淹水条件对水稻芽撒播成苗的影响

对水稻芽撒播在不同灌溉方式下的成苗情况进行了研究。结果表明,无水层带泥浆撒播处理,根系发育与茎叶生长比较协调,成苗率达90.7%,秧苗综合性状好于其它处理,是水稻芽抛秧的首选方式;淹水48h后落干处理,有利于发根和扎根立苗,成苗率达92.7%,秧苗综合性状较好,是水稻芽抛秧应采用的第二种方式。     

水稻根系泌氧对水稻土磷素化学行为的影响

通过模拟试验研究了水稻根系泌氧作用对水稻土磷素化学行为以及水稻吸磷的影响。淹水极显著地增加土壤对磷的吸附,降低磷的解吸。而模拟的水稻泌氧作用则可明显降低土壤对磷的吸附,增加根际土壤的磷解吸和离子交换树脂对磷的吸收量。因此,水稻根系的泌氧作用应该是水稻在淹水明显降低土壤磷有效性情况下能正常从土壤获取磷的重要机制之一。淹水导致土壤磷有效性降低与淹水引起土壤磷组分转化有关。淹水2周,经富磷预处理而增加的Al-P组分,几乎全被转化为Fe-P。     

The impact of a hydroelectric dam on Neotropical fish communities: A spatio-temporal analysis of the Trophic Upsurge Hypothesis

We employed the trophic upsurge hypothesis as an analytical framework to describe the response of Neotropical fish communities to terrestrial inundation associated with river damming. Data were collected for the impact assessment of the Peixe Angical Dam, Tocantins River, Brazil. Monthly surveys were conducted at nine sites (seven upstream, two downstream) from 15 months before to 20 months after dam closure and a follow-up survey 60–83 months after closure. Fish responses differed in timing and magnitude across sites. In the new reservoir, populations peaked 8–13 months after flooding, demonstrating increases in richness (84 ± 52%), biomass (329 ± 266%) and abundance (681 ± 348%) with the maxima for richness and abundance tending to precede biomass maxima. Populations of all families increased but were greatest for Engraulidae, Hemiodontidae, Serrasalmidae and Characidae, and lower for the benthic catfish: Sciaenidae, Dorididae, Pimelodidae. Downstream populations peaked 5–12 months after closure or showed consistent decline. Five years after dam-closure richness and abundance were lower compared to predam levels, with populations at all sites demonstrating an ongoing decline. Reservoir creation triggers reproductive recruitment and otherwise pools spatially disparate populations from across the flooded valley. If the rise in richness is largely explained by the increased catchability of species otherwise present prior to flooding, it may be more appropriate to estimate species loss with reference to upsurge data. As peak biomass coincides with declining richness, modelling fisheries production from annually aggregated data may risk overestimating the potential for sustainable harvests. Upsurge–response curves can help identify the timing of critical ecological thresholds for flood-managed fisheries.     

Waterlogging differentially affects yield and its components in wheat,barley, rapeseed and field pea depending on the timing of occurrence

Waterlogging on croplands is increasing in various areas of the world. This study evaluated the yield penalty by early and late waterlogging on wheat (Triticum aestivum L.), barley (Hordeum vulgare L.), rapeseed (Brassica napus L.) and field pea (Pisum sativum L.). Plants cultivated outdoors were exposed to a 14-day waterlogging during vegetative (at 65 days after sowing (DAS)) or reproductive (at 85/87 DAS) stages, followed by drained conditions until maturity. Yield (seed weight per plant) and its components (number of spikes/siliques/pods per plant, number of grains per spike/silique/pod and 1,000 grain weight) were assessed at maturity, along with morphological (number of tillers/branches) and shoot and root dry weight responses after waterlogging and during recovery. Wheat was the most tolerant species achieving 86% and 71% of controls in yield with early and late waterlogging, related to fewer grains per spike. Barley and rapeseed tolerated early waterlogging (yields 85% and 79% of controls) as compared to late waterlogging (32% and 26% of controls), mainly due to fewer spikes per plant (barley) or reductions in seeds per silique (rapeseed). Field pea was greatly affected by waterlogging at both timings, attaining a yield of only 6% of controls on average due to much fewer pods and fewer seeds per pod. So, wheat could be an option for areas facing either winter or spring transient waterlogging (i.e. early or late stages); barley and rapeseed are recommended only with if water excess occurs in early stages and field pea is intolerant to waterlogging.     

A method for observing and manipulating roots and root associated fungi on plants growing in nonsterile substrates

Standard 14‐cm plastic‐petri dishes were used as root substrate chambers allowing controlled inoculation, regular inspection under the dissecting microscope, and manipulation of root infections with pathogens and mycorrhizal fungi under nonsterile conditions. Roots of young pine seedlings were placed on the root substrate and, especially those growing on the substrate surface under the lid, were very easy to manipulate. Mycorrhizal species and inoculation methods were compared and the infection process followed continuously under various conditions. The air pockets formed between the lid and the substrate favoured mycorrhiza formation. Brief, periodic flooding prevented formation of mycorrhizas in two mycorrhizal species having hydrophobic hyphae but did not prevent it in less hydrophobic species. IAA treatment of roots led to heavy production of mycorrhizas. Fruiting body formation in Lacearia laccata was induced and followed in the dish cultures. Pure mycorrhizal stock cultures were able to be revitalized in the dish cultures and reisolated in pure culture. The infection strategy of a weak root pathogen, Cylindrocarpon destructans, was studied with the same technique, which was also used for investigating treatments predisposing seedlings to pathogen infection.     

水稻“少灌多蓄”节水灌溉新技术研究与推广

厦门同安地区群众习惯采用淹灌法灌溉水稻,耗水量大,有效利用雨量少。同安灌溉试验站从１９９４～１９９６连续３年研究“少灌多蓄”节水灌溉新技术,即充分利用自然降雨使田间水层保持为０～３０ｍｍ,一般水层至０时再隔一天灌水至上限（３０ｍｍ）,降水时使水层上限保持在７０ｍｍ。这样在产量不减少情况下减少了灌水量与灌溉次数达三分之一,省水省工,此法已在当地推广近４６７ｈｍ２,平均增产３１８ｋｇ／ｈｍ２,节水３０％。     

淹水缓解直播早籼稻苗期低温冷害的生理特性研究

[目的]探究淹水对低温胁迫下直播早籼稻幼苗生长的影响,为南方稻区直播稻生产与抗逆栽培奠定生理基础.[方法]以耐冷品种湘早籼6号和冷敏感品种中嘉早17为材料,设置低温处理(8℃)、低温淹水处理(8℃+淹水)与常温对照(25℃)3个处理(处理3 d),分析秧苗农艺性状、抗氧化酶活性、渗透调节物质含量、光合酶活性和内源激素含...     

水肥交互作用对稻田氮素利用率和氮素平衡的影响

采用蒸渗仪方法和同位素示踪技术研究了稻田常规灌溉和节水灌溉条件下不同施肥水平和施肥方式的氮素利用率和氮素平衡,结果表明:稻谷氮素累积量占植株氮素累积量一半左右,间歇灌溉模式和传统淹灌模式氮素累积量的差异反应在茎和绿叶和实粒,而在黄叶和秕粒中差别不大;差值法测得氮肥利用率比同位素法偏高,但二者均表现为间歇灌溉氮肥利用率高于淹灌模式,且间歇灌溉模式下低氮水平氮肥利用率高于高氮处理;根据同位素示踪法计算氮素平衡,氮素在稻田系统中的分配为氨挥发和反硝化占37.4%~51.7%,土壤残留占20.4%~37.7%,作物吸收占9.2%~36.4%,淋失占0.3%~16.4%。     

盐度和水淹对海三棱藨草种子萌发及幼苗生长的影响

研究海三棱藨草(Scirpus mariqueter)种子和幼苗在盐度和水淹时长作用下的生存机制,为长江口滨海湿地生态修复提供重要的科学依据。通过模拟潮汐控制不同水淹时长(8、10、12、14 h/d)和盐度(0、5、10、15)进行实验,分析其对发芽率、发芽指数、叶绿素、超氧化物歧化酶(SOD)和丙二醛(MDA)等生长生理指标的影响。结果表明:盐度对海三棱藨草种子发芽率、发芽指数和海三棱藨草幼苗MDA影响最大;盐度和水淹时长的交互作用对海三棱藨草幼苗叶绿素和SOD影响最大。在盐度为0、水淹时长为12 h/d时发芽率最高;盐度15是海三棱藨草种子萌发的临界盐度;盐度为10、水淹时长12 h/d分株数最高;叶绿素在0盐度和12 h水淹时长交互处理下最高;SOD总活性在盐度为10、8 h/d水淹时长处理下最高;盐度为10、12 h/d水淹时长处理下MDA含量最低。这说明海三棱藨草在中等盐度(5、10)和中等水淹时长(10、12 h/d)时适应性最强。     

模拟三峡库区消落带水淹对3类土壤中桑树和水桦生长的影响

【目的】筛选出能适应长时间水淹的植物并明确其耐淹机理。【方法】以三峡库区2年生乡土树种桑树(Morus alba)和引进树种水桦(Betula nigra)为研究对象,结合库区水位运行规律和紫色土、水稻土、黄壤3种主要的土壤类型,通过盆栽模拟水淹试验,设置常规供水组和水淹组2个处理组,研究库区秋冬季长时间(时长90d)水淹对桑树与水桦生长特性和光合生理的影响。【结果】水淹胁迫显著影响了桑树和水桦的生长及生物量积累(P0.05),在90d水淹试验结束后,桑树与水桦茎基部均产生了一定数量的不定根,且在紫色土和水稻土上的存活率均达到100%,在黄壤上的存活率分别为85%和80%;其地上部与地下部生物量积累总体受到显著抑制,两树种的根冠比也显著降低(P0.05);桑树与水桦的总根长、根总表面积、根系活力等形态指标在水淹胁迫下均有不同程度下降,而根平均直径呈增大趋势。3种土壤上桑树和水桦的光合作用在水淹胁迫下发生显著变化,Pn显著降低,Gs、Ci、Tr较对照组均有不同程度下降,但Ls高于对照组。3种土壤上桑树和水桦的叶绿素a和叶绿素b含量显著下降,但叶绿素a/b值较对照组有一定程度增大,更接近于3∶1。水淹结束后,3种土壤上水淹组桑树和水桦的Fv/Fm与对照相比虽有一定程度下降,但仍保持在较高水平,其qP、ETR、ΦPSⅡ变化趋势与Fv/Fm相同,均呈现下降趋势,而其qN呈现升高趋势。【结论】在长达90d水淹的情况下,紫色土、水稻土、黄壤3种土壤上,桑树和水桦各生长指标及光合指标均保持在较高水平,表明桑树和水桦对长期水淹具有良好的适应性,可以作为三峡库区消落带植被恢复重建的适生树种。