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Abstract: The objective of this work was to describe the dynamics of senescence of field-grown maize from silking to harvest, at both leaf and plant level. At the leaf level, the dynamics of symptoms of senescence were considered on each leaf taken individually and described according to zones from the tip to the base of the leaf lamina. At the whole plant level, foliar ranks were each considered as an entity to describe the time course of senescence. To this end, we use a database built-up from field trials conducted during three consecutive years (1994–1996) and thus undergoing variable meteorological and soil water conditions. Leaf chlorophyll content was estimated using two different methods based on the optical properties of the leaves. In Trial I, chlorophyll estimates were based on leaf optical density measured with a MacBeth TR-924 densitometer. In Trial II and Trial III, chlorophyll estimations were based on measurement using a hand-held Minolta SPAD-502 device. In Trial II and Trial III, chlorophyll fluorescence analyses under filed conditions were performed. These analyses focused on the photosystem II (PSII) maximum efficiency (Fv′/Fm′) parameter in the light-adapted state. Measurements were done with a Waltz PAM-2000 portable fluorometer. We report detailed descriptions of the spatio-temporal dynamics of these indicators of senescence. We found that, after silking, a strong relationship exists between available water and leaf chlorophyll content. Further, the maximum efficiency of PSII decreased faster in maize plants undergoing low available soil water than in irrigated plants. The rank of a leaf is determinant of the time for the beginning of the decline in both chlorophyll content and maximum efficiency of PSII. At plant and leaf level, the onset of senescence was marked by a decrease in chlorophyll content that was not concomitant with a dramatic decrease in the maximum efficiency of PSII. Our analyses suggest that a non-linear functional relationship could exist between these two parameters during monocarpic senescence. In the mean time, the results presented in this paper could be used to refine the senescence related modules in plant and crop models. [Copyright &y& Elsevier]

The European Food Safety Authority concluded in February 2018 that " most uses of neonicotinoid insecticides represent a risk to wild bees and honeybees ". In 2016, the French government passed a law banning the use of the five neonicotinoids previously authorized: clothianidin, imidacloprid, thiamethoxam, acetamiprid and thiacloprid. In the framework of an expert assessment conducted by the French Agency for Food, Environmental and Occupational Health and Safety to identify possible derogations, we performed a thorough assessment of the available alternatives to the five banned neonicotinoids. For each pest targeted by neonicotinoids use, we identified the main alternative pest management methods, which we then ranked for (i) efficacy for controlling the target pest, (ii) applicability (whether directly useable by farmers or in need of further research and development), (iii) durability (risk of resistance in targeted pests), and (iv) practicability (ease of implementation by farmers). We identified 152 authorized uses of neonicotinoids in France, encompassing 120 crops and 279 pest insect species (or genera). An effective alternative to neonicotinoids use was available in 96% of the 2968 case studies analyzed from the literature (single combinations of one alternative pest control method or product × one target crop plant × one target pest insect). The most common alternative to neonicotinoids (89% of cases) was the use of another chemical insecticide (mostly pyrethroids). However, in 78% of cases, at least one non-chemical alternative method could replace neonicotinoids (e.g. microorganisms, semiochemicals or surface coating). The relevance of non-chemical alternatives to neonicotinoids depends on pest feeding habits. Leaf and flower feeders are easier to control with non-chemical methods, whereas wood and root feeders are more difficult to manage by such methods. We also found that further field studies were required for many promising non-chemical methods before their introduction into routine use by farmers. Our findings, transmitted to policymakers, indicate that non-chemical alternatives to neonicotinoids do exist. Furthermore, they highlight the need to promote these methods through regulation and funding, with a view to reducing pesticide use in agriculture. • Five neonicotinoids were banned in France, which were used to protect 120 crops from 279 pest insect species. • In 96% of cases, neonicotinoids can be replaced by effective and directly useable alternative pest control methods. • In 78% of cases, at least one non-chemical alternative method can replace neonicotinoids. • Leaf and flower feeders are easier to control with non-chemical methods than wood and root feeders. [ABSTRACT FROM AUTHOR]

• Characterisation of alfalfa production and electricity generation in agriphotovoltaics conditions. • Alfalfa biomass increased by 10% in average in the shade of the Agri-PV system for shading between 29% and 44%. • Photovoltaic production reduced by 15% due to the optimised tracking for plant growth. • This combined production allowed an increase in total productivity per unit area (LER) of 51% Agriphotovoltaic systems, consisting of the combination of crops and photovoltaic panels (PVPs) on the same area, have recently emerged as an opportunity to solve the competition for land use between food and energy production. Various crops, pedoclimatic contexts and structures and both fixed and mobile panels have been studied. Over a period of two years, this research has been investigating an agriphotovoltaic (APV) system with mobile panels along two axes of rotation. The studied crop is alfalfa, a grassland species that has received little attention under these conditions. In our experimental set-up, the alfalfa biomass increased by an average of 10 % over the two years of the experiment in the shade of the APV plant (between 29 % − 44 %) in comparison to full sunlight (835 g.m−2.year−1), but in a different way depending on the climatic year. The nutritional qualities were preserved while the canopy's morphology was adapted through an increase in the length of the stems and the surface area of the leaflets. Photovoltaic production was reduced by 15 % due to the optimised tracking for plant growth. This combined production allowed an increase in total productivity per unit area of 51 % (LER: 1.51). The positive agronomic results are explained by a decrease in evapotranspiration caused by the panels in a context where the crop is highly sensitive to water deficit with thin soil. To reach a more general conclusion on synergy, these results need to be completed over several years and compared with other studies in different soil and climatic contexts, as well as with modelling studies. [ABSTRACT FROM AUTHOR]