1,721,097 research outputs found
Entomogamy in wildflowers: What level of pollinator biodiversity is required?
No full textWildflowers are gaining increasing importance due to their beneficial impact on biodiversity and thus the health of ecosystems. Unfortunately, their mutualism with pollinator vectors that transport pollen to stigmas makes their survival vulnerable. The aim of this experiment was to verify the inbreeding depression in terms of seed-set of sixteen rare wildflower species, in the complete absence of pollinators. Despite being strongly species-dependent, this inbreeding depression was found to be consistent in perennial species. Conversely, the effects of self-pollination on other biological parameters such as 1,000 seed weight, germinability and viability were decidedly weaker and non-converging in the various wildflowers species. Each had differing flowering calendars for attracting a species-dependent intensity and biodiversity of visits by pollinators grouped into bees, bumblebees, solitary bees, hoverflies, bee flies, and butterflies. By correlating pollinator biodiversity during open pollination (Shannon index, H’) with the inbreeding depression (δ) caused by self-pollination (bagged flowers), a statistically significant inverse linear relationship (p < 0.05) between these two parameters was found. This linear regression highlights the lower need for biodiversity by the “generalist” wildflower species and a greater need in the “specialized” species characterized by a closer evolutionary mutualism with more restricted pollinator taxa. These data are discussed in terms of the risk of feed-back rarefaction of wildflowers and pollinators in both natural and agricultural ecosystems. Finally, strategies are suggested for promoting the ecological sustainability of wildflower biodiversity
“Active” weed seed bank: Soil texture and seed weight as key factors of burial-depth inhibition
Full text linkThe ability of weeds to survive over time is highly dependent on an ecological strategy that ensures a high level of viable seed remains in the soil. Seed bank persistence occurs because of the specific characteristics of seed dormancy and longevity and the hypoxic microenvironment, which surrounds the buried seeds. These experiments investigate the role of soil texture, burial depth, and seed weight in seed bank dynamics. Seeds of twelve weed species are sown at increasing depths in various soil textures, and emergence data are used to detect the burial depth at which 50% and 95% inhibition is induced, using appropriate regressions. Clay soil is found to increase the depth-mediated inhibition, while it is reduced by sandy particles. In each soil texture, the highest level of inhibition is found for the smallest seeds. Seed weight is found to be closely related to the maximum hypocotyl elongation measured in vitro, and consequently, the seedlings are unable to reach the soil surface beyond a certain depth threshold. However, the threshold of emergence depth is always lower than the potential hypocotyl elongation. The depth-mediated inhibition of buried seeds is even more pronounced in clay soil, highlighting that the small size of clay particles constitutes a greater obstacle during pre-emergence growth. Finally, the role of soil texture and weed seed size are discussed not only in terms of evaluating the layer of "active" seed bank (soil surface thickness capable of giving rise to germination and emergence), but also in terms of developing a consistent and persistent seed bank. Finally, the role of soil texture and weed seed size are discussed, and the layer of "active" seed bank (the soil surface thickness that enables germination and emergence) is assessed with the aim of developing a consistent and persistent seed bank. Assessing seed bank performance when buried under different soil textures can help increase the reliability of the forecast models of emergence dynamics, thus ensuring more rational and sustainable weed management
La soia: le esigenze, la tecnica colturale, le prove varietali. Risultati di ricerche sperimentali
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The biodiversity of edible flowers: Discovering new tastes and new health benefits
Full text linkFloriculture and horticulture have always been two parallel and very distinct agronomic realities. Floriculture is concerned with meeting the ornamental needs of our urban ecosystems, while horticulture is based on meeting food requirements. These two activities have now converged toward a food chain where flowers are conceived of as a sort of "new vegetable" and one of the most promising novelties to satisfy the growing need for food innovation both in terms of an organoleptic and nutraceutical profile. This novelty has rapidly evolved, especially following the growing scientific evidence of the human health benefits of flowers used as food. The typically high pigment concentration of the corollas (especially flavonoids and carotenoids), which have evolved to chromatically attract pollinators, indicates a marked nutraceutical activity especially in terms of antioxidant power. In this review, we first attempted to explore which species are most promising and which should be avoided due to real or suspected toxicity problems. The nutraceutical virtues were therefore highlighted trying to focus attention on those "functional phytochemicals" capable of counteracting some specific human pathologies. Furthermore, the organoleptic profile of edible flowers was investigated since this is one of the least known aspects. The cropping systems suitable for their cultivation were therefore hypothesized and finally the criticalities of edible flowers were addressed in terms of shelf life and marketing opportunities
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