包膜含缩节胺氯化钾对棉花产量及土壤钾素的影响

棉花是具无限生长特性的喜钾作物，为解决其生育期内多次追施钾肥和叶面喷施缩节胺的用工问题，实现轻简化种植目标，研究包膜含缩节胺氯化钾对棉花产量、经济效益和土壤钾素变化特征的影响。试验设5个处理，分别为一次基施180 kg?hm-2包膜含缩节胺氯化钾（CRKMC）、减少30%钾素用量（126 kg?hm-2）的包膜含缩节胺氯化钾（70%CRKMC）、基施180 kg·hm^-2普通包膜氯化钾（CRK）、分次施用180 kg?hm-2普通氯化钾（KCl）和对照（CK，不施钾肥），后三个处理叶面喷施三次缩节胺。结果表明：等量施钾条件下，CRKMC和CRK较KCl籽棉产量分别增加8.81%和9.36%，经济效益分别增加15.53%和12.86%，70%CRKMC较KCl增产6.53%，增加净收入13.64%。CRKMC抑制棉花盛花期前的株高，提高后期株高、茎粗和叶绿素含量，使生物量较KCl增加18.56%~24.98%，提高钾素吸收量，表观利用率增加25.06~38.83个百分点。CRKMC中的钾素和缩节胺在土壤中呈“先慢后快而后趋于平缓”的规律，释放高峰出现在盛花期至始絮期，显著提高蕾期以后土壤中的速效钾含量。因此，土壤基施包膜含缩节胺氯化钾，可合理协调棉花生长势指标，满足钾素吸收需求，减少30%用量仍有较高的经济效益和钾素利用率，实现了缩节胺和钾素在同一时空条件下的一体化调控，有助于棉花减肥、高产和轻简化种植。     

Citizens’ perception of and satisfaction with urban forests and green space: Results from selected Southeast European cities

In this paper the results of the first comprehensive study on perception of and satisfaction with urban forests and green space in seven Southeast European cities are presented. The aims of the paper are to analyse 1) citizen perceptions of the current state of urban forests and green space in their cities, 2) to what extent current urban forests and green space meet their needs and how this can be improved. A cross-sectional study was conducted by using a common face-to-face survey questionnaire. Respondents were selected based on census data though a stratified sampling procedure by taking into account age, gender and city district (n = 384 in each city). The results showed that citizens genuinely care for urban forests and green space in their cities, but are not satisfied with their current state. The respondents found issues related to misbehaviour of other users, the presence and quality of facilities, as well as the presence and quality of management or maintenance the most pressing. There were more statistically significant differences than similarities between cities. Socioeconomic variables explained perceptions only to some extent. Citizens were very supportive of educational campaigns about the importance of urban forests and green space as well as of better enforcement of the existing regulations though having more community wardens that were expected to tackle current unsatisfactory situations. Urban planning and urban forest and green space management in these cities are facing many problems characteristic for post-socialist countries. Study findings are expected to contribute to decision making in urban planning and natural resource management.     

Micro-scale heterogeneity in urban forest soils affects fine root foraging by ornamental seedlings of Buddhist pine and Northeast yew

Urban soils are frequently characterized by a strong heterogeneity caused by intense anthropogenic activity and land use changes. Soil heterogeneity is commonly known to affect tree root development, but little has been detected concerning root foraging by ornamental trees in heterogeneous urban soils at micro-scale. In this study, Buddhist pine [Podocarpus macrophyllus (Thunb.) D. Don] and Northeast yew (Taxus cuspidata S. et Z.) were selected as ornamental tree species for a two-year study. In the first-year, seedlings were cultured under contrasting photoperiods to generate different morphologies. In the second year, seedlings were transplanted to pots filled with soils collected from an urban forest. Controlled-release fertilizers (N-P₂O₅-K₂O, 14-13-13) were evenly broadcasted to a half patch of the pot (heterogeneity) or to both halves (homogeneity) on the surface 5 cm beneath the pot-top at the rate of 0.135 g N seedling⁻¹. In the fertilized heterogeneous patch, larger Buddhist pine seedlings had greater dry weight, length, surface area, volume, number of tips, and morphological foraging-precision in fine roots. Compared to Northeast yew seedlings under natural photoperiod in the first year, those under the extended photoperiod had larger size, greater fine root biomass, and length but lower foraging-precision in the second year. N and P concentrations in second-year fine roots mainly increased with the availability of patches generated by fertilization for both species. In conclusion, the ability to forage for nutrients by ornamental tree seedlings in heterogeneous urban forest soils was species-specific. Buddhist pine seedlings had higher foraging precision in heterogeneous urban soils than Northeast yew seedlings due to their response to the extended photoperiod during culture.     

Contribution of green manure legumes to nitrogen dynamics in traditional winter wheat cropping system in the Loess Plateau of China

Excessive application of N fertilizer in pursuit of higher yields is common due to poor soil fertility and low crop productivity. However, this practice causes serious soil depletion and N loss in the traditional wheat cropping system in the Loess Plateau of China. Growing summer legumes as the green manure (GM) crop is a viable solution because of its unique ability to fix atmospheric N₂. Actually, little is known about the contribution of GM N to grain and N utilization in the subsequent crop. Therefore, we conducted a four-year field experiment with four winter wheat-based rotations (summer fallow-wheat, Huai bean–wheat, soybean–wheat, and mung bean–wheat) and four nitrogen fertilizer rates applied to wheat (0, 108, 135, and 162 kg N/ha) to investigate the fate of GM nitrogen via decomposition, utilization by wheat, and contribution to grain production and nitrogen economy through GM legumes. Here we showed that GM legumes accumulated 53–76 kg N/ha per year. After decomposing for approximately one year, more than 32 kg N/ha was released from GM legumes. The amount of nitrogen released via GM decomposition that was subsequently utilized by wheat was 7–27 kg N/ha. Incorporation of GM legumes effectively replaced 13–48% (average 31%) of the applied mineral nitrogen fertilizer. Additionally, the GM approach during the fallow period reduced the risk of nitrate-N leaching to depths of 0–100 cm and 100–200 cm by 4.8 and 19.6 kg N/ha, respectively. The soil nitrogen pool was effectively improved by incorporation of GM legumes at the times of wheat sowing. Cultivation of leguminous GM during summer is a better option than bare fallow to maintain the soil nitrogen pool, and decrease the rates required for N fertilization not only in the Loess Plateau of China but also in other similar dryland regions worldwide.     

Gas chromatography for detection of citrus infestation by fruit fly larvae (Diptera: Tephritidae)

Tephritid fruit flies are serious economic pests worldwide. As larvae, they feed and develop within the pulp of host fruits, making infestation difficult to detect by visual inspection. At U.S. ports of entry, incoming produce shipments are checked for infestation by manually cutting open a small sample of fruit and searching for tephritid larvae. Consequently, there is a need for more sensitive, high-throughput screening methods. This study evaluated gas chromatography (GC) as a potential technology for improved detection of hidden infestation. Grapefruits (Citrus × paradisi Macfad.) infested with immature stages of the Caribbean fruit fly Anastrepha suspensa (Loew) (Diptera: Tephritidae) were examined to determine if infested fruit emitted a chemical profile distinct from that of non-infested fruit. Peaks identified by GC analysis were grouped into three classes. Chemicals detected in similar quantities in all samples, or slightly elevated in infested samples, were regarded as non-diagnostic background volatiles. Chemicals highly elevated after oviposition, during the last instar exit stage, and in experimentally-pierced fruit were interpreted to be indicators of citrus peel injury, and included d-limonene and β-ocimene. Chemicals elevated exclusively in the larval infestation stages were considered indicators of feeding damage and potentially diagnostic of infestation, and included hexyl butanoate and an unidentified compound. The peaks associated with injury and feeding were also detectable with a portable ultra-fast GC analyzer that required less than 80 s per sample. Further studies will investigate the potential application of these results for development of a rapid, non-destructive screening method for detection of tephritid infestation.     

Different roles of rhizosphere effect and long-term fertilization in the activity and community structure of ammonia oxidizers in a calcareous fluvo-aquic soil

Ammonia oxidation is a critical step in the soil nitrogen (N) cycle and can be affected by the application of mineral fertilizers or organic manure. However, little is known about the rhizosphere effect on the function and structure of ammonia-oxidizing bacterial (AOB) and archaeal (AOA) communities, the most important organisms responsible for ammonia oxidation in agricultural ecosystems. Here, the potential nitrification activity (PNA), population size and composition of AOB and AOA communities in both the rhizosphere and bulk soil from a long-term (31-year) fertilizer field experiment conducted during two seasons (wheat and maize) were investigated using the shaken slurry method, quantitative real-time polymerase chain reaction and denaturing gradient gel electrophoresis. N fertilization greatly enhanced PNA and AOB abundance, while manure application increased AOA abundance. The community structure of AOB exhibited more obvious shifts than that of AOA after long-term fertilization, resulting in more abundant AOB phylotypes similar to Nitrosospira clusters 3 and 4 in the N-fertilized treatments. Moreover, PNA was closely correlated with the abundance and community structure of AOB rather than that of AOA among soils during both seasons, indicating that AOB play an active role in ammonia oxidation. Conversely, the PNA and population sizes of AOB and AOA were typically higher in the rhizosphere than the bulk soil, implying a significant rhizosphere effect on ammonia oxidation. Cluster and redundancy analyses further showed that this rhizosphere effect played a more important role in shaping AOA community structure than long-term fertilization. Overall, the results indicate that AOB rather than AOA functionally dominate ammonia oxidation in the calcareous fluvo-aquic soil, and that rhizosphere effect and fertilization regime play different roles in the activity and community structures of AOB and AOA.     

Chukar Watering Patterns and Water Site Selection

We evaluated chukar (Alectoris chukar) watering patterns as well as habitat variables influencing water site selection in western Utah. Motion-sensing cameras and chukar dropping counts were primary techniques to evaluate watering patterns. We took vegetative and other habitat measurements at each water source (n = 43) to discriminate use from nonuse sites using logistic regression. Chukars watered during daylight hours with a modal hour from 1200 hours to 1300 hours daylight savings time. Annual patterns suggest limited use of water sources from November to May with first observed visits occurring in June and last observed visits in October. Shrub canopy cover was the only variable to discriminate between site types (P &spilt; 0.01). Cross validation showed a predictive success rate of 84%. Significant differences were found between use and nonuse sites in terms of security cover (P &spilt; 0.01), but not total cover (P &spigt; 0.05). Chukars seem to have a loose shrub canopy threshold near 11% that is likely due to predation risk. Water sources meeting this threshold received use, whereas those not meeting this threshold did not. Increasing shrub canopy cover above 11% did not translate into increased water source use. Managers might want to consider annual patterns when setting hunt season timing and structure as well as judging sites for new water developments based on shrub canopy cover. More generally, these results suggest a behavioral constraint on the use of water sources as a function of predation risk—we should expect other species to demonstrate similar behavioral constraints. These constraints must be considered in any effort to determine benefits or impacts of water developments.     

Relationship between sensory and NIR spectroscopy in consumer preference of table grape (cv Italia)

A combination of near infrared spectroscopy (NIR) instrumental measurements and sensory analysis was investigated to predict solids soluble content (SSC, assessed as Brix) and to classify preference in table grape cv Italia. SSC was monitored in each berry of whole bunches in order to evaluate intra-bunch distribution and variability. NIR spectra were recorded in the spectral region 12,000–4000 cm⁻¹ (833–2500 nm) using a set of 682 berries. The Partial Least Square (PLS) model based on cross-validation provided acceptable value for the main statistical parameters (coefficient of determination of cross-validation, r²: 0.85; standard error of cross-validation, SECV: 1.08; residual predictive deviation, RPD: 2.6) and was confirmed by external validation performed with 115 independent berries (coefficient of determination of prediction, r_p²: 0.82; standard error of prediction, SEP: 0.83). For consumer testing, the selected PLS model was used to predict the Brix value in 400 berries and Discriminant Analysis (DA) was then carried out to classify berries in terms of preference by relating NIR data to consumer judgment. The three defined preference clusters of berries were fully classified obtaining 100% membership. In cross-validation the value decreased especially for class 1 (78.5%) and 3 (75%) whereas class 2 obtained comparable values (98.7%). According to our results, NIR technology appears to be a promising technique for predicting SSC and obtaining information with regard to consumer preference in ‘Italia’ table grape for application of efficient and low cost on-line instruments in the fruit industry.     

福建省耕地土壤pH空间分布及影响因素分析

为研究福建省耕地土壤酸化防控、耕地质量和产能提升的科学途径,以福建省耕地土壤为研究对象,采用地统计学与ArcGIS并结合随机森林模型,对福建省4 261个耕地表层土壤调查样点数据进行分析,探究福建省耕地土壤pH空间分布特征及主要驱动因子。结果表明,福建省耕地土壤pH自东南沿海至内陆山地地区呈逐渐降低趋势:全省耕地土壤pH为3.00~9.62,平均值为5.35,变异系数为14.95%,69.3%的耕地土壤pH小于5.5;南平市(5.09)、三明市(5.16)、龙岩市(5.21)、宁德市(5.22)及漳州市(5.42)70%以上的耕地土壤pH<5.5;而厦门市(5.58)、泉州市(5.90)、福州市(5.62)及莆田市(5.96)50%以上耕地土壤pH>5.5。海拔、降雨量、土壤有机质、土壤质地、土壤类型和作物类型显著影响土壤pH,土壤pH与海拔、降雨量和有机质呈显著负相关关系。砂土土壤pH为5.38,显著高于壤土(5.20)和粘土(5.14);滨海盐土土壤pH为6.36,显著高于潮土、水稻土、砖红壤、紫色土、黄壤和红壤;黄壤和红壤土壤pH显著低于潮土和水稻土,潮土和水稻土土壤pH差异不显著;茶园土壤pH为4.67,显著低于果园、蔬菜、烤烟、水稻、块茎和油料作物土壤pH;油料、蔬菜和块茎类作物土壤pH显著高于水稻、烤烟和果园土壤pH,水稻和烤烟土壤pH差异不显著。随机森林模型分析显示,土壤有机质和海拔是驱动土壤pH变化的重要因子,其次是降雨量和作物类型。整体而言,福建省近70%的耕地土壤处于酸性或强酸性水平,建议通过养分综合管理、增施碱性物料等农业措施提升土壤pH,促进土地可持续利用。     

施镁量对土壤供镁及烤烟生长发育和产质量的影响

为明确福建‘翠碧一号’烤烟适宜的施镁量以及施镁对烟田土壤供镁的影响,采用田间试验研究不同施镁量对烟田不同时期土壤供镁、烟株物质积累和烤后烟叶产质量的影响。结果表明,随施镁量的增加,土壤交换性镁浓度上升,不同时期土壤供镁能力与施镁量表现为显著的直线线性相关关系。终采时烟株不同部位叶片镁含量和积累量也均与施镁量存在显著的直线线性相关关系。施镁处理的均价、产值、上等烟比例和上中等烟比例分别比不施镁处理提高了6.39%~11.67%、6.13%~14.63%、18.43%~31.46%和5.36%~8.96%。随施镁量的增加烤后烟叶总钾含量呈下降趋势。综合烤后不同部位烟叶感官评吸质量以施镁（以MgO计）量在19.5 kg/hm²处理最好,其次为39 kg/hm²处理;产值以施镁58.5 kg/hm²处理最高。施镁量对烟株生物量积累和烤后烟叶产量的影响规律性不明显。综合福建植烟土壤交换性镁含量的实际情况,以及土壤供镁、烟株物质积累和烤后烟叶质量,认为福建‘翠碧一号’烤烟生产中,施镁（以MgO计）量以19.5~39 kg/hm²为宜,既能保证土壤正常供镁和镁营养的相对平衡,又能满足烟株对镁营养的需求,提高烤后烟叶质量。