基于“三生”空间的重庆市土地利用演变与城镇化关系研究

[目的] 分析重庆市土地利用时空演变规律,探究土地利用转型及景观格局响应的演变特征与城镇化的关系,为重庆市"三生"土地规划与城镇化可持续发展提供数据支持。[方法] 基于"三生空间"功能分类的视角构建用地分类标准,利用2000,2010,2020年土地遥感影像和夜间灯光数据,采用转移矩阵、相关性分析及回归分析法进行分析。[结果] ①2000-2020年重庆市生产、生态空间总体减少,生活空间持续扩张。2000-2010年,生产、生态空间减少191.87,252.95 km²,生活空间增大446.03 km²;2010-2020年,生产空间面积减少13.76 km²,生态空间减少324.05 km²,生活空间增大314.87 km²。②重庆市生产功能向生活功能转化较为明显。随着城镇化加强,生态空间转向生产空间显著,功能转变明显聚集于重庆市中心区域。③重庆市空间景观破碎度减小,景观复杂度逐渐提高,林草水生态空间占据主导优势。④2000-2010,2010-2020年土地利用面积变化对夜间灯光值的影响存在差异;2000年,城镇生活空间、农村生活空间变化对夜间灯光变化影响起主导作用,而2020年工业生产空间、城镇生活空间变化对夜间灯光变化影响较强。[结论] 重庆市各类空间发生相互转换,利用不同"三生"空间类型变化和城镇化的关系,推动土地规划与城镇化协调发展。     

新疆乌鲁木齐市“三生”用地的空间冲突研究

[目的]探析新疆乌鲁木齐市“三生”用地变化及其引起的空间冲突变动,为该地区的土地资源优化配置提供参考依据。[方法]利用外部压力、脆弱性和稳定性3个因子构建格网尺度下的空间冲突测度模型,对该地区2000—2018年空间冲突时空分异特征进行定量评价。[结果](1)2000—2018年,乌鲁木齐市北部为城市生活用地的主要增长方向,农业生产用地空间格局呈现破碎化趋势,生态用地是乌鲁木齐市三生用地的主要组成部分,应避免人类活动对新增核心生态用地的占用。(2)各个时期乌鲁木齐市“三生”空间冲突等级均表现为：稳定可控>轻度冲突>中度冲突>重度冲突。(3)重度冲突空间单元增幅最大,表明乌鲁木齐市重度冲突失控的地区范围有扩大的趋势。这应是乌鲁木齐市空间冲突调控的重点区域。(4)不同空间类型的空间冲突存在一定差异。乌鲁木齐市冲突强度从大到小依次为：生产空间>生活空间>生态空间。[结论]乌鲁木齐市“三生”用地变化与区域经济社会发展具有较强的吻合性,未来应逐步改变生活空间过速扩张而导致冲突水平逐渐增强的现象。应更加重视城市生活用地的动态监测,保护核心生态用地,以实现“三生”用地更...     

基于洛伦兹曲线和土地利用转型的喀斯特山区“三生”空间分布研究

[目的]对贵州省都匀市"三生"空间分布进行研究,为喀斯特山区"三生"空间可持续发展、县域科学开展国土空间规划、生态环境保护提供参考依据。[方法]采用洛伦兹曲线、基尼系数及转型模型对都匀市2009—2018年"三生"空间进行综合研究。[结果]①2018年,都匀市"三生"空间现状主要以生态空间为主,生态空间占都匀市国土面积的69.19%,比例较高;其次为生产空间,比例为26.87%;而生活空间则占比相对较小。②2009—2018年间生产空间和生态空间面积呈现出下降趋势,生活空间面积则呈现出增长趋势,从二级空间转移来看,城镇和农村生活空间面积增长来自农业生产空间和林地生态空间,城市建设发展占用部分林地资源和农业资源。③从2009—2018年洛伦兹曲线和基尼系数来看生态空间和生产空间分布相对平均,而生活空间与其他空间相比更远离绝对平均线,下凹程度大,2009—2018年基尼系数均介于0.3～0.4间,生活空间分布基本合理。④从区位熵来看,生态空间优势区域主要为研究区西部地区,生活空间优势区域主要集中在中部地区,生产空间优势区域主要为南部及东部地区。[结论]都匀市"三生"空间分布基本合理,城市以生态空间为主,在今后城市建设中,应在保障生态空间的同时,合理进行城市发展,避免过多占用生态用地。     

山西省2005-2018年“三生”功能的时空分异特征及其影响因素

[目的] 探究山西省不同县域“三生”功能时空动态演化特征并分析其影响因素,为国土空间规划提供依据。[方法] 基于山西省107个县2005,2010,2018年土地利用类型和统计数据,采用综合指数模型、动态度和空间计量模型分析其“三生”功能时空演化过程及影响因素。[结果] ①2005—2018年山西省“三生”功能空间分异明显,生产、生活功能格局特征趋同,呈现出“平原高,山区低”的分布格局;生态功能分布特征与生产生活相反,空间格局稳定;“三生”综合功能提升明显,表现为“南高北低,中部高东西低”的局面。②2005—2018年生产和生态功能水平缓慢变化,呈现出先上升后下降波动变化趋势;生活功能处于快速提升阶段,提升明显;“三生”综合功能持续提高,但提升缓慢。“三生”功能协调性提高,但功能单一化程度较高。③“三生”功能时空分异是自然地理环境、自然资源禀赋及社会经济因素综合作用的结果,“三生”功能受制于自然地理条件,自然资源禀赋是“三生”功能的基础和保障,社会经济因素则是“三生”功能的主要驱动力。[结论] 山西省各县域需要在自然地理条件约束和经济社会转型发展背景下,促进“三生”功能各自提升与彼此协调,需要在明确各自主体功能定位的基础上,因地制宜,合理发展,依托自身区域优势与资源禀赋,构建起利益联结机制,推动山西省整体协调可持续发展。     

桂西南-北部湾地区“三生”空间适宜性评价

[目的] 对桂西南-北部湾地区进行"三生"空间适宜性评价，为复杂的过渡性地理空间实现"三生"协调和陆海统筹提供参考，为科学划定国土空间布局提供理论支持。[方法] 构建桂西南-北部湾"三生"空间适宜性评价指标体系，利用变异系数法确定指标权重，综合运用ArcGIS技术对评价结果进行叠加分析。[结果] ①生产适宜性与生态适宜性在桂西南喀斯特与北部湾地区组成的过渡性复杂地理空间分布特征具有"互异性"，从喀斯特到海岸带地区，生产空间适宜逐级递增，生态空间适宜逐级递减。②生活空间适宜性等级以城市为中心向周围递减，喀斯特地区的生活空间适宜性总体上弱于北部湾地区。③在复合空间适宜性评价中，以生态空间为主导的复合空间比例最大（接近1/2），生产空间次之，生活空间最小。④海洋"三生"空间适宜性比例由大到小依次为：生产-生态-生产生活，沿岸海洋生态空间与陆地生产生活空间存在冲突。[结论] 生态和生产空间适宜性主要受自然条件制约，生活空间适宜性主要受行政区位条件影响。海岸带的生态保护与社会经济发展存在博弈现象。     

“三生空间”视角下宜昌市景观生态安全评价及其耦合特征分析

为了探究典型生态脆弱区的景观生态安全格局变化规律,以湖北省宜昌市为研究对象,基于2000—2015年4期土地利用遥感监测数据和社会经济数据,从三生空间视角构建“三生空间”(生产空间、生活空间和生态空间)土地利用分类模型,对宜昌市近15年间景观生态安全时空演变特征及耦合协调度进行了系统分析。结果表明:(1)2000—2015年,宜昌市以林地为主的生态空间面积占比最大,且各时期占比均在71%以上;(2)2000—2015年,宜昌市景观生态安全整体呈现西北—西南高、东部低的空间分布特征,安全区集中分布在土家族自治县、夷陵区,不安全区主要分布在当阳市等低海拔地区;(3)2000—2015年宜昌市景观生态风险冷点、次冷点数量增加,次热点和热点均呈现先增加后减少态势。(4)宜昌市“三生空间”景观生态安全的耦合协调度水平不高,整体上呈现“东高西低”的空间分布特征,西北、西南山区景观生态安全耦合协调度明显优于东部地区。研究结果表明区域土地利用格局和人类社会经济活动影响以及制约区域景观生态安全及其耦合协调性,故需优化区域生态空间格局、提升土地资源集约利用效率,促进宜昌市生态环境可持续发展。     

湟水河流域景观格局与生态风险时空特征及驱动因子探测

[目的] 分析景观格局变化特征及景观生态风险时空演变规律与影响驱动因子,为流域综合治理,生态系统管理和可持续发展提供理论依据。[方法] 基于湟水河流域2000,2010,2020年3期土地利用数据,采用景观指数法构建流域景观生态风险评价模型,耦合ArcGIS 10.6,Fragstats 4.2,GeoDa 1.20讨论景观格局与生态风险的时空动态特征,利用地理探测器识别驱动景观生态风险空间分异的主导因子。[结果] ①草地和耕地是湟水河流域的优势地类,土地转移主要发生在耕地、草地和建设用地之间,城市扩张是近20 a土地利用变化的主要特征。②2000—2020年景观生态风险先增后减小,生态服务价值与景观生态风险表现出负相关性。③景观生态风险空间分布主要呈现“高—高”和“低—低”集聚,高程是导致景观生态风险空间格局分异的主导因子,因子交互作用对景观生态风险空间分异有增强效应。④景观生态风险空间格局具有明显的海拔梯度效应。可根据海拔梯度将湟水河流域划分为重点管控区、严格管控区和一般管控区。[结论] 生态治理和生态修复是湟水河流域景观生态风险指数下降的主要原因,不同生态风险空间管控区应采取差异化调控措施,土地利用优化管理与用途管制在生态风险调控中需高度关注。     

乡村振兴视角下“三生”空间格局演变及优化策略——以陕西省米脂县高西沟村为例

[目的] 探寻城镇化快速发展条件下作为生态示范村的陕西省米脂县高西沟村的土地利用转型特征,为陕北黄土高原地区的乡村“三生”空间可持续发展提供参考。 [方法] 通过土地利用动态度、土地利用转移矩阵分析高西沟1953—2022年的“三生”空间特征,并结合实地调研对村域多年“三生”空间格局演变特征及对应的空间治理优化策略展开分析。 [结果] ①1953—2022年,高西沟生产空间呈减小趋势,生活空间和生态空间呈增大趋势。1953—1973年,生态空间变化幅度最大,绿地生态空间从12.07 hm²增加到100.33 hm²,其他生态空间从12.07 hm²减小到100.33 hm²,生产空间逐渐减小,从145.67 hm²减小到110.07 hm²。1986—2022年,生产空间减少了42.4 hm²,生活空间增加了5 hm²,生态空间增加了37.39 hm²。 ②1986—2022年,高西沟“三生”空间转型体现在绿地生态空间和农村生活空间的增加,农业生产空间、其他生态空间和水域生态空间的减少。有67.83 hm²的农业生产空间和59.95 hm²的其他生态空间转化为绿地生态空间,而部分绿地生态空间转化为农业生产空间和农村生活空间,其转移面积分别为21.20和3.22 hm²。 ③高西沟针对生产空间效益不足的问题,采取改变广种薄收的耕种方式,大幅提高粮食产量,改变单一的农业生产状况,实现多种经营模式并存的举措;针对生活空间品质低下的问题,采取全力抓牢基建,量力新建家园,鼓励青年外出,从事其他产业的举措;针对生态空间破坏严重的问题,采取控制水土流失,退耕还林还草,打造旅游文化,推广生态风光的举措。 [结论] 根据早期“三生”空间的主要问题,高西沟做出适宜的优化策略,提高土地利用率,扩大林草面积,使绿地生态空间达到80%。农林牧的高效发展,生产、生活、生态的全面改善,使高西沟成为黄土丘陵区的生态示范代表。     

中原城市群“三生”用地转型及其生态环境效应

[目的]分析2000—2020年中原城市群“三生”用地的时空演变特征及其生态环境效应，为快速城镇化地区“三生”空间格局优化以及区域生态环境保护等提供科学参考。[方法]基于中原城市群2000,2010和2020年3期土地利用数据，采用生态环境质量指数和景观格局指数两种方法，定量分析中原城市群“三生”用地转型的生态环境效应。[结果](1)研究区生产用地面积明显减少(-7 890 km~2),生态用地面积相对稳定(仅变化0.1%),生活用地面积快速增加(7 638 km~2);2000—2010年的“三生”用地转换面积远低于2010—2020年。(2)研究区生态环境质量指数先升后降，在区域整体上呈现“西高东低”的空间格局。郑州市下降幅度最大，济源市提高最多；生态环境质量指数(EV)与最大斑块指数(LPI)、景观形状指数(LSI)、斑块结合度指数(COHESION)、聚集度指数(AI)、香农多样性指数(SHDI)和香农均匀性指数(SHEI)高度相关。(3)生态环境改善趋势小于恶化趋势，恶化的主要因素为林草生态用地向农业生产用地转化，以及生活用地对农业生产用地的占用。(4)各类景观破碎化加剧，聚...     

耦合MOP-FLUS模型的滇中城市群“三生”空间格局优化

生产空间、生活空间、生态空间之间联系紧密,决定国土空间的最高演化目标,为了协调区域经济社会的发展,通过构建符合城市群发展实际的“三生”空间分类体系划定国土空间; 基于目标条件与情景设定,通过MOP模型实现“三生”空间综合效益最大化; 利用FLUS模型优化“三生”空间布局,并采用景观格局指数对其优化结果进行了分析评价。结果表明:优先满足生产和生活空间发展情景的生态效益最低,城镇化进程加快的同时生态空间发展受到抑制,生态环境脆弱; 优先满足生态空间发展情景的经济效益最低,生态环境虽然得到良好保护,但同时生产与生活空间面积占比较小,分布破碎,不利于区域经济发展; “三生”空间均衡协调发展情景的经济效益提高4.46%,生态效益提高1.87%,空间布局均衡统一。因此该情景能够合理平衡生态建设与经济发展,在丰富生态过程和格局结构上具有优越性,可为滇中城市群国土空间资源配置、“三生”空间优化等决策提供一定的参考和借鉴。     

“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.