Seasonal and Annual Variations of CO_2 Fluxes in Rain-Fed Winter Wheat Agro-Ecosystem of Loess Plateau, China

To accurately evaluate the carbon sequestration potential and better elucidate the relationship between the carbon cycle and regional climate change, using eddy covariance system, we conducted a long-term measurement of CO 2 fluxes in the rain-fed winter wheat field of the Chinese Loess Plateau. The results showed that the annual net ecosystem CO 2 exchange （NEE） was （-71.6±5.7） and （-65.3±5.3） g C m-2 y-1 for 2008-2009 and 2009-2010 crop years, respectively, suggesting that the agro-ecosystem was a carbon sink （117.4-126.2 g C m-2 yr-1）. However, after considering the harvested grain, the agro- ecosystem turned into a moderate carbon source. The variations in NEE and ecosystem respiration （R eco ） were sensitive to changes in soil water content （SWC）. When SWC ranged form 0.15 to 0.21 m3 m-3, we found a highly significant relationship between NEE and photosynthetically active radiation （PAR）, and a highly significant relationship between R eco and soil temperature （T s ）. However, the highly significant relationships were not observed when SWC was outside the range of 0.15-0.21 m3 m-3. Further, in spring, the R eco instantly responded to a rapid increase in SWC after effective rainfall events, which could induce 2 to 4-fold increase in daily R eco , whereas the R eco was also inhibited by heavy summer rainfall when soils were saturated. Accumulated R eco in summer fallow period decreased carbon fixed in growing season by 16- 25%, indicating that the period imposed negative impacts on annual carbon sequestration.

Effects of Farmyard Manure and Inorganic Fertilizer Application on Soil Physico-Chemical Properties and Nutrient Balance in Rain-Fed Lowland Rice Ecosystem

A field experiment was conducted to assess the effects of combined application of farm yard manure (FYM) and inorganic NP fertilizers on soil physico-chemical properties and nutrient balance in a rain-fed lowland rice production system in Fogera plain, northwestern Ethiopia. The study was carried out during the main cropping seasons of 2010 and 2011. Twenty-seven treatments comprising a factorial combination of three rates of FYM (0, 7.5, and 15 t·ha-1), three rates of nitrogen (0, 60, 120 kg·N·ha-1) and three rates of phosphorus (0, 50 and 100 kg·P2O5·ha-1) were tested. The experiments were laid out as a randomized complete block design with three replications. Bulk density, organic matter content, and available water holding capacity, total N, and available P of the soil were measured just after harvesting the rice crop. Results showed that application of 15 t·FYM·ha-1 significantly increased soil organic matter and available water holding capacity but decreased the soil bulk density, creating a good soil condition for enhanced growth of the rice crop. Application of 15 tFYM·ha-1 increased the level of soil total nitrogen from 0.203% to 0.349%. Combined application of 15 t·ha-1·FYM and 100 kg·P2O5·ha-1 increased the available phosphorous from 11.9 ppm to 38.1 ppm. Positive balances of soil N and P resulted from combined application of FYM and inorganic N and P sources. Application of 15·t ha-1·FYM and 120 kg·N·ha-1resulted in 214.8 kg·ha-1·N positive balance while application of 15 t·ha-1·FYM and 100 kg·P2O5·ha-1 resulted in a positive balance of 69.3 kg·P2O5·ha-1 available P. From the results of this experiment, it could be concluded that combined application of FYM and inorganic N and P fertilizers improved the chemical and physical properties, which may lead to enhanced and sustainable production of rice in the study area.

Potato yield gaps across the rainfed Yin-mountain Hilly Area of China

Yin-mountain Hilly Area is one of the ideal regions for potato （Solanum tuberosum） production in China. However, potato yield is severely limited as a result of rain-fed crop mode due to water deficiency, as well as an inadequate farming practices. In this study, yield gaps were determined by using attainable yield （Ya） as a benchmark under optimized management practices, i.e., micro-ridge and side planting with plastic-mulching （MS）, and flat planting with plastic-mulching （PM）. The yields under MS and PM modes are defined as Yal and Ya2, respectively. Under the same field with MS and PM modes but different densities and fertilizer usages and so on, it was defined as simulated farmers＇ practices. The yield of simulated farmers＇ practices （Yfl） reached 57.3 and 69.6% of Yal and Ya2, respectively, while the average yield of 298 randomly surveyed farmers （Yf2） reached only 37.0 and 47.8% of Yal and Ya2 for rain-fed potato, respectively. The gaps of water use efficiency exhibited similar pattern. Further analysis shows that improper measures in rainwater conservation and accumulation, and other management practices contributed to 18.5, 18.2, and 42.6% of yield gap between Yal and Yf2. Improper nutrition management, including overuse of nitrogen and the deficiency of phosphorus andpotassium supplication, was one of the important reasons of yield gap. The results indicate the possibilities of increasing rain-fed potato yields by optimized water and fertilizermanagements in the Yin-mountain Hilly Area.

Water use efficiencies of maize cultivars grown under rain-fed conditions

Enhancing water use efficiencies of rain-fed maize is a requirement for sustainable maize production, particularly in areas prone to low/drought and erratic rainfall patterns. This study was conducted to assess the relationship between total biomass/grain yield and water use efficiencies of three maize cultivars (Golden Crystal, Mamaba and Obatanpa) grown under rain-fed conditions in a coastal savannah agro-ecological environment of Ghana. Results of the study showed that a unified linear model, WUETDM = 0.03TDM with R2 = 0.765 and P ≤ 0.001, described adequately the relation between wa-ter use efficiency and total biomass (dry matter), which is applicable for the three maize cultivars for both the major and minor cropping seasons. A linear model could only, however, describe adequately well the relation between WUEGY and GY for the major (WUEGY = 0.001GY – 0.67;R2 = 0.996;P ≤ 0.001) and minor (WUEGY = 0.002GY + 0.289;R2 = 0.992;P ≤ 0.001) cropping seasons for all the maize cultivars. The linear models developed for the maize cultivars, re-lating WUEGY to GY, are specific to each of the crop growing seasons, indicating that seasonal rainfall impacts significantly on harvest index of the maize cultivars but differently in each of the crop growing seasons as a results of dif-ferences in seasonal rainfall. However, the models could be used to estimate water use efficiencies of each of the three maize cultivars given the appropriate TDM and GY as inputs for the environment under which the study was conducted.

Resilience, reliability and risk analyses of maize, sorghum and sunflower in rain-fed systems using a soil moisture modeling approach

This paper is aimed at examining the applicability of methods for resilience, reliability and risk analyses of rain-fed agricultural systems from modeled continuous soil moisture availability in rain-fed crop lands. The methodology involves integration of soil and climatic data in a simple soil moisture accounting model to assess soil moisture availability, and a risk used as indicator of sustainability of rain-fed agricultural systems. It is also attempted to demonstrate the role of soil moisture modeling in risk analysis and agricultural water management in a semi-arid region in Limpopo Basin where rain-fed agriculture is practiced. For this purpose, a daily-time step soil moisture accounting model is employed to simulate daily soil moisture, evaporation, surface runoff, and deep percolation using 40 years (1961-2000) of agroclimatic data, and cropping cycle data of maize, sorghum and sunflower. Using a sustainability criterion on crop water requirement and soil moisture availability, we determined resilience, risk and reliability as a quantitative measure of sustainability of rain-fed agriculture of these three crops. These soil moisture simulations and the sustainability criteria revealed further confirmation of the relative sensitivity to drought of these crops. Generally it is found that the risk of failure is relatively low for sorghum and relatively high for maize and sunflower in the two sites with some differences of severity of failure owing to the slightly different agroclimatic settings.

Carbon Budget Dynamics over a Rain-Fed Maize Agricultural Ecosystem in Northeast China and Its Regulation

Based on the eddy-covariance observation data over rain-fed maize agricultural ecosystem during 2005-2011, the dynamics of net ecosystem CO2 exchange (NEE) and its control mechanism were analyzed in the present study. We found that the average carbon budget of non-growing season, growing season and annual were 153.16 - 202.03 g C/m2, −689.36 - −488.17 g C/m2, and −316.96 - −487.33 g C/m2, respectively. Maize carbon content of grain yield was −226.6 - −339.94 g C/m2, accounting for 55.4% of carbon budget in the growing season. From sowing to seven-leaf stage, the carbon budget of this ecosystem was characterized by carbon release, with the rate of 0.028 ±0.0056 mg CO2 m−2⋅s−1. From seven-leaf to mature stage, the carbon budget was characterized by carbon absorption, with the rate of −0.256 ±0.0693 mg CO2 m−2⋅s−1. The key meteorological factors affecting annual carbon budget included daily average temperature (R = −0.81, P = 0.03) and saturated vapor pressure deficit (R = −0.64, P = 0.12). At the same photosynthetically active radiation (PAR) level, CO2 assimilation rate was linearly correlated with leaf area index (P 【0.05), and the slopes increased with PAR, indicating the increase in net ecosystem CO2 exchange in growing season was unlikely to be resulted from the extension of growing season. On the contrary, the carbon sink of rain-fed maize ecosystem in growing season might be decreased by extending the growing season ahead of the sowing date.

Analysis and Forecasting of the Impact of Climatic Parameters on the Yield of Rain-Fed Rice Cultivation in the Office Riz Mopti in Mali

During the period spanning the 1970s and1980s, countries in the West African Sahel experienced severe drought. Its impact on agriculture and ecosystems has highlighted the importance of monitoring the Sahelian rainy season. In Sahelian countries such as Mali, rainfall is the major determinant of crop production. Unfortunately, rainfall is highly variable in time and space. Therefore, this study is conducted to analyze and forecast the impact of climatic parameters on the rain-fed rice yield cultivation in the Office Riz Mopti region. The data were collected from satellite imagery, archived meteorology data, yield and rice characteristics. The study employed Hanning filter to highlight interannual fluctuation, a test of Pettitt and the standardized precipitation index (SPI) to analyze the rainfall variability. Climate change scenarios under the RCP 8.5 scenario (HadGEM-2 ES) and agroclimatic (Cropwat) model are carried out to simulate the future climate and its impact on rice yields. The results of satellite image classifications of 1986 and 2016 show an increase of rice fields with a noticeable decrease of bare soil. The analysis of the SPI reveals that over the 30 years considered, 56.67% of the rainy seasons were dry (1986-2006) and 43.33% were wet (2007-2015). The modelling approach is applied over 1986-2006 and 2007-2015 periods—considered as typical dry and rainy years—and applied over the future, with forecasts of climate change scenarios in 2034. The results show a decrease in potential yield during dry and slightly wet years. The yields of rain-fed rice will be generally low between 2016 and 2027. Deficits are observed over the entire study area, in comparison with the potential yield. Thus, this situation could expose the population to food insecurity.

雨养农业区黄芩轻简化膜间直播种植技术规程

为进一步推进甘肃省雨养农业区黄芩种植机械化、精量化和轻简化生产,结合多年的试验示范和生产实践,从范围、规范性引用文件、术语和定义、生产环境、栽培技术、田间管理、采收与产地加工等方面总结出了雨养农业区黄芩轻简化膜间直播种植技术规程。

灌溉和雨养条件下不同品种小麦的农艺性状与产量关系研究

论文以百农207、周麦18、洛旱7号3个品种小麦为试验材料,对其在灌溉和雨养两种条件下的产量三因素和其他农艺性状与产量的关系进行研究.结果表明:在灌溉条件下,百农207的经济产量最高,洛旱7号和周麦18次之;在雨养条件下,百农207产量最高,周麦18和洛旱7号次之.产量及其构成因素对雨养胁迫的敏感程度存在着极显著的差异.在产量构成因素与经济产量的相关关系和通径关系中,穗粒数对经济产量的贡献最大;在雨养胁迫环境条件下,3个品种小麦的株高冬前分蘖、最高分蘖、成穗率、生物产量、经济产量和秸秆系数比灌溉条件下均有一定程度的下降,且这些性状的减少均达到了极显著水平.3个品种小麦的收获指数在两种环境条件下的增减均未达到显著水平.综合以上结果可知,百农207对水分条件的敏感程度最低,产量最为突出.

雨养农业区冬小麦品种灌浆期抗旱耐逆性评价技术规程

为进一步推进抗旱耐逆小麦品种的快速筛选及其推广应用,提高耐旱育种效率,通过半干旱雨养农业区田间生产条件下灌浆期小麦气孔性状多年多点的测定,明确小麦灌浆期抗旱耐逆性判定规则,联合主成分分析和隶属函数值方法,从适用范围、规范性引用文件、术语和定义、技术原理、基本要求、田间管理、气孔性状调查分析、评价指标的计算及评价等级等方面总结出雨养农业区冬小麦品种灌浆期抗旱耐逆性综合评价技术规程。

半干旱雨养区小麦叶片光合生理生态特征及其对环境的响应

分析了黄土高原半干旱雨养农业区田间春小麦叶片光合生理生态特征及其对环境因子的响应。结果表明,天气晴朗时,净光合速率日变化呈典型的双峰曲线,有“午休”现象,上午明显高于下午,且不同生育期峰值出现的迟早不同。蒸腾速率日变化呈不明显的双峰型,其出现最大值的时间晚于净光合速率出现最大值的时间。在生长季节,叶片净光合速率、蒸腾速率和气孔导度均受到多个环境因子的共同影响。不同时期,起主导作用的环境因子不同,且同一个因子对几个生理指标的影响程度和强度都有差异,其中,光合有效辐射是对蒸腾速率影响最强烈的环境因子,湿度对光合作用的影响大于温度。受环境因子制约最为显著的生理指标是叶片的蒸腾速率和气孔导度。

降雨对旱作春玉米农田土壤呼吸动态的影响

土壤呼吸是调控全球碳平衡和气候变化的关键过程之一,降雨作为重要的扰动因子,在不同区域和不同环境条件下,对土壤呼吸具有复杂的影响。研究降雨对农田土壤呼吸及其分量的影响,对准确预测未来气候变化下陆地生态系统碳平衡具有重要意义。对黄土高原东部典型春玉米农田生态系统生长季内3次降雨前后土壤呼吸及其分量进行了原位连续观测,结果表明:在土壤湿润的条件下,降雨对春玉米农田土壤呼吸及其分量具有明显的抑制作用,在土壤湿度大于27%后土壤呼吸及其分量随土壤湿度上升呈明显下降,且对温度的敏感性降低。土壤呼吸及其分量在降雨前后的变化受土壤温度和土壤湿度的共同影响。降雨量、降雨历时和雨前土壤含水量决定了土壤呼吸及其分量对降雨响应的程度和时长。土壤呼吸及其分量对土壤温度的敏感性各不相同,微生物呼吸对温度的敏感性最高,Q10为5.14;其次是土壤呼吸,Q10为3.86;根呼吸的温度敏感性相对最低,Q10为3.24。由于土壤呼吸分量对温度和湿度的敏感性不同,降雨后根呼吸的比例有所升高。

黄土高原旱地小麦覆膜增产与氮肥增效分析

【目的】研究覆膜栽培条件下黄土高原旱地冬小麦产量形成规律和氮肥吸收运移特征,为旱地小麦高产高效生产提供理论依据。【方法】于2012—2016年在晋南黄土旱塬冬小麦种植区,通过农户模式(FP)、农户施肥+垄膜沟播模式(RFSF1)、监控施肥+垄膜沟播处理(RFSF2)和监控施肥+全膜覆土穴播处理(WFFHS)4种不同栽培模式,具体分析不同施肥和覆膜措施互作对黄土旱塬冬小麦产量形成、地上部氮素积累转移、土壤硝态氮残留以及土壤氮素平衡的影响。【结果】试验期间,农户模式冬小麦平均产量为3 367 kg·hm^(-2),通过监控施肥覆膜种植,平均产量可提升至4 491 kg·hm^(-2),监控施肥对籽粒产量形成的贡献率为14.8%,监控施肥和覆膜协同贡献率达24.7%—42.1%。黄土旱塬冬小麦产量形成主要取决于公顷穗数,其次是千粒重。WFFHS处理因其合理的群体构建和良好水肥条件具有最高公顷穗数、千粒重和籽粒产量,平均分别为581×104穗/hm2、44.3 g和4 785 kg·hm^(-2)。从地上部氮素转运看,冬小麦地上部吸收氮素的花后转运量与生物产量和经济产量呈极显著正相关,相关系数分别为0.959**和0.960**。农户模式小麦籽粒中3/4氮素来源于花前营养器官的转移,1/4氮素来源于花后根系土壤吸收。通过监控施肥覆膜种植可显著提高花前营养器官氮素向籽粒的转移量,其转运贡献率在81.4%—88.8%。从土壤氮素残留看,长期过量施氮已导致黄土旱塬麦田土壤硝态氮在1 m土层的累积,累积量在100 kg·hm^(-2)以上,20—60 cm土层为累积峰值。经过连续4年种植,农户模式2 m土壤硝态氮累积量达277 kg·hm^(-2),较2012年播前增加了87.7%,其中75%的硝态氮集中在0—120 cm土层,监控施肥覆膜种植处理2 m土壤硝态氮累积量较2012年播前仅增加15.7%—24.2%。试验期间土壤残留硝态氮有随降水向下淋移的趋势,表现为2016年收获期各处理在120—200 cm土层较2012年播前有10.2%—133.7%的增幅。从4年土壤氮平衡角度总体评价,土壤残留氮素具有一定后效作用,各处理氮肥表观利用率在28.8%—56.7%,氮肥表观残留率在12.1%—28.9%,氮肥表观损失率在31.2%—49.6%。监控施肥覆膜种植可减少土壤氮表观损失量和土壤残留量,增加氮表观矿化量。其中WFFHS处理更大程度上利用了历年土壤残留硝态氮和有机质的矿化氮,具有相对低的氮素表观残留率(12.1%)和氮素表观损失率(31.2%)以及相对高的氮素表观利用率(56.7%)。【结论】全膜覆土穴播监控施肥种植可更好地改善土壤水肥供应条件,更大程度利用历年土壤残留硝态氮,增加地上部氮素积累量、积累氮素向籽粒的转移贡献率,构建合理群体,最终获得显著的增产效应和较高的氮素利用效率,是黄土高原冬小麦区有效的栽培措施。

旱地小麦降水年型与氮素供应对产量的互作效应与土壤水分动态的研究

本文研究了中国黄土高原同一自然年度下的3个模拟降水,施用氮素的生产效应及至作效应,明确了在400～600mm降水范围内的产量变幅、生产潜力,及土壤水分动态变化规律。产量随着水分的增加报酬递增,水分生产效率提高,耗水系数降低。氮肥和降水有明显的相互促进作用,增加降水可促进化肥肥效,适量增加氮素可提高降水利用效率。归纳二者的关系是水多肥多增产幅度大,水少肥多导致减产,水多肥少增产幅度小,水少肥少产量最低,研究找到了水肥互作效应的定量关系,还明确了在降水充足的条件下,旱地小麦适量增施氮肥并采取部分春季追肥具有明显增产效果,这为旱地小麦春季不追肥的传统习惯提供了改进的意见。

西北黄土高原半干旱区全膜覆土穴播对土壤水热环境和小麦产量的影响

全膜覆土穴播是西北黄土高原旱作区大面积应用于密植作物栽培的关键增产技术,可显著提高降水利用率和作物生产力,但目前对其增产机制和环境效应缺乏系统研究分析。在2011—2013年以春小麦陇春27号为试验材料,设全膜覆土穴播(FMS)、地膜覆盖穴播(FM)和露地穴播(CK)3个处理,研究半干旱旱作区全膜覆土穴播的土壤水热效应及其对小麦产量的影响。结果表明,小麦苗期FMS在0—25 cm土层的平均地温比CK提高1.4—3.5℃,但孕穗到灌浆期正午地表地温比FM和CK分别降低5.3—6.4℃和3.1—4.3℃。FMS和FM使小麦拔节前0—200 cm土层土壤贮水量分别增加33.1和29.3 mm,且可促进小麦对深层水分(100—200 cm)的利用,FMS成熟期100—200 cm土层土壤贮水量比播前下降44.4—69.6 mm,较CK高8.4—145.5%,但FMS在休闲期补充土壤水分77—127 mm,分别较FM和CK增加4.5%—40.9%和12.8%—109.5%;FMS的休闲效率为30.5%—52.6%,比CK高12.8%—109.5%,比FM高4.5%—40.9%。基于对土壤水热环境和作物耗水的影响,FMS的产量达1750—3180 kg/hm2,水分利用效率为5.5—11.5 kg hm-2mm-1,分别比CK增加40%—220%和27%—239%,而且干旱年份的增加幅度更高。因此,FMS改善了小麦生长前期的土壤水热条件,调节作物不同生育期的耗水强度,显著提高作物水分利用效率和产量,并提高降水休闲效率,使小麦生育期耗散的土壤水分在休闲期得到有效补充。

黄土高原肥水坑施技术下苹果树根系及土壤水分布

为了解黄土丘陵区雨养条件下山地老果园布设肥水坑(water-wertilizer pit,WFP)技术对红富士老果树(Malus pumila Mill)根系及土壤水分空间分布特征的影响,以无肥水坑处理为对照(CK),利用管式TDR系统监测0~300 cm土层土壤含水率,利用根钻法获得21a生旱地果园0~300 cm土层的根系干质量密度。结果表明:WFP能够显著增加果园含水率低值区间(≥40~80 cm土层)土壤含水率,WFP60(60 cm坑深)处理土壤平均含水率增量(145.4%)最显著。WFP40(40 cm坑深)根际土壤湿润区主要集中在≥40~100cm土层,WFP60在≥20~140 cm土层,WFP80(80 cm坑深)主要集中在深层土壤≥140 cm土层。在0~200cm试验土层,WFP60处理土壤多次平均含水率值都最高,为11.02%,依次为WFP40(10.67%)和WFP80(9.80%)。总根系质量密度WFP60处理最大(594.76 g/m3),WFP40(579.08 g/m3)和WFP80(491.82 g/m3)次之,CK最小(372.12 g/m3)。根系在0~100、≥100~200和≥200~300 cm土层中的分配比例为:CK(69.88%、13.74%和16.38)、WFP40(66.04%、14.26%和19.70%)、WFP60(70.35%、24.08%和5.58%)和WFP80(46.54%、15.04%和38.42%),其根系分布与水分分布正相关。该研究表明WFP能够显著改变土壤水分在不同土层深度的分布,坑深越大向下湿润的土体范围也越深;从而显著促进果树根系的生长和根系在不同湿润土层的分配比例关系。总体而言,WFP60处理效果显著好于WFP40和WFP80处理。研究结果将对黄土高原旱地果园集雨和灌溉制度的制定和肥水坑技术的推广提供参考。

灌溉和旱作条件下腐植酸复合肥对小麦生理特性及产量的影响

为探讨不同供水条件下腐植酸复合肥对小麦的生物学效应,研究了腐植酸复合肥在灌溉和旱作两种条件下对小麦生理特性和产量的影响。结果表明,两种供水条件下,腐植酸复合肥均可显著提高0～20cm和20～40cm土层小麦根系鲜重和根系活力,促进根系生长发育。腐植酸复合肥处理明显提高了小麦灌浆后期旗叶实际光化学效率(φPSⅡ)和光合电子传递速率(ETR),尤以旱作条件下增加幅度较高。腐植酸复合肥处理小麦旗叶SOD活性明显提高,MDA含量降低,有利于提高小麦活性氧清除能力,延缓衰老。与化肥处理相比,腐植酸复合肥处理小麦穗数和穗粒数增加,产量显著提高,且旱作小麦的增产幅度(10.26%)大于灌溉小麦(7.77%)。表明旱作条件下,腐植酸复合肥对小麦生理特性的改善作用更好,增产幅度更大。

不同覆盖方式对旱地玉米田土壤环境及玉米产量的影响

分析普通地膜覆盖、小麦秸秆覆盖及露地栽培3种不同处理对旱地玉米田土壤环 境、玉米产量构成因素的影响,结果表明:覆盖栽培能改善土壤环境,降低土壤容重,提高土壤 水分利用率,调节土温、湿度,协调水热资源利用的同步性;秸秆覆盖能增加土壤养分含量,特 别是速效钾含量;在玉米生长后期,提高叶面积指数,延长叶片功能,提高玉米的光合能力从而 防止玉米早衰,增加穗重,提高玉米产量。

中国旱灾农业承灾体脆弱性诊断与评价(英文)

旱灾是世界上影响面最广、造成农业损失最大的自然灾害类型,世界近一半的国家干旱严重。中国旱灾频繁,每年旱灾损失占各种自然灾害损失的15%以上,随着人口和农业的快速发展,农业承灾体脆弱性对灾情的放大也在增加。基于灾害系统理论,从致灾因子和耕地承灾体的区域组合角度,在旱灾频发高值区,选择雨养农业、灌溉农业和水田农业为主要承灾体类型,构建了农业旱灾脆弱性生产压力和生活压力,灾前—灾中易损性和灾中—灾后适应性等农业旱灾承灾体脆弱性诊断指标体系。提出脆弱性评价的区域模型,即:雨养农业的易损—适应模型(兴和)、灌溉农业的生产—生活压力模型(邢台)和水田农业的需水—灌水模型(鼎城)。基于农业承灾体脆弱性评价,提出制定适应降水变化的波动土地利用结构调整区域政策、建立农业生态—生产范式、建立“水银行”管理机制、建立用水效益和开源节流的评估体系以及加强“截水—抽水—控水”为一体的灌溉系统工程建设,提高灌溉应急能力等对策,以期为农业旱灾的防御和区域粮食安全决策提供科学依据。

气候变暖对高寒阴湿地区春小麦生长发育和产量的影响

利用甘肃省岷县农业气象观测站1987—2004年的观测资料,探讨了气候变暖对高寒阴湿雨养农业区春小麦生长发育和产量的影响。结果表明:近18年来该地区气候变化呈明显的暖干化趋势,并且变暖的幅度和速率远远大于全国近50年的平均值,春小麦对气候变暖的响应表现在生长期缩短、产量增加;春小麦整个生长过程中,温度升高对各发育阶段的影响不完全一致,各阶段变暖对产量及产量构成要素的影响也存在差异,开花-乳熟期的温度增加和产量的相关性最大,达到极显著水平(P<0.01);出苗-拔节期、开花-成熟期的温度增加以及拔节-孕穗期的温度降低,是引起每穗籽粒数增加而不孕小穗率减少,最终导致产量增加的直接原因;春小麦生长期间日平均气温每升高1℃,生长期缩短约9.2d,产量增加约26.2%;预计随着未来气候进一步变暖该地区的春小麦生长发育和产量将会继续受到影响。