恶唑菌酮在柑橘土壤中的残留动态研究

采用气相色谱(GC-ECD)测定了恶唑菌酮在柑桔及土壤中的残留量,方法的最低检出浓度分别是:对20g桔皮和土壤样品为0.0048mg/kg,对50g桔肉样品为0.001mg/kg,。动态和最终残留试验结果表明:恶唑菌酮在柑桔全果和土壤中的半衰期分别为21.73￣23.98d和9.68￣11.81d;按推荐剂量即恶唑菌酮6.25%WG稀释1000倍液喷施桔树,最多4次,最后一次施药距采收间隔期为20d,恶唑菌酮在收获的柑桔全果和桔肉中的残留量均低于最大残留限量,食用桔肉是安全的。     

甘肃白龙江河谷浅山区冬季温度分布、逆温特征及宜桔地选择

本文探讨了陇南白龙江流域河谷浅山区冬季温度分布及逆温出现的特点;阐述了逆温形成的原因及与桔树生物学特性相适应的“逆温暖层”农业气候、生态的优势;根据冬季宏观温度和山体逆温分布规律,提出了浅山“暖层”宜桔地选择的方法。     

丛枝菌根真菌对柑橘组培苗生长和抗氧化酶的影响

在温室条件下以枳〔Poncirus trifoliata(L.)Raf.〕组培苗为试材,研究了接种Glomus versiforme和G.mosseae对其生长、碳水化合物和抗氧化酶的影响.结果表明,接种G.versiforme的组培苗和接种G.mosseae的组培苗分别在第二级侧根和第一级侧根中观察到最高的菌根侵染率、泡囊数、丛枝数和侵入点.两种丛枝菌根真菌都显著提高了茎粗、叶面积、叶片数、根系体积、地上部干重、地下部干重、叶绿素和类胡萝卜素含量.两种丛枝菌根真菌显著促进了叶片和根系可溶性糖以及总的非结构碳水化合物含量.丛枝菌根真菌也提高了叶片和根系中SOD、POD和CAT活性,但显著抑制了叶片和根系中可溶性蛋白含量.G.versiforme对柑橘组培苗生长和碳水化合物的促进效果较好;G.mosseae对组培苗抗氧化酶的促进效果较好.表4参26     

桔园间作牧草的生态效益及其管理技术

在浙江省金华地区新垦植的红壤幼龄桔园及盛产成龄桔园进行了间作试验和调查研究。结果表明，幼龄桔园间作黑麦草或紫云英，能提高光能利用率，具有延缓秋冬土壤降温和春季土壤升温、减小土壤日温差幅度和冬季保暖、降低水土流失量等生态效应，但对夏梢生长具有不良的影响；成龄桔园长期间作紫云英也具有提高光能利用率，维持较高的肥料养分效率，明显改善土壤肥力，提高产量和改善柑桔外观品质等多种效益。桔园间作牧草应结合柑桔生产的要求，抓住适时拌肥播种、及时收割施肥和适时适量归还土壤３个管理技术要点。     

Social enquiry and the measurement of natural phenomena: the degradation of irrigation water in the Argolid Plain,Greece

Attempts to formulate appropriate policies for the management of agricultural systems are constrained by the limitations of acquiring information about changes in the natural system across space and through time. The adoption of natural science techniques to measure the transformation of natural phenomena requires considerable investment in time and expertise and may not always be capable of providing information about change in a way that meets the adaptive requirements of planning and policy. A more flexible approach to data collection will require the acceptance of less precise and more general physical data as the basis for understanding changes in complex agricultural systems. This raises interesting questions about the adoption of social enquiry techniques to provide information about changing natural phenomena. The progressive deterioration of water resources, as a result of intensive agricultural activity in the Argolid Plain of Greece, will be considered and the problems of measuring the extent of that degradation, and the processes leading to it, will be discussed.     

A concept model to estimate the potential distribution of the Asiatic citrus psyllid (Diaphorina citri Kuwayama) in Australia under climate change—A means for assessing biosecurity risk

Increasing global temperatures as a result of climate change are widely considered inevitable for Australia. Despite this, the specific effects of climate change on Australian agriculture are little studied and the effects on agricultural pests and diseases are virtually unknown. In this paper we consider the impact of climate change on the Asiatic citrus psyllid (Diaphorina citri Kuwayama [Hemiptera: Psyllidae]); one of two known vectors of huanglongbing (citrus greening); a debilitating disease which is caused in Asia by a phloem-limited bacterium ‘Candidatus Liberibacter asiaticus’ (α-Proteobacteria). D. citri does not occur in Australia, but if introduced would pose a major threat to the viability of the Australian citrus industry and to native Citrus species. This paper presents an approach developed to understand how climate change may influence the behaviour, distribution and breeding potential of D. citri. Here we developed and describe an initial dynamic point model of D. citri biology in relation to its citrus host and applied it to a scenario of increasing temperatures, as indicators of climate change, on a continental scale. A comparison between model outputs for the three time frames considered (1990, 2030 and 2070) confirms that increasing temperatures projected under climate change will affect the timing and duration of new citrus growth (flush) necessary for psyllid development throughout Australia. Flushing will start progressively earlier as the temperature increases and be of shorter duration. There will also be a gradual southward expansion of shorter durations of the occurrence of flush. Increasing temperatures will impact on D. citri both directly through alteration of its temperature dependant development cycle and indirectly through the impact on the host flushing cycle. For the whole of Australia, a comparison between model outputs for the three scenarios considered indicates the seasonality of D. citri development will change to match changes in citrus flush initiation. Results indicate that the risk of establishment by D. citri is projected to decrease under increasing temperatures, mainly due to shortened intervals when it can feed on new leaf flushes of the host. However, the spatially heterogeneous results also suggest that regions located on the southern coastline of Australia could become more suitable for D. citri than projected under current temperatures. These results confirm the value of a linked host-pest approach as based on D. citri climatic requirements alone the model would have accounted only for shorter development periods and predicted an increased risk of potential distribution.     

Differential sorption of herbicides as related to soil topography and organic matter 1

Abstract

The sorption of bromacil and simazine by the surface soil (0–15 cm) sampled at various positions along an 8% slope citrus grove (Candler fine sand; Typic Quartzipsamment) and at various depths (0–200 cm) at upper, middle, and lower positions along the slope were investigated. The sorption of both herbicides by the top 15 cm soil decreased considerably from the upper to mid position along the slope and increased at the lower position. The organic matter content and concentrations of Ca, Mg, K, P, and Cu in the soil showed evidence of transport of organic matter and mineral nutrients from the mid position on the slope and accumulation in the lower position. The differential sorption of herbicides by the soil samples taken at various positions along the slope was closely related to changes in organic matter content. Although sorption of bromacil and simazine varied considerably at various positions along the slope, the sorption of bromacil was very similar at depths below 30 cm regardless of positions along the slope. In the case of simazine, however, the sorption was much greater at all depths in the lower than in the upper and mid position of the slope. The sorption of both herbicides decreased considerably at depths below 30 cm at all positions along the slope, thus, indicating the potential for rapid leaching of the herbicides down the soil profile.     

pH值调控对柑橘废渣与污泥厌氧共发酵产酸影响

为提高挥发性脂肪酸(VFA)的产量,探究了柑橘废渣和剩余污泥不同VS(挥发性固体)配比及调控发酵过程pH值对产VFA性能的影响.结果表明:调节共发酵系统pH值为6对VFA的积累有促进作用,柑橘废渣VS/剩余污泥VS为2时的最大VFA产量为11183.12mg/L,是未控制pH值组最高VFA浓度的1.75倍.柑橘废渣中的...     

氮沉降对缙云山柑橘林不同季节土壤微生物群落结构的影响

土壤微生物积极参与生态系统的物质循环和转化.人类活动造成全球氮沉降量激增,引起土壤微生物群落结构和功能的改变,进而导致生态系统失衡.2014年6月—2015年5月在缙云山柑橘林建立野外模拟氮沉降试验样地,原位设置4个施肥水平:对照(N0,0 g·m~(-2)·a~(-1))(以N计,下同)、低氮(N20,20 g·m~(-2)·a~(-1)),中氮(N4 0,40 g·m~(-2)·a~(-1))和高氮(N60,60 g·m~(-2)·a~(-1)).施氮处理2 d后,采用磷脂脂肪酸(PLFA)标记法和ACE(Automated Soil CO_2Exchange Station,UK)自动土壤呼吸监测系统对土壤微生物群落结构、土壤温湿度进行测定.研究表明:(1)不同季节土壤微生物对氮沉降的响应各异,春季氮沉降抑制土壤微生物量,夏、秋、冬季N40处理提高了土壤微生物量,N20、N60表现为抑制土壤微生物量;氮沉降对土壤温度有显著影响,但对土壤湿度影响不明显(p0.05).(2)土壤微生物丰富度指数和Shannon-Wiener多样性指数在中氮沉降条件下达最大;Pielou均匀度指数则表现不一致,春季和夏季在中氮浓度下最大,秋季在高氮处理下最大,冬季则在低氮处理下最大.(3)土壤温度与放线菌呈显著负相关(p0.01);土壤湿度与细菌和总PLFA呈显著正相关(p0.01),与放线菌呈显著正相关(p0.05).综合分析表明,土壤微生物受土壤温度和含水量的共同影响,氮沉降降低了土壤微生物含量,此研究结果支持了氮沉降抑制土壤微生物的认识.