排序方式： 共有14条查询结果，搜索用时 31 毫秒
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化学药剂诱导玉米孤雌生殖 总被引：9，自引：0，他引：9
本实验用DMSO、MH、PEG、6－BA、激动素等10种单一药剂及其各种组合处理对京杂六号玉米诱导孤雌生殖,共处理了1191穗,平均结实率为0.110％;筛选出最好的处理为组合药剂DMSO2％＋MH50mg·L-1＋PEG500mg·L-1处理抽丝后5d的花丝,其结实率为0．52％;单一药剂以NAA－Na10mg·L-1与DMSO2％的诱导效果最好;组合药剂的诱导效果优于单一药剂的诱导效果;大部分药剂有一最适浓度,浓度过高或过低诱导率有递减的趋势;处理时期以抽丝后5d为最佳;处理花丝的诱导效果好于处理子房的诱导效果。对所诱导的孤雌生殖一代（Pa1）植株观察,初步断定有遗传同质化的自交系产生。 相似文献
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Physiological and behavioural responses to hypoxia in an invasive freshwater fish species and a native competitor 
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下载免费PDF全文 Julie J.H. Nati Jan Lindström William Yeomans Shaun S. Killen 《Ecology of Freshwater Fish》2018,27(3):813-821
The spread of invasive species is one of the major environmental concerns which can have negative effects on biodiversity. While several life history traits have been identified as being important for increasing the invasiveness of introduced species, the physiological factors that allow certain species to become successful invaders remain poorly understood. It has been speculated that good invaders are thriving in disturbed environments. In unfavourable conditions, as during hypoxic events, invasive species might be better adapted in their physiological and behavioural responses towards this stressor. We compared physiological and behavioural traits between two freshwater fish species: the European bullhead (Cottus gobio), an invasive fish species in Scotland, and its native competitor the stone loach (Barbatula barbatula) over different dissolved oxygen concentrations (DO). Contrary to expectations, bullhead displayed a reduced hypoxia tolerance as compared to stone loach, indicated by a higher threshold (Pcrit) for the maintenance of standard metabolism. Avoidance behaviour during progressive hypoxia was similar between bullhead and stone loach. When given a choice between an open normoxic zone and a shelter located in hypoxia, both species spent most of their time hiding under the shelter in hypoxic conditions (bullhead: 100%; stone loach: 93.93%–99.73%), although stone loach showed brief excursions into normoxic conditions under 25% DO level. These results suggest that stone loach might be more resistant to hypoxia as compared to bullhead, and thus that increased hypoxia tolerance is likely not a trait by which bullhead have been able to expand their range within the United Kingdom. 相似文献
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There is an urgent need for new, mechanized systems that may restitute some profitability to buffer strip harvesting and motivate regular maintenance. An opportunity for innovation is offered by the growing success of chip-fed boilers, since the production of chips is simpler than that of logs and has a higher potential for cost reduction. Within this context, a study was conducted in Italy with the goals of: (a) designing three alternative chip harvesting methods for buffer strips, (b) field-testing the performance of each alternative, and (c) developing a model for estimating the cost of these methods under varying operational and economic conditions. The three harvesting methods reflected different mechanization levels, with escalating investment requirements. Overall, the study demonstrated that frequent maintenance of young, single row buffer strips generates profits only when thoroughly mechanized. Using a dedicated feller-buncher, a front-end loader for extraction and an industrial truck-mounted chipper brought the delivered cost below the 14 €/m3 loose chips (approximately 4 €/GJ) presently paid by the district heating stations. However, the intermediate-mechanization system showed the highest potential for improvements. The␣study generated a spreadsheet-based model for predicting the effects of varying work conditions and cost hypotheses. 相似文献