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Seed plant diversity is under threat due to human over-exploitation and changes in land use. There is a need to identify regions where seed plant diversity is most at risk and establish nature reserves to protect the most important species. This study collected province scale seed plant richness data and corresponding environmental, social and, economic data in China in order to assess the impact of environmental and socio-economic factors on seed plant diversity and to quantify the relative importance of climate, human disturbance, and habitat heterogeneity on the distribution of seed plant diversity. A downscaling model was established to map the spatial distribution of seed plant diversity at a 1-km resolution. The results showed that temperature and precipitation seasonality, potential evapotranspiration, humidity index, altitude range, and gross domestic product were important determinants of seed plant diversity. The relative contribution of temperature seasonality was the most important factor (explaining 29.9–36.2% of the variation). Climate, human disturbance, and habitat heterogeneity explained much of the seed plant richness and density variation (about 69.4–71.9%). A scale-down model explained 72% of seed plant richness variation and showed that the center of seed plant species diversity was mainly located in the southeast area of China in the Qing-Tibet Plateau, Yun-Gui Plateau, Hengduan Mountain region, middle of the Sichuan Basins, Taiwan island, and Hainan island. This study improves our understanding of biodiversity hotspot regions and is a useful tool for biodiversity conservation policy and nature reserve management in China.
The interaction between seed plants and animals during pollination and fruit and seed dispersal is well known, and marks the sexual reproduction process. During the history of the plant kingdom, the development of sexual reproduction has been governed by changes in the environment of the plant, together with the increasing complexity of organisms. The interactions between gametes and the environment are prepared during gametogenesis, and therefore reproduction and dispersal are related from the beginning. The dynamic environment should be considered as an interactive partner. The more intensive interactions in multicellular organisms make the interaction in seed plants far more complex. Sexual reproduction plays a key role in the progress of the interaction between the dynamic environment and the biosphere. Sexual reproduction embodies the renewal and dispersal of organisms. This means that the interactions between organisms and their environment are not only an essential element of sexual reproduction but also a characteristic of life, based on the unity of organism and environment. The driving force of the increasing complexity of life is the dynamic environment and the persisting organism.
Of the several theories for the origin of the ovule advanced in this century, based largely on fossil evidence, the telome concept and double integument theory are accepted as the most plausible. Derivation of the integument through fusion of sterile telomes is the salient feature. For all theories, a common point of agreement is that the entire nucellus is a megasporangium. Evidence from both Paleozoic and extant ovules indicates that some of the integumentary telomes were fertile; that the nucellus is a sporangiophore of fertile telome origin; and that among all features cited to characterize ovules, the unique nature of the megaspores alone is definitive. Changes in the megaspore that extended the period of nutrient absorption over the course of female gametophyte development were probably achieved in a Late Devonian population of progymnosperms, indicating a monophyletic origin for seed plants. Ancient primitive features in ovule structure recur in genetically transformed plants and in natural populations of advanced taxa as well. In ovules of the bel1-3 mutant of Arabidopsis thaliana, a single integument takes the form of two or three columnar axes structurally similar to the integumentary axes of Devonian ovules. A single homeotic recessive gene derived by mutation of its dominant allele expresses this departure from the typical bitegmic form. The phenomenon suggests that expression of primitive form may be suppressed over the course of ovule evolution and later reinstated by homeotic gene mutation.
In two-year field investigations (2008 and 2009) the effect of used preparations on heath status of roots and seedling shoots of celery cvs Edward Mentor and Talar was studied. During experiments Biochikol 020 PC (chitosan 20 g/l), Biosept 33 SL (grapefruit extract 33%), Polyversum WP (106 oospores Pythium oligandrum/1 g) and standard fungicide Gwarant 500 SC (chlorothalonil 500 g/l) and Topsin M 500 SC (tiophanate metyl 500 g/dm3) were used for rootdressing. Fungicides Gwarant 500 SC and Topsin M 500 SC, significantly improved the health status of seedling shoots and seed-yield. The efficacy of preparations Biosept 33 SL and Biochikol 020 PC was lower than standard fungicide, but statistically significantly improved health status and yield compared to control. The application of biopreparation Polyversum WP did not influence significantly to the health of seedling shoots of all tested varieties, and did not increase the yield of seeds.
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