我国各地区农业气象灾害演变进趋势分析

对我国各地区1953～1966年和1978～1996年2个时段的主要农业气象灾害进行比较分析.结果表明,我国绝大部分地区农业气象灾害存在发生频率增加、发生面积扩大及灾害发生趋于平稳等3种演变趋势.同时根据灰色系统理论诊断出各地区影响农业生产的主导气象灾害,并按照各种灾害对总受灾面积的影响序列将全国各地区粗略划分为8种类型,为制定区域农业发展战略,合理安排农业生产提供参考依据.     

基于大比例尺数据库的福建省耕地土壤固碳速率和潜力研究

明确土壤固碳速率和潜力是制定耕地固碳减排措施的基础。以我国典型亚热带地区—福建省不同地理位置的闽侯、浦城、同安、武平和永定5个县为研究区,运用生物地球化学过程模型DNDC（DeNitrification and Decomposition）,模拟这5个县在目前区域尺度最详细的1:5万土壤数据库下1980─2009年和2010─2039年有机碳动态变化,并运用尺度上推的方法估算出全省耕地土壤固碳速率和潜力。结果表明,福建省耕地土壤1980─2009年的固碳总量为7.37 Tg,而2010─2039年的固碳潜力为7.04 Tg,两个时段的年均固碳速率分别为：190 kg·hm-2和176 kg·hm-2,说明目前的农田管理措施有利于研究区长期固碳。其中,水稻土和盐渍水稻土分别在土类和亚类级别中固碳速率最大,不同时段均大于175 kg·hm-2·a-1;而红壤在土类和亚类级别中固碳速率皆最小,不同时段均小于3 kg·hm-2·a-1。总体来看,1980─2009年和2010─2039年水稻土的固碳总量均占全省耕地固碳总量的92%以上,是今后制定固碳减排措施的重点。     

1992年度全国农业气象条件评述(1991年12月至1992年11月)

1992年度干旱灾害相对较重,其中以北方冬旱、黄淮地区初夏旱及南方伏秋旱范围较大,部分地区和时段旱情较重;洪涝灾害相对偏轻,汛期大范围或持续性暴雨天气少,几大主要江河水势平稳.年内气温变幅较大,热量条件明显不如往年,其中北方以东北的夏季低温尤为突出,其降温幅度之大,持续时间之长为近几年所少见.南方以春播及初夏的低温连阴雨较为明显,前者对华南早稻育秧及江南油菜生长影响较大,后者对江南早稻产量形成有不利影响.本年度有8个台风或热带风暴在我国登陆,比1991年多2个,局部地区受灾较重.风雹灾害少,程度轻;病虫害以棉铃虫危害相对较重.总的来看,1992年度农业生产的气象条件并不优越,除冬小麦为丰收年景外,春小麦、早稻、一季稻、晚稻均为一般年景,而油菜、玉米、棉花等作物为偏歉年景.     

气候变化背景下中国农业干旱时空变化特征分析

基于1951−2018年各省（自治区）农作物播种面积、干旱受灾面积、干旱成灾面积等数据,构建了干旱影响强度和干旱成灾强度特征指标,并分析近70a各省（自治区）空间尺度的农业干旱灾害的分布、发生次数、变化趋势和气候变暖背景下的阶段性变化特点。研究表明：（1）内蒙古自治区、山西省和河北省等省（自治区）的干旱受灾面积、干旱成灾面积、干旱影响强度和干旱成灾强度的多年平均值均位于前列;（2）中度及以上干旱等级发生次数最多的前10位均为北方省份（自治区）,总次数均≥25次,其中内蒙古自治区、山西省和陕西省位居农业干旱发生次数最多前三位;（3）16省（自治区）的干旱受灾面积和干旱影响强度存在减小趋势,但大部分地区即23个省（自治区）的干旱成灾面积和27个省（自治区）的干旱成灾强度存在增加趋势;（4）受气候变化影响,各省（自治区）在气候较冷的I阶段（1951−1984年）农业干旱较轻,在气候增暖明显的II阶段（1985−1997年）农业干旱大幅加重,在气候增暖趋缓的III阶段（1998−2018年）农业干旱受灾面积、成灾面积和干旱影响强度普遍减小,但其成灾强度在加重。总之,农业干旱具有明显的南轻北重特征,且北方农业干旱更加频繁,因此北方地区仍需加强防御,减轻重大干旱对农业的影响。     

陕北丘陵区水坝地粮食高产栽培技术研究

根据最优设计的原理 ,采用了组合设计的思想 ,接近于正交设计、旋转设计和饱和设计 ,故称为最优混合设计。 1998年小区最高产量为 12 919.5kg·hm-2 ,1999年小区最高产量达到 13815kg·hm-2 ,2 0 0 0年小区产最高产量达 15 0 18.0kg·hm-2 。由电脑筛选出 343个方案 ,其中 ,15 0 0 0～ 176 2 5kg·hm-2 的最优组合方案是 :施有机肥 6 0 0 0 0kg·hm-2 ,追肥N素 46 2～ 483kg·hm-2 ,播前浇底墒水 6 0 0t·hm-2 ,补灌 1377～ 145 8t·hm-2 ,密度 :马铃薯套种高粱 ,马铃薯 72 70 5～ 83415株·hm-2 ,高粱 6 5 2 0 5～ 75 915株·hm-2 。     

面向极端气候事件的冀鲁豫地区农业气象灾害分析

[目的]研究冀鲁豫地区表征极端气候事件的极端气候指数时空变化特征,揭示区域内极端气候事件变化规律及其对农业气象灾害的影响,为农业生产合理利用气候资源,提高防灾减灾能力提供科学依据。[方法]基于冀鲁豫地区1960—2020年52个气象站点数据,1970—2019年农作物受灾面积数据,利用一元线性回归、滑动平均、R/S分析、IDW、Mann-Kendall和Pettitt检验分析了极端气候指数变化特征,通过灰色关联度和相关分析法研究了极端气候事件对农业气象灾害的影响。[结果]1960—2020年,冀鲁豫地区气候呈暖干化趋势,表征高温(低温)事件的指数呈上升(下降)趋势,气候逐年暖化;降水量略微下降,降水强度缓慢上升;未来该区气温会强持续上升,降水量(降水强度)会弱持续下降(上升)。近61年来该地区极端高温事件发生频率与持续时间呈大范围上升趋势,冀北与鲁东地区最为显著;河北中南部和山东中部地区极端低温事件发生频率与持续时间显著降低;山东中部与河南中东部地区降水极端化特征显著。1970—2019年,研究区农作物洪涝、旱灾、风雹受灾面积(受灾率)呈下降趋势,低温冻害受灾面积(受灾率)略有增加;旱...     

我国各地区农业气象灾害演变趋势分析

对我国各地区１９５３－１９６６年和１９７８－１９９６年２个时段的主要农业的气象灾害进行比较分析。结果表明,我国绝大部分区农业气象灾害存在发生频率增加、发生面积扩大及灾害发生趋于平衡等３种演变趋势。同时根据灰色系统理论诊断出各地区影响农业生产的主导气象灾害,并按照各种灾害对总受灾面积的影响序列将全国各地区粗略划分为８种类型,为制定区域农业发展战略,合理安排农业生产提供参考依据。     

宁夏气象灾害变化及其对粮食产量的影响

利用宁夏23个站点1961-2004年的年降水量、冰雹发生次数和无霜期数据,1991-2006年宁夏水稻、小麦、玉米、马铃薯产量数据,粮食总产量和干旱、冰雹、冷冻害的受灾成灾面积数据,分析了宁夏干旱、冰雹和霜冻三种主要气象灾害的变化趋势及其对粮食生产的影响.结果表明:近年来,宁夏地区的旱灾指数在波动中增加,干旱发生的强度和频率有增加趋势,干旱的影响加重;冰雹的年均发生次数有明显减少趋势,但冰雹影响的程度和范围有所增大;无霜期天数增加,霜期缩短.干旱是影响宁夏主要粮食作物产量和粮食总产量的最主要的灾害;对于冷冻害和冰雹对粮食作物产量的影响,一方面与灾害的发生时间和发生区域有关,另一方面还与作物的主要生育期及作物种植的地理位置有关.     

1985-2020年黄河中游多沙粗沙区水土流失动态变化

[目的] 掌握黄河中游多沙粗沙区水土流失空间分布状况,为黄河流域水土流失治理、生态环境保护和高质量发展提供数据支撑和科学建议。[方法] 利用2020年水土流失动态监测和1985,1999年全国水土流失遥感普查成果,开展黄河中游多沙粗沙区水土流失动态变化分析。[结果] ①研究区域水土流失面积减少43.22%,高强度水土流失面积减少90.80%,水土流失状况明显改善;1985—1999年和1999—2020年两个时段,前时段变化相对较小,后时段变化较大。②两个时段内水土流失强度均降低,1999—2020年降低幅度明显大于1985—1999年且高强度水土流失面积大幅减少。1985—1999年以剧烈侵蚀面积减少为主,1999—2020年强烈、极强烈、剧烈侵蚀等高强度侵蚀面积下降明显。[结论] 研究区生态环境状况改善的主要驱动力是区域水土保持监督管理工作的加强,预防保护与水土保持综合治理的协同推进,经济社会的发展,保护环境和生态政策的引导等。虽然研究区水土流失日趋严重的态势得到了遏制,但其依然是黄土高原乃至中国水土流失最严重的地区,后续仍需持续采取适宜措施保护好生态环境。     

中国西部地区水土流失状况

本次遥感调查结果显示,西部地区12省区潜在和已经发生水土流失地区的耕地总面积为45.3 77万km2,其中中度以上水土流失的耕地面积达29.348万km2,占耕地面积的64.67%.从发展程度来看,以严重水土流失为主,占37.35%,极严重占29.35%,严重和极严重合计占到 60%以上,说明我国西部地区耕地水土流失是非常严重的.西部地区潜在或已经发生水土流失的地区,草地总面积99.664万km2,已经发生中度以上程度的水土流失草地面积62.98万 km2,占63.19%.从发展程度来看,草地水土流失以中度为主,占87.52%.所以从发展程度上看,耕地水土流失要比草地水土流失严重的多.西部地区耕地和草地水土流失面积合计92.329万km2,其中草地水土流失占68.21%,耕地水土流失占31.79%.     

“绿色革命”以来大气CO2浓度升高对C3作物营养品质的影响

自20世纪60年代"绿色革命"以来,育种技术和农耕技术的发展促进了农作物产量的大幅提升,然而作物的营养品质出现下降趋势。在相似的遗传背景下,大气CO_2浓度升高会使单位体积农作物产品的营养元素含量下降,因此"绿色革命"至今,农作物产品的营养元素下降可能受大气CO_2浓度升高影响。通过植物生长箱模拟"绿色革命"初期和目前的大气CO_2浓度水平(310μmol/mol和400μmol/mol),针对主要C_3作物水稻、小麦和大豆,研究"绿色革命"以来大气CO_2浓度升高对其籽粒的C、N、Fe、Zn元素含量的影响,结果表明:CO_2浓度升高对3种作物籽粒的C元素含量几乎没有影响,变化幅度在±1.5%之间;籽粒的N、Fe、Zn元素含量普遍呈现下降趋势,但均未达到显著水平。     

Potential of wild species for genetic enhancement of some semi-arid food crops

Discovery and incorporation of genes from wild species provide means to sustain crop improvement, particularly when levels of resistance in the cultigens are low and virulent strains of pests and pathogens overcome the host plant resistance. The extent of utilization and the potential of the wild genepool for genetic enhancement were reviewed in five important food crops viz. sorghum, pearl millet, chickpea, pigeonpea and groundnut grown in the semi-arid tropics. Introgression from compatible wild germplasm in the primary gene pool resulted in transfer of new cytoplasmic male sterility systems in pearl millet and pigeonpea, development of high protein, cleistogamous flower and dwarf pigeonpea lines and foliar disease resistant groundnut cultivars. Utilization of wild species in secondary and tertiary gene pools has been generally limited due to sterility, restricted recombination or cross incompatibility. Nevertheless, these species are extremely important as they contain high levels of resistance to several important biotic and abiotic stresses. Several of them, like those belonging to the Parasorghum section and the rhizomatous Arachis species are sources of multiple resistances and hold great promise to sustain crop productivity.     

Faculty positions:Center for Agricultural Resources Research,Chinese Academy of Sciences

正The Center for Agricultural Resources Research(CARR),the Institute of Genetics and Developmental Biology(IGDB),Chinese Academy of Sciences,invites applicants for several research group leader positions.CARR is one of the research organizations in Chinese Academy of Sciences(CAS).We seek nominations and applications     

Soil-profile distribution of primary and secondary plant-available nutrients under conventional and no tillage

Nutrient distributions under no tillage (NT) compared with conventional disk-and-bed tillage (CT) management in the warm, humid region of the southeastern USA need to be assessed so that future placement, quantity, and type of fertilizers can be altered, if necessary, to efficiently match crop demands. We determined soil-profile distributions of pH, N, P, S, K, Ca, Mg, Na, Zn, Fe, Mn, and Cu to a depth of 0.9 m at the end of 8.5 years of continuous CT and NT management on a Weswood silty clay loam (fine, mixed, thermic Fluventic Ustochrept) in southcentral Texas. Most dramatic changes occurred within the 0–0.05 m depth, where soil under NT had lower pH, Fe, and Cu than under CT, but greater P, K, Zn, and Mn. Greater P and K under NT than under CT also occurred below the till-zone (0.15–0.3 m). At a depth of 0–0.3 m, soil under NT contained greater amounts of extractable P, K, Zn, Fe, Mn, and Cu than under CT. Nitrogen fertilization had little effect on nutrient distributions, except resulting in greater extractable K at 0–0.05 m and greater nitrate at 0–0.15 m. Few changes in soil-profile distributions were observed for extractable S, Ca, Mg, and Na. Long-term continuous use of NT on this fine-textured, high-fertility (except for N) soil had no apparent adverse effects on nutrient distributions relative to CT, but enhanced conservation and availability of P, K, Zn, Fe, Mn, and Cu near the soil surface where crop roots proliferate.     

Assessing the effectiveness of conservation measures: Resolving the “wicked” problem of the Steller sea lion

“Wicked” problems are those that are complex and that change when solutions are applied. Many conflicts in conservation fall into this category. The study approached the problem of how to constrain the apparent wickedness of a problem in the conservation management of a species by using simple empirical indicators to carry out iterative assessment of the risk to a population and to document how this risk evolves in relation to the addition of new data and the implementation of management actions. Effects of high levels of uncertainty within data and also concerning population structure were examined through stochastic simulation and by exploration of scenarios. Historical trends in the example used, the Steller sea lion, showed rapid declines in abundance in some regions during the 1980s. The current total population is 130,000-150,000 Steller sea lions through Alaska and British Columbia and this number has been stable since about 1990 in spite of regional differences in population dynamics. Regional differences in the sequence of changes in the number of pups and non-pups, suggested that an internal re-distribution of juveniles could have happened between 1980 and 1990. Current productivity also appears close to the long-term mean. Stochastic population projection using various scenarios showed that, based upon this history, the risk of extinction for the population has declined and is below reasonable thresholds for considering the population to be endangered. The trends in risk suggest that management actions taken since 1990 have probably been effective. Consequently, the conservation management objectives for the Steller sea lion are probably being met. The approach provides a mechanism, based upon experience and scenario analysis, for exploring future policy options and may help to constrain the debate amongst stakeholders about the cost-benefit trade-offs associated with different options.     

Collection and preliminary evaluation of native turfgrass accessions in Italy

Despite a raising interest on turfs in Italy, all theavailable varieties of this kind in the Country are of foreign origin, and areoften poorly adapted to the prevailing climatic conditions. This prompted tobegin a collection activity of indigenous turfgrass species, with the ultimategoal of identifying promising materials for future breeding based on localgenetic resources. The collection was carried out in three areas of Italy, viz.the northern Po Plain, the coastal region of Liguria, and the island of Sardiniathat are characterised, respectively, by subcontinental, warm temperate, andtypical Mediterranean climate. Altogether, 141 sites were visited, yielding 226accessions belonging to eight species of potential interest for turfs:Poa pratensis, Poa trivialis,Festuca rubra, Festuca arundinacea,Lolium perenne, Agrostis stolonifera,Agrostis tenuis, and Cynodon dactylon,this last being a warm-season grass. Poa pratensis andCynodon dactylon were mostly collected in northern Italyand Sardinia, respectively, whereas Festuca arundinacea andLolium perenne were rather ubiquitous. The collection sitesranged from 0 to 1040 m asl, but sites over 750 m wereonly visited in the inner part of Sardinia. All the accessions, collected aswhole plants, were transplanted at Lodi, northern Italy, where they are beingevaluated. Their preliminary evaluation for traits of importance for turf use,such as sward colour and overall quality, highlighted the great variation andthe occurrence of interesting accessions in all species. Other characters wererecorded, bearing specific importance in individual species, and in all casespromising accessions were identified. The germplasm of Festucarubra, Festuca arundinacea, and Loliumperenne proved highly infected by endophytic (symbiotic) fungi of thegenus Neotyphodium.     

Enhanced establishment and growth of giant cardon cactus in an eroded field in the Sonoran Desert using native legume trees as nurse plants aided by plant growth-promoting microorganisms and compost

To evaluate the feasibility of long-term desert reforestation technology of mixed vegetation, cardon cactus (Pachycereus pringlei) seedlings from indoor and outdoor nurseries were planted in the field adjacent to one seedling of potential legume nurse trees: mesquite amargo (Prosopis articulata), yellow palo verde (Parkinsonia microphylla), and blue palo verde (Parkinsonia florida). Some of the planting holes were also supplemented with common dairy compost. Additionally, the combinations of legume tree–cactus were inoculated with either a consortium of desert arbuscular mycorrhizal (AM) fungi, plant growth promoting bacteria (PGPB; the diazotroph Azospirillum brasilense Cd, and the phosphate solubilizer Paenibacillus sp.), or a mixture of all. The field experiments were evaluated periodically during 30 months for survival and growth. Cardons reared in an outdoor screen house survived better in the field than those reared in a controlled growth chamber and hardened later outdoors. Association with any legume nurse tree increased survival and enhanced growth of untreated cardons. For cardons growing alone, application of either compost, AM fungi, and all the treatments combined increased survival. For these plants, no treatment affected plant growth during the first 3 months after transplanting. Later, all treatments, except for AM fungi, enhanced plant growth. However, only 2 years after transplanting the enhanced growth effect of AM fungi was also significant. In the presence of the legume nurse trees, transient positive effects on cardon growth were recorded. General evaluation after 30 months of cultivation showed that the treatments positively affected cardon growth when growing alone or in combination only with mesquite amargo but not with the other two legume trees. This study proposes that young legume trees have the capacity to enhance survival and growth of cardon cactus, depending on the legume cactus combination. Additional treatments such as compost or PGPB can either amplify the effect or else attenuate it.     

Karyotypic and genome size variation in Cajanus cajan (L.) Millsp. (pigeonpea) and some wild relatives

Detailed karyotypes and 4C DNA amounts have been studied in five cultivars of Cajanus cajan and 20 species belonging to Cajanus, Rhynchosia, Dunbaria, Flemingia and Paracalyx. C. cajan shows intraspecific variability and its karyotype is most similar to that of C. cajanifolius (sect. Cajanus) in the morphology and number of satellite chromosomes and the lack of any correlation between chromosome size within the complement and asymmetry. Karyotypes of C. lineatus and C. sericeus belonging to sect. Atylia are similar with respect to maximum r-index and the ratio of longest and shortest chromosomes in their respective complements. C. acutifolius (sect. Frutocosa) is distinct in having a very low ratio (1.44) between the longest and the shortest chromosomes, while in C. albicans, C. goensis, C. scarabaeoides (sect. Cantharospermum) there is no chromosome pair with r-index >2.0. C. mollis and C. volubilis (sect. Volubilis) show similarity with regard to ratio between the longest and the shortest chromosomes and a distinct chromosome pair with an arm ratio of 2.7 and C. platycarpus is distinct (sect. Rhynchosoides) in having the smallest ratio (1.36) between the longest and the shortest chromosomes. 4C DNA amounts in Cajanus and Rhynchosia vary between 3.28 pg to 11.69 pg and 4.92 pg to 11.13 pg respectively, while in Dunbaria, Flemingia and Paracalyx these vary between 4.70 and 7:06 pg. In the genus Cajanus karyotypic features and 4C DNA amounts agree with the sectional classification and bring out a close relationship between C. cajan and C. cajanifolius. This is supported by studies based on seed protein patterns, isozyme analysis, trypsin and chymotrypsin inhibitor patterns, RFLP and RAPD data and crossability relationships. A clear relation between DNA amount and abnormalities effecting the extent of pairing and recombination in interspecific hybrids shows the importance of this study in developing future breeding programme involving C. cajan and its wild relatives that are of potential value.     

Effect of some fungicide seed treatments on the survival of Bradyrhizobium japonicum and on the nodulation and yield of soybean [Glycine max. (L) Merr.]

Several commercial fungicide seed treatments were evaluated for their possible effect on the survival of Bradyrhizobium japonicum on seeds and on the nodulation and yield of soybeans in a greenhouse and a field experiment. quinolate Pro (carbendazim and oxine copper), Vitavax 200FF (carboxin and thiram), and Monceren (pencycuron) had a small effect or no effect on the survival of B. japonicum and on the nodulation and yield of soybeans. They can thus be considered compatible with soybean seed inoculation. Germipro UFB (carbendazim and iprodione), Apron 35J (metalaxyl), and Tachigaren (hymexazol) decreased B. japonicum survival and the nodulation and yield of soybeans and thus cannot be considered compatible with soybean seed inoculation.     

Leaf position and genotype differences for mineral element concentrations in sorghum grown on tropical acid soil 1

Mineral element deficiencies and toxicities are common problems associated with sorghum [Sorghum bicolor (L.) Moench] production on acid soils. To better understand some of the mineral element problems and the analysis of plant tissue of sorghum plants grown on acid soils, four sorghum genotypes were grown on an acid Oxisol at Carimagua, Colombia limed with dolomite at 2 and 6 Mg ha^‐1.

Samples for mineral element analyses were obtained from leaves at different positions on the four genotypes. Concentrations of P and Mg were highest in the flag leaf (Leaf No. 1) and decreased as the position on the plant declined from the top of the plant for plants grown at 2 Mg lime ha^‐1. Similar decreases in P, Mg, K, and Zn concentrations occurred in plants grown with 6 Mg lime ha^‐1. Concentrations of Ca, S, Si, Mn, Fe, Cu, and Al increased as leaf position declined from the flag leaf for plants grown at 2 and 6 Mg lime ha^‐1. The higher lime supply enhanced Ca and reduced Mn and Fe concentrations in leaves. Differences in mineral element concentrations for the four genotypes used were fairly extensive. The elements to show the greatest range among genotypes were Al and Si and the elements to show the least range among genotypes were P, K, and S. Care should be used in collecting leaf samples for plant analysis and genotypic differences for accumulation of mineral elements should be considered in interpretation of results.