Impact of nitrogen supply on glucosinolate content and phenolic acids in cauliflower varieties

Application of nitrogen (N) is a common practice used to achieve profitable yields in horticultural crops and N application can be used as a tool to manipulate the enhancement of phytochemicals in vegetable crops to address consumer-oriented quality production. Our previous findings recommended 90?kg?ha^?1 for certain types of cauliflower varieties without compromising yields. Thus, this study was aimed to investigate the effect of N application on glucosinolates and phenolic acids, at harvest, in varieties ‘Largardo’, ‘Eskimo’ and ‘CF-744’ grown in the field. N was applied as ammonium nitrate (NH₄NO₃) at concentrations from 0, 60, 90, 120, 150 to 180?kg?ha^?1. Variety ‘CF-744’ was more sensitive to N supply and at 180?kg?ha^?1 N it showed the highest accumulation of glucosinolates (sinigrin, glucoiberin, progoitrin, 4-methoxyglucobrassicin) at harvest. However, 90?kg?ha^?1 N supply demonstrated the highest accumulation of majority of the glucosinolates in varieties ‘Largardo’ and ‘Eskimo’. Different varieties responded differently to N supply and glucosinolate levels in cauliflowers. Also, different varieties responded differently to N supply and antioxidant property. In all three varieties, the N supply at 120?kg?ha^?1 showed the highest accumulation of protocatechoic acid, 4-hydroxy benzoic acid, ρ-coumaric acid and caffeic acid.     

温室栽培条件下N2O排放量和浓度分布对肥料和施肥的短期响应

In vegetable cultivation, the majority of N2O emissions occur after fertilization; it is therefore important to understand any factors contributing to this process. An experiment was conducted to investigate short-term N2O dynamics following topdressing in a greenhouse vegetable field in South China. During two topdressing processes, three different urea-N treatments with irrigation were conducted in May and June in a tomato (Lycopersicum esculentum) cultivation. The N2O fluxes, soil concentration profiles and soil environments at the 0-60 cm depths at 10 cm intervals were measured both immediately prior to and 5 days after topdressing. The N2O fluxes before topdressing ranged from 6.7±2.1 to 55.0±28.8 μ g N m 2 h 1 ; even higher numbers were recorded in highly fertilized plots. The NO3-N accumulation in the soil caused by vegetable cultivation during the 5 years prior to the start of the experiment, resulted in high background N2O fluxes. One day after topdressing (1 DAT) in May and June, N2O fluxes increased, which coincided with sharp increases in soil N2O concentrations at depths of 2.5 and 15 cm and in NO3-N and NH+4 -N contents at depths of 0-20 cm. From 1 to 5 DAT, fluctuations in the N2O fluxes did not harmonize with the N2O concentrations at a depth of 2.5 cm, which was attributed to different gas diffusion rates at depths of 0-10 cm. These results suggested that surface soil N and environmental conditions were crucial for determining the short-term N2O ebullitions during topdressing in greenhouse vegetable cultivation.     

设施菜地长期施肥对土壤线虫群落结构和多样性的影响

基于设施菜田肥料定位试验地,研究了长期施用化肥对土壤线虫群落结构及多样性的影响,为设施蔬菜的合理施肥和可持续生产提供理论依据。研究期间,共鉴定土壤线虫38个属,其中假海矛属(Pseudhalenchus)、短体属(Pratylenchus)和真滑刃属(Aphelenchus)为优势属。长期施用化肥显著增加各研究土层的线虫总数,并改变线虫的群落结构。长期施化肥对0～10 cm土层线虫各生态指数的影响不显著。在10～20 cm和20～40 cm土层,长期施用化肥显著提高食真菌与食细菌线虫比例(F/B)而降低线虫通路比值(NCR),表明其促进以食真菌为主的腐屑食物网分解通道;其显著提高优势度指数(λ)而降低香农指数(H)'、均匀度指数(J)和丰富度指数(SR),表明长期施用化肥导致土壤线虫多样性降低。土壤线虫可以作为评价施肥对土壤质量影响的生物指标。     

蔬菜地面源污染生态拦截系统与效果

针对蔬菜种植业面源污染日益严重的现状,该文选取浙江省太湖流域典型的蔬菜集约化种植区为研究对象,以因地制宜、实用高效、维护便捷、成本合理为原则,在研究区域构建了农田生态沟渠-生态消纳塘水肥一体化-过滤型主排水渠生态拦截系统,并对拦截系统效果进行综合分析研究,探索高效实用的农田面源污染生态拦截技术。结果表明,与2010年相比,工程建成运行后2011年、2012年总氮去除率分别达33%～52%、43%～67%,总磷去除率达23%～59%、43%～82%,在雨季6-9月间,去除效果最佳,且2012年效果优于2011年。该系统有效削减了菜地废水氮、磷等营养元素的排放,达到改善水质、美化景观、提升经济的综合效果,为蔬菜种植区面源污染控制提供技术工程示范,具有典型的推广应用价值。该文可为农田面源污染拦截技术研究及应用提供参考。     

Organic matter fractions and N mineralization in vegetable‐cropped sandy soils

Soil organic nitrogen mineralization rates and possible predictors thereof were investigated for vegetable‐growing soils in Belgium. Soil organic matter (SOM) was fractionated into sand (> 53 μm) and silt+clay (< 53 μm) fractions. The latter fraction was further separated into 6%NaOCl‐oxidation labile (6%NaOCl‐ox) and resistant N and C and subsequently into 10%HF‐extractable (mineral bound) and resistant (recalcitrant) N and C. The N mineralization turnover rate (% of soil N/year) correlated with several of the investigated N or C fractions and stepwise linear regression confirmed that the 6%NaOCl‐ox N was the best predictor. However, the small R² (0.42) of the regression model suggests that soil parameters other than the soil fractions isolated here would be required to explain the significant residual variation in N mineralization rate. A next step could be to look for alternative SOM fractionations capable of isolating bioavailable N. However, it would appear that the observed relationships between N fractions and N mineralization may not be causal but indirect. The number of vegetable crops per rotation did not influence N mineralization, but it did influence 6%NaOCl‐ox N, probably as an effect of differences in crop residues returned and organic manure supply. However, the nature of this relation between management, SOM quality and N mineralization is not clear. Explanation of correlations between N mineralization and presumed bioavailable N fractions, like the 6%NaOCl‐ox N, requires further mechanistic elucidation of the N mineralization process.     

冬小麦灌浆期蚜虫危害高光谱特征研究

为了有效控制农业生产中麦蚜的危害,提高利用遥感技术对麦蚜监测预报的时效性,在冬小麦蚜虫发生的关键生育时期（灌浆期）,获取了26个地面调查点的蚜害等级和冠层光谱数据。对比分析了不同蚜害等级的冠层光谱,发现随着蚜虫危害程度的加重,在可见光、近红外和短波红外波段的冬小麦冠层反射率均逐渐减小。通过进一步筛选各波段范围的最敏感波段,初步构建了冬小麦蚜害高光谱指数,并建立了蚜害高光谱指数与蚜害等级的遥感反演模型。结果表明,该模型可以用来反演灌浆期冬小麦的蚜害等级,为高光谱遥感识别和监测冬小麦灌浆期蚜虫危害提供理论依据。     

保护地菜田土壤氮素淋溶阻控措施及其效果研究

在保护地菜田条件下,以水果苤蓝为供试作物,研究优化施肥、C/N调控、种植填闲作物等3种不同措施对土壤硝态氮累积与淋溶的影响。结果表明,种植当季,优化施肥和C/N调控处理均可有效阻控硝态氮淋溶。综合考虑水果苤蓝生长期和填闲/休闲期,3种措施阻控硝态氮淋溶的强度,由强到弱依次为:种植填闲作物>优化施肥>C/N调控。建议控制施肥量的同时,采用合理的管理方式,多方面阻控硝态氮的累积与淋溶,保护环境安全。     

不同受害程度的棉株对棉蚜种群的影响

通过室内对不同密度棉蚜两次为害棉株的生态学参数测定，结果表明：棉株在受到棉蚜二次为害后，无论是棉株生长点或是不同生长期棉株受害，均可影响棉蚜种群数量下降，增长率降低，发育历期增大，扩散率提高，体色趋变黄色。可以证明受害棉株明显存有诱导抗性，且６片真叶以后的诱导抗性大于６片真叶以前。     

不同厂家六号溶剂油对植物油中溶剂残留量测定结果影响的研究

扦取５份大豆油样品,分别使用两个厂家的六号溶剂油制备标准样品,利用峰高定量法和峰面积定量法测定溶剂残留量,测定结果不同。大多数情况下,植物油样品种六号溶剂油组成与标准样品的不同,采用较高的记录仪纸速和峰面积定量,才能使溶剂残留测定结果较为准确。     

Variation in some agronomically important characters in a germplasm collection of beet (Beta vulgaris L.)

Summary A geographically representative selection of germplasm of Beta vulgaris, section Beta has been assessed for characteristics important in sugarbeet breeding, including downy mildew resistance, resistance to aphid colonisation and infection by the beet virus yellow complex. The occurrence of maintainer lines for cytoplasmic male-steriles was also investigated. Desirable qualities were found in some accessions, including nothern European wild vulgaris ssp. maritima and some old multigerm cultivars of fodder beets.