经验正交函数与地统计相结合分析降水时空变异

把经验正交函数展开和地统计分析有机结合,以河南省近51年雨季降水为例,进行降水时空变异特征研究。结果表明,用经验正交函数把降水变量场的主要空间分布结构分离出来,可正确地提取时间函数向量;再运用地统计分析对河南省多年雨季降水空间函数特征向量进行空间变异结构分析与插值,得出了河南省雨季降水量空间分布的主要4种类型:总体一致型、南北差异型、东西差异型和豫西山区异常型;然后对时间函数进行分析,得到了对应空间分布型的年际变化趋势规律。     

河南省国土空间开发与生态环境耦合关联时空格局研究

国土空间开发与生态环境间是相互关联及协调促进的关系,探究其耦合协调度及空间关联格局对地区实现高质量发展和生态文明建设意义重大。本文采用熵值法和指标体系评价法分别测算了2008—2018年河南省地级市的国土空间开发程度及生态环境水平,在此基础上,运用耦合协调度模型和空间自相关分析评价了两者耦合协调度及空间关联的时空分异特征。研究表明,2008—2018年河南省各地市国土空间开发水平整体稳中有进,生态环境水平呈缓慢缩减并提升的态势。河南省国土空间开发与生态环境的耦合协调度主要处于濒临失调与勉强协调阶段,并随时间推移呈增强趋势,空间分布差异明显,整体呈现“中东部协调过渡,中部和西北部协调提升”的特征。全局空间自相关表明国土空间开发及生态环境水平均存在显著正相关性;两者耦合协调度历年呈正相关性,且具有明显集聚特征,HH型多以“组团”形式出现,LL型由“散布”式向“组团”式转变,LH型多散布在LL型周边;空间上看,中部和西部地区耦合协调度较高,区域间多形成HH集聚区,东部和南部地区耦合协调不足,多形成LL集聚区。     

京津冀地区耕地利用时空分异与影响机制分析

京津冀地区耕地资源的不均衡分布使得社会经济发展的地域差异性突出,厘清其耕地时空异质性对于地区协调可持续发展有着重要意义。基于京津冀地区,采用耕地动态变化模型及地理探测器等方法对1990—2020年间其耕地空间分布演化与影响机制进行了探讨。结果表明:北京市率先进入工业化城镇建设,天津市次之,河北省滞后,相对的耕地变化动态度高值也先后出现。耕地分布集聚特征显著,呈现"东南密西北疏"的核密度格局。土地利用结构改变特征明显,面积净增长的主要有建设用地、林地及水域,面积净减少的主要有耕地、草地及未利用地。耕地流失主要表现出环北京及环渤海为中心的聚集式特征,且东部流失的热度比西部高,南部比北部高。社会经济及政策因素对耕地利用的影响力呈上升趋势,而自然因素的影响力呈下降趋势。本研究结果可为京津冀地区耕地保护、区域协调发展提供科学依据。     

区域农业灌溉用水量预测研究进展

农业灌溉用水量的准确预测对于研究农业水资源高效利用,合理优化配置水资源具有十分重要的意义。根据农业灌溉用水量预测方法及区域尺度转换,研究总结区域农业灌溉用水量预测的现状,提出研究中存在的问题。结果表明:灌溉用水量预测模型主要基于作物需水机理、数理统计规律以及启发式算法;农业灌溉用水量预测方法存在局限性、灌区尺度转换研究较少,以及影响因素存在时空变异性等问题。研究结果可为区域农业灌溉用水量预测研究方向提供参考。     

Explaining rice yields and yield gaps in Central Luzon,Philippines: An application of stochastic frontier analysis and crop modelling

Explaining yield gaps is crucial to understand the main technical constraints faced by farmers to increase land productivity. The objective of this study is to decompose the yield gap into efficiency, resource and technology yield gaps for irrigated lowland rice-based farming systems in Central Luzon, Philippines, and to explain those yield gaps using data related to crop management, biophysical constraints and available technologies.Stochastic frontier analysis was used to quantify and explain the efficiency and resource yield gaps and a crop growth model (ORYZA v3) was used to compute the technology yield gap. We combined these two methodologies into a theoretical framework to explain rice yield gaps in farmers’ fields included in the Central Luzon Loop Survey, an unbalanced panel dataset of about 100 households, collected every four to five years during the period 1966–2012.The mean yield gap estimated for the period 1979–2012 was 3.2 ton ha⁻¹ in the wet season (WS) and 4.8 ton ha⁻¹ in the dry season (DS). An average efficiency yield gap of 1.3 ton ha⁻¹ was estimated and partly explained by untimely application of mineral fertilizers and biotic control factors. The mean resource yield gap was small in both seasons but somewhat larger in the DS (1.3 ton ha⁻¹) than in the WS (1.0 ton ha⁻¹). This can be partly explained by the greater N, P and K use in the highest yielding fields than in lowest yielding fields which was observed in the DS but not in the WS. The technology yield gap was on average less than 1.0 ton ha⁻¹ during the WS prior to 2003 and ca. 1.6 ton ha⁻¹ from 2003 to 2012 while in the DS it has been consistently large with a mean of 2.2 ton ha⁻¹. Varietal shift and sub-optimal application of inputs (e.g. quantity of irrigation water and N) are the most plausible explanations for this yield gap during the WS and DS, respectively.We conclude that the technology yield gap explains nearly half of the difference between potential and actual yields while the efficiency and resource yield gaps explain each a quarter of that difference in the DS. As for the WS, particular attention should be given to the efficiency yield gap which, although decreasing with time, still accounted for nearly 40% of the overall yield gap.     

变化环境下沈乌灌域土地利用/覆盖时空变化分析

为了研究变化环境下内蒙古河套灌区沈乌灌域土地利用/覆盖时空变化,并对今后节水改造和节水规划提供指导依据,以沈乌灌域1995、2005年及2015年Landsat影像为数据源,采用基于CART算法的决策树分类对灌域20 a来5种土地利用/覆盖类型进行了分类,并计算了各土地利用/覆盖类型的单一动态度、双向动态度、变化趋势和状态指数,研究了引黄水量等环境变化因子作用下灌域土地利用/覆盖的时空变化。结果表明,(1)1995—2015年沈乌灌域内沙地和盐碱地分别减少了43.77%和62.54%,植被和荒地分别增加了75.10%和92.32%。(2)沙地、盐碱地和荒地向植被的转化是植被面积增加的主要原因;荒地频繁与沙地、盐碱地发生相互转化,相互转化的位置主要出现在沙地和渠道的周边。(3)引水量和地下水埋深是盐碱地、水体的变化主要因子,工程建设是沙地和植被覆盖区变化的主要因子。为缓解灌域的用水矛盾,今后在制定节水规划时应统筹考虑土地利用类型/覆盖与节水改造的关系。     

Growth response of 98 barley (Hordeum vulgare L.) genotypes to elevated CO2 and identification of related quantitative trait loci using genome‐wide association studies

Elevated CO₂ (eCO₂) concentrations can stimulate crop growth, but little is known about intraspecific variability in the response to eCO₂ and the underlying genetics in cereals. Field experiments over two years with 98 barley genotypes were conducted in open‐top chambers (OTCs) under ambient CO₂ (400 ppm) and eCO₂ (700 ppm) concentrations. At crop maturity, different fractions of aboveground biomass (AGB) were measured, and genome‐wide association studies (GWASs) were conducted to identify quantitative trait loci (QTL). Averaged across all genotypes, eCO₂ significantly enhanced AGB by 15%, while the increase in culm and ear biomass alone was not significant. The AGB response to eCO₂ of the individual genotypes ranged from c. ?36% to +95% compared with ambient CO₂ (aCO₂), showing a large variability of growth responses. In GWAS, 51 associations between SNP markers and the relative changes (eCO₂/aCO₂) in biomass were detected on different chromosomes. Loci potentially involved in biomass alterations under eCO₂ were identified. The wide range of variability in responses might be exploited by marker‐based breeding for climate‐resilient barley.     

基于OMI数据白银市SO2浓度时空分布特征研究

选取Aure卫星搭载的臭氧监测仪(OMI)Level-2痕量数据,采用遥感图像处理方法和地理信息系统分析技术,解译甘肃省白银市大气边界层SO2浓度,探究2011-2013年大气SO2时空分布特征,估算SO2 的排放总量。结果表明,研究区SO2量值分布极不平衡,呈现离散面状分布格局,中高值区域主要集中在白银区城市建成区域的中南部地区及平川区城市建成区域的中西部地区；浓度在各月份呈现“U”型分布,表现出冬季浓度最高,夏季最低的特点；不存在明显高值范围,但中高柱量值浓度SO2柱量值区的范围明显增加。研究表明,通过OMI痕量数据,建立模型对地面环境的栅格数据评价,为白银市SO2远程监测提供理论依据和方法参考。     

Heritabilities of nutritive quality factors and interrelationships with yield in selected progenies of tall fescue

Nine polycross (PX) and nine different self (S₁) progenies were randomly chosen from 43 selected tall fescue genotypes and evaluated for in vitro digestible organic matter (IVDOM), crude protein, neutral detergent fibre, acid detergent fibre and acid detergent lignin of whole plants, leaf blades and stems (stem plus leaf sheath) at each of four harvest dates in 1991 and 1992. Significant variation for all whole‐plant and leaf quality traits occurred among the PX progenies at the May harvest. Variation among S₁ progenies was significant for almost all of the stem traits. Genetic variance components for both progeny groups were significant for almost all of the traits, confirming the presence of additive genetic variation. Heritability estimates on a progeny‐mean basis ranged from medium to high for almost all the traits of the whole‐plant and the leaf and stem fractions. The results suggest that spring would be the time at which direct selection for high IVDOM or low fibre content would be successful and that selection for leaf or stem quality traits improves whole‐plant quality. Selection for quality traits in the summer or in the autumn would be difficult since no significant genetic variability was found.     

Characterization of potato potyvirus Y (PVY) isolates from seed potato batches. Situation of the NTN, Wilga and Z isolates

A collection of 38 PVY isolates from seed potato batches, originating from several Western European countries, was characterized by using current biological, serological and molecular tools differentiating PVY strains and groups. The correlation between the three kinds of tests was good but not absolute. No single serological or PCR method was able to discriminate among the five isolate groups found. Twenty-nine isolates belonged to the PVY^N strain and six to the PVY^O strain. No PVY^C was found. Two other isolates reacted serologically like PVY^O, but were unable to elicit a hypersensitive response from the Ny_tbr gene and probably represent the PVY^Z group. At the molecular level, these two isolates showed a combination of both PVY^O and PVY^N and could be recombinants of these strains. Another isolate reacted serologically like PVY^O, but induced vein necrosis in tobacco, like PVY^N-Wilga. Some PVY^N isolates caused tuber ring necrosis in glasshouse conditions. These might belong to the PVY^NTN group. The PVY^NTN, PVY^N-Wilga and PVY^Z groups probably represent pathotypes within strains PVY^N and PVY^O, respectively. The present study also confirms previous reports showing a high genetic variation at the 5 end within the PVYN strain.