短时间高温处理下桃芽淀粉和可溶性糖含量变化与自然休眠解除的关系   总被引：2，自引：0，他引：2  

王海波  高东升  王孝娣  李疆 《果树学报》2005,22(6):615-619

以6年生曙光油桃为试材,研究40℃、45℃、50℃3个梯度高温短时间处理对花芽和叶芽的存活率、萌芽级数以及淀粉和可溶性糖含量的影响,探讨短时间高温处理对桃芽自然休眠的调控效应。结果表明:随短时间高温处理时期的推迟,处理温度的升高,处理持续时间的延长,短时间高温处理对桃芽自然休眠的解除作用增强。11月30日高温处理中,40℃高温处理对桃芽自然休眠解除呈负调控效应,其萌芽级数和可溶性糖含量均低于对照,而淀粉含量高于对照;45℃和50℃高温处理对桃芽自然休眠解除呈正调控效应,其萌芽级数和可溶性糖含量与对照相比明显升高,而淀粉含量显著降低,虽然部分花芽和叶芽因高温处理而死亡,但是在存活芽中短时间高温对桃芽自然休眠的解除作用明显增强。12月10日高温处理中,40℃高温处理对桃芽自然休眠解除的调控效应不明显,45℃和50℃高温处理和11月30日处理相同,具有正调控效应,只是前者对桃芽自然休眠的解除效果优于后者。不同高温处理桃芽的萌芽级数和淀粉含量及可溶性糖含量之间的相关性分析表明,淀粉含量的降低,可溶性糖含量的升高即淀粉向可溶性糖的快速转变是高温解除休眠的部分原因。  相似文献   

Modelling carbon dynamics in mixed grass–red clover swards     

Bengt Torssell  Henrik Eckersten  Alois Kornher  Per Nyman  Ullalena Boström 《Agricultural Systems》2007

Growth and carbon dynamics in mixed grass–red clover leys were simulated using a growth model for pure stands based on radiation use, allocation within plant and loss of biomass. The model and its parameter values were taken from previous applications of the model to pure swards of grass and red clover grown in the same experiment at the same sites and years.  相似文献   

Earthworm biomass response to soil management in semi-arid tropical Alfisol agroecosystems     

M. Vikram Reddy  V. P. Kiran Kumar  V. Ravinder Reddy  P. Balashouri  D. F. Yule  A. L. Cogle  L. S. Jangawad 《Biology and Fertility of Soils》1995,19(4):317-321

Earthworms recorded during 1989–1993 across 15 soil management treatments, comprising three different tillagexthree organic amendments (bare, farmyard manure, and rice straw) and six perennial ley treatments, belonged to two endogeic species, Octochaetona phillotti (Michaelsen) and Lampito mauritii Kinberg, while in a nearby undisturbed natural revegetation area three species were found, including the above two and Octonochaeta rosea (Stephenson). The earthworm biomass showed significant temporal and spatial variations and was higher during the post monsoon period than in the early rainy season. No worm biomass was recorded during the dry season. In the tillage and organic amendment treatments, the biomass was drastically reduced from September 1989 to September 1991 after the application of carbofuran and some herbicides, and was significantly reduced during these two years compared to that of 1992. The maximum monthly earthworm biomass ranged between 2.5 and 17.9 g m^-2 across the treatments and increased several-fold in the nearby natural revegetation area (75.9 g m^-2). It significantly increased in perennial ley treatments compared to annual treatments with organic amendments. Thus the earthworm biomass varied significantly (P<0.01) across the 15 treatments, indicating discernible effects of soil management.Visiting Scientist (under the Rockefeller Foundation Environmental Research Fellowship in International Agriculture)  相似文献   

冬季低水温鳜短期饥饿和摄食的生理状态比较     

徐杭忠  张皓迪  王贵龙  刘天骥  李洪琴  刘匆  李虹  翟旭亮  薛洋  罗莉 《水产学报》2022,46(9):1572-1581

为比较鳜短期饥饿与摄食的生理状态,实验以我国鳜主产区广东省的冬季水温为参照,在(13±1)°C的水温条件下,选取体质量为(84.13±0.14) g的鳜90尾,分为饥饿组(饥饿15 d)和摄食组(摄食15 d),实验结束后测定各项理化指标。结果显示：(1)摄食组鳜的体质量、肝糖原、全鱼与肌肉的粗蛋白、粗脂肪含量均显著高于饥饿组,摄食组增重7.54%,而饥饿组减重8.39%。(2)摄食组鳜血浆谷丙转氨酶和谷草转氨酶活性显著低于饥饿组,但甘油三酯含量显著高于饥饿组,各类血细胞数量与血糖水平则无明显差异。(3)摄食组鳜的消化酶活性显著高于饥饿组,肠道组织结构发育更好。(4)摄食组鳜肝脏抗氧化能力显著高于饥饿组,且饥饿组部分肝细胞有明显的结构损伤,脂滴数量显著少于摄食组。(5)摄食组鳜的血浆溶菌酶活性和血浆、脾脏、肾脏免疫球蛋白M含量显著高于饥饿组。(6)摄食组与饥饿组鳜背肌氨基酸组成无显著差异。但脂肪酸组成有显著差异,摄食组鳜背肌饱和脂肪酸与单不饱和脂肪酸总量显著低于饥饿组,而多不饱和脂肪酸与高不饱和脂肪酸总量显著高于饥饿组。研究表明,在本实验条件下,摄食组增重而饥饿组减重,两种处理增重量差...  相似文献   

短学期制下植物学实验课程开设探索   总被引：2，自引：0，他引：2  

刘振国 《安徽农业科学》2010,38(22):12259-12260

介绍了短学期制下植物学实验课程概况,指出了课程开设面临的问题,提出了相应的解决对策与建议。  相似文献   

Reduced tillage in temperate organic farming: implications for crop management and forage production     

M. Krauss    A. Berner    D. Burger    A. Wiemken    U. Niggli  & P. Mäder 《Soil Use and Management》2010,26(1):12-20

To promote conservation tillage in organic farming systems, weed control and ley removal within arable-ley rotations need to be optimized. A long-term field trial was thus established in Frick, Switzerland in 2002 on a clayey soil and with a mean precipitation of 1000 mm/year. The tillage experiment distinguished between conventional tillage with mouldboard ploughing (CT, 15 cm depth) and reduced tillage (RT), including a chisel plough (15 cm) and a stubble cleaner (5 cm). Results of a 2-year grass-clover ley (2006/2007) and silage maize (2008) are presented. Due to dry conditions, mean grass-clover yields were 25% higher in RT than in CT, indicating better water retention of RT soils. Clover cover and mineral contents of the fodder mixture were also higher in RT. The ley was successfully removed in autumn 2007 in RT plots, and a winter pea catch crop was sown before maize. In CT, ploughing took place in spring 2008. Maize yields were 34% higher in RT than in CT, despite a two- to three-fold higher but still tolerable weed infestation. Maize in RT plots benefited from an additional 61.5 kg of easily decomposable organic N/ha incorporated into the soil via the pea mulch. Measurement of arbuscular mycorrhizal colonization of maize roots indicated a similar mechanical disturbance of the topsoil through the reduced ley removal system compared with ploughing. It is suggested that RT is applicable in organic farming, even in arable-ley rotations, but long-term effects need further assessment.  相似文献   

Nitrous oxide emissions and methane oxidation by soil following cultivation of two different leguminous pastures   总被引：2，自引：0，他引：2  

T. J. van der Weerden  R. R. Sherlock  P. H. Williams  K. C. Cameron 《Biology and Fertility of Soils》1999,30(1-2):52-60

 Nitrous oxide (N₂O) emissions and methane (CH₄) consumption were quantified following cultivation of two contrasting 4-year-old pastures. A clover sward was ploughed (to 150–200 mm depth) while a mixed herb ley sward was either ploughed (to 150–200 mm depth) or rotovated (to 50 mm depth). Cumulative N₂O emissions were significantly greater following ploughing of the clover sward, with 4.01 kg N₂O-N ha^–1 being emitted in a 48-day period. Emissions following ploughing and rotovating of the ley sward were much less and were not statistically different from each other, with 0.26 and 0.17 kg N₂O-N ha^–1 being measured, respectively, over a 55-day period. The large difference in cumulative N₂O between the clover and ley sites is presumably due to the initially higher soil NO₃ ^– content, greater water filled pore space and lower soil pH at the clover site. Results from a denitrification enzyme assay conducted on soils from both sites showed a strong negative relationship (r=–0.82) between soil pH and the N₂O:(N₂O+N₂) ratio. It is suggested that further research is required to determine if control of soil pH may provide a relatively cheap mitigation option for N₂O emissions from these soils. There were no significant differences in CH₄ oxidation rates due to sward type or form of cultivation. Received: 1 November 1998  相似文献   

Short-term Memory Testing in Domestic Horses: Experimental Design Plays a Role     

Evelyn B. Hanggi 《Journal of Equine Veterinary Science》2010

This study investigated whether four horses could recall the location of a food objective in a two-choice delayed response test. During testing, horses stood unrestrained in a station where they observed the delivery of 30 g of grain into one of two containers. They were then released and allowed to go toward a container under the following contexts: immediate release or delayed release of 5, 10, 15, 20, or 30 seconds. Results showed that horses remembered the correct objective not only under the immediate release condition but also for all delayed release conditions tested. Observational data were also collected to determine whether the horses were indeed relying on memory to solve the delayed response problems or whether they were using orienting cues to maintain focus on the correct container. These data showed that the horses did not maintain visual contact with the objective during many of the trials; instead, they attended to an assortment of distractions in the surrounding area. Contrary to a previous report in which horses could not accurately respond in a similar situation after 10-second delays, these findings suggest that at least some horses are not as limited with respect to their ability to recall things and have an adequate spatial short-term memory. Experimental design seems to play a significant role in the outcome of this type of research.  相似文献   

Residual Nitrogen Effects in Organically Cultivated Beetroot Following a Harvested/Green Manured Grass-Clover Ley     

Anita Gunnarsson  Börje Lindén  Ulla Gertsson 《Journal of plant nutrition》2013,36(8):1355-1381

ABSTRACT

The residual nitrogen (N) effect on beetroot following harvested grass-clover (H-ley) or corresponding twice-cut green manure (GM-ley) was compared with a barley control. The residual N at beetroot harvest, calculated as N in beetroot crop and mineral N in the 0–90 cm soil layer, was 83 kg ha^?1 for the GM-ley when barley was set to zero. The effect of GM-ley exceeded that of 3H-ley (3 harvests) by 74 kg N ha^?1 and 2H-ley (2 harvests) by 42 kg N ha^?1. Prediction of residual effects was studied using a model with a humification coefficient (hc) of 0.35 and another with different hc values for different plant materials. The former gave the best fit to observed data in regression analysis. The latter gave the best fit to observed data in absolute values. The residual N effect of GM biomass from summer cuttings corresponded to 40–70% of the potential effect.  相似文献   

Contribution of anecic earthworms to biopore formation during cultivation of perennial ley crops     

Timo Kautz  Marcel Lüsebrink  Stefan Pätzold  Doris Vetterlein  Ralf Pude  Miriam Athmann  Paul M. Küpper  Ute Perkons  Ulrich Köpke 《Pedobiologia》2014

Large sized biopores (diameter >2 mm) in the subsoil can be created by tap roots, which leave voids after their decay, or by the burrowing activity of anecic earthworms which may benefit from the temporary lack in tillage in perennial cropping systems. However, the interactions between root growth and earthworm activity in the process of biopore formation during perennial ley cropping are not well understood. The aim of this field study was to quantify the development of the abundance of the anecic earthworm Lumbricus terrestris and the biopore density during the cultivation of lucerne (Medicago sativa L.), chicory (Cichorium intybus L.) and tall fescue (Festuca arundinacea Schreb.) grown for either one, two or three years. An increased abundance of L. terrestris was already recorded after two years of continuous ley when compared with one year cultivation. The ley crop species had only minor influence on the abundance of L. terrestris. Biopore densities of both diameter classes under study (2–5 mm and >5 mm) were not significantly affected by the duration of ley cropping. In contrast, biopore densities were influenced by ley crop species. More biopores of diameter class 2–5 mm were recorded after chicory than after fescue. Lucerne cropping resulted in intermediate biopore density. Additionally, in an incubation experiment under field conditions, we quantified whether L. terrestris preferentially created new biopores or colonized abandoned, previously existing ones. After three weeks of incubation, one third of the adult individuals incubated in the experimental area created new biopores at 0.4 m soil depth. A similar percentage of individuals colonized previously existing biopores, partially widening the lumen of smaller sized biopores. The remaining individuals remained in the topsoil. Sub-adult individuals rarely formed new pores. Half of the introduced sub-adults remained in the topsoil. We conclude that in crop rotations new biopores can be generated during perennial ley cropping by taproot systems of ley crops, but that a two to three- year period without tillage is not sufficient for populations of anecic earthworms to make a marked contribution to biopore density in the subsoil. The relevance of anecic earthworms for altering physical and chemical properties of biopores during ley cropping still needs further investigation.  相似文献