壳聚糖浸种对干旱胁迫下苜蓿种子发芽的缓解作用     

常青山  张利霞  张巧明  王宁  张婵  吕凤娟  黄青哲  朱荣玮 《种子》2015,(3):39-43

以苜蓿种子为试材,采用不同浓度壳聚糖溶液对苜蓿进行浸种处理,测定其对干旱胁迫下苜蓿种子发芽和幼苗生长的影响,旨在寻找苜蓿发芽阶段抗干旱胁迫的最佳浸种浓度。结果表明:随着壳聚糖溶液处理浓度的升高,干旱胁迫下苜蓿种子发芽率、发芽势、发芽指数、活力指数、苗高与根长均呈现先上升后下降的趋势。隶属函数综合分析表明,壳聚糖溶液浸种对干旱胁迫下苜蓿种子发芽能力的影响效果由大到小依次为:100 mg/L、50 mg/L、25 mg/L、150 mg/L、0 mg/L、200 mg/L,以100 mg/L的壳聚糖浸种处理对提高苜蓿种子发芽阶段抗干旱胁迫的效果最佳。  相似文献   

Changes to a soil on irrigation with a sanitary landfill leachate     

K. Y. Chan 《Water, air, and soil pollution》1982,17(3):295-304

A detailed soil column leaching experiment was set up to investigate the changes in properties to a soil as a result of irrigation with an alkaline sanitary landfill leachate (pH 10.3). Chemistry of the soil was drastically altered as a consequence of the interaction. The soil was titrated from pH 5 to pH 10 and was changed from an exchangeable Mg dominated soil to an exchangeable Ca dominated soil. Magnesium was displaced by ion exchange reaction at acid pH, but at pH 10, 14.2 meq 100 g^?1 of Mg, i.e. up to three times the cation exchange capacity of Mg, was adsorbed in non-exchangeable forms at the immediate surface of the soil column by specific adsorption reactions. The leachate-treated soil was not stable on distilled water leaching. Structural breakdown led to clay dispersion and reduction in pore space, resulting in a 64 times reduction in hydraulic conductivity, 1.6 × 10^?4 to 2.5 × 10^?6 cm s^?1. The structural breakdown could be explained in term of the increase in Na adsorption ratio of the treated soil and the subsequent reduction in electrolyte concentration following the distilled water treatment.  相似文献   

An evaluation of the precision,and various sources of error,in daily and cumulative precipitation chemistry sampling     

A. J. S. Tang  W. H. Chan  D. B. Orr  W. S. Bardswick  M. A. Lusis 《Water, air, and soil pollution》1987,36(1-2):91-102

Experiments have been carried out to assess the precision and various potential sources of error in precipitation chemistry and deposition measurements made by the Acidic Precipitation in Ontario Study (APIOS). It was found that reproducibility of daily precipitation concentration measurements of S0₄ ^? and NO₃ ^? using colocated Aerochem Metrics samplers is 96% or better for 50% of the time, and 73% or better for 95 % of the time. For these parameters, MIC Type A 28-d samplers give reproducibilities of 94% or better 50% of the time, and 79% or better 95 % of the time. The reproducibility for the concentration of the other major ions, and loading (concentration times sample depth) is somewhat poorer. Concentration changes due to sample degradation or evaporative losses under field conditions are negligible or small on average, even for 28-d samples. For 28-d concentration measurements using MIC Type A collectors, errors due to evaporation amount to about 3% as an annual average, and 5% during the summer period. For S0₄ ^? and NO₃ ^?, overall long-term errors due to exposure under field conditions (including dry contamination and degradation due to chemical reactions), and sample handling, are less than 10%, at least for the techniques used in APIOS. A major potential source of error still to be quantified is unrepresentative sampling by automatic wet-only collectros (i.e., missing of initial portions of precipitation events due to sluggish sensor response, or less than 100% collection efficiencies of precipitation amounts).  相似文献   

不同土壤熏蒸剂对烤烟苗床杂草的药效试验     

黄磊  赵宏伟  万秀清  郭兆奎  李丽杰  乔婵 《中国林副特产》2011,(5):74-76

以烟草品种龙江911为供试材料,对适每地、维博亩和斯美地这3种不同土壤熏蒸剂防除烟草苗床杂草效果进行了试验。结果表明,适每地和斯美地这两种土壤熏蒸剂对苗床杂草均有较好的防除效果。综合防除效果及安全性等因素．以斯美地效果最理想,其次是适每地,均可在黑龙江省烟区推广使用。  相似文献   

Seasonal changes in surface aggregate stability under different tillage and crops     

K. Y. Chan  D. P. Heenan  R. Ashley 《Soil & Tillage Research》1994,28(3-4):301-314

Temporal changes in the surface aggregate stability of an Oxic Paleustalf under different tillage practices (direct drilled/stubble retained versus conventional cultivated/stubble burnt) and under different crops (wheat (Triticum aestivum L.) versus lupin (Lupinus angustifolius L.)) were monitored at a 10-year-old rotation site in Wagga Wagga, N.S.W., Australia.

Seasonal fluctuations in aggregate stability were observed under all treatments and were greater than the differences detected between the different tillage and cropping treatments. The seasonal variation was significantly related to the soil water content at the time of sampling and the lowest stability occurred during the autumn/winter period. Cropping under direct drilling and stubble retention resulted in significantly higher stability and lower seasonal fluctuations in stability than under conventional tillage and stubble burning. Despite the seasonal fluctuation, water stability over the season of both of the macroaggregate (more than 250 μm) and microaggregate (less than 50 μm) fractions increased significantly.

While the mean (temporal) stability of the different treatments was significantly related to the mean organic carbon content (r = 0.91) and polysaccharide content, the temporal changes were not related to the soil organic carbon content nor the living root length density.

Lupin had a more beneficial effect on promoting macroaggregate stability than wheat under the conventional tillage/stubble burnt treatment but no significant difference was found under the direct drilled/stubble retained treatment.  相似文献   

Enzyme-linked immunosorbent assay of ochratoxin A in barley   总被引：3，自引：0，他引：3  

M R Morgan  R McNerney  H W Chan 《Journal of the Association of Official Analytical Chemists》1983,66(6):1481-1484

A noncompetitive, double antibody enzyme-linked immunosorbent assay for ochratoxin A using microtitration plates has been developed and applied to samples of barley. The anti-ochratoxin A antiserum, which is used at high dilution, does not cross-react significantly with ochratoxin B or ochratoxin a. Assay sensitivity for determination of the toxin in barley samples is 60 ng/kg. Minimal sample preparation is required before assay.  相似文献   

空心菜对入星云湖河水的净化及其生物产出分析   总被引：2，自引：1，他引：2  

杨绍聪  吕艳玲  沐婵  张艳军  钱荣青  李晓亮  李泉清 《农业环境科学学报》2015,34(2):370-376

为充分开发利用入星云湖河水的N、P等营养资源,降低其富营养化水平,改善和保护星云湖生态系统,于2010—2013年采用微区试验与大区试验相结合、静态试验与动态试验相结合的方法,研究了漂浮空心菜(Ipomoea aquatica)对入星云湖河水净化及其生物产出的规律。结果表明:漂浮空心菜对入湖河水具有较好的水质净化效应,静态条件下空心菜对入湖河水全N、水溶性P的去除率高达90%以上,动态条件下则达50%左右,空心菜吸收入湖河水N、P、K的量分别平均为348.4、50.9、530.4 kg·hm-2·a-1,且其绝大部分被空心菜的茎叶吸收(占93.0%,为864.5 kg·hm-2·a-1)。空心菜对入湖河水的净化量,以水溶性N计平均为27 321 m3·hm-2·a-1,以水溶性P计平均为67 569 m3·hm-2·a-1;空心菜的生长主要依赖入湖河水中N、P等营养物质(两者呈正相关),通过茎叶大量吸收并同化入湖河水中的N、P等养分后,空心菜获得了较高的茎叶生物产出量(占90.9%,鲜重量平均为112 032.0 kg·hm-2·a-1)。利用入星云湖河水漂浮种植空心菜,产生了明显的生态效益和经济效益。  相似文献   

Small interfering RNA-induced transcriptional gene silencing in human cells   总被引：1，自引：0，他引：1  

Morris KV  Chan SW  Jacobsen SE  Looney DJ 《Science (New York, N.Y.)》2004,305(5688):1289-1292

  相似文献   

Mutations in a human ROBO gene disrupt hindbrain axon pathway crossing and morphogenesis     

Jen JC  Chan WM  Bosley TM  Wan J  Carr JR  Rüb U  Shattuck D  Salamon G  Kudo LC  Ou J  Lin DD  Salih MA  Kansu T  Al Dhalaan H  Al Zayed Z  MacDonald DB  Stigsby B  Plaitakis A  Dretakis EK  Gottlob I  Pieh C  Traboulsi EI  Wang Q  Wang L  Andrews C  Yamada K  Demer JL  Karim S  Alger JR  Geschwind DH  Deller T  Sicotte NL  Nelson SF  Baloh RW  Engle EC 《Science (New York, N.Y.)》2004,304(5676):1509-1513

The mechanisms controlling axon guidance are of fundamental importance in understanding brain development. Growing corticospinal and somatosensory axons cross the midline in the medulla to reach their targets and thus form the basis of contralateral motor control and sensory input. The motor and sensory projections appeared uncrossed in patients with horizontal gaze palsy with progressive scoliosis (HGPPS). In patients affected with HGPPS, we identified mutations in the ROBO3 gene, which shares homology with roundabout genes important in axon guidance in developing Drosophila, zebrafish, and mouse. Like its murine homolog Rig1/Robo3, but unlike other Robo proteins, ROBO3 is required for hindbrain axon midline crossing.  相似文献   

Rapid changes in throughput from single motor cortex neurons to muscle activity     

Davidson AG  Chan V  O'Dell R  Schieber MH 《Science (New York, N.Y.)》2007,318(5858):1934-1937

Motor cortex output is capable of considerable reorganization, which involves modulation of excitability within the cortex. Does such reorganization also involve changes beyond the cortex, at the level of throughput from single motor cortex neurons to muscle activity? We examined such throughput during a paradigm that provided incentive for enhancing functional connectivity from motor cortex neurons to muscles. Short-latency throughput from a recorded neuron to muscle activity not present during some behavioral epochs often appeared during others. Such changes in throughput could not always be attributed to a higher neuron firing rate, to more ongoing muscle activity, or to neuronal synchronization, indicating that reorganization of motor cortex output may involve rapid changes in functional connectivity from single motor cortex neurons to alpha-motoneuron pools.  相似文献