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Effect of tillage and burial depth and density of seed on viability and seedling emergence of weedy rice 预览
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作者 ZHANG Zheng GAO Ping-lei +3 位作者 DAI Wei-min SONG Xiao-ling HU Feng QIANG Sheng 《农业科学学报:英文版》 SCIE CAS CSCD 2019年第8期1914-1923,共10页
Weedy rice(Oryza sativa f. spontanea) is one of the three worst paddy weeds in most rice growing areas. The unexpected heavy infestation is derived from a persistence of soil seed bank of weedy rice, which the shatter... Weedy rice(Oryza sativa f. spontanea) is one of the three worst paddy weeds in most rice growing areas. The unexpected heavy infestation is derived from a persistence of soil seed bank of weedy rice, which the shattered seeds chiefly feed back to. Information on soil seed bank dynamics is imperative to predict the infestation of weeds. In the present paper,the effect of rotary tillage on weedy rice seed bank structure was studied first, and a burial experiment of marked seeds was conducted to observe the overwintering survival, seed viability and seedling emergence of weedy rice. The results showed that the proportion of weedy rice seeds in deeper soil increased but seedling emergence decreased with increasing plowing depth. The viability of weedy rice seeds decreased as the burial duration time extended but more slowly in deeper soil layers. Additionally, there was no significant effect of burial density on seed viability. Moreover, the logistic model fitted well(R~2≥0.95, P≤0.01) with the depressive trends of seed viability with increasing burial time under all burial depths and densities which can provide us further information about seed survival. In field experiments, number of seedling emergence significantly decreased as seed burial depth increased, conversely, proportion of seedling emergence increased as seed burial density decreased. This study has important implications for determining strategies for weedy rice management by exhausting its seed bank through the alteration of tillage practices. 展开更多
关键词 SEED BURIAL depth SEED BURIAL DENSITY germination WINTERING survival SEED vertical distribution
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人工老化处理对菠菜种子生理生化指标及萌发相关基因表达量的影响
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作者 鲜萱 齐传东 +5 位作者 陈琦 覃思嘉 郑禾 辛燕 陶增蛟 郭仰东 《中国农业大学学报》 CAS CSCD 北大核心 2019年第3期45-53,共9页
为探究菠菜种子老化后活力下降的原因和生理生化指标及基因表达量的变化规律,采用高温高湿人工加速老化的方法处理菠菜种子,并测定菠菜种子人工老化过程中的一系列生理生化指标及萌发相关基因表达量的变化。结果表明:随着老化时间的延长... 为探究菠菜种子老化后活力下降的原因和生理生化指标及基因表达量的变化规律,采用高温高湿人工加速老化的方法处理菠菜种子,并测定菠菜种子人工老化过程中的一系列生理生化指标及萌发相关基因表达量的变化。结果表明:随着老化时间的延长,菠菜种子的根长、发芽势和发芽率,超氧化物歧化酶、过氧化物酶、过氧化氢酶、抗坏血酸过氧化物酶活性以及萌发相关基因(GAI1、GA2ox、RACK1、DGAT、ARP1、ARF、ABA8ox1和VP1)的表达量对比未经老化处理的均逐渐下降;可溶性糖和丙二醛的含量逐渐增加。由于抗氧化酶活性的降低,体内的氧自由基得不到及时的清除,从而导致膜质过氧化作用加剧最后引起生物膜的损伤,这是影响种子萌发和加速种子老化的重要原因之一。 展开更多
关键词 菠菜 种子 人工老化 生理生化指标 基因表达量 种子活力
掌叶木种子及其籽油性状综合评价模型构建和优选 预览
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作者 郭松 李在留 薛建辉 《农业工程学报》 EI CAS CSCD 北大核心 2019年第6期314-322,共9页
为提高木本粮油植物掌叶木不同种源种子及籽油性状的综合评价结果准确性和评价方法的优选,指导掌叶木优良种源筛选和良种选育,该文构建了一套综合评价模型,对广西乐业、田林、凤山和环江以及贵州独山5个种源掌叶木种子及籽油相关的14项... 为提高木本粮油植物掌叶木不同种源种子及籽油性状的综合评价结果准确性和评价方法的优选,指导掌叶木优良种源筛选和良种选育,该文构建了一套综合评价模型,对广西乐业、田林、凤山和环江以及贵州独山5个种源掌叶木种子及籽油相关的14项指标采用主成分分析法、因子分析法、离差最大法、熵值法4种单一方法进行评价排序,并对4种方法的评价结果采用均值、Borda、Copeland共3种组合方法进行评价排序,均通过肯德尔和谐系数一致性检验后确定最终评价排序;采用斯皮尔曼等级相关系数对最终评价排序与4种单一方法评价排序进行相关性分析,并筛选最好单一评价方法。结果表明:4种单一评价方法下种源排序虽存在一定差异但通过了肯德尔和谐系数一致性检验;3种组合评价排序均相同,各种源最终评价排序从高到低依次为凤山、乐业、独山、环江、田林。最终评价排序与主成分分析法、因子分析法、离差最大法和熵值法等4种单一方法评价排序的斯皮尔曼等级相关数值分别为1.00、0.90、1.00、0.90,相关性均达到显著水平(P<0.05);主成分分析法和熵值法所得种子千粒质量的权重值均列各指标首位。因此,基于4种单一评价方法和3种组合评价方法的综合评模型为多种源掌叶木种子及籽油性状提供更为科学合理的排序结果;从易用、简便和有效性角度,掌叶木种子及籽油性状的最优单一评价方法为熵值法,评价中最重要的指标为种子千粒质量,凤山种源掌叶木种子及籽油性状最优。研究结果可为掌叶木种质资源高效利用提供理论依据,也可为种子及油脂领域综合评价研究提供新思路。 展开更多
关键词 种子 油脂 掌叶木 籽油 综合评价模型 肯德尔和谐系数
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辣椒种子湘研1586在东帝汶的杂交制种技术 预览 被引量:1
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作者 蒋敏明 方远祥 曹拥军 《蔬菜》 2019年第2期76-79,共4页
为解决制种成本高的问题,在东帝汶进行了辣椒制种研究。2015—2017年对湘研1586在东帝汶进行了杂交制种,整个生产周期约5个月,平均产量达510 kg/hm2(2017年),表明湘研1586较为适合在东帝汶进行制种。从育苗、整地定植、田间管理、采花... 为解决制种成本高的问题,在东帝汶进行了辣椒制种研究。2015—2017年对湘研1586在东帝汶进行了杂交制种,整个生产周期约5个月,平均产量达510 kg/hm2(2017年),表明湘研1586较为适合在东帝汶进行制种。从育苗、整地定植、田间管理、采花授粉、脱粒晾晒及病虫害防治方面总结了湘研1586在东帝汶的制种技术。 展开更多
关键词 辣椒 种子 制种技术 杂交
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野生云南肉豆蔻种子形态变异与脂肪酸组成分析 预览
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作者 张凤良 李小琴 +4 位作者 毛常丽 杨湉 赵祺 张辉 吴裕 《中国油脂》 CAS CSCD 北大核心 2019年第2期76-80,共5页
以云南省景洪市基诺乡天然林中的云南肉豆蔻种子为材料,进行种子表型性状、含油率和脂肪酸组成分析。结果表明:这一居群内22株树的种长为34. 73~45. 89 mm,种宽为20. 36~26. 54mm,单粒重为7. 67~16. 86 g,种仁含油率为6. 37%~15. 83%;通... 以云南省景洪市基诺乡天然林中的云南肉豆蔻种子为材料,进行种子表型性状、含油率和脂肪酸组成分析。结果表明:这一居群内22株树的种长为34. 73~45. 89 mm,种宽为20. 36~26. 54mm,单粒重为7. 67~16. 86 g,种仁含油率为6. 37%~15. 83%;通过GC及GC-MS分析,种仁油中共检测到14种常见脂肪酸,即十二烷酸(C12∶0)、十三烷酸(C13∶0)、十四烷酸(C14∶0)、十五烷酸(C15∶0)、十六碳烯酸(C16∶1)、十六烷酸(C16∶0)、十七烷酸(C17∶0)、十八碳二烯酸(C18∶2)、十八碳烯酸(C18∶1)、十八烷酸(C18∶0)、二十碳烯酸(C20∶1)、二十烷酸(C20∶0)、二十二烷酸(C22∶0)、二十四烷酸(C24∶0),其中十八碳烯酸发现位置异构现象,即C18∶1(9)和C18∶1(11)。十四烷酸相对含量为53. 58%~62. 52%,均值为58. 73%,是含量最高的脂肪酸。 展开更多
关键词 云南肉豆蔻 种子 种仁 含油率 脂肪酸组成
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Effects of Different Storage Conditions on Physiological and Biochemical Characteristics of Polygala tenuifolia Willd. Seeds 预览
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作者 Zhaoying ZHANG Yanan ZHANG +3 位作者 Lili SONG Jun WANG Shuying QIN Wenquan WANG 《药用植物研究(英文版)》 2019年第2期69-72,共4页
[Objectives] Taking Polygala tenuifolia Willd. seeds as experimental material, the changes of physiological and biochemical characteristics of seeds under different storage temperatures and seed moisture contents were... [Objectives] Taking Polygala tenuifolia Willd. seeds as experimental material, the changes of physiological and biochemical characteristics of seeds under different storage temperatures and seed moisture contents were studied.[Methods] The seeds of P. tenuifolia Willd. with moisture contents of 3%, 5% and 15% were stored at-10 ℃, 0 ℃, 20 ℃ and 36 ℃, respectively, and the storage time was one year. The physiological and biochemical characteristics of the seeds, such as conductivity, SOD activity, POD activity, and soluble sugar content were studied.[Results] After one-year storage, as the storage temperature and seed moisture content increased, the relative conductivity, MDA content and soluble sugar content of P. tenuifolia Willd. seeds increased, while the SOD activity, POD activity, and protein content declined. This phenomenon was most obvious in the P. tenuifolia Willd. seeds with moisture content of 15%.[Conclusions] This study will provide reference for seed storage of medicinal plants. 展开更多
关键词 STORAGE temperature SEED MOISTURE content POLYGALA tenuifolia Willd. SEED VIGOR
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Evaluating germinability of eight desert halophytes under long-term seed storage:Implications for conservation
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作者 Sanjay Gairola Hatem A. Shabana +2 位作者 Tamer Mahmoud Ali El-Keblawy Andrea Santo 《植物多样性:英文版》 CAS CSCD 2019年第4期229-236,共8页
Ex situ conservation in seed banks is a potential complementary conservation strategy for native plant species.It is well established that ex situ seed banking of native wild plants prolongs seed viability and thereby... Ex situ conservation in seed banks is a potential complementary conservation strategy for native plant species.It is well established that ex situ seed banking of native wild plants prolongs seed viability and thereby preserves genetic and species diversity for future use.We evaluated ex situ storage potential of eight halophytic species from deserts in the United Arab Emirates(UAE)by studying seed germination.Specifically,we examined the germinability of freshly collected seeds and seeds stored for three years in a seed bank.We also examined the effect of light conditions on fresh and stored seed germination.Fresh seeds of seven of the eight species tested had a higher germination rates under 12/12 h light/dark fluctuations than did those exposed to total darkness.Storage reduced light sensitivity in Halocnemum strobilaceum,Suaeda aegyptiaca,Salsola drummondii and Salsola imbricata,but increased the requirement for light in Arthrocnemum macrostachyum.In Anabasis setifera,storage decreased germination percentage when there was a 12-hour light/dark fluctuation,but increased germination rate when exposed to the dark treatment.Storage significantly reduced germination in both the light/dark and dark treatments in Suaeda vermiculata and S.aegyptiaca.Germination speed also responded differently to storage;whereas Timson's index significantly increased in A.macrostachyum and H.strobilaceum,it significantly decreased for S.drummondii,S.aegyptiaca and S.vermiculata.Germination of these species at a range of temperatures requires further testing;additionally,we strongly suggest that these laboratory findings be complemented by field studies. 展开更多
关键词 Ex situ CONSERVATION HALOPHYTES SEED bank collection SEED GERMINATION Salt tolerance SSBH
Elevation-related variation in the population characteristics of distylous Primula nivalis affects female fitness and inbreeding depression
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作者 Aysajan Abdusalam Qing Jun Li 《植物多样性:英文版》 CAS CSCD 2019年第4期250-257,共8页
The population characteristics of distylous species are highly sensitive to stochastic natural selection pressure.Therefore,populations growing under different environmental conditions may vary in floral morph ratios,... The population characteristics of distylous species are highly sensitive to stochastic natural selection pressure.Therefore,populations growing under different environmental conditions may vary in floral morph ratios,potentially affecting female fitness and leading to inbreeding depression.However,the variation in offspring quality among populations as a result of inbreeding depression is poorly understood in distylous species.This study investigates variations in plant density,seed mass,seed viabilityfemale fitness,and post-dispersal inbreeding depression in both sexual morphs(long-styled and shortstyled plants)of the distylous Primula nivalis that were subjected to different pollination treatments along an elevational gradient from 1657 to 2704 m a.s.l.Population characteristics(morph plant density and ratio)and fruit set were significantly affected by sexual morph and elevation.Plant density and fruitset frequencies were lower for short-styled than for long-styled plants at 2704 m a.s.l.The seeds from the cross-pollinated flowers of both morphs were higher in quality than those of self-pollinated flowers.The female fitness of seeds from cross-pollinated flowers of both morphs was higher than that of seeds from open-pollinated and self-pollinated flowers.The female fitness of seeds from long-styled flowers was higher than that of seeds from short-styled flowers at all elevations.Inbreeding depression increased with elevation among plants with short-styled flowers but not among those with long-styled flowers.Variation in the elevation-dependent mating system might influence female fitness and affect inbreeding depression in both floral morphs.In conclusion,the low quality of seeds from short-styled flowers at high elevations might decrease short-styled flower frequency,affecting population characteristics. 展开更多
关键词 INBREEDING depression POLLINATION treatment SEED mass SEED quality
地震交换标准数据的压缩技术和数据解压 预览
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作者 杨周胜 杨晶琼 姚远 《地震研究》 CSCD 北大核心 2019年第1期144-149,I0002共7页
研究地震数据存储及交换的SEED和miniSEED格式标准,对存储格式中的Steim1和Steim2的压缩方法和编码方式进行了深入分析,对比了国内外SEED格式的差异,利用MATLAB软件实现了SEED和miniSEED格式压缩数据的解压和应用。
关键词 SEED miniSEED Steim1 Steim2 数据压缩 编码方式 数据解压
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马齿形玉米种子尖端激光定向与胚面识别装置研制 预览
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作者 邢洁洁 徐丽明 +4 位作者 马帅 袁全春 陈晨 曾鉴 牛丛 《农业工程学报》 EI CAS CSCD 北大核心 2019年第3期52-59,共8页
为了实现玉米种子的尖端定向与胚面识别,该文以现有尖端定向装置输出的马齿型玉米种子为对象,基于激光开关和测距原理,提出了一种尖端定向与胚面识别方法:依据马齿形玉米种子尖端窄大头宽的轮廓特征,利用激光开关传感器等部件对玉米种... 为了实现玉米种子的尖端定向与胚面识别,该文以现有尖端定向装置输出的马齿型玉米种子为对象,基于激光开关和测距原理,提出了一种尖端定向与胚面识别方法:依据马齿形玉米种子尖端窄大头宽的轮廓特征,利用激光开关传感器等部件对玉米种子的尖端朝向进行识别,并将大头朝前的玉米种子进行剔除;依据马齿形玉米种子胚面上有胚沟而反面较为平整的表面特征,利用激光测距传感器等部件对尖端朝前的玉米种子进行胚面识别。设计并搭建了玉米种子尖端定向与胚面识别装置,配合现有的尖端定向装置进行试验,结果表明:尖端定向与胚面识别装置的尖端定向成功率达到99.1%,相比现有的尖端定向装置提升了9.5个百分点,胚面识别准确率为96.4%。该方法基本可以实现玉米种子的尖端定向,同时保证胚面识别准确率达到较高水准。该文提出的玉米种子尖端定向与胚面识别方法可为后续玉米种子的自动化定向包装提供参考。 展开更多
关键词 机械化 种子 设计 玉米种子尖端定向 胚面识别 激光传感器
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Capturing, protecting and restoring plant diversity in the UK: RBG Kew and the Millennium Seed Bank
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作者 Ted Chapman Stephanie Miles Clare Trivedi 《植物多样性:英文版》 CAS CSCD 2019年第2期124-131,共8页
Ex situ seed banking is a practical and cost-effective means of preserving wild plant diversity and a crucial complement to the in situ conservation and restoration of species and habitats. As pressures on the natural... Ex situ seed banking is a practical and cost-effective means of preserving wild plant diversity and a crucial complement to the in situ conservation and restoration of species and habitats. As pressures on the natural environment have grown, so has the call for seed banks to provide scientifically-robust,practical solutions to seed-related problems in nature conservation, from single-species recovery and reintroduction to the restoration of complex, dynamic communities at the largest scales. In this paper, we discuss how the Royal Botanic Gardens, Kew and its Millennium Seed Bank have responded to this call in the United Kingdom. We demonstrate that banked seed collections can provide a range of otherwiseunavailable, high quality, known-origin, genetically-diverse biological materials. The data, expertise and specialist facilities that accompany these collections are also valuable, helping overcome constraints to the collection, production and effective use of native seed. Challenges remain-to ensure ex situ collections protect the species and genetic diversity that will enable plants to adapt to a changing environment, and to find new ways for seed banks to mobilise their resources at a landscape scale. 展开更多
关键词 SEED BANKING Ex situ conservation Botanic garden Species-reintroduction Ecological restoration Native SEED production
Central role of the LEAFY COTYLEDON1 transcription factor in seed development^FA
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作者 Leonardo Jo Julie M.Pelletier John J.Harada 《植物学报:英文版》 SCIE CAS CSCD 2019年第5期564-580,共17页
Seed development is a complex period of the flowering plant life cycle.After fertilization,the three main regions of the seed,embryo,endosperm and seed coat,undergo a series of developmental processes that result in t... Seed development is a complex period of the flowering plant life cycle.After fertilization,the three main regions of the seed,embryo,endosperm and seed coat,undergo a series of developmental processes that result in the production of a mature seed that is developmentally arrested,desiccated,and metabolically quiescent.These processes are highly coordinated,both temporally and spatially,to ensure the proper growth and development of the seed.The transcription factor,LEAFY COTYLEDON1(LEC1),is a central regulator that controls several aspects of embryo and endosperm development,including embryo morphogenesis,photosynthesis,and storage reserve accumulation.Thus,LEC1 regulates distinct sets of genes at different stages of seed development.Despite its critical importance for seed development,an understanding of the mechanisms underlying LECi's multifunctionality is only beginning to be obtained.Recent studies describe the roles of specific transcription factors and the hormones,gibberellic acid and abscisic acid,in controlling the activity and transcriptional specificity of LEC1 across seed development.Moreover,studies indicate that LEC1 acts as a pioneer transcript!on factor to promote epigenetic reprogramming during embryogenesis.In this review,we discuss the mechanisms that enable LEC1 to serve as a central regulator of seed development. 展开更多
关键词 SEED DEVELOPMENT FLOWERING plant SEED DEVELOPMENT
种子化学成分与种子活力相关性研究进展 预览
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作者 赵燕昊 张倩霞 谢炜 《现代农业科技》 2019年第15期1-3,共3页
种子活力是评定种子质量的重要指标。本文针对种子内部不同化学成分及含量与种子活力的相关性研究进行了综述,分析了高活力种子所具备的典型种子化学特性,以期为选育鉴定活力高的优质新品种以及提高种子贮藏时间和品质提供参考。
关键词 种子 化学成分 种子活力 相关性 研究进展
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Small size does not restrain frugivory and seed dispersal across the evolutionary radiation of Galapagos lava lizards
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作者 Sandra HERVIAS-PAREJO Ruben HELENO +7 位作者 Beatriz RUMEU Beatriz GUZMAN Pablo VARGAS Jens M. OLESEN Anna TRAVESET Carlos VERA Edgar BENAVIDES Manuel NOGALES 《动物学报:英文版》 SCIE CAS CSCD 2019年第4期353-361,共9页
Frugivory in lizards is often assumed to be constrained by body size;only large individuals are considered capable of consuming fruits, with the potential of acting as seed dispersers. However, only one previous study... Frugivory in lizards is often assumed to be constrained by body size;only large individuals are considered capable of consuming fruits, with the potential of acting as seed dispersers. However, only one previous study has tested the correlation of frugivory with body and head size at an archipelago scale across closely related species. All nine lava lizards (Microlophus spp.) were studied on the eleven largest Galapagos islands from 2010 to 2016 to investigate whether frugivory is related to body and head size. We also tested whether fruit abunda nee in flue nces fruit con sumption and explored the effect of seed ingestion on seedling emergence time and percentage. Our results showed that across islands, lava lizards varied considerably in size (64-102 mm in mean snoutvent length) and level of frugivory (1-23%, i.e., percentage of droppings with seeds). However, level of frugivory was only weakly affected by size as fruit consumption was also common among small lizards. Lava lizards consumed fruits throughout the year and factors other than fruit abundance may be more importa nt drivers of fruit selecti on (e.g., fruit size, energy con tent of pulp). From 2,530 droppings, 1,714 seeds of at least 61 plant species were identified, 76% of the species being native to the Galapagos. Most seeds (91%) showed no external structural damage. Seedling emergence time (44 versus 118 days) and percentage (20% versus 12%) were enhanced for lizardingested seeds compared to control (uningested) fruits. De-pulping by lizards (i.e., removal of pulp with potential germi nation inhibitors) might in crease the chances that at least some seeds find suitable recruitment conditi ons. We con eluded that lizards are importa nt seed dispersers throughout the year and across the whole archipelago, regardless of body size. 展开更多
关键词 Microlophus oceanic islands plant-animal interactions SEED DISPERSER size SEED dispersal effectiveness seedling emergence
芥菜型油菜硫代葡萄糖苷基因的研究进展 预览
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作者 燕孟娇 宋培玲 +7 位作者 皇甫海燕 郝丽芬 郭晨 皇甫九茹 贾晓清 吴晶 史志丹 李子钦 《北方农业学报》 2019年第1期33-41,共9页
硫代葡萄糖苷(简称硫苷)是芥菜型油菜的一类重要次级代谢产物,在植物防御、风味、抗癌等方面有重要作用。但过量的硫苷及其衍生物产生的有毒成分会限制油菜的合理利用。近年来随着对模式植物拟南芥中硫苷合成途径的深入研究,以及芥菜型... 硫代葡萄糖苷(简称硫苷)是芥菜型油菜的一类重要次级代谢产物,在植物防御、风味、抗癌等方面有重要作用。但过量的硫苷及其衍生物产生的有毒成分会限制油菜的合理利用。近年来随着对模式植物拟南芥中硫苷合成途径的深入研究,以及芥菜型油菜基因组测序的完成,通过突变硫苷合成途径的MYB、CYP79、CYP83、GTR等相关基因家族来降低硫苷含量已成为研究热点。该文章就硫苷的生物学功能、拟南芥中合成与调节相关基因,以及芥菜型油菜已有的降低硫苷含量的研究进行综述。 展开更多
关键词 芥菜型油菜 拟南芥 硫代葡萄糖苷 种子 基因
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Effects of mepiquat chloride on yield and main properties of cotton seed under different plant densities 预览
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作者 ZHAO Wenqing YAN Qiang +5 位作者 YANG Hongkun YANG Xiaoni WANG Leran CHEN Binglin MENG Yali ZHOU Zhiguo 《棉花研究(英文)》 2019年第2期77-86,共10页
Background:Cottonseed oil and protein content as well as germination traits are major indicators of seed quality.However,the responses of these indicators to plant density and mepiquat chloride(MC)are still uncertain.... Background:Cottonseed oil and protein content as well as germination traits are major indicators of seed quality.However,the responses of these indicators to plant density and mepiquat chloride(MC)are still uncertain.To investigate plant density and MC effects on cotto nseed yield and main quality parameters,we con ducted a twoyear field experiment including four plant densities(1.35,2.55,3.75 and 4.95 plants·m^-2)and two closes of MC(0 and 135g·hm^-2)in Dafeng,Jiangsu Province,in 2013 and 2014.Results:The application of MC reduced plant height,fruit branch length and fruiting branch number under different plant densities,resulting in a lower and more compact plant canopy.Cottonseed yield showed a nonlinear increase as plant density increasing and achieved the highest value at 3.75 plants·m^-2,regardless of MC application.No significant interactio ns were found between plant density and MC for cotton seed yield and quality parameters.The 100-seed weight,cottonseed oil content and vigor index significantly decreased as plant density increased,while these parameters significantly increased with MC applying under different plant densities.Seed vigor index was positively correlated with 100-seed weight and seed oil con tent across different plant densities and MC treatments.Conclusions:Thus,application of MC could realize a win-win situation between cottonseed yield and main quality parameters under various densities;and plant density of 3.75 plants·m^-2 combined with 135 g·hm^-2 of MC applying is optimal for high cottonseed yield and quality in this cotton production area. 展开更多
关键词 Mepiquat chloride Plant density Cottonseed yield Oil content Seed germination
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Cumulative activation in social networks
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作者 Xiaohan SHAN Wei CHEN +2 位作者 Qiang LI Xiaoming SUN Jialin ZHANG 《中国科学:信息科学(英文版)》 SCIE EI CSCD 2019年第5期108-128,共21页
Most studies on influence maximization focus on one-shot propagation, i.e., the influence is propagated from seed users only once following a probabilistic diffusion model and users’ activation are determined via sin... Most studies on influence maximization focus on one-shot propagation, i.e., the influence is propagated from seed users only once following a probabilistic diffusion model and users’ activation are determined via single cascade. In reality it is often the case that a user needs to be cumulatively impacted by receiving enough pieces of information propagated to her before she makes the final purchase decision. In this paper we model such cumulative activation as the following process: first multiple pieces of information are propagated independently in the social network following the classical independent cascade model, then the user will be activated(and adopt the product) if the cumulative pieces of information she received reaches her cumulative activation threshold. Two optimization problems are investigated under this framework: seed minimization with cumulative activation(SM-CA), which asks how to select a seed set with minimum size such that the number of cumulatively active nodes reaches a given requirement η;influence maximization with cumulative activation(IM-CA), which asks how to choose a seed set with fixed budget to maximize the number of cumulatively active nodes. For SM-CA problem, we design a greedy algorithm that yields a bicriteria O(ln n)-approximation when η = n, where n is the number of nodes in the network. For both SM-CA problem with η < n and IM-CA problem, we prove strong inapproximability results. Despite the hardness results, we propose two efficient heuristic algorithms for SM-CA and IM-CA respectively based on the reverse reachable set approach. Experimental results on different real-world social networks show that our algorithms significantly outperform baseline algorithms. 展开更多
关键词 social networks CUMULATIVE ACTIVATION influence MAXIMIZATION SEED MINIMIZATION
同一种源锥连栎的种子形态特征及变异 预览
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作者 常恩福 肖桂英 +5 位作者 李品荣 李娅 张清 丁玉雄 黄春良 景跃波 《西部林业科学》 CAS 北大核心 2019年第2期159-164,共6页
以建水县5个锥连栎种群的34个家系为研究材料,通过种长、种宽、种形指数、单粒重及千粒重5个性状指标的测定,分析锥连栎不同家系间及种群间种子形态特征及变异。结果表明,锥连栎种子的5个性状指标在家系内、家系间及种群间均存在着显著... 以建水县5个锥连栎种群的34个家系为研究材料,通过种长、种宽、种形指数、单粒重及千粒重5个性状指标的测定,分析锥连栎不同家系间及种群间种子形态特征及变异。结果表明,锥连栎种子的5个性状指标在家系内、家系间及种群间均存在着显著差异(P<0.05)或极显著差异(P<0.01)。不同家系及种群间种子性状的变异均以单粒重及千粒重最大,种长、种宽及种形指数3个性状更趋于稳定,种群间变异小于家系间的变异。其种子的形状主要受遗传控制,受环境影响较小,种子大小及质量则受分布区海拔的影响而存在一定的垂直变异。基于聚类分析结果,可优先选择格安、双剑峰、红田、燕子洞4个种群的4号、8号、9号、10号、15号、19号、20号、21号和34号共9个种子质量优良的家系作为锥连栎的采种母树。就种群而言,则是红田种群和双剑峰种群作为采种林分。 展开更多
关键词 喀斯特 锥连栎 种子 形态 变异
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林芝地区光核桃种子表型性状变异的影响因素分析 预览
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作者 刘会芳 鹿鑫 +3 位作者 关法春 吴玉德 宗宪春 桑利群 《西南民族大学学报:自然科学版》 CAS 2019年第4期343-348,共6页
旨在通过光核桃种子表型性状变异特点来揭示影响表型性状遗传变异的因素,更好地开发及利用光核桃资源.对林芝地区50处的光核桃种子样本的横径、厚度、纵径、果形指数及单粒重几项形态学指标进行研究.结果表明:各表型性状P值均小于0.01,... 旨在通过光核桃种子表型性状变异特点来揭示影响表型性状遗传变异的因素,更好地开发及利用光核桃资源.对林芝地区50处的光核桃种子样本的横径、厚度、纵径、果形指数及单粒重几项形态学指标进行研究.结果表明:各表型性状P值均小于0.01,说明光核桃种子的表型性状产生了显著的遗传分化,其中,单粒重的变异系数最高(28. 71%),厚度的变异系数最低(10.43%);聚类分析后可将不同样本种质资源整体分为3个类群,但不同样本的形态分类与地理来源无一致关系,而海拔高度与光核桃种子的各表型性状高度相关,同时果形指数及单粒重与果肉可溶性固形物高度相关.因此,西藏林芝地区光核桃在表型性状上存在由海拔梯度引起的变异,而非地理区隔因素. 展开更多
关键词 光核桃 种子 表型性状
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意大利甜菜种子繁育与加工技术
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作者 周艳丽 卢秉福 《中国甜菜糖业》 2019年第2期14-18,共5页
意大利是欧洲最重要的甜菜种子繁育基地,已经形成了成熟的甜菜制种技术和种子评价体系,分子标记技术SNP应用于甜菜育种与种子检测。种子加工工艺整个生产过程均由电脑控制、自动化生产,甜菜种子丸粒化后外形尺寸均匀一致,种子加工的最... 意大利是欧洲最重要的甜菜种子繁育基地,已经形成了成熟的甜菜制种技术和种子评价体系,分子标记技术SNP应用于甜菜育种与种子检测。种子加工工艺整个生产过程均由电脑控制、自动化生产,甜菜种子丸粒化后外形尺寸均匀一致,种子加工的最后工序都要经过药剂处理,包装以单位计量,每单位10万粒。甜菜种子质量是决定甜菜产质量的重要因素,借鉴意大利先进甜菜种子生产技术,改进我国甜菜种子繁育、加工、检测技术流程,建立甜菜种子繁育与加工技术体系,提高甜菜种子质量。 展开更多
关键词 甜菜 种子 繁育 加工 意大利
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