Season-specific varietal management as an option to increase rainfed lowland rice production in East African high altitude cropping systems

Due to land expansion and an increase in productivity, rice production in sub-Saharan Africa has been growing at a rate of 6% in the past decade. Rainfed rice production systems have accounted for a large share of this expansion. In these systems, the potential growing period not only depends on the length of the rainy season and thus water availability, but is often, especially in the highlands of East Africa, bordered by the onset of the cool period of the year, when low minimum temperatures compromise rice yields. The objective of this study was to investigate the yield potential of 30 rice varieties contrasting in crop duration and cold tolerance in the highlands of East Africa, with its limited length of growing period. A field trial was conducted in the cropping seasons in 2016 and 2017 at the Fogera rice research station, Ethiopia. As a function of the onset of rains, rice was sown mid-July in 2016 and early July in 2017. Early sowing in 2017 led to an extended crop duration and significantly lower yields of the short-duration varieties, and to a shortened duration and significantly higher yields of the medium- and long-duration varieties, when compared to late sowing in 2016. Late sowing compromised yield of the medium- and long-duration varieties because of low temperatures during booting stage, which led to high spikelet sterility. Early sowing resulted in low yields of the short-duration varieties, probably due to low solar radiation during the cloudy rainy season, which coincided with the vegetative stage. Therefore, choice of variety should be a function of the variable onset of the rainy season and related sowing date. However, crop models precisely calibrated for potential varieties and the respective environmental conditions could fully support the selection of a suitable variety, depending on the date of sowing, for example with the help of online tools or smartphone applications.     

直立型扁蓿豆对干旱胁迫和复水的响应及适应策略

以直立型扁蓿豆[Medicago ruthenica（L.）Sojak.cv.Zhilixing]为材料，于苗期连续干旱处理12 d后复水4 d，研究直立型扁蓿豆幼苗形态结构特征、生理代谢及生物量分配对干旱胁迫及复水的响应，揭示直立型扁蓿豆对干旱胁迫及复水的适应策略。结果表明：随着干旱胁迫时间延长，直立型扁蓿豆叶片气孔开放率逐渐降低，处理9 d后气孔及表皮细胞密度比正常浇水处理（CK）分别增加48.5%和36.6%，形成小而密的表皮细胞和气孔。生理上，除MDA含量随胁迫时间的延长逐渐增加外，其余指标均先升高后降低，干旱胁迫9 d时达最高，SOD、POD、叶绿素、可溶性糖、可溶性蛋白及脯氨酸分别较CK提高88.9%、111.2%、86.7%、140.5%、147.8%和124.6%。同时，生物量随胁迫时间的延长先增大后减小，于干旱胁迫9 d达最大值，比CK增加16.4%，总的分配格局表现出地上生物量投资高于地下，地下生物量投资比例随胁迫时间的延长逐渐增加，而地上生物量变化与其相反。复水后各指标均能恢复至CK水平或超过CK，表现出极强的复水敏感性和潜在恢复能力。该品种扁蓿豆对干旱胁迫及复水的适应主要分为3个时期：主动适应期，其生理参数的可塑性指数为形态参数的1.33倍，主要通过抗氧化及渗透调节来减少水分散失增加水分吸收、缓解氧化伤害以适应干旱逆境；被动适应期，其形态参数的可塑性指数为生理参数的1.31倍，主要采用牺牲生物量的生存策略以及降低色素含量减少光吸收的光保护机制来提高逆境下的生存能力；复水恢复期，根冠比、气孔开放率、气孔及表皮细胞密度比CK分别增加25.9%、29.7%、24.2%和16.3%，其较高的根冠比和叶片较高的气孔开放率及小而密的气孔及表皮细胞特征，保证了直立型扁蓿豆吸水能力以及水分运输效率的迅速恢复。综上，直立型扁蓿豆抗旱能力较强，能够通过形态生理的改变以及调整不同器官的生物量分配来应对与适应干旱逆境及复水，且在不同处理阶段采取不同的适应策略以达到生存目的。     

Changes in the carbon concentrations and other soil properties of some Scottish agricultural soils: Evidence from a resampling campaign

The change in soil carbon (C) concentration, soil pH and major nutrients for approximately 1,000 topsoil sampled from on-farm experimental sites over a thirty-year period from 1950 to 1980 in north-east Scotland are summarized. This period coincided with increased agricultural intensification, which included regular liming and fertilizer additions. During 2017, 37 of these sites were resampled and reanlaysed. While pH and extractable phosphorus (P) and potassium (K) increased over this period, there was no detectable change in the percentage loss on ignition. Composite soil samples were taken by auger from a depth of 0–15 cm and compared with the corresponding archived samples collected at the initiation of each experiment. Analysis of these resampled soils indicated no significant change in soil carbon (C), although soil pH, extractable magnesium (Mg) and K and Nitrogen (N) concentrations were significantly greater (p < .001) but extractable soil P concentration was significantly less (p = .015) compared with the original samples. Even though measuring C concentration alone is a poor indicator of overall changes in soil C stocks, it does provide a relative quick “early warning” of C losses that would justify a more comprehensive measure of stocks.     

干旱胁迫对不同种源云南松幼苗生物量与根系形态的影响

通过盆栽控水，采用双因素随机区组设计研究了9个不同地理种源云南松幼苗生物量分配和根系形态对干旱胁迫的响应，比较了干旱胁迫下幼苗生物量及其分配以及根系形态在种源间的差异，并通过隶属函数法对不同种源幼苗干旱适应性进行了初步评价。结果表明:1）干旱胁迫下，各种源云南松幼苗地径下降明显，苗高未发生显著变化，各器官生物量和总生物量多呈下降趋势，干旱胁迫并没有导致幼苗根生物量分配比和根冠比的增加，但根系长、比根长、根表面积和比根面积在干旱胁迫下增加显著。2）不同种源云南松幼苗地径、苗高、生物量及其分配比和根系形态在干旱处理下均存在显著差异，其中地径和苗高分别以西昌和双柏种源最大，各器官生物量和总生物量以双柏、西昌和册亨种源较高，察隅种源各器官和总生物量较低，但该种源具有最大的根生物量分配比和根冠比；会泽种源根长、根表面积、比根长和比根面积均最大。研究发现，在土壤水分限制条件下，云南松幼苗以根系形态变化代替根系生物量增加的策略来适应干旱，各种源云南松幼苗生长对干旱胁迫响应的差异可能是由种源地理气候因子长期影响所形成的不同适应性策略所导致。经平均隶属函数值法初步评价了不同种源云南松幼苗对干旱适应性的强弱，结果显示，西藏察隅、云南会泽和四川西昌种源对土壤干旱的适应性较强，云南双柏、贵州册亨、云南云龙种源居中，而云南新平、永仁和禄丰种源适应性较弱。     

下丘脑-垂体-肾上腺轴参与动物采食调控的研究进展

采食是动物维持生命活动的基本生理过程，是动物生长发育的基础。畜禽采食量的高低直接影响到营养物质的摄入量及生产性能的发挥。在畜牧业生产中，影响采食的因素很多，而应激是其中一个非常重要的影响因素。动物机体的应激反应主要由下丘脑-垂体-肾上腺（HPA）轴来调控。下丘脑、垂体和肾上腺皮质通过释放促肾上腺皮质激素释放激素（CRH）、促肾上腺皮质激素（ACTH）和糖皮质激素（GC）这3种应激激素来协同调控动物的应激反应。应激激素对采食行为的调节是一个非常复杂的过程，主要通过稳态和非稳态途径来调节采食，可以双向调控食物的摄入量。稳态途径指的是通过调控机体能量稳态而调控采食。CRH和ACTH通过抑制下丘脑促食欲肽的表达而抑制采食；而GC在中枢和外周发挥着完全相反的作用。非稳态途径指的是通过影响中脑奖赏系统调控采食的愉悦感，是近年来食欲调控研究的热点，越来越多的研究证明了应激激素与奖赏系统的联系。作者针对应激激素调控采食的最新研究报道进行综述，以期为生产实践中新型的采食调控技术研发提供一定的参考。     

油菜高光效种质综合鉴选指标体系与方法

高光效种质是开展作物高光效育种的基础。在剖析油菜高光效种质筛选要求、面临困难、研究缺陷的基础上,针对油菜超高产育种目标和生产实际需求,构建出油菜高光效的综合筛选指标体系和方法,对油菜种质进行数量化综合评价,并开展定向选育和杂交改良。在实际应用中取得良好效果,获得一批油菜高光效种质,为利用“高光效+杂种优势”途径开展油菜高光效育种奠定了物质基础。     

Effect of endothelin-1 on inflammation and oxidative stress in COPD

AIM:To investigate the effect of endothelin-1 on inflammation and oxidative stress in chronic obstructive pulmonary disease (COPD). METHODS:Healthy non-smokers (30 cases), healthy smokers (30 cases) and COPD patients (29 cases) were collected and induced to produce sputum. The concentration of endothelin-1 in the induced sputum was detected. The model of emphysema was established by cigarette smoke extract to stimulate SD rats. Endothelin A receptor antagonist BQ123 and non-selective endothelin receptor antagonist bosentan were used to intervene with the model rats. The experiment was divided into control group, cigarette-treated group, selective antagonist group and non-selective antagonist group. The protein levels of cleaved caspase-3 in the lung tissue were determined by Western blot. Gelatin zymography was used to analyze the activity of matrix metalloproteinase-2 (MMP-2) and MMP-9 in the lung tissue. The levels of interleukin-1β (IL-1β) and tumor necrosis factor-α (TNF-α) were measured by ELISA. The bioantioxidant power (BAP) was detected by BAP assay kit. RESULTS:The concentrations of endothelin-1 in induced sputum of healthy smokers and COPD patients were significantly higher than that of healthy non-smokers (P<0.05), and the level of endothelin-1 in COPD patients was significantly higher than that in healthy smokers (P<0.05). The levels of cleaved caspase-3, MMP-2, MMP-9, TNF-α and IL-1β in the lung tissues from cigarette-treated group were significantly higher than those in control group (P<0.05). The endothelin A receptor antagonist significantly inhibited the levels of cleaved caspase-3, MMP-2, MMP-9, TNF-α and IL-1β (P<0.05). The serum BAP in cigarette-treated group was significantly lower than that in control group (P<0.05). However, endothelin A receptor antagonist significantly increased serum BAP (P<0.05). CONCLUSION:Endothelin-1 may play an important role in the development and progression of COPD through regulating apoptosis, matrix metalloproteinase activity, inflammation and oxidative stress.     

镉胁迫对烟草种子萌发和烟苗生长发育的影响

为探讨不同镉（Cd）胁迫对不同烟草品种种子萌发、幼苗生长的生理生态效应的影响,以吉烟9号、吉烟10号、延晒六号3个烟草品种为材料,研究了不同浓度的Cd溶液对烟草种子萌发以及烟苗生长发育的影响。结果表明,Cd胁迫下烟草种子发芽势、发芽率、发芽指数、活力指数、苗高均受到抑制;烟苗叶绿素含量降低,根冠比变小,生长受到抑制,CAT活性、SOD活性、可溶性糖含量随Cd浓度的增加呈先增后降的趋势,POD活性、MDA含量、Pro含量、Cd含量均随Cd浓度的增加而增加。可见Cd胁迫能不同程度地影响烟草种子萌发和烟苗生长发育,烟苗体内的抗氧化酶系统被破坏,多种酶活性不协调,生理生化过程紊乱,最终导致烟苗受害。     

外源NO及反向调控PEG胁迫下苜蓿萌发种子抗氧化酶及其同工酶动态的研究

以紫花苜蓿为材料,用一氧化氮供体硝普钠(SNP)及一氧化氮清除剂c-PTIO对苜蓿种子进行浸种处理,采用分光光度法和同工酶电泳技术来研究外源NO及反向调控对PEG胁迫下紫花苜蓿抗氧化酶活性及其同工酶的影响,并探讨NO调控苜蓿种子耐旱性的生理机制。结果表明:PEG胁迫下外施0.1 mmol·L^-1 SNP,第6天时较PEG处理POD活性降低了32.72%;第4天时SOD、CAT活性较PEG处理升高了10.48%、23.60%,有效缓解了PEG对紫花苜蓿萌发中种子的氧化损伤,提高其抗氧化能力。PEG胁迫下添加 c-PTIO抑制了苜蓿萌发期的抗氧化系统活性。从同工酶的谱带数量和强弱来看,POD同工酶各区带活力均随PEG胁迫时间的延长而增加,在第2天酶带只有1条,而第4天酶带呈现9条;SOD和CAT同工酶表达量变化不显著,但酶带强弱有一定变化,S3酶带随处理时间的延长表达量逐渐减弱;CAT同工酶谱带则一直保持2条带,无明显强弱变化。因此,外源NO在PEG胁迫下紫花苜蓿萌发中抗氧化酶快速响应并在维护氧自由基代谢平衡中起重要保护作用。     

Captopril exerts myocardial protective effect in coronary microembolization rats by inhibiting oxidative stress injury and alleviating inflammatory response

AIM: To investigate the effects of captopril (CAP) on oxidative stress injury and inflammatory response induced by coronary microembolization (CME) and its related molecular mechanisms. METHODS: The rat model of CME was established by clamping the rat artery and injecting blood microemboli. The rats were divided into control group, CME group and CME+CAP group, with 6 rats in each group. The myocardial tissues of each group were collected. The changes of myocardial structure and the degree of inflammatory response were analyzed by HE staining. Cardiomyocyte apoptosis was detected by TUNEL staining. The fluorescence intensity of cleaved caspase-3 was detected by immunofluorescence obervation. The protein levels of cleaved caspase-3 and Bax were determined by Western blot. The activity of superoxide dismutase (SOD) and catalase was measured by ELISA. The production of reactive oxygen species (ROS) was detected by DHE fluorescence staining. RESULTS: CAP significantly reduced the myocardial structural changes (P<0.05), inflammatory cell infiltration (P<0.01), number of apoptotic cardiomyocytes (P<0.01), the protein levels of cleaved caspase-3 and Bax (P<0.01), and ROS production levels (P<0.01), but promoted the activity of antioxidant markers SOD and catalase (P<0.01) in the CME rats.CONCLUSION: CAP attenuates CME-induced myocardial injury by resisting oxidative stress and alleviating inflammatory response.