No abstract

In Algerian desert, oases are characterized by the presence of date palm (Phoenix dactylifera L.) as a dominant species. This plant gives fruit but also creates a favourable microclimate for other crops. The date palm is essential for the oasis agro-ecosystem equilibrium, the latter being a group of small family farms, has been the subject of serious damages in recent years, it's blossoming. Two cultivars are dominated redarding to their economic importance in local market with 96% (Ghars and Deglet Nour). Recently, a clear degradation of oases was noticed due to the lack of interest from growers to replace old and dead palms. These palm grove have aged palm, high height and a fragile stamina which limiting the cultural operations and affecting grimly the production. Actually, the old palm groves in the Northeast of Algerian Sahara are divided into types: "Bour" and "Old palm groves".

Relation entre les variations thermo-hygrométriques et la maturité des dattes à Biskra (Cas Deglet Nour) La variation des conditions climatiques a un impact direct sur la croissance des plantes et sur le rendement des cultures, tant en qualité qu'en quantité. Ces dernières années, de nombreuses études ont prouvé l'hypothèse du réchauffement climatique. Dans ce contexte, l'étude du comportement des plantes cultivées est devenue une nécessité, afin de garantir la sécurité alimentaire des populations. Notre contribution porte sur l'influence de la température et de l'humidité relative de l'air sur le cycle de développement des dattes Deglet Nour à Biskra. Pour atteindre nos objectifs, nous avons suivi le cycle phénologique du palmier dattier, cultivar Deglet Nour, pendant deux années (2018 et 2019). En même temps, des enregistreurs thermo-hygrométriques ont été installés à l'intérieur des palmeraies de Lichana et d'El-Kantara. Enfin, nous avons calculé l'accumulation thermique et le temps nécessaire à la maturation des dattes. Les dattes Deglet Nour, dans la wilaya (province) de Biskra, ont besoin d'une accumulation thermique d'environ 3450-4250 °C pour mûrir, ce qui équivaut à une durée de 30-44 semaines. Les résultats montrent que la température et l'humidité de l'air ont tendance à augmenter, alors que les dates d'apparition et d'ouverture des spathes et de la maturité des fruits sont devenues plus précoces.

Oasis settlements in Saharan lands present a particular model of life for rural individuals’ adaptation to environmental challenges. This study investigated human outdoor thermal comfort in a palm grove of the Tolga region, Algeria, during the phenological cycle of the date palm. Date palms are the primary economic source of the cultivators, who mainly live in houses inside the cultivated area. For this study, an area of 21 hectares with 220 palm trees was selected. The phenological cycle of the date palm was divided into three growth stages, including seasonal variations as well. The cycle covers a period of 8 months from March to November. Therefore, on-site monitoring of the microclimate was performed during March–November 2021. The climatic factors of air temperature and humidity were monitored at an interval of 10 min. The discomfort index based on temperature ranges covering discomfort conditions was used. The results showed that the cultivators work under extreme temperatures for 5.5 months during the phenological cycle. The spring period was more comfortable, while slight to extreme discomfort was observed in the summer and fall seasons, especially between midday and 7 p.m. Temperatures below 25 °C are comfortable for the cultivators; however, severe discomfort occurs at 30 °C or above. Moreover, the humidity was not a dominant factor for discomfort. These findings can be helpful for architects and planners to devise solutions that can fulfil human comfort requirements and date palm cultivar conditions, specifically during extreme thermal situations.