排序方式： 共有37条查询结果，搜索用时 31 毫秒
21.
不同光质LED光源对黄瓜幼苗光合参数、水分利用效率和叶绿体超微结构的影响 总被引：1，自引：0，他引：1
采用发光二极管（LED）为光源,以白光作对照,研究了红光、蓝光和红蓝组合光对黄瓜品种“银胚99”幼苗叶片光合参数及水分利用效率的影响,并观察了叶绿体超微结构的变化。结果表明,蓝光和红蓝组合光均显著提高了叶片的净光合作用,在处理到第10天时,蓝光提高幅度最大,较白光高出27.29%;在处理到第20天时,红蓝组合光8R/2B提高叶片光合速率幅度最大,较白光高出56.94%。红蓝组合光处理下叶片的后期净光合速率下降较小,水分利用效率提高显著。与白光相比,红光处理对叶片净光合速率的影响不存在差异,且在处理第20天时叶片净光合速率和水分利用效率与第10天相比,有明显下降。叶片叶绿体超微结构显示,不同光质对黄瓜幼苗叶绿体发育有显著影响;白光不利于叶片叶绿体的成熟,红光造成叶片叶绿体淀粉粒过分积累,抑制了光合产物从叶片中的输出;红蓝组合光8R/2B和7R/3B处理则有利于叶绿体基质、基粒片层的形成和同化产物的输出。 相似文献
22.
GIS支持下的小麦区域化苗情遥感监测应用研究 总被引：2，自引：0，他引：2
在地理信息系统（ＧＩＳ）支持下,将处理好的归一化相干被指数（ＮＶＩ）图与地形图、土壤质地图、政我图、年降水量图、年平均气温图、小麦生育期积温图等背景图件叠加,进行比较客观的小麦遥感生态分层。并制成常年非麦象元分布底图。在此基础上,根据地面则网实地调查资料,建立了一套适合不同监测层的遥感监测指标。最后,将剔除常年非麦象元后的ＮＶＩ图与遥感生态区分层图进行集成,采用不同指标划分小麦苗情等级,从而提高了 相似文献
23.
The plant reproductive effort, the seed germination rate and the seedling survival and development of Zostera marina (eelgrass) were assessed in four populations (Fuzeta, Culatra, Barrinha and Armona) at the species’ southern distribution limit in the Eastern Atlantic, the Ria Formosa lagoon. Germinated seeds were individually placed in Petri dishes with natural sandy sediments and kept in a culture chamber at the same temperature and salinity conditions as the natural environment. In addition, seeds from three different depths of Fuzeta population were cultivated in outdoor mesocosms. The populations of Fuzeta and Barrinha showed higher seed production and the seeds produced were heavier than the other populations. The germination of the seeds both in the laboratory and in the outdoor tanks began c. 8–12 weeks after the collection of the flowering shoots at a water temperature of 22 °C. The spontaneous germination in the laboratory (2.4–5.3%) and in the mesocosm experiment (5.6–8.9%) was low and from all the germinated seeds (n = 20) only three reached the seedling stage. The spontaneously germinated seeds from Fuzeta survived for a longer period than those from Barrinha, but only the germinated seeds of Barrinha reached the seedling stage (one‐leaf seedling stage). In outdoor tanks, higher seed germination and earlier seedling emergence (2 weeks after seeding) and survival (for 208 days) occurred for the seeds obtained from the shallow meadow. The reproductive effort of Z. marina populations of Ria Formosa showed that flowering shoots and seed traits are site‐specific. The low reproductive success indicated by the low germination and seedling survival suggests a bottleneck in the species’ reproductive cycle that may account for the scarce presence of the species in Ria Formosa lagoon. The high water temperatures of Ria Formosa in winter may partly explain this bottleneck. Increased temperatures due to climate change may reduce even further the sexual reproduction of Z. marina in its southern distributional limit in the Eastern Atlantic. 相似文献
24.
Promotive effects of alginate-derived oligosaccharides on the inducing drought resistance of tomato 总被引：2，自引：0，他引：2
LIU Ruizhi） JIANG Xiaolu） ）* GUAN Huashi） LI Xiaoxia） DU Yishuai） WANG Peng） MOU Haijin） ） Key Laboratory of Marine Drugs Ministry of Education Ocean University of China Qingdao P.R. China ） College of Food Science Engineering P.R. China ） Meteorological Observation Center of China Meteorological Administration Beijing P.R. China 《中国海洋大学学报(英文版)》2009,8(3):303-311
In order to determine the role of alginate-derived oligosaccharides (ADO) in drought stress resistance of tomato (Lycopersicon esculentum Miller) seedlings, the leaves were exposed to different concentrations of ADO (0.05%, 0.10%, 0.20%, 0.30% and 0.50%) after
drought stress was simulated by exposing the roots to 0.6 molL−1 PEG-6000 solution for 6 h. Changes in biomass, electrolyte leakage and malondialdehyde (MDA), free proline, total soluble
sugars (TSS) and abscisic acid (ABA), the enzyme activities of catalase (CAT), superoxide dismutase (SOD), peroxidase (POD)
and phenylalanine ammonia-lyase (PAL) were measured to investigate the effects of ADO treatment. The results showed that the
treatment with an ADO concentration of 0.20% exhibited the highest performance of drought stress resistance in the tomato
seedlings by decreasing the electrolyte leakage and the concentration of MDA, increasing the contents of free proline, TSS
and ABA, and increasing the activities of CAT, SOD, POD and PAL after treatment with ADO. It is suggested that changes in
electrolyte leakage, MDA, osmotic solutes, ABA, anti-oxidative enzyme and PAL activities were responsible for the increased
drought stress resistance in tomato seedlings. To our best knowledge, this is the first report of the effect of ADO treatment
on enhancing the drought stress resistance of tomato seedlings. 相似文献
25.
Bioavailability and toxicity of antimony 总被引：1，自引：0，他引：1
Antimony (Sb) is a toxic trace element widely distributed in the lithosphere and mainly associated with arsenic. Sb compounds are considered to be pollutants of high interest, however, the biogeochemical behaviour of Sb is still largely unknown, especially compared to other well-known toxic elements. In particular, questions remain about the availability of Sb to vascular plants. In this work, we focused on the following problems: (i) Sb uptake by plants; (ii) the availability of Sb to plants and (iii) variations in uptake and distribution of essential plant nutrients and trace elements resulting from bioaccumulation of Sb in Triticum aestivum (wheat) seedlings. The seedlings were either germinated or grown in media enriched with Sb. By the end of germination, concentrations of Sb in the seedlings germinated in Sb-amended media increased significantly. Sb content was highest in the roots and lowest in the leaves of the seedlings. After transfer of the seedlings germinated in an Sb-free medium to Sb-enriched media, Sb concentration in the seedlings increased with time, especially in the roots. Bioaccumulation of Sb influenced concentrations of different macro- and trace elements in all parts of the plants. The least variations were observed in the leaves, probably because the increase of Sb concentration in leaves was not as significant as in the seeds and roots. 相似文献
26.
27.
28.
29.
天鹅湖大叶藻种苗补充情况调查 总被引：2，自引：0，他引：2
本研究以山东荣成典型潟湖——天鹅湖内的大叶藻(Zostera marina L.)海草床为研究对象,从2015年3月到6月对大叶藻种子萌发形成的幼苗进行进了月度调查,包括春季大叶藻种苗的密度、株高、叶鞘高、叶数、叶宽以及分枝情况。结果表明,天鹅湖大叶藻种子在3月即开始萌发,但萌发量较少,种苗密度较低;4月种子大量萌发,种苗密度不断升高,并达到峰值,为(481.77?303.42)株/m2;5月份种子萌发结束,种苗密度下降,同时开始克隆生长;6月份种苗不断生长,分枝数增多,种苗开始出现有性生殖枝。至此,春季种苗的萌发过程结束,进入有性生殖过程。 相似文献
30.
The range expansion patterns of Spartina alterniflora and the roles which sexual reproduction and asexual propagation play in range expansion were investigated at the Chongming Dongtan nature reserve in the Yangtze Estuary, China. Two range expansion patterns of S. alterniflora at its advancing fronts could be found (1) S. alterniflora–mudflat front (S–M) and (2) S. alterniflora–Scirpus mariqueter–mudflat front (S–S–M). One feature revealed by this study was that a flush of seedling recruitment and establishment in spring was a crucial way for S. alterniflora to colonize new habitats and achieve a fast rate of range expansion. The mean number of seedlings recruited at the S–M front was much higher than that at the S–S–M front. Once established, the survivorship of seedlings was high, both at the S–M and S–S–M fronts. The established seedlings formed new tussocks quickly by vegetative tillering and growth of rhizomes and these finally merged into dense meadows. The mean distance of range expansion of S. alterniflora, after one growing season at the S–M front, was 25.4 ± 3.1 m yr−1 and 2.7 ± 0.5 m yr−1 at the S–S–M front. Sexual reproduction by seedlings and asexual propagation by tillering and growth of rhizomes were the two main means by which S. alterniflora could maintain a fast rate of range expansion on the salt marshes of the Yangtze Estuary. The colonization behaviors of S. alterniflora on advancing fronts differed as a reaction to various external and internal factors. The impact of abiotic and biotic factors governing the range expansion of S. alterniflora and its implications for the spatial structure of tidal wetlands are discussed. 相似文献