Search results for "plant physiology"
showing 10 items of 118 documents
Effects of simulated environmental changes on growth and growth form in a late snowbed population of pohlia wahlenbergii (Web. et Mohr) Andr
2003
In a factorial field experiment we increased the temperature (Open Top Chambers) and nutrients (nitrogen, phosphorus, and potassium [NPK]) to simulate predicted future climate changes and studied the growth response of the acrocarpous bryophyte Pohlia wahlenbergii (Bryaceae) in a wet snowbed environment. The species shows a positive growth-length response to added nutrients and increased temperature. The stronger response to nutrients indicates a strong limitation of nutrients in the snowbed environment. There was an immediate response to nutrient treatment, whereas the temperature response was delayed. The growth response shows a clear interaction between temperature and nutrients. The imm…
Experimental warming had little effect on carbon-based secondary compounds, carbon and nitrogen in selected alpine plants and lichens
2011
Accepted version of an article published in the journal: Environmental and Experimental Botany. Published version available on Science Direct: http://dx.doi.org/10.1016/j.envexpbot.2011.04.011 Global warming is expected to change plant defence through its influence on plant primary resources. Increased temperature (T) will increase photosynthesis, and thus carbon (C) availability, but may also increase soil mineralization and availability of nitrogen (N). More access to C and N is expected to mainly increase plant growth, and, according to hypotheses on resource based defence, this could lower plant concentrations of carbon-based secondary compounds (CBSCs). We used two already established …
Quantitative importance of staminodes for female reproductive success inParnassia palustrisunder contrasting environmental conditions
2003
The five sterile stamens, or staminodes, in Parnassia palustris act both as false and as true nectaries. They attract pollinators with their conspicuous, but non-rewarding tips, and also produce nectar at the base. We removed staminodes experimentally and compared pollinator visitation rate and duration and seed set in flowers with and without staminodes in two different populations. We also examined the relative importance of the staminode size to other plant traits. Finally, we bagged, emasculated, and supplementary cross-pollinated flowers to determine the pollination strategy and whether reproduction was limited by pollen availability. Flowers in both populations were highly dependent o…
Gada koka 2020 – Eiropas dižskābarža – herbārijs
2020
Latvijas Dendrologu biedrība (LDB) par 2020. gada koku izvēlējās Eiropas dižskābardi Fagus sylvatica L. Latvijas Universitātes Muzeja Botānikas un mikoloģijas kolekciju herbārijā glabājas arī šīs sugas pārstāvju herbārijs - žāvēti un presēti zariņi ar lapām. Rakstā ir Eiropas dižskābarža sugas apraksts un 5 attēli no LU Muzeja herbārija, ar informāciju par to ievākšanas vietām un laikiem.
Ernesta Foldāta piedzīvojumi Venecuēlā un dzeja par to
2019
Latvijas Universitātes Goda doktora, Latvijas Zinātņu Akadēmijas Ārzemju Goda locekļa, Venecuēlas Centrālās Universitātes un Nacionālo parku institūta emeritētā profesora, orhideju pētnieka Ernesta Foldāta (1925-2003) apraksti par piedzīvojumiem Venecuēlā un dzeja par to.
Untargeted metabolomics of rind essential oils allowed to differentiate two closely related clementine varieties
2021
[EN] Chemical characterization of clementine varieties (Citrus clementina Hort. ex Tan.) essential oils (EO) can lead to variety identification and valorization of their potential use in food and aroma industries. The goal of this study was the chemometric discrimination between two very closely related and morphologically identical clementine varieties, Clemenules (NL) and Clemenpons (PO), based on their rind EO, to identify the differential volatile organic compounds (VOCs) and to determine their antioxidant capacity. EO rind volatile profile was determined by gas chromatography coupled to mass spectrometry in Citrus fruit at different ripening stages grown two independent years in two di…
Videi draudzīgā un bioloģiskā lauksaimniecībā vasaras miežiem (Hordeum vulgare L.) nozīmīgu pazīmju ģenātiskā kartēšana
2018
Divdesmit pirmā gadsimta izaicinājums ir nodrošināt pieaugošo pasaules cilvēku populāciju ar pārtiku. Mieži ir pasaulē ceturtā un Latvijā otrā visvairāk audzētā graudaugu kultūra. Mūsdienu prasībām atbilstošu šķirņu veidošanai nepieciešamas zināšanas par auga pazīmju ģenētisko un fizioloģisko pamatu. Promocijas darbā ar asociāciju kartēšanu un kvantitatīvo pazīmju lokusu (QTL) kartēšanu meklēti videi draudzīgā un bioloģiskā lauksaimniecībā nozīmīgas miežu pazīmes nosakošie kvantitatīvie lokusi. Apstiprināti iepriekš publicēti pazīmju nosakošie QTL un identificēti jauni ar bioloģiskajā lauksaimniecībā būtiskām pazīmēm saistīti QTL. Salīdzināta bioloģisko un konvencionālo audzēšanas apstākļu …
2001
Duration from sowing to flowering is the most important trait influencing adaptation in pigeon pea (Cajanus cajan), but the inheritance of this trait has not been elucidated clearly. Crosses were made between two early (60 to 70d) and one late (160 to 170d) flowering pigeonpea genotype and F1, F2 and BC1 populations produced. These populations, comprising 60 to 100 parents, 30 F1, 400F2 and 40 to 50 BC1 plants, were grown under natural (mean13.4 hd-1) and artificially extended (to 15 hd-1) daylength and duration from sowing to first flowering recorded. Genetic analysis of the segregation ratios, supported by Chi-square tests, indicated that the duration from sowing to flowering in each of t…
Morpho-physiological variations in response to NaCl stress during vegetative and reproductive development of rice
2012
The complex nature of plant resistance to adverse environmental conditions, such as salinity and drought requires a better understanding of the stress-induced changes that may be involved in tolerance mechanisms. Here we investigate stress-related morpho-physiological effects during vegetative and reproductive growth in two Japonica rice cultivars (Bomba and Bahia) exposed to a range of NaCl concentrations from the seedling stage. The stress-related detrimental effects were observed either earlier or to a higher extent in cv. Bomba than in Bahia. Damages to the photosynthetic apparatus were related to loss of chlorophyll (Chl) and to a decrease of the maximum potential efficiency of PSII (F…
Effect of polyamines on in vitro anther culture of Citrus clementina Hort. ex Tan
2006
The improvement of the induction rate in Citrus anther culture is important for taking practical advantage of the haploid potential in breeding. The influence of polyamines on anther culture of Citrus clementina, cv Nules, with particular attention to the free, soluble and insoluble-conjugated polyamine levels, has been investigated. Putrescine, spermidine and putrescine plus spermidine, were added to the standard induction medium. Before culture, spermidine was the most abundant among the free polyamines detected in anthers. The exogenous supply of either putrescine or spermidine, either independently or combined, effected greater uptake and accumulation of polyamines. The addition of 2 mM…