Search results for "Pollen"

Comparative study of the efficiency of buffer zones and harvest discarding on gene flow containment in oilseed rape. A modelling approach

2009

International audience; Oilseed rape (OSR) genes can escape fields in space via pollen and seeds and in time via volunteers resulting from seeds lost before or during oilseed rape harvests. Previous simulation studies and field observations showed that co-existence at the landscape level of contrasting OSR varieties such as genetically modified (GM) and non-GM varieties require costly measures that are difficult to implement, such as isolation distances between OSR fields and stringent volunteer control in all fields and road margins. In the present study, two local strategies, non-GM buffer zones aroundGMfields and discarding the harvest of boundary plants of non-GM fields, were tested in …

Limonium ilergabonum (Plumbaginaceae), a new species from northeastern Iberian Peninsula

2017

A new species of Limonium (Plumbaginaceae), L . ilergabonum sp. nov. , is described from the inland gypsum soils of the northeastern Iberian Peninsula (Flix, Tarragona province, Spain). The new species is closely related to the Iberian L. hibericum on morphological traits as assessed by multivariate ordination analysis (PCA), but it can be distinguished by the narrower leaves, inflorescence shape, and longer calyx. Limonium ilergabonum shows mixoploidy (2 n = 18, 2 n = 27), irregular pollen shapes, low levels of pollen stainability, and a single pollen-stigma combination morph (B type). All evidences suggest that L . ilergabonum is a polyploid relict species with an apomictic breeding syste…

The unique inflorescence structure of Dorema aucheri (Apiaceae): An adaptation to the arid environment

2021

Abstract Arid environments demand specific adaptations from plants in vegetative and reproductive systems. Self–compatibility, high pollen production and few well developed fruits are adapted to increase sexual reproductive success. Dorema aucheri is an arid–adapted, perennial monocarpic species endemic to southern Iran. It has a unique inflorescence structure. In this study, significance of inflorescence architecture for reproductive success was investigated in a wild population. The huge yellow inflorescences were frequently visited by manifold insects. The species is andromonoecious and spatially subdivided in a distal part with perfect flowers and a proximal part with male flowers. Flow…

Gadoria (Antirrhineae, Plantaginaceae): A new genus, endemic from Sierra de Gádor, Almería, Spain

2017

The surprising discovery of a population of a new species of Antirrhineae (Plantaginaceae) has also given rise to the description of a new genus situated in the subtribe Maurandyinae: Gadoria falukei. This is supported by the characteristics of the flower, pollen grains, seeds and capsule, and phylogenetic results based on DNA sequences. The species is endemic from Sierra de Gádor, Almería, Spain. Scanning electron microscopy was used to explore micromorphology of the capsule, indument, and seed and pollen grains ornamentation. Additionally, chromosomal number, preliminary insights on reproductive biology, phylogenetic position within Antirrhineae, ecological data and conservation status of…

Effect of a gap on gene flow between otherwise adjacent transgenic Brassica napus crops.

2003

Gene flow resulting from cross pollination becomes an issue when transgenic crops are involved and the genetic modification carries a trait of ecological importance. As crop fields are often separated by a barren gap, such as an intervening roadway or unplanted area, I measured cross contamination between two herbicide-resistant transgenic fields (canola, Brassica napus) across a gap of up to 12 m. I focused on pollen exchange from the field border up to 7 m inside each field over two seasons. In the absence of a gap, I found that gene dispersal diminished rapidly with distance, with more than 40% of transgenic progeny found within the first meter from the edge of the adjacent crop. Cross c…

Crop and density effects on weed beet growth and reproduction

2004

Summary Weed beet populations growing in each crop of the arable rotation could be a relay for the gene flow from adjacent transgenic herbicide-resistant sugarbeet. In this study, weed beet growth and reproduction were assessed under several conditions which could be found in the rotation: various weed beet densities (ranging from 1 to 120 plants m−2) and various crops (winter wheat, spring barley, spring pea, sugarbeet, maize, ryegrass). Measurements were carried out both on life-cycle dynamics (bolting time, time to flowering onset, dynamics of flower opening) and on other quantitative data (survival rate, bolting rate and pollen, flower and seed production). Increasing weed beet density …

Stipa ×fallax (Poaceae: Pooideae: Stipeae), a new natural hybrid from Tajikistan, and a new combination in Stipa drobovii

2017

Stipa ×fallax nothosp. nov . (Poaceae), from western Pamir Alai Mts (Tajikistan), is described and illustrated. Field observation, numerical analyses of morphology, and pollen grain viability data show that it originated from hybridization between S. drobovii and S. macroglossa subsp. macroglossa , species representing sections Smirnovia and Stipa , respectively. Stipa ×fallax is morphologically close to S. ×alaica and S. ×hissarica , but is distinguished by its shortly pilose lower part of the awn and densely pubescent leaves. Characters distinguishing S. ×fallax from its parental species as well as similar hybrid taxa in section Smirnovia that also grow in Central Asia are presented. The …

Prolonged stigma and flower lifespan in females of the gynodioecious plant Geranium sylvaticum

2017

tIn gynodioecious plants females need a reproductive advantage over hermaphrodites to be maintainedin the same population. Generally, three main proximate causes for a female advantage are considered:inbreeding avoidance, different resource allocation patterns, and differences in ecological interactions.A mechanism potentially causing a female advantage that is rarely discussed is a difference in flo-ral longevity between the genders. Females may have a longer stigma lifespan than hermaphrodites,which can affect pollination. Stigma and flower lifespan are rarely documented in gynodioecious species,although it is a common observation in dioecious species that female plants flower longer than…

Efficacy and effectiveness of sublingual immunotherapy for grass pollen allergy: Reply to the letter of Marcucci F

2016

Pesticide residues in honey bees, pollen and beeswax: Assessing beehive exposure

2018

In order to study the distribution of pesticide residues in beekeeping matrices, samples of live in-hive worker honey bees (Apis mellifera), fresh stored pollen and beeswax were collected during 2016–2017 from 45 apiaries located in different landscape contexts in Spain. A total of 133 samples were screened for 63 pesticides or their degradation products to estimate the pesticide exposure to honey bee health through the calculation of the hazard quotient (HQ). The influence of the surrounding environment on the content of pesticides in pollen was assessed by comparing the concentrations of pesticide residues found in apiaries from intensive farming landscapes to those found in apiaries loca…