不同水肥浓度对涌泉根灌枣树叶面积和产量的影响

以陕西榆林山地矮化密植梨枣树为研究对象,分析了不同水肥浓度对涌泉根灌枣树生育期内叶面积指数、果实发育和产量的影响。结果表明,不同水肥处理叶面积指数在枣树果实膨大期达到高峰,且稳定持续至果实成熟期末期,随后叶面积指数开始下降。叶面积指数随着萌芽展叶期灌水量的增加而增加,所有水肥处理下,枣数叶面积指数最大的是高水中肥处理(W1N2)；所有处理中,高水、低水处理与低肥相组合,果实体积最大,中灌水处理为不施肥时果实的体积最大。单位枝长的果实数目最高的是中水中肥处理(W2N2),最低的是低水处理(W3),在一定范围内,适当施肥能促进枣果单位枝长的果实数目的增加,但肥液浓度过大,反而会抑制其增加。在一定条件下,所有处理中产量最高的是中水中肥处理(W2N2),产量超过2000kg/亩,最低的是低水高肥处理(W3N1),产量不到1000kg/亩。因此可以选择中水中肥处理(W2N2),能获得最高的产量。     

Trx-1 over-expression attenuates oxidative stress injury in MPP+ -induced PC12 cells by regulating NF-κB signaling pathway

AIM:To investigate the inhibitory effect of thioredoxin 1 (Trx-1) over-expression on oxidative stress injury in 1-methyl-4-phenylpyridinium (MPP⁺)-induced rat pheochromocytoma PC12 cells by regulating NF-κB signaling pathway.METHODS:The PC12 cells were damaged by treatment with MPP⁺ at 1, 3 and 5 mmol/L, and the optimal concentration of 3 mmol/L was selected. The cell viability was measured by MTT assay. The oxidative stress indexes lactate dehydrogenase (LDH) activity, superoxide dismutase (SOD) activity and malondialdehyde (MDA) content in the cell culture supernatant were detected, and the protein expression of Trx-1 was determined by Western blot. Lentiviral infection with Ad-Trx-1-GFP sequence was used to establish a model of MPP⁺-treated PC12 cells with Trx-1 over-expression. The effects of Trx-1 over-expression on the cell viability, oxidative stress responses and NF-κB signaling pathway were determined by MTT assay, commercial kits and Western blot. The effects of phorbol 12-myristate 13-acetate (PMA), an activator of NF-κB signaling pathway, on the viability and oxidative stress of PC12 cells were observed. The NF-κB signaling pathway inhibitor pyrrolidine dithiocarbamate (PDTC) was used in MPP⁺-treated PC12 cells with Trx-1 over-expression, and the cell viability and oxidative stress responses were measured. RESULTS:The viability of PC12 cells, SOD activity in the supernatant and protein expression of Trx-1 were decreased, while LDH activity and MDA content in the supernatant were increased significantly by treatment with MPP⁺ at 1, 3 and 5 mmol/L. The effect of MPP⁺ at 3 mmol/L and 5 mmol/L was significantly greater than that at 1 mmol/L (P<0.05), and no significant difference between 3 mmol/L and 5 mmol/L was observed (P>0.05). The inhibitory effect of MPP⁺ on the viability of PC12 cells, and the oxidative stress injury and activation of NF-κB signaling pathway induced by MPP⁺ were significantly attenuated by over-expression of Trx-1. The inhibitory effect of MPP⁺ on the viability of PC12 cells and the oxidative stress injury induced by MPP⁺ were promoted by the activation of NF-κB signaling pathway, while the protective effects of Trx-1 over-expression on the MPP⁺-treated PC12 cells were enhanced by the inhibition of NF-κB signaling pathway. CONCLUSION:Over-expression of Trx-1 protects MPP⁺-treated PC12 cells from oxidative stress injury by regulating NF-κB signaling pathway.     

不同供磷水平对辣椒根系形态和根际特征的影响

以辣椒品种线椒王为试验材料，采用盆栽方式，通过分析不同施磷水平下辣椒根系形态和根系生理的变化，探究辣 椒磷高效利用的主要根系及根际过程。结果表明，辣椒地上部和根系生物量随供磷水平的增加呈现先增加后下降的趋势，整 株磷浓度以及整株磷累积量呈增加趋势。随供磷水平增加，根系总根长呈先增加后下降趋势，根系平均直径、根冠比呈逐渐 降低趋势；辣椒根系菌根侵染率和土壤酸性磷酸酶活性呈现先增加后下降的趋势。相关分析结果表明，土壤有效磷浓度和整 株磷浓度与根系平均直径、菌根侵染率呈极显著负相关，与总根长可用一元二次方程拟合，表明辣椒根系适应低磷的根际特 征可能是通过增加根系生物量及总根长，同时降低根系平均直径来实现的。     

食用型紫心甘薯新品种湘紫薯174 的选育

湘紫薯174 是以浙紫薯1 号为母本、浙紫薯3 号为父本杂交选育而成的食用型紫心甘薯新品种，薯块纺锤形，薯皮 紫红色，薯肉紫色，结薯较集中整齐，单株结薯4～5 个，大中薯率82.7% 以上，熟食味好，抗黑斑病，中抗根腐病、茎线 虫病和薯瘟病；每667 m² 鲜薯产量1 913～2 359 kg，薯干产量549～736 kg；花青素含量为714.5 mg · kg^-1（FW）。适宜在湖 南、湖北、江西、江苏、浙江等地春夏薯区种植。     

400克/升氯氟醚菌唑悬浮剂对香蕉叶斑病的防治效果

通过大田试验研究了400克/升氯氟醚菌唑悬浮剂防治香蕉叶斑病效果及其对香蕉产量的影响。研究结果表明,分别以20毫升、13.3毫升、10毫升400克/升氯氟醚菌唑悬浮剂兑水60公斤分3次喷雾施药,第二次施药后14d后对香蕉叶斑病防治效果在60.43-66.52%,第三次施药后14d后对香蕉叶斑病防治效果在75.72-80.72%,并对香蕉的单株产量有明显增产效果。其中尤以20毫升400克/升氯氟醚菌唑悬浮剂兑水60公斤剂量喷雾处理的效果最好。     

不同因素影响下层状土壤水分入渗特征及水力学参数估计

层状土壤是自然界常见的土体结构,其水分运移规律不同于均质土;大气降水、灌溉水等水分的入渗是土壤水文过程的一个重要环节,同时它也与地下水补给、污染物运移等过程紧密相关。土壤初始含水量、土体构型及供水强度等因素均会影响水分的入渗过程。为探究积水深度、土体构型、初始含水量三种因素对层状土壤水分运移的影响,通过室内积水入渗试验对湿润锋、累积入渗量、土壤剖面压力水头进行观测,并利用Hydrus-1D模型反演水力参数并对相应条件下的水分运移规律进行模拟和分析。结果表明,层状土壤中湿润锋随时间的推进方式由非线性过渡至线性,入渗率逐渐减小。三种因素作用下,层状土壤水分运移特征有明显差异:积水深度、土壤初始含水量增加时,湿润锋运移速率和入渗率均增大,且各观测点压力水头升高加快,土壤不饱和程度降低;上砂壤下粉砂壤构型较上粉砂壤下砂壤构型而言,整体湿润锋推进速率和入渗率较大,出流快,且入渗后期界面处的压力水头高于其他观测点。且结果表明,反演的水力学参数较拟合实测的参数更适用于层状土壤入渗的模拟和预测。该研究旨在揭示和掌握层状土壤水分运移规律和影响因素的作用机制,并进一步为农田灌溉措施的合理制定提供科学依据。     

Exploring tree diversity and stand structure of savanna woodlands in southeastern Sudan

Savanna woodlands in Sudan host great biodiversity, provide a plethora of ecosystem goods and services to local communities, and sustain numerous ecological functions. Although the importance of the Acacia trees in these areas is well known, up-to-date information about these woodlands' diversity is limited and changes in their woody vegetation composition, density, diversity and relative frequency are not monitored over time. This study explored tree diversity and stand stage structure in Nuara Reserved Forest, a typical savanna woodland ecosystem in southeastern Sudan. A total of 638 circular sample plots (1000 m² for each) were established using a systematic sampling grid method. The distance between plots was 200 m. In each plot, all living trees with diameter at breast height (DBH) ≥5.00 cm were identified and counted, and their DBH values were recorded. From these data, tree composition, diversity, density and stage structure were assessed. There were 12,259 individual trees representing four species (Acacia seyal, Balanites aegyptiaca, Acacia Senegal and Acacia mellifera) that belong to two families. The dominant species was Acacia seyal. Average tree density was 191 trees/hm² and the Shannon-Weiner index for trees diversity was 0.204. Overall, young trees comprised 86.30% of the forest. The state of tree richness and density in the study area was low compared to other similar environments in the region and around the world. We recommended adoption of a proper management system that includes monitoring of woody vegetation diversity in this forest, and management actions to enhance tree diversity and sustain ecosystem services to local communities. In addition to care for the dominant Acacia seyal stands, more attention and conservation should be devoted to reestablishing Acacia senegal and Acacia mellifera trees because of their high ecological and economic values for local communities.     

Performance and uncertainty analysis of a short-term climate reconstruction based on multi-source data in the Tianshan Mountains region,China

Short-term climate reconstruction, i.e., the reproduction of short-term(several decades) historical climatic time series based on the relationship between observed data and available longer-term reference data in a certain area, can extend the length of climatic time series and offset the shortage of observations. This can be used to assess regional climate change over a much longer time scale. Based on monthly grid climate data from a Coupled Model Inter-comparison Project phase 5(CMIP5) dataset for the period of 1850–2000, the Climatic Research Unit(CRU) dataset for the period of 1901–2000 and the observed data from 53 meteorological stations located in the Tianshan Mountains region(TMR) of China during the period of 1961–2011, we calibrated and validated monthly average temperature(MAT) and monthly accumulated precipitation(MAP) in the TMR using the delta, physical scaling(SP) and artificial neural network(ANN) methods. Performance and uncertainty during the calibration(1971–1999) and verification(1961–1970) periods were assessed and compared using traditional performance indices and a revised set pair analysis(RSPA) method. The calibration and verification processes were subjected to various sources of uncertainty due to the influence of different reconstructed variables, different data sources, and/or different methods used. According to traditional performance indices, both the CRU and CMIP5 datasets resulted in satisfactory calibrated and verified MAT time series at 53 meteorological stations and MAP time series at 20 meteorological stations using the delta and SP methods for the period of 1961–1999. However, the results differed from those obtained by the RSPA method. This showed that the CRU dataset produced a low degree of uncertainty(positive connection degree) during the calibration and verification of MAT using the delta and SP methods compared to the CMIP5 dataset. Overall, the calibrated and verified MAP had a high degree of uncertainty(negative connection degree) regardless of the dataset or reconstruction method used. Therefore, the reconstructed time series of MAT for the period of 1850(or 1901)–1960 based on the CRU and CMIP5 datasets using the delta and SP methods could be used for further study. The results of this study will be useful for short-term(several decades) regional climate reconstruction and longer-term(100 a or more) assessments of regional climate change.     

典型喀斯特洼地植被恢复过程中土壤碳氮储量动态及其对极端内涝灾害的响应

西南喀斯特地区是我国主要的生态脆弱区之一,石漠化严重,旱涝灾害频发。植被恢复是提升脆弱生态系统土壤碳氮固持的有效方式,但该区不同植被恢复方式土壤碳氮动态监测的研究还很缺乏。本研究以典型喀斯特峰丛洼地为对象,选取人工林、牧草地、人工林+牧草地、撂荒地自然恢复4种最主要的植被恢复方式为研究对象,以耕地作为对照,对比分析退耕前(2004年)、退耕10年(2014年)和13年后(2017年)土壤碳氮储量动态变化特征。其中2004—2014年研究区未发生极端内涝灾害, 2014—2017年连续发生2次极端内涝灾害事件。研究结果表明,退耕10年后, 4种恢复方式下土壤有机碳(SOC)储量均显著增加,但退耕13年后,除撂荒地SOC持续增加外,其他3种恢复方式下SOC表现出下降趋势。植被恢复后土壤全氮(TN)储量提升相对缓慢,退耕10年仅牧草地显著增加,退耕13年后人工林+牧草和撂荒地TN增加,且撂荒地在退耕后呈持续增加趋势。相关性分析结果表明,土壤交换性Ca~(2+)与SOC、TN均呈显著正相关关系,且与2014年相比, 2017年不同植物恢复方式下土壤交换性Ca~(2+)均显著下降,这可能与研究区2015年和2016年连续内涝灾害有关。以上结果说明,不同恢复方式均能显著提升喀斯特地区土壤碳氮固持,并以自然恢复最佳,其生态系统能有效抵御极端气候灾害带来的负面影响。     

运用植被指数时序特征对落叶松人工林分类

为探究植被指数时序特征是否有利于落叶松人工林提取,以孟家岗林场为研究试验区域,根据落叶松人工林季相和物候特征,利用Landsat8OLI影像数据提取研究区内5种植被的归一化植被指数(I NDV)、差值植被指数(I DV)、比值植被指数(I RV)、增强型植被指数(I EV),构建相应的植被指数时序特征。采用最大似然和随机森林两种方法对单一时相影像和加入植被指数时序特征的影像进行对比试验。结果表明:影像中加入植被指数时序特征后,最大似然算法的分类总体精度为89.53%,Kappa系数为0.87,比单一时序特征的影像分类精度提高了13.35%;随机森林算法的森林类型分类总体精度为93.22%,Kappa系数为0.92,比单一时序特征的影像分类精度提高了19.8%。因此,加入植被指数时序特征后能得到更高的落叶松人工林提取精度。