Sunlight and water are factors that affect seedling development. However, the effects of acclimatization of seedlings to sunlight and water stress remain poorly understood. This study aimed to examine the interactive effects of acclimatization to light and water stress on argan tree (Argania spinosa) seedlings in nurseries. An experiment was conducted with 504 seedlings using two sunlight treatments (L1 and L2, i.e. 100% and 60% of full sunlight, respectively), and three watering treatments (well-watered, moderate stress and severe stress, i.e. 100%, 50% and 25% of field capacity, respectively). According to our results, water stress treatments caused a reduction in total biomass accumulation, nitrogen and phosphorus uptake. Water stress significantly increased other macroelements, H2O2 and MDA levels and antioxidant enzyme activities compared to well-watered seedlings. Seedlings grown under moderate shade (L2) showed higher macroelement uptake, which probably contributed to the increase in total biomass in all water treatments. The highest membrane stability index (MSI) values, H2O2 and MDA levels and lowest antioxidant enzyme activities were recorded in acclimatized argan seedlings under moderate shading (L2). These results suggest that moderate shade can effectively prevent stress caused by light excess and can also mitigate the harmful effects of water stress on A. spinosa seedlings.

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Cette étude vise à comparer 36 clones d'Eucalyptus plantés au niveau de deux tests clonaux situés à Dar Ben Hcine et Machrâa El Kettane en Mâamora. Elle consiste à sélectionner les clones les plus adaptés et les plus productifs en vue d'une vulgarisation auprès du reboiseur au Maroc. Les caractères étudiés comprennent le taux de réussite de la plantation, le taux d'attaque des arbres par Phoracantha semipunctata, la hauteur totale, la surface terrière, le volume total et son accroissement moyen annuel. L'estimation de la production a nécessité l'élaboration de tarifs de cubage appropriés. L'analyse de la variance à un seul critère de classification, tenant compte de l'effet singulier du clone et l'analyse de la variance à deux critères de classification, tenant compte de l'effet conjoint « clone-site », ont permis de ressortir les résultats suivants : à Machrâa El Kettane, les meilleurs clones distingués par leur production, adaptation et vigueur sont les clones 3933 et 4291. Dans ce même site, les clones 3395, 3758, 949, et 4717 sont hautement productifs mais très vulnérables à l'attaque de Phoracantha. Les clones 3311, 3375, 4103, 3310, 4727, 3169, 3673, et 2895 sont résistants, mais sont moyennement à faiblement productifs ; à Dar Ben Hcine, la majorité des clones est sévèrement attaquée, à l'exception des clones 4727 et 2622 moins attaqués mais peu productifs. L'étude des corrélations entre l'ensemble des variables étudiées, montre que le taux d'attaque et le taux de réussite sont indépendants. Cette étude met en évidence une liaison forte entre le taux de réussite et les caractères de production (une bonne adaptation s'accompagne d'une haute production). À Dar Ben Hcine, le taux d'attaque est significativement corrélé avec les caractères de production, en raison du stade avancé des attaques, tandis qu'à Machrâa El Kettane, cette corrélation n'est pas significative, probablement en raison d'attaques encore récentes. L'étude de la stabilité des clones, met en évidence 6 clones stables (clones 3683, 3818, 4230, 3389, 4717, 3933), 2 clones stables pour les caractères d'adaptation (clones 4291, 4727) et 2 clones stables pour les caractères de production (clones 4706, 949).

Plant species characteristic of arid and semi-arid zones, such as Argania spinosa (L.) Skeels, have a taproot that allows them to reach the soil horizons more quickly. Unfortunately, in the nursery, the containers of culture used for the production of seedlings do not support an excellent development of the root architecture that can be able to resist the shock of transplantation, in particular of the hydric stress. This study aimed to evaluate the physiological and biochemical behavior of Argania spinosa seedlings grown in containers of different depths under water stress. An experiment was conducted with 90 seedlings from the different containers (P1 for depth of 16 cm, P2 for depth of 30 cm, and P3 for depth of 60 cm), and three watering treatments (well-watered 100% of field capacity, moderate stress with 50% of field capacity and severe stress with 25% of the field capacity). Our results showed that seedlings from the 16 cm container had lower values of water status. Malondialdehyde content, electrolyte leakage, hydrogen peroxide, and superoxide radical content gave higher values on seedlings from the shallow container. The benefits of increasing the container depth of nursery seedlings contribute to the improvement of physiological and biochemical responses of seedlings under water stress. To fully validate our findings, a long-term field study must be conducted.

Tree species identification and their geospatial distribution mapping are crucial for forest monitoring and management. The satellite-based remote sensing time series of Sentinel missions (Sentinel-1 and Sentinel-2) are a perfect tool to map the type, location, and extent of forest cover over large areas at local or global scale. This study is focused on the geospatial mapping of the endemic argan tree (Argania spinosa (L.) Skeels) and the identification of two other tree species (sandarac gum and olive trees) using optical and synthetic aperture radar (SAR) time series. The objective of the present work is to detect the actual state of forest species trees, more specifically the argan tree, in order to be able to study and analyze forest changes (degradation) and make new strategies to protect this endemic tree. The study was conducted over an area located in Essaouira province, Morocco. The support vector machine (SVM) algorithm was used for the classification of the two types of data. We first classified the optical data for tree species identification and mapping. Second, the SAR time series were used to identify the argan tree and distinguish it from other species. Finally, the two types of satellite images were combined to improve and compare the results of classification with those obtained from single-source data. The overall accuracy (OA) of optical classification reached 86.9% with a kappa coefficient of 0.84 and declined strongly to 37.22% (kappa of 0.29) for SAR classification. The fusion of multisensor data (optical and SAR images) reached an OA of 86.51%. A postclassification was performed to improve the results. The classified images were smoothed, and therefore, the quantitative and qualitative results showed an improvement, in particular for optical classification with a highest OA of 89.78% (kappa coefficient of 0.88). The study confirmed the potential of the multitemporal optical data for accurate forest cover mapping and endemic species identification.