水分亏缺指数在全国干旱遥感监测中的应用研究

水分亏缺指数(WDI)是建立在作物水分胁迫指数理论基础上,并假设陆地表面温度是冠层温度与土壤表面温度线性加权及土壤与植被冠层之间不存在感热交换的情况下,结合陆气温差与植被指数得到的区域干旱评价指标。本文利用MODISTerra陆地表面温度和植被指数数据产品,采用NDVITs空间法分别计算了2000年4月上旬和5月中旬气温空间分布的基础上,结合陆气温差和植被指数计算全国范围WDI,并与表层土壤含水量进行对比。结果表明:WDI能够比较合理地用来监测区域干旱,不仅适用于裸地条件,还能够有效地应用于完全植被或部分植被覆盖条件下的干旱监测,克服了CWSI只能应用于郁闭植被冠层的限制。     

Seasonal patterns of root-surface phosphatase activities in a Mediterranean shrubland. Responses to experimental warming and drought

Mediterranean ecosystems are water limited and the current general circulation Models (GCM) and ecophysiological models forecast a warming and a further increase of drought in the next decades. A stronger water stress can decrease the capacity for nutrient absorption by plants. We conducted a field experiment to simulate forecasted drought and warming in a Mediterranean calcareous shrubland to assess the performance of root-surface phosphatase activities of the dominant shrub Globularia alypum. These enzyme activities were higher in autumn and spring, when the climate conditions were optimal for plant activity, than in summer or winter, when there was either lack of water or cold temperatures. A decrease in soil moisture in drought plots decreased root-surface phosphatase activity (29% in summer and 25% in autumn). The decrease in root-surface phosphatase activity in drought plots coincided with a decrease in P leaf concentrations and P accumulation in aboveground biomass and loss of photosynthetic capacity of some dominant shrub species of this ecosystem, and with a tendency to increase total soil-P. These results suggest that the expected drier conditions in this Mediterranean shrubland in the next decades will slow down the P uptake by plants, thereby, diminishing the P contents in biomass and increasing total P contents in soil in non-available forms and that this can be, in part, attributable to a result of the decrease in root-surface phosphatase activity.     

西藏地区降水资源评价与农田水利建设的建议

西藏高原自然降水不多，干湿季明显，干旱频率高；近三十多年来气候有变干的趋势；水资源丰富，但利用率很低。干旱缺水是农业生产的主要制约因素；为较大提高农业生产水平，提出了因地制宜开展农田水利建设的建议。     

气候变化对安徽省淮河区域旱涝灾害的影响及适应对策

通过历史旱涝灾害面积和产量资料的统计分析安徽省淮河区域旱涝灾害和降水分布的演变规律，研究气候变化对该区旱涝灾害和粮食减产率的影响，并在分析未来气候变化对旱涝灾害影响的基础上阐述减缓旱涝灾害的适应性对策。     

不同干旱强度对糜子产量的影响及其在估产中的应用

该利用盆栽试验结果，通过分析糜子在不同生育阶段受不同强度干旱的产量反应，得出：糜子各生育期的受旱缺水指数Ｒｉ减产指数Ｒｉ，及产量反应系数Ｋｙｉ。认为糜子在灌浆期对干旱敏感性最强，此阶段受旱，日减产率量大，水分生产力最低，灌水效果最佳。拔节＋扬花期产量和干旱之间的反应最弱。糜子生育期耗水分蘖期最多，占总量的２８．６％，正常供水盆栽全生育期耗水１８５ｍｍ，不同干旱度下为１６７ｍｍ．水分生产力平均为０     

红壤旱地四种春夏作物水势比较研究

大豆、花生、红薯、玉米是低丘红壤区主要的夏季旱地作物,研究表明:四种不同作物在相同或相似的环境条件下,作物水势时空分布的趋势一致;大豆(初花期)、玉米(大喇叭口期)、花生(开花结荚期)、红薯(块根膨大期)永久萎蔫时叶水势依次为:-2.3MPa、-2.10MPa、-1.75MPa、-1.30MPa,土壤水势分别为-1.159MPa、-0.818MPa、-1.534MPa、-1.644MPa。正常情况下,作物叶片水势大小及作物耐旱性顺序为:红薯>花生>大豆、玉米。小麦茬口玉米(抽穗期)和大豆(初花期)因叶片水势连续一周分别低于-2.2MPa和-2.3MPa被旱死。     

硒、钴配施基肥对紫花苜蓿抗旱性的影响

通过播前基施硒钻微肥,研究硒钴配施对紫花苜蓿叶片内游离脯氨酸、K含量、叶绿素含量以及氮代谢等生理功能的调节作用.结果表明:硒钻用量分别为765g/hm2和1548g/hm2不但能有效地促进苜蓿叶片内游离脯氨酸的积累和硝酸还原酶(NR)活性的提高,增强苜蓿体内氮代谢的水平,而凡能提高现蕾期到开花期苜蓿叶片中叶绿素含量.硒钴用量分别为570g/hm2和1548g/hm2能有效地提高苜蓿叶片中K的积累量.     

Evaluation of perennial wild <Emphasis Type="Italic">Cicer</Emphasis> species for drought resistance

About 90% of chickpea (Cicer arietinum L.) in the world is grown under rainfed conditions where drought is one of the major constraints limiting its productivity. Unlike the cultivated chickpea, wild Cicer species possesses sources of resistance to multiple stresses; we therefore evaluated perennial wild Cicer species for resistance to drought. C. anatolicum, C. microphyllum, C. montbretii, C. oxydon and C. songaricum were compared with special checks; C. echinospermum, C. pinnatifidum and C. reticulatum and five cultivated chickpeas. After the cultivated chickpeas were killed, accessions were evaluated using a 1–5 scale, where 1 = highly drought resistant (no visible drought effect and full recovery after three successive wiltings) and 5 = highly drought susceptible (leaves and branches dried out, no recovery at all). All accessions of perennial wild Cicer species were significantly superior to those annual wild species and the cultivated chickpeas including the best drought tolerant chickpea, ICC 4958 under drought conditions. Perennial wild Cicer species did not only recover after wilting and drying out above ground level, they also tolerated high temperatures up to 41.8°C. But, they do not cross with the cultivated chickpeas. C. anatolicum should be taken account in long term breeding programs because it has closer affinities to the first crossability group than the others.     

Influence of mycorrhiza vs. soluble phosphate on growth,nodulation, and N2 fixation (15N) in alfalfa under different levels of water potential

Summary The legume Medicago sativa (+Rhizobium melilott) was grown under controlled conditions to study the interactions between soluble P in soil (four levels), or a mycorrhizal inoculum, and the degree of water potential (four levels) in relation to plant development and N₂ fixation. ¹⁵N-labelled ammonium sulphate was added to each pot for a qualitative estimate of N₂ fixation, in order to rank the effects of the different treatments.Dry-matter yield, nutrient content and nodulation increased with the amount of plant-available P in the soil, and decreased as the water stress increased, for each P-level. The mycorrhizal effect on dry matter, N yield, and on nodulation was little affected by the water potential. Since P uptake was affected by the water content in mycorrhizal plants, additional mechanisms, other than those mediated by P, must be involved in the mycorrhizal activity.There was a positive correlation between N yield and nodulation for the different P levels and the mycorrhizal treatment at all water levels. A high correlation between plant unlabelled N content and atom% ¹⁵N excess was also found for all levels of P. In mycorrhizal plants, however, the correlation between unlabelled N yield and ¹⁵N was lower. This suggests that mycorrhiza supply plants with other N sources in addition to those derived from the improvement on N₂ fixation.     

Microbial community changes in heathland soil communities along a geographical gradient: interaction with climate change manipulations

Climate change constitutes a serious threat for European heathlands as unlike other sources of damage, such as over-grazing, local remediation is not a possibility. Within the large pan-European projects, CLIMOOR and VULCAN, the effect of periodic drought and increased temperature were investigated in four heathland ecosystems along a geographical and climatic gradient across Europe. Fluorogenically labelled substrates for four enzymes (glucosidase, sulphatase, phosphatase, leucine amino peptidase) were used to measure extra-cellular enzyme activity in soil samples from each of the CLIMOOR sites. Microbial extra-cellular enzyme production is linked to microbial activity as well as soil physico-chemical properties, making soil enzymes one of the more reactive components of terrestrial ecosystems and potentially excellent indicators of soil microbial functional status and diversity.Across all sites and over all the substrates, organic matter content was exponentially, inversely related to enzyme activity. Although the increase in temperature produced by the CLIMOOR roofs was small (on average 0.9 °C), this was sufficient to increase enzyme activity in all sites (on average by 45%). The increase was within the range of seasonal variability at each of the sites. The effect of drought on enzyme activity was more pronounced in the Northern European sites than the southern European, and most moisture limited, site. This suggests that the effect of temperature increases may be observed across all regions; however, the soils of northern Europe may be more sensitive to changes in rainfall patterns than more moisture limited Southern European soils.