水稻拔节期和抽穗期低温对稻米品质影响

【目的】为了探讨低温冷害对水稻品质的影响,以便为气候变化背景下辽宁地区水稻的高效栽培和品质认证提供理论依据。【方法】以水稻90-35为供试品种,分别于拔节期和抽穗期通过TRP-1000D型人工智能气候箱进行不同低温处理(比外界低5℃和低3℃,均持续5 d),以正常栽培管理作对照,5个处理,分别记为CK、A1、A2、B1、B2,分析拔节期和抽穗期不同等级低温胁迫处理对水稻的营养品质、研磨品质和外观品质的影响。【结果】低温胁迫下90-35水稻的蛋白质含量、直链淀粉含量较CK显著增加,处理A1、A2、B1、B2的蛋白质含量分别比CK增加3.45%、1.15%、6.90%、8.05%,除处理B1外直链淀粉含量分别比CK增加1.75%、0.44%、0.44%;脂肪酸含量和精米率较CK显著减少,处理A1、A2、B1、B2的脂肪酸含量分别比CK减少17.75%、7.5%、25%、11%,精米率分别比CK减少2.1%、6.95%、0.22%、7.5%。拔节期低温胁迫下糙米率和垩白粒率显著减少,处理A1、A2的糙米率分别比CK减少0.73%、1.09%,垩白粒率分别比CK减少33.3%、22.2%;抽雄期低温胁迫下糙米率和垩白粒率显著增加,处理B1、B2的的糙米率分别比CK增加0.6%、3.02%,垩白粒率分别比CK增加255.6%、133.3%,即低温胁迫使其营养品质和研磨品质中的精米率受到负面影响,而拔节期适当低温胁迫处理对其研磨品质中的糙米率和外观品质有益。【结论】水稻90-35在不同生育时期经受不同低温胁迫处理后,水稻的营养品质、研磨品质和外观品质均受到不同程度的影响。     

Combined effects of salt stress and cucurbit downy mildew (Pseudoperospora cubensis Berk. and Curt. Rostov.) infection on growth,physiological traits and antioxidant activity in cucumber (Cucumis sativus L.) seedlings

Abiotic and biotic stresses both decrease quality and quantity of cultivated plants. We compared responses of Cucumis sativus L. cvs Sardes and Beith alpha which were treated with 50 or 100 mM NaCl and/or infected by Pseudoperospora cubensis Berk. and Curt. Rostov.. Both cultivars were affected remarkably when fungus infection was combined with salt stress however; cv Sardes was found out to be relatively tolerant with sustainable growth performance, better leaf water status and lower lipid peroxidation levels under this condition. This relative tolerance could be related to the fine tuning of the activities of the antioxidative enzymes and proline levels.     

Osmotic Adjustment in Maize (Zea mays L.): Changes with Ontogeny and its Relationship with Phenotypic Stability

Genetic variation for osmotic adjustment was examined in a group of maize hybrids during vegetative and silking stages. Estimates of osmotic adjustment were derived from measurements of leaf relative water content (RWC) and osmotic potential (Ψ o ) before day-break. The degree of adjustment was estimated from the In RWC/In Ψ o relationship. All cultivars examined showed some degree of osmotic adjustment and significant differences (P < 0.05) were found among them. The utility of measurements in early vegetative stages as a mean of selection for osmotic adjustment in silking stage was established. A positive tendency was observed between osmotic adjustment and phenotypic stability.     

热水溶出茧层丝胶蛋白的结构变化

对不同时间热水溶出的茧层丝胶的氨基酸组成、热分解温度和分子结构等进行了测定分析．结果表明，随着热水溶出时间的延长，茧层丝胶蛋白中的酸性氨基酸因易溶于水而略有下降，热分解温度因受取向性、结晶性的影响而有所增高，分子结构也由无规则卷曲转化为β构象．丝胶蛋白被降解而成分子大小不一的混合类型     

Pearl Millet Phenology and Growth in Relation to Thermal Time under Arid Environment

Pearl millet ( Pennisetum glaucum L.R.Br.) hybrid MH 179 was grown under two moisture regimes viz., optimal moisture and rainfed conditions. The field experiment was continued for three consecutive rainy seasons to quantify the pearl millet development with thermal time. The possible influence of variation in natural sowing date on the relationships between crop development and thermal time have been described. At cardinal temperatures of 10°C (base temperature below which pearl millet development ceases), 33°C (optimal temperature for development) and 45°C (maximum temperature at and above which no development takes place), the crop required 1490–1794°Cd thermal time to reach physiological maturity. The thermal time requirement for different developmental stages was influenced by the sowing time and moisture availability during the growing season of the crop.
The leaf tip appearance on the main shoot of pearl millet in relation to thermal time was almost linear under both moisture conditions requiring about 44–50°Cd ± 2.6 °Cd leaf⁻¹, till the appearance of the flag (last) leaf. However, leaf tip appearance on primary tillers was slightly slower and required 53-58°Cd ± 4.7°Cd for each new leaf. Appearance of first primary tiller was later (at 320°Cd after emergence) under the rainfed condition as compared to the crop under the optimal moisture (at 250°Cd).Thereafter, the tiller appearance in relation to thermal time under both moisture conditions was at a linear rate of about 53-56°Cd ± 9.5°Cd tiller⁻¹.
Effect of microclimatic variations, canopy temperature, radiation and photoperiod on the phenology-thermal time relationships have been discussed under both the moisture conditions.     

Induced thermotolerance and expression of heat shock protein 70 in sea cucumber <Emphasis Type="Italic">Apostichopus japonicus</Emphasis>

ABSTRACT:   Thermal limits, induced thermotolerance and the expression of heat shock protein 70 (Hsp70) in an echinoderm Apostichopus japonicus were studied. The sublethal and lethal temperatures for the juveniles were 30 and 34°C, respectively; a previous sublethal heat shock exposure (30°C, 2 h) could increase the survival rates of the sea cucumbers when they were exposed to 34°C. This induced thermotolerance could last for at least 2 days. Levels of Hsp70 increased substantially after sublethal heat shock exposure and linearly decreased with time. This result indicated that a close relationship existed between the induction of thermotolerance and the levels of Hsp70 in A. japonicus.     

热应激对鸡新城疫疫苗免疫效果的影响

本试验利用伊莎蛋雏鸡，分别接种新城疫油乳剂灭活苗和Ｎ－７９弱毒苗，油乳剂灭活苗免疫的各试验组抗体滴度稍有下降，与对照组间无明显的差异；Ｎ－７９弱毒苗免疫的各试验组，高温处理２４小时的雏鸡，抗体滴度稍低于对照组，但无明显差异；而高温处理４８小时的各组，抗体滴度均显著低于对照组（ｐ＜０．０５）。     

Performance of Agricultural Systems under Contrasting Growing Season Conditions in South-western Quebec

Climate change will alter temperature and rainfall patterns over North American agricultural regions and there will be a need to adapt crop production systems to the altered conditions. A set of field experiments were conducted in south-western Quebec, Canada, with soybean ( Glycine max L.), corn ( Zea mays L.), sorghum ( Sorghum bicolor L.) × sudangrass ( Sorghum sudanense Piper) hybrid and switchgrass ( Panicum virgatum L.) under two tillage and three nitrogen fertility regimes, to study their performance in three successive growing seasons (2001–2003), two of them with unusually warm and dry conditions. The annual crops were established in two tillage systems: conventional and no-till (NT). All crops except soybean were fertilized with three levels of nitrogen: corn – 0, 90 and 180 kg N ha⁻¹, sorghum-sudangrass – 0, 75 and 150 kg N ha⁻¹, switchgrass – 0, 30 and 60 kg N ha⁻¹. The 2001 and 2002 seasons were hotter and drier than the 2003 season, which was the most favourable for crop growth. The capacity of the crops to yield in dry seasons was as follow: switchgrass > sorghum-sudangrass > corn > soybean. The corn and sorghum-sudangrass responses to nitrogen fertilizer were low in 2001 due to the combined effect of dry growing season and coarse soil texture. Soybean did not perform well under NT. Corn yielded better at the highest nitrogen fertilizer rate under NT when the early season was warmer than the normal. Our results show that switchgrass and sorghum-sudangrass could be an option in south-western Quebec if the frequency of hot and dry seasons increase in the future, because of climate change.     

热胁迫对白梭吻鲈鳃组织结构及抗氧化指标的影响

温度是导致鱼类生理变化的最重要的环境因素之一。热应激导致氧化应激，破坏抗氧化防御系统，并导致脂质和组织病理学的损害。白梭吻鲈(Sander lucioperca)属于亚冷水性鱼类，最适生长水温20～24℃。近年来，由于夏季气温极高，中国池塘出现了大量的白梭吻鲈死亡，白梭吻鲈的水产养殖业一直面临着高温的严峻挑战。鱼鳃参与鱼类许多重要功能，如呼吸，渗透调节和排泄，与外部环境保持密切接触，对水质变化特别敏感。为探究热胁迫对白梭吻鲈鳃组织结构及抗氧化指标的影响，将100尾鱼暴露于28℃，31℃，34℃，36℃热应激2h，以23℃作为对照组。收集鳃用于石蜡切片制备，并将苏木精伊红（HE）染色用于一般组织学观察。测定超氧化歧化酶（SOD）、过氧化氢酶（CAT）、谷胱甘肽过氧化物酶（GPX）活性和丙二醛（MDA）等抗氧化指标。结果显示，28 ℃组鳃小片发生充血，31 ℃组部分鳃小片末端卷曲变形、上皮细胞水肿，34 ℃组鳃小片变形加重，且有少量融合，上皮细胞水肿加重、明显隆起，鳃小片之间粘液细胞肥大、增生，36 ℃组相邻鳃小片大量融合且严重变形，卷曲混乱排列，大量上皮细胞坏死、脱落，鳃丝粘液细胞增生、肥大；随着胁迫温度升高，鳃中SOD、CAT、GPX、MDA均整体呈现先升高、后降低的变化趋势，且在36℃时显著下降。这表明在热应激后，鱼体内ROS增加，脂质过氧化增加。由于体内产生大量的ROS和H2O2，机体也增加了GPX和CAT的合成。当暴露在36℃时，胁迫强度超过白梭吻鲈的适应能力，抗氧化系统功能无法正常进行。表明热胁迫对白梭吻鲈鳃组织有损伤，且随着热胁迫温度的升高，其鳃受损情况越发严重。     

多层建筑框架结构光弹性应力分析

对多层建筑框架结构在风载下的应力分布了进行了光弹性分析，通过模型梁和柱的等差线，测出其反弯点位置及剪力植，算出梁和柱端部弯矩值。同时，对该结构进行了有限元计算，并将光弹性分析，有限元计算放Ｄ值法的结果进行了比较。及