退化人工柠条林灌下沙埋干预的土壤水文效应

灌丛沙堆是旱区灌丛植被水文过程的快通道,也是调节土壤水分平衡的关键点。以荒漠草原退化人工柠条林为研究对象,通过人工沙埋的方式改变灌丛沙堆大小与形态,在连续监测分析基础上(2012—2016年),探讨了人工沙埋干预下灌丛沙堆土壤水文过程与水文效应的动态响应。结果表明:与对照相比,(1)沙埋干预并未显著改变表层0—10cm主要的水文物理指标,但是显著提高了5—10cm土壤水分入渗速率,同时0—5cm初渗率显著降低;(2)沙埋干预明显提高了降水后表层0—5cm土壤的即时持水性,同时降水后表层土壤水分含量衰减过程呈现出很强的季节性变化;(3)2012—2016年生长季末沙埋处理的0—100cm土壤相对储水率分别为11.3%,-6.5%,4.5%,4.3%,15.7%,这种效应集中在0—60cm,对照处理下层土壤(60—100cm)水分含量的波动性更强。总体而言,沙埋干预对表层土壤水文物理特性无显著影响,但是显著提高了5—10cm土层水分入渗性能并降低了0—5cm初渗率;但是这种局部入渗性能的加强并未提高水分补给深度,上下层间水文联系反而弱化。沙埋干预的长期水文效应及其作为旱化成龄人工林适应性管理措施的适宜性还有待进一步的跟踪监测与分析。     

华北平原不同降水年型和作物种植模式下的产量和耗水模拟

华北平原是中国重要的粮食生产基地,在国家粮食产业中地位较高,但长期灌溉造成了华北平原地下水资源的严重亏损,地下水位持续下降。该研究利用APSIM模型对华北平原1986－2015年不同种植模式下的产量和耗水情况进行模拟研究,为华北平原调整作物种植模式、农业水资源管理以及农业发展政策的制定提供科学依据。研究结果表明：APSIM模型能够较好地模拟冬小麦和夏玉米的生育期、产量及水分利用特征,其中生育期模拟结果的误差在5 d之内,产量、ET和下渗量模拟结果的R2均在0.84以上,表明该模型在华北平原具有较好的适用性;在华北平原地区,冬小麦-夏玉米一年两熟种植模式（M2Y1）年均产量（13 445 kg/hm2）最高,但耗水量（724 mm）也是最大,水分亏损（233 mm）最为严重;一年一熟种植模式（M1Y1）年均耗水量（534 mm）较小,水分亏损量（43 mm）最少,但产量（9 215 kg/hm2）较低;两年三熟种植模式（M3Y2）兼顾产量和耗水,在保证一定产量的前提下减少了耗水量,产量耗水综合效果最好,适合在华北平原推广实行。此外,该研究对栾城站丰水年、平水年和枯水年等不同降水年型下的3种种植模式产量耗水特征进行了对比分析,研究表明在华北平原降水资源对于作物生长有重要意义,年降水量越大,作物产量越高,水分亏损量越少。     

Factor Analysis and Comprehensive Evaluation of the Fruit Quality of ‘Yangjiaocui’ Melons

【Objective】The aim of this study was to identify the typical indices of fruit quality and high quality materials of ‘Yangjiaocui’ melons to provide reference and basis for melon quality evaluation and breeding. 【Method】Eighteen indices, including economic trait and flesh quality of fruits from 6 cultivars and 26 high-generation inbred lines of ‘Yangjiaocui’ melons were determined. Based on factor analysis, stepwise regression, correlation analysis and two-dimension ordination map, the typical indices of fruit quality and high quality materials were identified. 【Result】 Among the 18 indices, single fruit mass, hardness, vitamin C (V_C) content, titratable acid content, sugar-acid ratio and solid acid ratio showed greater variability, and the variation coefficients were more than 20%. However, the variability of fruit transverse diameter, flesh thickness rate and pH were relatively lower and the variation coefficients were less than 10%. Three common factors were extracted from economic trait indices with 87.71% cumulative variance contribution rate and the explanatory indices were fruit longitudinal diameter, fruit transverse diameter, fruit shape index, fruit cavity longitudinal diameter, fruit cavity transverse diameter and flesh thickness rate. From quality indices, 4 common factors were extracted with 90.03% cumulative variance contribution rate and the explanatory indices were V_C content, hardness, total soluble solids content, total sugar content, titratable acid content, sugar-acid ratio and solid-acid ratio. Based on the comprehensive analysis of these selected 6 economic trait indices and 7 flesh quality indices, 5 common factors were extracted with 87.35% cumulative variance contribution rate. According to the correlation among the indices and the principle of simplicity and ease of use and avoidance of overlapping information, 5 indices, including fruit longitudinal diameter, flesh thickness rate, hardness, total sugar content and titratable acid content, could be used as typical indices to evaluate the fruit quality of ‘Yangjiaocui’ melons. The comprehensive quality score of all materials were ranked depended on scores and variance contribution rate of the above 5 common factor and two-dimension ordination map. Finally, 10 materials were selected as high quality materials. 【Conclusion】 Fruit longitudinal diameter, flesh thickness rate, hardness, total sugar content and titratable acid content could be used as typical indices to evaluate fruit quality of ‘Yangjiaocui’ melons. Inbred lines 25, 24, 22, 21, 8, 1, 17, 18, 20 and 23 were high quality materials.     

三峡水库对坝下河流水文情势影响研究

选取三峡水库下游宜昌水文站1950-2016年近70年的流量资料,采用Mann-Kendall法,分析宜昌水文站流量变化趋势。基于水文改变指标法(IHA)和变化范围法(RVA)评价三峡工程蓄水前后宜昌水文站32个IHA指标的水文改变程度,分析高度改变的水文指标,并基于32个IHA指标计算的水文改变度(D0)和DHRAM,分析三峡水库蓄水前后宜昌水文站整体水文情势变化,对宜昌站的水文改变程度进行定量评价。结果表明,在研究期间内,宜昌站年均流量呈减少趋势,在Mann-Kendall趋势检验中通过了95%的显著性检验,表明年均流量减少趋势显著;非汛期流量增加,汛期流量减少;年均最小流量和年均最大流量分别表现为增大和减少的趋势,年最小流量出现时间提前;低脉冲发生频率消失,高脉冲发生次数和历时略有下降;上升率和下降率均有减少趋势,逆转次数的水文改变度达到100%。通过DHRAM和D0计算后,水文情势整体为中度改变。     

Response of hydrological drought to meteorological drought in the eastern Mediterranean Basin of Turkey

The hydrographic eastern Mediterranean Basin of Turkey is a drought sensitive area. The basin is an important agricultural area and it is necessary to determine the extent of extreme regional climatic changes as they occur in this basin. Pearson's correlation coefficient was used to show the correlation between standardized precipitation index(SPI) and standardized streamflow index(SSI) values on different time scales. Data from five meteorological stations and seven stream gauging stations in four sub-basins of the eastern Mediterranean Basin were analyzed over the period from 1967 to 2017. The correlation between SSI and SPI indicated that in response to meteorological drought, hydrological drought experiences a one-year delay then occurs in the following year. This is more evident at all stations from the mid-1990 s. The main factor causing hydrological drought is prolonged low precipitation or the presence of a particularly dry year. Results showed that over a long period(12 months), hydrological drought is longer and more severe in the upper part than the lower part of the sub-basins. According to SPI-12 values, an uninterrupted drought period is observed from 2002–2003 to 2008–2009. Results indicated that among the drought events, moderate drought is the most common on all timescales in all sub-basins during the past 51 years. Long-term dry periods with moderate and severe droughts are observed for up to 10 years or more since the late 1990 s, especially in the upper part of the sub-basins. As precipitation increases in late autumn and early winter, the stream flow also increases and thus the highest and most positive correlation values(0.26–0.54) are found in January. Correlation values(ranging between –0.11 and –0.01) are weaker and negative in summer and autumn due to low rainfall. This is more evident at all stations in September. The relation between hydrological and meteorological droughts is more evident, with the correlation values above 0.50 on longer timescales(12-and 24-months). The results presented in this study allow an understanding of the characteristics of drought events and are instructive for overcoming drought. This will facilitate the development of strategies for the appropriate management of water resources in the eastern Mediterranean Basin, which has a high agricultural potential.     

莲花湖库区几种主要林型水文功能的分析和评价

对莲花湖库区流域人工林主要林型的降水截持效益、林地和荒草地枯落物层持水性能、土壤层物理性状及其蓄水效益进行了研究。结果表明：红松人工林、落叶松人工林和杂木林林冠截留率分别为34.83%,13.05%,19.61%,树干茎流率分别为6.79%,0.58%,4.01%,穿透率分别为58.37%,86.18%,77.66%。兴安落叶松林、红松林、杂木林和荒草地枯落物层最大持水率分别为278.2%,295.3%,260.3%,154.8%。莲花湖库区不同植被类型下枯落物持水能力为红松林最好,荒草地最差。各林型土壤最大蓄水量变化范围为1 838.6-2 186.3t/hm^2,依次为落叶松林〉杂木林〉红松林〉荒草地;从土层厚度来说,土壤入渗速率随土层厚度的下移表现出逐步降低的趋势,即空间特征表现出土层上部〉中部〉下部。以坡面径流观测场为观测手段,分析了4个径流小区产流产沙与降雨因子的相关关系,结果表明,场降雨产流量和产沙量与降雨量和雨强均呈良好的相关关系。     

试论农民代言人出现的背景及其对农民话语权回归的作用

介绍了在目前我国农民存在着制度缺陷型、能力欠缺型及信息断裂型话语缺失的背景下,一些非农精英人士自觉自愿承担起农民代言人的角色,为推动"三农"问题的解决发挥了巨大的作用。并提出农民代言人的终极使命应该是帮助农民完全掌握与其他阶层平等的话语权,实现从"代农民言"到"农民自己言"的转变。     

底层土对一年生苹果树生长发育的影响

一年生苹果树枝年生长量与表层根生长量相关显著，底层土肥沃疏松，植株生长中庸健壮，碳素积累水平高，底层土透气性良好而肥分低，粗根量大，底层土轻度盐碱，植株有最大生长量，但秋梢长，组织不充实，碳素积累少。     

河北北部二代粘虫发生的预测

根据丰南县1981～1990年粘虫田间发生的调查资料,经回报检验,10a 粘虫发生情况的回报准确率均为90%,明显高于经验预报,而且能在粘虫实际发生前1个月做出定量预报,具有较好的实用价值。     

延边地区高温年水稻不同品种产量表现

为了解气候变暖趋势下现有水稻品种在延边地区的生育特征及其产量表现,利用国内外41个粳稻品种在本地区进行产量对比试验。结果表明,熟期适合的品种在生育前期高温年表现早熟、早衰,增产幅度较小,而属于偏晚熟型的品种抽穗期提早,增产幅度大。认为在全球气候变暖趋势下,准确预测生育期积温变化趋势,合理布局不同熟期品种是延边地区低温年保稳产,高温年防早衰、争高产的重要途径之一。