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Physiological Maturity (physiological + maturity)
Selected AbstractsDirect and correlated responses to selection on age at physiological maturity in Drosophila simulansJOURNAL OF EVOLUTIONARY BIOLOGY, Issue 6 2000D. E. L. Promislow Biologists who study the timing of development in insects have focused on variation in duration of pre-adult stages almost without exception. However, development is not complete until adults are not only morphologically mature, but also reproductively mature. Here we describe an experiment in the fruit fly, Drosophila simulans, in which we used artificial selection to create lines with shortened and lengthened duration from eclosion to the age when the first egg was laid. We found significant genetic variation for this trait. The response to selection on age when the first egg was laid was due to variation among females. Delayed adult development was correlated with rapid pre-adult development and longer life span in females. The approach we use here resolves some difficulties with previous approaches used to study the genetics of senescence, and provides an opportunity to study the hitherto unexamined predictions derived from classic models for the evolution of senescence. [source] The effect of delayed harvest on moisture content, insect damage, moulds and aflatoxin contamination of maize in Mayuge district of UgandaJOURNAL OF THE SCIENCE OF FOOD AND AGRICULTURE, Issue 15 2005Archileo N Kaaya Abstract Field drying is a traditional practice carried out by farmers in Uganda and it is one of those practices reported to affect the postharvest quality of maize. A study was therefore conducted to establish the effects of delayed harvest on moisture content, insect damage, moulds and aflatoxin contamination of maize in Mayuge district. Sixteen farmers were selected from Bayitambogwe sub-county, eight from each of the villages of Bugodi and Musita. Maize was sampled from each farmer's field in 2003B and 2004A seasons at harvest stages of physiological maturity and after delayed harvest for 1, 2, 3 and 4 weeks. Each sample was analysed for mould incidence, moisture content, insect damage and aflatoxin contamination. In each season, mould incidence, insect damage and aflatoxin levels significantly (P < 0.05) increased with delayed time of harvest. Moisture content reduced with delayed harvest time but the maize did not dry to the required safe storage moisture content of ,15%. Seasonal effects were only significant for moisture content: the 2003B crop had consistently lower moisture content than 2004A crop. These results indicate that, for improved harvest quality of maize, farmers should harvest no later than 3 weeks after maize has attained physiological maturity. Copyright İ 2005 Society of Chemical Industry [source] Field testing of honeybee-dispersed Trichoderma spp. to manage sunflower head rot (Sclerotinia sclerotiorum)PLANT PATHOLOGY, Issue 3 2002A. R. Escande Efficacy of Trichoderma spp. to reduce sunflower head rot caused by Sclerotinia sclerotiorum was evaluated in the field. A mixture of six isolates, including Trichoderma koningii, T. aureoviride and T. longibrachiatum, was tested in five field trials at Balcarce, Argentina. Trichoderma formulation (TF) included Trichoderma conidia and viable hyphal fragments, industrial talc and milled corn kernels. Honeybees (Apis mellifera) were used to disperse TF for six weeks from the onset of flowering. Two days after the first TF delivery, sunflower heads were inoculated with S. sclerotiorum ascospores. When 100 g TF was taken by honeybees in a 10-h per day period, head rot incidence was significantly reduced. This approach was successful in reducing disease incidence until physiological maturity of the crop, in environments highly conducive to head-rot development. [source] Whole-seed development in Sicyos angulatus (Cucurbitaceae, Sicyeae) and a comparison with the development of water-impermeable seeds in five other familiesPLANT SPECIES BIOLOGY, Issue 3 2010XIAOXIA QU Abstract Sicyos is the only member of the Cucurbitaceae known to have water-impermeable seeds, that is, physical dormancy (PY), and development of seeds with PY has not been studied in detail in this family. Our primary aim was to describe seed development in Sicyos angulatus from pollination to seed maturity and to compare it with the development of water-impermeable seeds in other families reported in the literature. Full seed stage (highest moisture content [MC]) occurred 4,6 days after pollination (DAP) and physiological maturity occurred 20 DAP. Seeds became water impermeable 32 DAP, with 14.6% MC. The hilum was the site of water loss during the final stage of maturation drying. Excised embryos could germinate from 20 DAP to 36 DAP, whereas no intact seeds germinated during any stage of seed development. Mechanical scarification did not promote germination of seeds after the seed coat became water impermeable at 32,36 DAP. Based on a previous study of seed dormancy and germination in S. angulatus, we suggest that germination in these scarified seeds may have been prevented by resistance of inner membrane and fruit-seed coat to embryo expansion. The MC when seeds became impermeable (14.6%) is in the range of that reported for seeds of species in five other families with PY. Information on seed development in S. angulatus will be useful in planning the timing of management strategies for this pernicious annual weed. [source] Growth and yield of winter wheat (Triticum aestivum L.) and corn (Zea mays L.) near a high voltage transmission lineBIOELECTROMAGNETICS, Issue 2 2003G. Soja Abstract The objective of this study was to determine the effects of an electromagnetic field from a high voltage transmission line on the yield of agricultural crops cultivated underneath and near the transmission line. For 5 years, experiments with winter wheat and corn were carried out near the 380 kV transmission line Dürnrohr (Austria),Slavetice (Czech Republic). Different field strengths were tested by planting the crops at different distances from the transmission line. The plants were grown in experimental plots (1.77 m2), aligned to equal electric field strengths, and were cultivated according to standard agricultural practice. The soil for all plots was homogenized layer-specifically to a depth of 0.5 m to guarantee uniform soil conditions in the plant root environment. The soil was sampled annually for determinations of carbon content and the behavior of microbial biomass. During development of the vegetation, samples were collected at regular intervals for growth rate analyses. At physiological maturity, the plots (n,=,8) were harvested for grain and straw yield determinations. The average electric and magnetic field strengths at four distances from the transmission line (nominal distances: 40, 14, 8, and 2 m) were between 0.2 and 4.0 kV/m and between 0.4 and 4.5 µT, respectively. No effect of the field exposures on soil microbial biomass could be detected. The wheat grain yields were 7% higher (average of 5 years) in the plots with the lowest field exposure than in the plots nearer to the transmission line (P,<,.10). The responses of the plants were more pronounced in years with drought episodes during grain filling than in humid years. No significant yield differences were found for corn yields. The extent of the yield variations attributed to the distance from the transmission line was small compared to the observed annual variations in climatic or soil specific site characteristics. Bioelectromagnetics 24:91,102, 2003. İ 2003 Wiley-Liss, Inc. [source] | ||||||||||