湘南地区杂柑天草高接换冠关键技术

天草杂柑的高接换冠的关键技术主要是：注意选择母树并适当修剪；合理采穗和保湿；科学嫁接；嫁接后精心管理．     

Comparison of models of simazine transport and fate in the subsurface environment in a citrus farm

Contamination of groundwater by agrochemicals is now widely recognized as an extremely important environmental problem. Modern agricultural practices involve the combined use of irrigation with the application of large amounts of agrochemicals to maximize crop yield. Due to flood irrigation and natural runoff, agricultural activities might generate soil, surface water and groundwater contamination problems and leaching of pesticides. Modeling of the transport and fate of pesticides, such as simazine, may help understand the long-term potential risk to the subsurface environment. This paper illustrates a comparative study via the use of three different pesticide transport simulation models and the applicability of those models in determining the groundwater vulnerability to pesticides contamination in a citrus orchard located at the Lower Rio Grande Valley (LRGV). The three models used in the study are the pesticide root zone model-3 (PRZM-3), the pesticide analytical model (PESTAN) and integrated pesticide transport modeling (IPTM). The concentration values obtained from all three models are in agreement, and they show a decreasing trend from the surface through the vadose zone. The problem is how to use this information and, specifically, how to combine the testimony of a number of experts into a single useful judgment. With the aid of the fuzzy multiattribute decision making method, PRZM-3 is deemed as the most promising one for such precision farming applications.     

Differential leaching of nutrients from soluble vs. controlled-release fertilizers

Extremely sandy soils and poorly distributed high annual rainfall in the state of Florida contribute to significant leaching losses of nutrients from routine fertilization practices. A leaching column experiment was conducted to evaluate the leaching losses of nutrients when using currently available N, P, K blend fertilizers for young citrus tree fertilization. Fertilizer blends included NH₄NO₃, Ca(NO₃)₂, IBDU, IBDU plus Escote, Nutralene, Osmocote, and Meister. Following leaching of 1000 ml of water through soil columns, which simulates leaching conditions with 26 cm of rainfall, the amount of NO₃ and NH₄ recovered in the leachate from soil columns amended with an NH₄NO₃ blend accounted for 37% and 88% of the respective nutrients contained in the quantity of blend per column. The corresponding values for soil columns amended with a Ca(NO₃)₂ blend were 48% and 100%. Leraching losses of both NO₃ (<3%) and NH₄ (<4%) were drastically decreased when using controlled-release fertilizers. The recoveries of P and K in 1000 ml of leachate were 1.3% and 8%, respectively, of the nutrients added as Osmocote, which contained coated P and K sources. In the case of the rest of fertilizer blends, the recoveries of P and K in 1000 ml of leachate were as high as 52%–100% and 28%–100%, respectively. Therefore, controlled-release technology offers an important capability for minimizing leaching losses of nutrients.     

VA菌根在柑桔上的应用及其前景

由于菌根在农业、林业生产中的重要性,对菌根的研究,尤其是对VA菌根的研究已引起人们广泛的重视.本文对VA菌根的研究及利用现状,尤其是VA菌根与植物营养,VA茵根与植物的抗性生理以及VA菌根、根瘤菌与植物三联体的效应等方面的动态作一综述,并对柑桔菌根今后的研究提出几点建议,其中包括菌根资源的调查、菌根资源圃的建立、柑桔菌根与环境、菌根与柑桔的抗性生理等。     

沙田柚根围AM真菌的生境适宜性和季节变化性

以山地长寿沙田柚成年果树为对象,研究不同生境和季节对丛枝菌根(Arbuscular mycorrhiza,AM)真菌侵染以及根围土壤中AM真菌孢子密度的影响.试验结果表明,不同生境下,菌根侵染率和AM真菌孢子密度都是以梯田最高,坡地次之,洼地最低;在坡地和洼地生境下,生草区均高于清耕区.两块试验地AM真菌的菌丝侵染率均为夏季最高(16.8%±1.9%和16.0%±1.8%),秋季次之,冬季最低;丛枝和泡囊的形成也是夏/秋季较高,春/冬季较低;而根围土壤中AM真菌孢子密度则是秋季最高[(159±19)个/100 g和(167±17)个/100 g],夏季次之,冬季最低.总之,对于长寿沙田柚成年果树,AM真菌的菌根侵染率在夏季梯田最高,根围土壤中的AM真菌孢子密度在秋季梯田最高;在坡地和洼地生境中,生草处理均可显著提高菌根侵染率和AM真菌孢子密度.图4参27     

柚园间种作物及施用不同有机肥对土壤与柚果的影响

柚树间种短期经济作物在提高柚园经济效益的同时,还可提高土壤的有机质和N、P、K养分质量分数,改善柚园小区气候,增加有机肥来源。间种物残余体作为绿肥,可显著地提高柚果产量和质量。     

Economic and Ecological Consequences of the Disappearance of Traditional Practices Related to Chestnut Groves

Based on an interdisciplinary study of nine localities, the authors analyse the role of human and local factors involved in the disappearance of chestnut groves. This analysis enables us to understand the significant elements involved, causes, restricting factors, potentialities which explain today's situation, and to hypothesise upon the evolution of the chestnut groves and the Southern Cevennes in the years to come. These hypotheses emphasise the necessary changes in attitudes and the extra research required to lead a positive future action in order to manage this territory in a rational way.     

湘南地区天草主要病虫害发生特点及综合防治

天草主要病害有炭疽病、煤烟病、日灼病和缺素症,主要害螨害虫有红蜘蛛、锈壁虱、蚜虫、潜叶蛾、柑桔象虫类、柑桔凤蝶和介壳虫类.文章总结了这些主要病虫害在天草上发生特点、时期及防治方法.     

Application of compost of two-phase olive mill waste on olive grove: Effects on soil,olive fruit and olive oil quality

Composting is a method for preparing organic fertilizers that represents a suitable management option for the recycling of two-phase olive mill waste (TPOMW) in agriculture. Four different composts were prepared by mixing TPOMW with different agro-industrial by-products (olive pruning, sheep manure and horse manure), which were used either as bulking agents or as N sources. The mature composts were added during six consecutive years to a typical “Picual” olive tree grove in the Jaén province (Spain). The effects of compost addition on soil characteristics, crop yield and nutritional status and also the quality of the olive oil were evaluated at the end of the experiment and compared to a control treated only with mineral fertilization. The most important effects on soil characteristics included a significant increase in the availability of N, P, K and an increase of soil organic matter content. The application of TPOMW compost produced a significant increase in olive oil content in the fruit. The compost amended plots had a 15% higher olive oil content than those treatment with inorganic fertilization. These organics amendments maintained the composition and quality of the olive oil.     

NaCl胁迫对不同柑橘砧木品种抗氧化系统的影响

采用土培的方式,研究了不同浓度的NaC(l0,50,100,150,250,350mmol·L-1)对岑溪酸橘Citrus reticulata Blanco、龙州土柠檬Citrus limonia Osbeck和临桂砧板柚Citrus grandis Osbeck叶片抗氧化酶(SOD、POD、CAT、APX)活性以及谷胱甘肽(GSH)、丙二醛(MDA)、超氧自由基(O2·-)含量的影响。结果表明,随着NaCl处理浓度的增加,岑溪酸橘、龙州土柠檬和临桂砧板柚3种柑橘叶片中O2·-均有不同程度的增加,表明在NaCl处理下3种柑橘均受到了不同程度的O2·-胁迫。NaCl处理对岑溪酸橘和龙州土柠檬SOD、POD活性,临桂砧板柚MDA含量的影响不显著(P0.05),但引起临桂砧板柚SOD活性、岑溪酸橘和龙州土柠檬APX活性显著增加(P0.05)。在不同浓度的NaCl处理下,3种柑橘叶片的CAT活性均有不同程度的下降,但GSH的含量随着NaCl浓度的增加而增加,在NaCl处理浓度为350mmol·L-1时,岑溪酸橘、龙州土柠檬、临桂砧板柚GSH含量分别比对照提高了137%、59.1%、90.8%,表明GSH在解毒NaCl胁迫时起重要作用。