太行山水柿果实成熟过程中主要成分含量的动态变化

对太行山水柿转色期后果实成熟过程中总糖、蛋白质、单宁等主要成分的变化规律进行研究,以确定最佳采收期.结果表明,在果实成熟过程中,可溶固形物和总糖的含量呈上升趋势,可溶固形物和总糖含量分别为180 g.kg-1,150 g.kg-1左右达到峰值,然后趋于平稳;单宁和蛋白质含量呈逐渐减少趋势,其含量分别在12 g.kg-1,6 g.kg-1左右时相对平稳;原果胶含量逐渐降低,可溶性果胶含量逐渐上升;总酸含量较低,整个过程变化不大.因此采收期的确定应以含糖量为准,当表皮呈现品种特有的橙黄色,含糖量达150~170 g.kg-1时采收,此时水柿可维持较高的硬度,有助于运输中的稳定性和完整性.     

Causes of Sterility in Seed Set of Rice under Salinity Stress

The effects of salinity at 50 mM NaCl on floral characteristics, yield components, and biochemical and physiological attributes of the sensitive rice variety IR‐28 were studied under controlled conditions to determine the causes of sterility in seed set under salinity stress. The results showed significant decreases in panicle weight, panicle length, primary branches/panicle, filled seeds/panicle, unfilled seeds/panicle, filled seeds/plant, unfilled seeds/plant, total seeds/panicle, total seed weight/panicle, 1000‐seed weight and total seed weight/plant. The sodium content in different leaves and floral parts increased significantly. In contrast, the potassium content was decreased significantly in leaves and floral parts. A reduction in chlorophyll a and b was also noted in different parts of the leaves. Inhibition of transpiration and photosynthesis was observed in flag leaves at the grain‐filling stage. Soluble carbohydrates in different leaves were reduced significantly in salinized plants but their content in different floral parts was increased, with the exception of primary and secondary branch spikelets. Under salinity stress, total protein concentration in flag, second and third leaves were higher than in control plants. The viability of rice pollen was reduced significantly in salinized plants. It was further observed that starch synthetase activity (α1–4‐glucan glucosyle transferases) in developing rice grains was inhibited very significantly under salinity stress. From these results, it is inferred that sterility and significant reductions in seed set in rice were not merely due to reduction or inhibition of different biochemical constituents and physiological functions, but were mainly due to limitation of soluble carbohydrate translocation in primary and secondary spikelets, accumulation of more sodium and less potassium in all the floral parts, and highly significant inhibition of specific activity of starch synthetase in developing rice grains, thus resulting in failure of seed set.     

Energy reserves and reproductive investment in male three-spined sticklebacks, Gasterosteus aculeatus

Abstract – In a 6-month study of male sticklebacks from a single cohort of an annual population, energy reserves (carbohydrate, lipid and protein) in the carcass and gonad were found to increase from December to May. Energy reserves in the liver increased from December to March before declining between March and April, a period of marked gonadal growth in this population. Examination at the individual level of the interrelationships among the various components of the energy store (corrected for differences in body size) identified overall body condition as a major component of variation and highlighted a negative relationship between energetic investment in gonadal tissue and energy reserves in various somatic compartments. Early in the season, relative gonadal weight was largely unrelated to somatic energy reserves, but from March onwards there was a negative correlation between these two variables. These data suggest that a significant flux of glycogen and lipid from the somatic to the gonadal tissue occurs in male sticklebacks in the period just prior to the breeding season, with the extent of gonadal growth varying between individuals and occurring at the expense of overall nutritional status. ^Note     

Frequency and timing of stem removal influence Corylus americana resprout vigor in oak savanna

Shrubs are an important component of many ecosystems, contributing to spatial and resource heterogeneity and adding to life form and species diversity. Many shrub species have adapted to regular disturbances such as fire by resprouting after stem removal. The relative vigor with which shrubs resprout influences post-disturbance size and density of individuals and thus, can alter community structure. However, little is known about how disturbance frequency and seasonality influence resprouting. We studied resprout vigor of the native shrub American hazel (Corylus americana Walter) in oak savanna in Minnesota, USA. We measured resprout growth of individual shrubs in response to the frequency and timing of clipping in relatively open and shaded conditions. We hypothesized that resprouting of C. americana would be negatively related to clip frequency, due to more rapid depletion of stored resources necessary for resprouting, and positively related to light availability. In 12 weeks following a single clipping, shrubs recovered 82% of the lost stem biomass in open savanna, but only 17% in shaded forest. In both open and closed sites, shrubs clipped three times or more resprouted only 10-15% as much biomass as those clipped once. Moreover, the timing of clipping had as large an effect on resprout potential as the number of clipping events, and small differences in timing were important. Plants clipped once in mid or late June or in July regrew 57, 17, and 8% as much biomass, respectively in the six weeks following clipping as those clipped in early June. These results illustrate that both the timing and number of disturbance events within a growing season can strongly influence shrub growth, which can have important implications for ecosystem structure, function, and management.     

低磷条件下熊猫豆光合特性及碳水化合物累积变化研究

利用水培方法研究了熊猫豆对低磷胁迫随时间的生理响应.结果表明,磷胁迫下熊猫豆根系最大根长增加46％;但叶片面积变小,且发育延迟.缺磷时熊猫豆幼苗叶片光合速率、气孔导度、叶绿素含量以及蒸腾速率均下降,但是胞间CO2上升;缺磷植株还原性糖、可溶性总糖含量均降低,但是还原糖向根系的分配比例增加;缺磷植株根系活力上升、酸性磷酸...     

饲粮结构与非结构性碳水化合物比例对绵羊瘤胃代谢参数的影响

旨在探讨绵羊饲粮结构与非结构性碳水化合物比例(SC/NSC为1.57(Ⅰ)、1.95(Ⅱ)、2.29(Ⅲ))对瘤胃发酵参数(pH、VFA、总氮、NH3-N、尿素氮、蛋白氮)的影响。选用6只约1.5岁,体质量25~30 kg,装有瘤胃瘘管的甘肃高山细毛羊羯羊,按3×3重复拉丁方设计(预试期10 d,正试期9 d)。结果表明:采食饲粮Ⅰ的绵羊瘤胃液pH平均值显著低于采食饲粮Ⅱ(P<0.01)、Ⅲ(P<0.05)的绵羊;除处理Ⅰ采食后3 h的pH较低(5.86)外,所有pH测值均在6.2~7.0范围内。瘤胃液TVFA平均值(mmol.L-1)呈现Ⅰ、Ⅱ高于Ⅲ的趋势(P=0.09);处理间乙、丙及其他酸的摩尔比和乙酸/丙酸比均值无显著差异(P>0.05),Ⅰ的丁酸摩尔比均值显著高于Ⅲ(P<0.05)。瘤胃液总氮和蛋白氮均值随SC/NSC值增高而显著下降(P<0.01或P<0.05);氨氮与尿素氮均值在处理间无显著差异(P>0.05)。结果显示,饲粮粗料份额高于60%时,随SC/NSC值增高,绵羊瘤胃液pH上升,TVFA、总氮和蛋白氮平均浓度下降,对氨氮与尿素氮浓度则无显著影响。     

检测猪脑心肌炎病毒重组非结构蛋白2C间接ELISA方法的建立

以猪脑心肌炎病毒(Encephalomyocarditis virus,EMCV)重组非结构蛋白2C作为包被抗原,确定间接ELISA反应的最佳工作条件;通过病毒阻断试验和交叉试验检验方法的特异性;通过与血清中和试验比较,确定方法的敏感性;通过对试验感染猪的血清2C抗体产生动态的检测,分析建立方法用于EMCV感染早期诊断的意义。结果显示,建立的间接ELISA方法能够特异地检出EMCV感染猪的血清2C抗体,与猪瘟病毒(CSFV)、伪狂犬病病毒(PRV)、猪圆环病毒2型(PCV2)、猪繁殖与呼吸综合征病毒(PRRSV)等的抗血清没有交叉反应;与血清中和试验检测结果的符合率为95.7%(22/23),相对敏感性为90.9%(10/11);仔猪感染EMCV后第4天,应用建立的间接ELISA方法即能够检出血清中的特异性2C抗体。结果表明,建立了可以替代血清中和试验的基于EMCV重组非结构蛋白2C的间接ELISA方法。     

Effect of Leaf Sugar and Starch Concentrations on Apparent Photosynthesis in Alfalfa

Rates of apparent photosynthesis (AP), dark respiration, photorespiration, mesophyll resistance, and concentrations of soluble starch, sugars, chlorophyll and nitrogen were measured in alfalfa leaves ( Medicago sativa L.) grown under high or low light levels in an attempt to evaluate the effect of nonstructural carbohydrate concentration on net CO₂ assimilation.
Leaf N and chlorophyll levels of high light plants exceeded those of low-light plants. Constant light increased both starch and sugar levels in low-light plants, but had little effect on high-light plants. Rates of AP declined in low-light plants upon transfer to constant light conditions, apparently due to increases in stomatal and mesophyll resistance. Leaf starch levels were negatively correlated (P > 0.05) with rates of AP and positively correlated with mesophyll resistance in both groups of plants but leaf sugar content was not correlated with either AP or mesophyll resistance.
Starch and sugar levels of high-light plants declined substantially upon transfer to constant darkness, while low-light plants were less affected. Rates of AP declined in both groups of plants due to increases in both mesophyll and stomatal resistances. Neither sugar nor starch levels were correlated with AP or mesophyll conductance in this treatment.
The data support the hypothesis of feedback inhibition of photosynthesis, mediated through an increase in mesophyll resistance, which is associated with high levels of starch in the leaves.     

油菜、荞麦根分泌物中糖及有机酸组分的研究

利用连续流动收集系统收集了油菜、荞麦根分泌物，对介质ｐＨ变化、分泌物中碳水化合物组成及有机酸进行了测定。结果表明，荞麦、油菜生长介质中ｐＨ值变化的差异反映了它们泌质子能力的差异。在油菜分泌物中检测出高水平的鼠李糖，在荞麦中则是阿拉伯糖含量最高。草酸、琥珀酸是两种作物根分泌物的主要有机酸。苹果酸、柠檬酸在油菜根分泌物中没有检测出。     

"火红鸟"赫蕉采后处理方法对其瓶插寿命的影响

观测"火红鸟"切花采收后不同离水时间和杀茵剂、糖类等不同处理对"火红鸟"瓶插寿命的影响.结果表明:切花采收离水30min后,其瓶插寿命即受明显影响;100-120mg/Kg的漂白粉溶液能使"火红鸟"的瓶插寿命延长3d,糖类不能延长"火红鸟"切花的瓶插寿命.