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The acaricidal activity of acetone and ethanol extracts of 12 plant species was evaluated using the contact method on Rhipicephalus turanicus (Acari: Ixodidae) ticks at an initial concentration of 20% (200 mg/mL). Eight of the 12 plants had mortality greater than 50% and the acetone extracts had better acaricidal activity than the ethanol extracts. The acetone extract of Calpurnia aurea (leaves and flowers) had the highest corrected mortality (CM) of 92.2% followed by Schkuhria pinnata (whole plant) with a CM of 88.9%, Ficus sycomorus (bark and stems) 86.7% and Senna italica subsp. arachoides (roots, leaves and fruits) 83.3%. Selected extracts were tested at five different concentrations using the adult immersion test. From dose–response assays, EC₅₀ values of 61.82 mg/mL, 115.21 mg/mL and 161.02 mg/mL were obtained for the acetone extracts of S. pinnata (whole plant), S. italica subsp. arachoides (roots, leaves and fruits) and C. aurea (leaves and flowers) respectively. The ethanol extract of Monsonia angustifolia (whole plant) had the highest CM of 97.8% followed by S. pinnata (whole plant) with a CM of 86.7%, C. aurea (leaves and flowers) 81.1% and Cleome gynandra (leaves) 77.8%. There is potential for the development of environmentally benign botanicals as natural acaricides against R. turanicus.

La croissance secondaire est à l'origine de l'accumulation de biomasse pérenne par les arbres et détermine en partie la capacité des écosystèmes forestiers à stocker du carbone. Cependant, les contraintes environnementales sur la croissance en milieu méditerranéen sont encore mal décrites et nous ne savons pas comment les changements climatiques futurs vont les modifier. L'objectif de la thèse est de déterminer, principalement à partir de l'étude de l'allocation du carbone à la croissance secondaire, les réponses fonctionnelles saisonnières et interannuelles du chêne vert (Quercus ilex L.) aux variations climatiques en région méditerranéenne. L'utilisation de différentes approches expérimentales, à des échelles spatiales allant du cerne à l'écosystème et à des échelles temporelles allant de la journée à plusieurs dizaines d'années, a permis de mettre en évidence l'effet de différentes contraintes environnementales (disponibilité en eau, réchauffement de la température, et densité du peuplement) sur la croissance secondaire et la composition isotopique du cerne. L'étude de la phénologie de la croissance montre que celle-ci est contrôlée directement par les températures hivernales et le déficit hydrique, plus que par la disponibilité en éléments carbonés issus de la photosynthèse. De 1968 à 2013, les changements climatiques ont entrainé une contrainte hydrique de plus en plus précoce qui s'est trouvée compensée par un début de croissance initié plus tôt dans l'année, sous l'effet du réchauffement des températures hivernales, et une meilleure efficacité d'utilisation de l'eau, sous l'effet de l'augmentation de la concentration en CO2 atmosphérique. La réduction de la mortalité et l'augmentation de la croissance observée dans des parcelles éclaircies montre que cette pratique sylvicole permet de préparer les taillis de chêne vert à l'intensification de la sècheresse prévue pour la région méditerranéenne. Tree secondary growth is responsible for woody biomass accumulation and is a major component of carbon storage in forest ecosystems. Environmental constraints on secondary growth in Mediterranean ecosystems must, however, be described in more to details to better understand how they will be modified by climate change. This dissertation aims at studying the functional responses of Mediterranean holm oak (Quercus ilex) to seasonal and inter-annual climate variations through the study of carbon allocation to secondary growth. Different experimental approaches, at spatial scales ranging from tree rings to the ecosystem and at temporal scales from the day to several decades, were used to identify the main environmental constraints (water availability, temperature warming, competition) to secondary growth and carbon isotopic composition of tree rings. The phenology of stem growth shows evidence for a direct environmental control on annual growth by winter temperature and summer drought that is more limiting than the carbon supply from photosynthesis. Climate change from 1968 to 2013 resulted in earlier water limitation on secondary growth, which was compensated by earlier growth onset, due to warmer winter temperature, and higher water use efficiency, due to increased atmospheric CO2 concentration. Thinning reduced tree mortality and increased stem growth, so thinning management in old holm oak coppices could prepare the ecosystem to better withstand the increasing drought forecasted for the Mediterranean region.

European physical journal special topics 228(2), 261-623 (2019). doi:10.1140/epjst/e2019-900045-4 Published by Springer, Berlin ; Heidelberg

AbstractIrrigation of paddy fields to arsenic (As) containing groundwater leads to As accumulation in rice grains and causes serious health risk to the people worldwide. To reduce As intake via consumption of contaminated rice grain, identification of the mechanisms for As accumulation and detoxification in rice is a prerequisite. Herein, we report involvement of a member of rice NRAMP (Natural Resistance‐Associated Macrophage Protein) transporter, OsNRAMP1, in As, in addition to cadmium (Cd), accumulation through expression in yeast and Arabidopsis. Expression of OsNRAMP1 in yeast mutant (fet3fet4) rescued iron (Fe) uptake and exhibited enhanced accumulation of As and Cd. Expression of OsNRAMP1 in Arabidopsis provided tolerance with enhanced As and Cd accumulation in root and shoot. Cellular localization revealed that OsNRAMP1 resides on plasma membrane of endodermis and pericycle cells and may assist in xylem loading for root to shoot mobilization. This is the first report demonstrating role of NRAMP in xylem mediated loading and enhanced accumulation of As and Cd in plants. We propose that genetic modification of OsNRAMP1 in rice might be helpful in developing rice with low As and Cd content in grain and minimize the risk of food chain contamination to these toxic metals.

The development of photobioreactor is important for sustainable production of renewable fuels, wastewater treatment and CO2 fixation. For the design and scale-up of a photobioreactor, CFD can be used as an indispensable tool. The present study reviews the recent status of computational flow modelling of various types of photobioreactors, involving fluid dynamics, light transport, and algal growth kinetics. An integrated modelling approach of hydrodynamics, light intensity, mass transfer, and biokinetics in photobioreactor is discussed further. Also, this reviews intensified system to improve the mixing, and light intensity of photobioreactors. Finally, the prospects and challenges of CFD modelling in photobioreactors are discussed. Multi-scale modelling approach and development of low-cost efficient computational framework are the areas to be considered for modelling of photobioreactor in near future. In addition, it is necessary to use process intensification techniques for photobioreactors for improving their hydrodynamics, mixing and mass transfer performances, and algal growth productivity.