Constant and diurnally-varying temperature regimes lead to different temperature sensitivities of soil organic carbon decomposition

In a 122-day incubation experiment with two soil types under four temperature treatments, we examined whether the temperature sensitivity of soil organic carbon (SOC) decomposition differed between constant and diurnally-varying soil temperature regimes. We calculated the Q₁₀ values after accounting for changes in substrate availability and quality among treatments over time. The Q₁₀ values under constant temperature regime were consistently and significantly higher than those under diurnally-varying temperature regime, particularly in the later stages of decomposition (by up to 30%). This result indicated that different temperature regime was one of the important factors causing the current controversy about the temperature sensitivity of SOC decomposition in published reports.     

闽北杉木人工林标准表编制及应用的研究

以平均高为自变量,采用有约束的非线性最小二乘法建立林分最大蓄积量预估模型,结合形高模型,编制了杉木人工林标准表。为便于生产应用和生长预测,还建立了平均高和优势高的对等转换模型,配合地位指数曲线模型,导出了可变疏密度收获表。     

基于CFD软件的轴流式风力灭火机叶轮性能模拟研究

利用CFD软件对轴流式风力灭火机叶轮的内部流场进行数值模拟,与风机试验台的试验数值对比,验证了数值模拟分析的正确性,得到了风机内部流场情况.通过对内部流场分析,为叶轮的结构优化提供了重要的理论依据,并对扭角和安装角调整改进,使设计方案最佳.     

环洞庭湖棉区杂交棉种植密度探讨

通过在环洞庭湖棉区的桃源县进行湘杂棉8号的种植密度试验, 结果表明:在相同培管条件下,不同密度处理间农艺性状、籽棉产量等都表现出明显的差异,籽棉产量以24 000 株/hm2处理最高,为环洞庭湖棉区杂交棉的适宜种植密度.     

不同类型黑松混交林土壤微生物土壤酶和土壤养分含量的研究

对 3种类型黑松混交林及纯林的土壤微生物、土壤酶及土壤养分因子进行了测定和分析 ,结果表明 :各土壤类型土壤微生物数量、土壤酶的活性均表现出差异 ,混交林的土壤养分含量均高于纯林 ,尤以黑松×刺槐、黑松×麻栎混交林显著 ;土壤微生物数量、土壤酶活性与土壤养分含量之间呈显著相关关系     

生殖生长期遮阴对大豆脂肪酸积累动态的影响

大豆脂肪酸组分及配比影响大豆油脂的营养价值和贮运加工环节,是决定大豆油脂品质的最重要因素.尽管品种的遗传特性决定着脂肪酸各组分含量高低,生态环境通过影响脂肪酸的积累动态,同样影响着脂肪酸的含量.以品质不同的3个大豆品种(系)为材料,研究了生长生殖期遮阴对大豆籽粒发育过程脂肪酸各组分积累动态的影响.遮阴显著降低了黑农35和垦农18成熟籽粒内的棕榈酸和硬脂酸的含量(降幅达1.51%),并显著升高了亚油酸的含量(升幅达2.02%);与此相反,遮阴升高了海339大豆成熟籽粒内棕榈酸和硬脂酸含量(升幅达1.01%),并显著降低了亚油酸含量(降幅达2.63%).与对照相比,遮阴升高了海339大豆成熟籽粒内油酸含量(升幅达2.01%),但降低了黑农35成熟籽粒内油酸含量(降幅达1.72%),对垦农18成熟籽粒内油酸含量无影响.遮荫对大豆各脂肪酸组分含量动态的影响,因大豆品质和脂肪酸组分的不同而各异.开花后30 d是遮阴影响大豆籽粒内各脂肪酸组分积累的关键期,表明大豆群体过早郁闭将影响到大豆脂肪酸的品质,应根据不同品质大豆脂肪酸积累的生理特性确定合理的群体栽培管理措施.     

Mechanical insights into the effect of fluctuation in soil moisture on nitrous oxide emissions from paddy soil

Paddy fields are subjected to fluctuating water regimes as a result of the alternate drying and wetting water management, which often incurs a sensitive change in N₂O emissions from paddy soils. However, how the soil moisture regulates the emission of N₂O from paddy soil remains uncertain. In this study, three incubation experiments were designed to study the effects of constant and fluctuating soil moisture on N₂O emission and the sources of N₂O emission from paddy soil. Results showed that the N₂O emission from paddy soil at 100 % WHC (water-holding capacity) was higher than that at 40, 65, 80, 120, and 160 % WHC, indicating that 100 % WHC was the optimum soil moisture content for N₂O emission under the incubation experiment. Small peak of N₂O flux appeared when the soil moisture content from 250 % WHC decreased near to 100 % WHC, lower than that triggered by nitrogen (N) fertilization, which was mainly owing to the low NH₄ ⁺ concentration at this period. Nitrification dominated the emissions of N₂O from paddy soil at 250 % WHC (54.96 %), higher than that of nitrification-coupled denitrification (6.74 %) and denitrification (38.3 %). The contribution of denitrification to N₂O emissions (44.10 %) was equivalent to that of nitrification (44.45 %) in soil at 100 % WHC, which was higher than that of 250 % WHC treatment. In conclusion, the finding suggested that the peak of N₂O in paddy soils during midseason aeration could be attributed to the occurrence of optimum soil moisture under sufficient N availability, favorable for the production and accumulation of N₂O.     

3种生物农药及植物源农药防治东亚飞蝗效果评价

通过2005—2006年在河南省中牟县黄河滩区利用生物农药、植物源农药和常用化学农药防治东亚飞蝗的田间笼罩试验结果表明：30%杀蝗绿僵菌油悬浮剂167ml/hm2、250ml/hm2,药后14d的平均防效可达到90%左右,1%苦皮藤素乳油300ml/hm2、0.3%苦参碱水剂900ml/hm2两个处理的平均防效均达到90%以上,与中毒化学农药氟虫腈的防效接近,而优于低毒化学农药马拉硫磷的防效。鉴于杀蝗绿僵菌、苦皮藤素、苦参碱三种药剂均为低毒的生物农药和植物源农药,可作为替代有机磷和菊酯类农药用于东亚飞蝗的防治。     

2000—2020年漓江流域生态服务价值时空分异

[目的] 研究2000—2020年漓江流域生态服务价值(ESV)时空分异格局及变化规律,为优化土地利用结构和实现“双碳”目标提供空间治理方法。[方法] 基于遥感信息挖掘和地理信息分析平台,用价值核算及其动态度、敏感性分析方法评估生态服务价值,用空间自相关方法研究ESV时空格局,用地理探测方法诊断ESV分异的主导因素及驱动机制。[结果] ①漓江流域土地利用/覆盖空间异质性显著;林地、耕地面积最大,但变化平稳,建设用地增长迅速。②漓江流域生态服务价值约合3.75×10⁷元,其中林地、草地的ESV值最高,占总价值的52.44%。其变化呈先迅速增加、后缓慢减少的趋势,其中原材料生产、水土保持价值增强显著,而食物供给、水源涵养价值降低明显。③ESV总体上呈中游低值与上、下游高值的分异格局,表现为正向的空间集聚特征。[结论] 城镇扩张是漓江流域ESV时空分异及其动态变化的核心驱动,人类活动对ESV的扰动趋向增强。     

家蚕细胞色素C基因的克隆及其蛋白在家蚕凋亡细胞中的释放

 【目的】细胞色素C是线粒体凋亡路径上的关键因子,通过家蚕细胞色素C基因的克隆和其蛋白在家蚕凋亡细胞中的释放研究,为家蚕细胞凋亡的研究奠定基础。【方法】利用生物信息学和分子生物学方法克隆家蚕细胞色素C基因,通过紫外线照射诱导家蚕细胞凋亡,应用流式细胞仪和Western-blotting检测家蚕凋亡细胞的线粒体膜电位变化和细胞色素C的释放。【结果】在家蚕中克隆了一个含有细胞色素C保守结构域的同源基因,该基因cDNA长570 bp,有3个外显子,开放阅读框（open reading frame,ORF）长324 bp,编码108个氨基酸,存在参与细胞凋亡时与下游凋亡蛋白酶激活因子（Apaf－1）相互作用的保守关键位点;紫外线诱导家蚕胚胎细胞BmE-SWU1凋亡后12 h,细胞线粒体跨膜电位明显下降,同时检测到了细胞色素C由线粒体向细胞质释放。【结论】在家蚕细胞凋亡中可能存在细胞色素C由线粒体释放的路径。