Search results for "Pollen"

Reconstruction of palaeovegetation and sedimentation conditions in the area of ancient Lake Burtnieks, northern Latvia

2010

Palaeobotanical investigations were carried out with the aim of reconstructing the development of palaeovegetation and formation of sediments in the northeastern area of ancient Lake Burtnieks. Pollen and plant macroremain studies provide information on vegetation development in the surroundings of the lake, including Stone Age settlements of Braukšas I and Braukšas II. Results of the investigations indicate that the development of vegetation together with sedimentation conditions in the palaeolake have changed since the Younger Dryas until today. Vegetation composition varies in different parts of the ancient Lake Burtnieks area due to past changes in lake water level which reached differe…

Analytical procedure elaboration of total flavonoid content determination and antimicrobial activity of bee bread extracts

2019

Sixteen ethanolic extracts were obtained from seven different bee bread samples. The total flavonoid content in the extracts was determined by aluminium-chloride method and was in the range of 8.3 mg/L ± 6.24% to 195.3 mg/L ± 1.35% and 28.8 mg/L ± 19.33% to 603.3 mg/L ± 4.64% with reference to quercetin and rutin, respectively. The relative standard deviations (RSD) for parallel measurements for the calibration curves of quercetin dehydrate and rutin trihydrate were in the range of 0.51% to 9.39% and 5.02% to 19.91%, respectively. The RSD for parallel measurements for the extracts with reference to quercetin dihydrate and rutin trihydrate were in the range of 0.23% to 11.64% and 4.64% to 19…

Functional characterization of the plastidial 3-phosphoglycerate dehydrogenase family in Arabidopsis.

2013

This work contributes to unraveling the role of the phosphorylated pathway of serine (Ser) biosynthesis in Arabidopsis (Arabidopsis thaliana) by functionally characterizing genes coding for the first enzyme of this pathway, 3-phosphoglycerate dehydrogenase (PGDH). We identified two Arabidopsis plastid-localized PGDH genes (3-PGDH and EMBRYO SAC DEVELOPMENT ARREST9 [EDA9]) with a high percentage of amino acid identity with a previously identified PGDH. All three genes displayed a different expression pattern indicating that they are not functionally redundant. pgdh and 3-pgdh mutants presented no drastic visual phenotypes, but eda9 displayed delayed embryo development, leading to aborted emb…

Abrupt Alnus population decline at the end of the first millennium CE in Europe - The event ecology, possible causes and implications

2019

The study, based on the examination of 70 published and unpublished pollen profiles from Poland and supplementary data from the surrounding regions, shows that an abrupt, episodic Alnus population decline at the end of the first millennium CE was a much more widespread event than has been previously reported, spanning large areas of the temperate and boreal zones in Europe. The data from Poland suggest that the decline was roughly synchronous and most likely occurred between the 9th and 10th centuries, with strong indications for the 10th century. The pollen data indicate that human impacts were not a major factor in the event. Instead, we hypothesize that one or a series of abrupt climatic…

Forced Flowering in Mandarin Trees Under Phytotron Conditions

2019

[EN] Phytotron has been widely used to assess the effect of numerous parameters on the development of many species. However, less information is available on how to achieve fast profuse flowering in young fruit trees with this plant growth chamber. This study aimed to outline the design and performance of a fast clear methodology to force flowering in young mandarin trees (cv. Nova and cv. Clemenules) and to analyze the influence of induction intensity on inflorescence type. The combination of a short water stress period with simulated spring conditions (day 13 h, 22 °C, night 11 h, 12 °C) in the phytotron allowed flowers to be obtained only after 68-72 days from the time the experiment beg…

Physiological,anatomical and biomass partitioning responses to ozone in the Mediterranean endemic plant Lamottea dianae

2011

Ozone effects on the perennial forb Lamottea dianae were studied in an open-top chamber experiment. Ozone was found to induce reductions in CO 2 assimilation and water use efficiency in the leaves of this species. These reductions were mainly related to a decline in the in vivo CO 2 fixation capacity of Rubisco (V c,max), rather than to stomatal limitations or photoinhibitory damage (F v:F m). In addition to chloroplast degeneration, other observed effects were callose accumulation, formation of pectinaceous wart-like cell wall exudates and phloem alterations. Moreover, ozone exposure significantly reduced root dry biomass. The possible relevance of these adverse effects for Mediterranean f…

Breeding system and fruit set in African Marantaceae

2013

Abstract Marantaceae are a pantropically distributed family of perennial herbs and lianas in the understory of tropical rainforests. They are characterized by a unique pollen transfer mechanism. To understand its functional significance and evolution, field investigations have been conducted in Gabon. Data from 28 (of 35) species from Central Africa are achieved. The pollen–ovule ratio (34–140:1; exception Sarcophrynium 2.5:1) falls into the range of facultative autogamous species. All investigated species were proven to be self-compatible; however, only two were autogamous. Natural fruit set was generally low (10.9 ± 10%). The highest natural fruit set was found in Marantochloa purpurea (2…

Il foro di Pollentia-Urbs Salvia

2017

Agronomic treatments to avoid seed presence in ‘Nadorcott’ mandarin I. Effect on in vivo pollen tube growth

2022

Abstract Fresh market demands high quality fruit and, therefore, citrus growers and researchers are constantly looking for solutions to avoid seed presence. Current horticultural techniques have low effectiveness or high cost. The objective of this study is to evaluate the inhibition effect of seven products on the in vivo pollen tube growth in Nadorcott mandarin, which is a high-value seedy variety. To achieve this main objective, three inorganic fertilizers (ammonium nitrate, potassium nitrate, sulfur), and four saccharides (saccharose, methyl cellulose, callose, chitosan) were applied to Nadorcott stigmas 24 h before and after hand pollination. Pollen tubes were counted 1, 3, and 5 days …

Quantitative DNA Analyses for Airborne Birch Pollen

2015

Birch trees produce large amounts of highly allergenic pollen grains that are distributed by wind and impact human health by causing seasonal hay fever, pollen-related asthma, and other allergic diseases. Traditionally, pollen forecasts are based on conventional microscopic counting techniques that are labor-intensive and limited in the reliable identification of species. Molecular biological techniques provide an alternative approach that is less labor-intensive and enables identification of any species by its genetic fingerprint. A particularly promising method is quantitative Real-Time polymerase chain reaction (qPCR), which can be used to determine the number of DNA copies and thus poll…