Fruit quality was improved for this species with an increase of brix refractometric index and a decrease of acidity. These parameters were evolved in the same manner for plum but the observed differences were not significant. For almond, kernel quality remained unaffected by water restriction at T₇₅. However, the epidermal wrinkles of kernels were more embossed, in response to treatment T₅₀, which affected their appearance. Except leaf area, the evolution of shoots growth, chlorophyll content and leaf temperature showed that the physiology of all species was affected by water stress created by the application of the two irrigation treatments but without profound influence, particularly in plum. In conclusion, irrigation-water may be economized during slowdown periods of fruit growth without major negative effect up to 25% ETc for peach and almond and up to 50% ETc for plum.

In Morocco, walnut tree (Juglans regia L.) cultivation is ancestral with complicated misidentification and unknown local genetic diversity. Atlas Mountains host a rich walnut tree germplasm, which has arisen from seedlings. The use of molecular markers makes it possible to overcomes confusion usually encountered in phenotypic characterization, thereby elucidating the real genetic diversity magnitude. This study aimed to investigate the genetic relationships among 33 local walnut trees grown in two contrasted agroecosystems, while comparing them with 8 Bulgarian varieties belonging to an ex-situ collection, using ISSR markers. The use of 13 primers generated 120 reproducible ISSR markers, with 7 to 13 bands and an average of nine bands per primer. This number reflected the high level of polymorphism between genotypes revealed by the selected primers. The average polymorphism rate was 75.2%, with the polymorphic information content varying from 0.212 to 0.370 and with an average of 0.32. Genetic distances and the pairwise comparison showed that all pairs of genotypes are distinct using more than 10 markers with a maximum of 50 bands. The dendrogram showed an obvious phylo-geographic structuring and the differentiation of genotypes by origin area. The Bulgarian cultivars form distinct groups that confirms the specificity of the Moroccan walnut gene pool. However, the dendrogram obtained showed that the Moroccan genotypes are genetically close to a certain number of Bulgarian genotypes. This indicates that some Moroccan genotypes and the Bulgarian varieties could have a common ancestor.

Summary —The first part of this paper provides a brief review of the requirements that apply to 14 Clabelling chamber technology, particularly for tree labelling, and of the means that can be used to meet them. Two main points are considered: the quality of the plant chamber environment -the necessity of thermal and hygrometric regulations is discussed -and the possibility of determining the exact amount of 14 CO 2 assimilated by the plant. The authors then describe a simple system allowing the quantitative labelling of entire trees, without temperature-or hygrometry-regulating devices which can be used in the morning. The CO 2 concentration is maintained at its natural level throughout the labelling procedure through an injection of cold CO 2 operated by an IRGA-driven computer. part, la totalité du 14 C étant injectée instantanément dès le début de l'opération, la régu-lation consiste à injecter du carbone «froid» pour compenser la photosynthèse, et l'équation (1 ) (paragraphe «Injection de CO 2 ») donne à tout moment la quantité totale de 14 C restant dans la chambre. Ainsi, 99,3% de la radioactivité a disparu lorsqu'on a renouvelé 5 fois la totalité du CO 2 présent dans la chambre, ce qui était réalisé en 4 h environ. Le CO 2 est fourni par la réaction d'une solution de Na 2 CO 3 gouttant dans un flacon d'acide sulfurique à 33% (fig 1)

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The effects of regulated deficit irrigation (RDI) on the performance of almond cv. Tuono, peach cv. JH-Hall and plum cv. Stanley were assessed on the Saiss Plain (NW, Morocco) over three consecutive growing seasons (2011-2013). Irrigation treatments consisted of a control, irrigation applied to fully satisfy crop water requirements (100% ETC), and two RDI treatments, irrigation applied to 75% ETC (RDI-75) and 50% ETC (RDI-50). These three treatments were applied during fruit-growth slowdown periods corresponding to Stages II and III in almond and Stage II in peach and plum. Yield and fruit quality traits were determined. The effect of RDI differed between species. Yield and fruit size were reduced significantly only in peach under RDI-50. Fruit quality improved in this species in the first year of the experiment, with an increase of sugar/acid ratio and polyphenol content. Plum quality also improved but the effects were significant only in the second and third years. Similar results were recorded in almond kernel, but their epidermal grooves were deeper under RDI-50, and this may have affected their commercial value. It is concluded that water can be saved during the fruit-growth slowdown period by up to 25% in peach and 50% in almond and plum with improvements in fruit quality without affecting total yield.

Rapeseed (Brassica napus L.) crop has a high yield potential in Morocco, particularly in the Gharb region. However, this area is subjected to relatively frequent water floods usually accompanied with soil waterlogging, which is harmful for the crop. This study aimed to assess the behavior and productivity of four Moroccan varieties under waterlogging stress conditions at four plant growth stages, against the control (absence of waterlogging). A field trial was carried out at the INRA experiment station of Allal Tazi during 2013/2014, and a pot experiment was conducted under shelter at the National School of Agriculture of Meknes during 2014/2015. The results obtained show that waterlogging stress significantly affected most of the studied parameters for all varieties and that germination and post-emergence seedling stages were the most sensitive to waterlogging stress conditions. Particularly, seed yield was drastically reduced for all varieties, and the reduction rate ranged from 19% for "INRA-CZH3" to 73% for "Narjisse" when waterlogging happened under rosette and young seedling stages, respectively. Overall, the variety "INRA-CZH3" presented the best agronomic performance and was the most tolerant to waterlogging occurring at different plant growth stages. Therefore, we recommend cultivation of this variety in the Gharb area. Its tolerance to such stress conditions is certainly attributed to its developed root system, its high seedling vigor and its large collar diameter. The two latter traits presented a high correlation with seed yield components and, thus, we recommend their use as selection criteria to breed for waterlogging rapeseed tolerance.Keywords: rapeseed / waterlogging stress / plant stage / tolerance / selection criteria Résumé -Évaluation de certaines variétés de colza (Brassica napus L.) soumises à un stress de ☆ Contribution to the Topical Issue "Rapeseed / Colza"