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Leaf senescence is a destructive process that allows the efficient recycling of nutrients from dying leaves to growing parts of the plant. It is the final stage of leaf development that can be induced in response to stress. This makes leaf senescence an adaptive process that is highly beneficial for whole plant survival under unpredictable environmental conditions. Thus, the manipulation of this process has the potential to improve crop plants to become more climate resilient. In this review we compare leaf senescence processes between distantly related species to identify knowledge gaps and opportunities for plant improvement strategies. We describe that main signalling pathways controlled by carbohydrates, reactive oxygen species and hormones are conserved. However, the role of ethylene in age-induced leaf senescence in cereals is obscure. Moreover, downstream senescence regulatory signalling events are largely unknown, and these may be considerably different between members of annual dicots and cereals. Because leaf senescence regulation is so intricately connected to basic metabolic and developmental processes, we propose to increase research efforts to discover natural variation in senescence regulation and pinpoint gene variants that are tried and tested in nature. • Leaf senescence is an important nutrient recovery programme in a wide range of plant species. • Plant development and stress regulate leaf senescence. • Phytohormones and oxidative stress play similar roles in the induction of senescence in dicots and cereals. • Downstream signalling events often differ between dicots and cereals. • Harnessing natural variation in senescence regulatory genes can improve crop yield. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • AMF colonization is lower in wetland-aquatic habitats than in the terrestrial ones. • In monocots AMF colonization is lower at both the species and family levels. • The hydrological conditions are negatively correlated with AMF colonization. • AMF colonization tends to be low in obligate wetland plants. • AMF association is not-always an advantageous trait in aquatic habitats. Abstract Plants that live in aquatic habitats are frequently subjected to oxygen limitation and many of them modify their anatomy and physiology to counteract hypoxia. In these habitats, the role of plant associations with arbuscular mycorrhizal fungi (AMF), which are widespread in terrestrial environments and frequently confer benefits to the associated plant, is still debated. Starting from data taken from 34 selected papers, this study focuses on the occurrence of AMF in the roots of wetland and aquatic plants, taking into account the hydrological conditions of the sites, the plant wetland indicators and life forms, plant taxonomy and colonization by dark septate endophytes. The results have demonstrated the importance of hydrology in controlling the frequency and intensity of AMF root colonization, which tends to be low in obligate wetland plants. Moreover, colonization is generally lower and, possibly, less functional in monocots than in dicots. We suggest that the hydrological conditions, by filtering species according to their water tolerance, shape plant community composition, and that although AMF colonization is one of the traits that may increase plant fitness, it is not the most important one. In fact, a range of nutritional and growth strategies, which are more variegated than in terrestrial habitats, exists in wetland/aquatic habitats, and these strategies may rely, or not, on AMF colonization, as a consequence of the habitat and species. [ABSTRACT FROM AUTHOR]

Despite the importance of mycorrhizal symbiosis, we understand little how different soil managements affect arbuscular mycorrhizal fungi (AMF) communities. Crop rotation is recommended in sustainable agriculture because of its benefits in soil fertility improvement and positive effect decreasing soil borne diseases incidence and pest abundance. Amplicon sequencing of LSU and SSU rRNA gene fragments was used to analyse AMF diversity in fields from one of the most productive regions in Argentina, which varied in the main class of the plant component included in the crop rotation scheme. The samples encompassed different agricultural settings; one involving only monocot plants in the crop rotation schemes, one including a dicot crop, and the other an alternation and/or a combination of monocot and dicot plant components. We found lower richness and diversity in soils under monocot succession than in a dicot/monocot rotation or consociation. We observed that agricultural management had an influence on beta diversity patterns. Principal coordinate analysis showed that communities from the dicot/monocot rotation or consociation samples clustered together and separated from the monocots samples. These findings suggested that the increment of soil AMF diversity is more dependent on the alternation between monocot and dicot crops than other factors related to the farming systems. [ABSTRACT FROM AUTHOR]

• Modèle mathématique de phyllotaxie. • Détermination de la disposition des sépales par celle de la bractée et des bractéoles. • Modélisation de tous les cas de disposition des sépales (monocots et dicots) décrits par Eichler (1875). Eichler (1875) hypothesized that the position of the bracteoles determines the position of sepals and made a near-exhaustive list of the different arrangements found in monocots and dicots. However, he was unable to provide a theoretical basis for these observations. Eichler's hypothesis has not had much success over the past 150 years. In this study, we find that the classical mathematical theory of phyllotaxy makes it possible to model all the arrangements listed by Eichler from the angular and radial positions of the bracteoles and subtending bracts. [ABSTRACT FROM AUTHOR]

Abstract: Agriculture is an important source of the greenhouse gas nitrous oxide (N2O) and the atmospherically important nitric oxide (NO). We evaluated the effects of different grazers and plant species composition on N2O and NO emissions in temperate grassland. Paddocks were grazed rotationally by either cattle or sheep. Mean N2O emissions were 38.7μg N2O-Nm−2 h−1, mean NO emissions 2.4μg NO-Nm−2 h−1. Cumulative NO-N emissions were larger for sheep- than for cattle-grazed paddocks. Plant species composition was insignificant compared to the effect of grazers on N oxide emissions. In a controlled application experiment, plots with cattle excreta showed larger N2O emissions than plots with sheep excreta, reaching peak emissions of 1921μg N2O-Nm−2 h−1 on cattle urine patches compared to 556μg N2O-Nm−2 h−1 on sheep urine patches, related to different N-inputs per excretion. Peak emissions of dung-treated plots were much smaller. The N2O emission factors were 0.4% for cattle urine, 0.5% for sheep urine, 0.05% for cattle dung and 0.09% for sheep dung. N oxide emissions on the paddock scale were larger for sheep- compared to cattle-grazing, despite larger emissions per cattle excretion. We attributed this to the more even spread of sheep excreta compared to cattle excreta. [Copyright &y& Elsevier]

Abstract: Increased forest area and wood production is a key goal for the European Union, together with avoidance of hazards that damage forests. Galicia is a region of northwest Spain that belongs to the Atlantic biogeographic region with very high wood production, but due to climate fire has a major negative impact on forest productivity (i.e. it represents 16% of the fires of Europe). Silvopastoral systems offer the potential to enhance forest productivity as well as to obtain income from newly afforested areas in the short term. Herbaceous pasture production within such systems can be optimized through species selection and through fertilization. The aim of the present study was to evaluate effect of three types of fertilization on two sward mixtures established under Pinus radiata D. Don cover on abandoned agricultural land over an initial period of 7 years. Tree and pasture growth were enhanced with organic fertilization, tree growth rate not being limited by summer drought, and compared with mineral treatment, trees growing up on sludge treatment had around 35 and 30% more height and diameter, respectively. Acidity tendency of Galician soils was reduced with mineral treatment. Soil pH was positively affected by mineral fertilization as it was reduced in less extent in this treatment (pH 6) than in organic (pH 5.3) or no fertilization treatment (pH 5.6), as crop cation extractions were reduced. The proportion of Na and Mg in the effective CEC was higher in fertilization with dairy sludge and no fertilization plots due to better tree canopy development. The interchangeable potassium content in ryegrass sown plots was reduced when no fertilization was applied due to dicot extractions, which can explain lower tree growth than in non-fertilized cocksfoot plots. Correct tree and pasture management, using appropriate sowing mixtures and fertilization types, makes it possible to improve the productivity of both components of the silvopastoral system. Our present results indicate that it is better to use organic fertilizers in the establishment of cocksfoot or ryegrass on sandy soils for tree and pasture growth enhancement. [Copyright &y& Elsevier]