Short-term effects of organic amendments on soil fertility and root growth of rubber trees on Hainan Island, China

Rubber[Hevea brasiliensis(Willd.ex A.Juss.)Müll.Arg.]plantations are the largest cultivated forest type in tropical China.Returning organic materials to the soil will help to maintain the quality and growth of rubber trees.Although many studies have demonstrated that organic waste materials can be used to improve soil fertility and structure to promote root growth,few studies have studied the eff ects of organic amendments on soil fertility and root growth in rubber tree plantations.Here,bagasse,coconut husk or biochar were applied with a chemical fertilizer to test their eff ects on soil properties after 6 months and compared with the eff ects of only the chemical fertilizer.Results showed that the soil organic matter content,total nitrogen,available phosphorus and available potassium after the chemical fertilizer(F)treatment were all signifi cantly lower than after the chemical fertilizer+bagasse(Fba),chemical fertilizer+coconut husk(Fco)or chemical fertilizer+biochar(Fbi)(p<0.05).Soil pH in all organic amendments was higher than in the F treatment,but was only signifi cantly higher in the Fbi treatment.In contrast,soil bulk density in the F treatment was signifi cantly higher than in treatments with the organic amendments(p<0.05).When compared with the F treatment,soil root dry mass increased signifi-cantly by 190%,176%and 33%in Fba,Fco and Fbi treatments,respectively(p<0.05).Similar results were found for root activity,number of root tips,root length,root surface area and root volume.Conclusively,the application of bagasse,coconut husk and biochar increased soil fertility and promoted root growth of rubber trees in the short term.However,bagasse and coconut husk were more eff ective than biochar in improving root growth of rubber trees.

Microorganism Characteristics in Decomposition Process of Rubber Tree Leaves Litter in Hainan Island

Microorganism plays an irreplaceable role in litter decomposition,and the dynamics of microbial activity in litter is of ecological significance in understanding the mechanism of litter decomposition. Therefore,the dynamic characteristics of microorganism in rubber litter decomposition were studied during 300 and 240 days by mesh bag method under different control measures in plantations. And the results were as following:(1) Microbial populations were closely related to litter residues and decomposition environments. The microbial population has been rising firstly and then falling on the ground but directly dropping under the ground by time.(2) Microbial populations under different environments as follows:0.07 mm aperture of mesh bag > 1 mm aperture of mesh bag,non-fertile hole > fertile hole,underground group > ground group. During the entire process of decomposition,the quantity of bacteria holed absolute superiority,then actinomycetes,finally fungi.(3) Through the correlation analysis,the total number of bacteria,fungi and microorganism in aboveground group was significantly associated with the decomposition rate,but there was little correlation to actinomycetes. It's suggested that fungi and bacteria are the main participants in litter decomposition on the ground. In underground group,the microbial groups were significantly or extremely significantly related to the dry weight of residues,but was not correlated to decomposition rate significantly,which suggested that litter provided food for underground microbes,and litter decomposition was more dependent on comprehensive effect of microbes,soil animals and soil environments.

Rubber Tree Distribution Mapping in Northeast Thailand

In many parts of mainland Southeast Asia rubber plantations are expanding rapidly in areas where the crop was not historically found. Monitoring and mapping the distribution of rubber trees in the region is necessary for developing a better understanding of the consequences of land-cover and land-use change on carbon and water cycles. In this study, we conducted rubber tree growth mapping in Northeast Thailand using Landsat 5 TM data. A Mahalanobis typicality method was used to identify different age rubber trees. Landsat 5 TM 30 m non-thermal reflective bands, NDVI and tasseled cap transformation components were selected as the model input metrics. The validation was carried out using provincial level agricultural statistical data on the rubber tree growth area. At regional (Northeast Thailand) and provincial scales, the estimates of mature and middle-age rubber stands produced from 30 m Landsat 5 TM data compared well (high statistical significance) with the provincial rubber tree growth statistical data.

First characterization of endophytic Corynespora cassiicola isolates with variant cassiicolin genes recovered from rubber trees in Brazil

Corynespora cassiicola is the causal agent of Corynespora Leaf Fall(CLF)disease.CLF is one of the most important fungal diseases of rubber trees in Asia and Africa but disease outbreaks have not been reported in South America.Cassiicolin,a small cysteine-rich glycoprotein secreted by the pathogenic C.cassiicola isolate CCP,was previously identified as a potential disease effector in rubber tree.Recently,the cassiicolin-encoding gene(Cas1)was characterized and shown to be expressed in the early phase of infection.In this study,we investigated whether previously undetected strains of C.cassiicola are present in South American rubber plantations by examining the fungal endophyte population found in asymptomatic rubber tree leaves.Four isolates were identified as C.cassiicola.Genes encoding new forms of the cassiicolin precursor protein(Cas3 and Cas4)were identified from these isolates.Three of four isolates were able to induce symptoms on the cultivar they were isolated from in a detached leaf assay,with different kinetics and intensities.One isolate had the same pathogenicity profile as the pathogenic isolate CCP;the other two isolates developed symptoms late during the course of infection,suggesting saprotrophic capabilities.However,no Cas3 or Cas4 transcripts could be detected upon inoculation with the endophytic isolates,whereas the reference gene Cas1 was expressed upon inoculation with the CCP isolate.This work demonstrated that C.cassiicola is present in South America in an endophytic form and that it may evolve from an endophytic to a saprophytic or even potentially pathogenic life style.

The legacy effects of rubber defoliation period on the refoliation phenology,leaf disease,and latex yield

The leaf phenology of trees has received particular attention for its crucial role in the global water and carbon balances,ecosystem,and species distribution.However,current studies on leaf phenology have mainly focused on temperate trees,while few studies including tropical trees.Little attention has been paid to globally extensive industrial plantations.Rubber plantations are important to both the local and global economies.In this study,we investigated the legacy effects of defoliation phenology on the following year’s leaf flushing,leaf disease,and also latex yield of rubber trees,an economically important tree to local people and the world.Results show that extended duration of defoliation increased the subsequent duration of refoliation and rates of infection by powdery mildew disease,but led to reduced latex yield in March.This legacy effect of rubber defoliation may relate to the carbohydrate reserved in the trees.A longer duration of defoliation would consume more reserved carbohydrates,reducing available reserves for disease defense and latex production.Extended duration of defoliation period was associated with either a lower temperature before the cessation of latex tapping in October-November and/or a higher temperature after the cessation of latex tapping in December-January.Leaf falling signals the end of photosynthetic activities in deciduous trees.Thus,the leaf falling phenology will impact ecological processes involving rubber trees.Our findings indicated that the inclusion of defoliation periods in future rubber trees’ research,will be crucial to furthering our understanding of leaf flushing,powdery mildew disease,and latex yield.

Exploration and Practice of Rubber Based Agroforestry Complex Systems in China

Agroforestry ecosystems are constructed by simulating natural ecosystems, applying the principles of symbiosis in nature, and organizing multiple plant populations to coexist, while conducting targeted cultivation and structural control scientifically. Rubber agroforestry complex ecosystems aim for sustainable development in terms of industry, ecology, resource utilization, and the livelihoods of producers. Rubber agroforestry complex ecosystems create a complex production structure system that integrates biology, society, and the economy through species combinations. Rubber trees and associated biological components coordinate with each other, mutually promote growth, and yield a variety of products for producers. Cultivation techniques and patterns of rubber agroforestry are essential components of these ecosystems. This study analyzes the production practices of rubber agroforestry complex cultivation, with a focus on the development and characteristics (complexity, systematicity, intensity, and hierarchy) of rubber agroforestry systems using a literature analysis and a survey approach. It explores the types and scales of complex planting, specifications and forms, and major effects of complex cultivation. This study identifies successful rubber agroforestry cultivation patterns and practical techniques, as well as the potential benefits of developing rubber agroforestry cultivation. It also points out the shortcomings in the development of complex planting, including an emphasis on production practices but insufficient theoretical research, a focus on production but inadequate attention to the market, and an emphasis on yield while overlooking the improvement of standards, brands, and added value. There are various complex patterns for young rubber plantations, but relatively fewer for mature plantations. Based on this analysis, this study suggests that future efforts should focus on in-depth research on interspecies and environmental interactions in rubber agroforestry ecosystems, clearly define key roles, accelerate the innovation of development patterns, and strengthen the foundation for development. It recommends promoting and demonstrating successful rubber agroforestry complex patterns and providing technical training, developing product branding for rubber agroforestry patterns, enhancing product value, expanding the application functions of rubber-forest mixed crop products, and establishing a stable and sustainable industry chain. This study provide practical experience and theoretical insights in rubber agroforestry complex systems from China the potential to enrich the knowledge of rubber agroforestry composite systems, provide practical experience to improve the operating income of smallholders, and even promote the sustainable development of rubber plantations.

Electrical treeing behaviors in silicone rubber under an impulse voltage considering high temperature

In this paper,work was conducted to reveal electrical tree behaviors（initiation and propagation）of silicone rubber（SIR） under an impulse voltage with high temperature.Impulse frequencies ranging from 10 Hz to 1 k Hz were applied and the temperature was controlled between 30 °C and 90 °C.Experimental results show that tree initiation voltage decreases with increasing pulse frequency,and the descending amplitude is different in different frequency bands.As the pulse frequency increases,more frequent partial discharges occur in the channel,increasing the tree growth rate and the final shape intensity.As for temperature,the initiation voltage decreases and the tree shape becomes denser as the temperature gets higher.Based on differential scanning calorimetry results,we believe that partial segment relaxation of SIR at high temperature leads to a decrease in the initiation voltage.However,the tree growth rate decreases with increasing temperature.Carbonization deposition in the channel under high temperature was observed under microscope and proven by Raman analysis.Different tree growth models considering tree channel characteristics are proposed.It is believed that increasing the conductivity in the tree channel restrains the partial discharge,holding back the tree growth at high temperature.

Studies on Rubber (<i>Hevea brasiliensis</i>) Trees Exist Plant Type after Planting and Available Tapping Tree of Rubber Plantation in China

Existing plant types of rubber tree after planting and available tapping tree were investigated, and there were about 28 rubber plantations with different tapping years of 8 varieties “CATAS7-33-97”, “CATAS8-79”, “CATAS7-20-59”, “PR107”, “RRIM600”, “GT1”, “INA873”, “93-114”in South China. The results showed that there were six kinds of existing plant types of rubber tree after planting of rubber plantations, which were available tapping trees, wind damaged trees, cold damaged trees, tapping panel dryness trees, absent trees and weak trees, respectively. These data investigated also showed rubber trees under available tapping, stoppage due to tapping panel dryness, absence, wind damage, cold damage and weakness were counted and calculated and made up for 72.21%, 14.75%, 5.61%, 3.86%, 2.68% and 1.89%. Tapping panel dryness trees, wind damage and absent trees are major factors for the loss of tapping rubber trees in the rubber plantations. Of these investigated varieties, available tapping trees per 100 trees of rubber plantation of “PR107”at the 1st, 12th, 14th, 16th, 20th, 24th tapping year were 96, 67, 70, 75, 66, 46 trees in Hainan planting zone, respectively. Available tapping trees per 100 trees of rubber plantation of “RRIM600”at the 9th, 15th, 20th, 22nd tapping year were 88, 62, 55, 36 trees in Yunnan planting zone, respectively. Available tapping trees per 100 trees of rubber plantation of “93-114” at the 10th, 19th, tapping year were 94, 62 trees in Guangdong planting zone. These results showed that available tapping trees of rubber plantation decreased with increasing tapping age under different planting zones in China.

中国橡胶树北移栽培研究的历史考察

以20世纪50-80年代中国开展的橡胶树北移栽培研究作为研究对象,从科学史的视角,系统梳理了在西方国家对我国实行橡胶禁运的背景下,中国科学院相关研究所与当时林垦部下辖地方农垦系统、地方科研院所面对国家需求,在华南与云南分别开展系统的中国热带生物资源考察,并在此基础上确定橡胶宜林地,开展橡胶树抗寒抗风研究,最终成功实现橡胶树北移栽培,满足了国家对橡胶这一战略物资需求的过程。这有助于深入理解20世纪50-80年代国家实施的“任务带动学科”的科学发展方针,同时对于认识当代科学研究如何满足国家需求、重大科学研究中不同机构如何更好开展协同攻关,具有重要的现实借鉴价值。

防治橡胶树褐根病0.5%戊唑醇膏剂的研制

由木层孔菌属有害层孔菌Phellinus noxius Corner引起的褐根病是我国橡胶树的主要根部病害之一。生产上常用挖隔离沟和灌根施药方式进行防治,但其耗费人力物力,防治成本高。为了寻求经济高效且环保的新技术,本研究通过对不同杀菌剂、填料、增稠剂、渗透剂和保湿剂进行筛选,制备了一种防治橡胶树褐根病的膏剂。随后,通过对外观、附着性、黏度、pH值、稳定性、成膜性及固含量流失率等性能指标的综合评价,确定了膏剂的最佳配方为:0.5%(质量分数,余同)戊唑醇、20%纳米硅藻土、2%羧甲基纤维素钠、6%乌迪尔树皮穿透剂、5%凡士林、5%棕榈油、5%乙二醇,余量为水。制备的膏剂为乳白色黏稠状,呈弱碱性,附着性强,黏度高,冷热储合格,成膜薄且有韧性,膜的固含量流失率为13.95%,耐雨水冲刷能力强。0.5%戊唑醇膏剂经过橡胶植株茎基部施药,通过气相色谱-串联质谱(GC-MS/MS)结合QuEChERs法检测橡胶根中戊唑醇的含量。结果表明,施药后24 h即可在植株根部检测到戊唑醇,96 h含量达到5.49 mg/kg,说明戊唑醇能穿透茎部树皮向下传导至根部。综上所述,膏剂剂型的研制为橡胶树褐根病的化学防治提供了一种新途径。

基于激光测距的橡胶树树干轮廓曲线自动化提取方法

为获取橡胶树树干轮廓曲线模型,解决割胶装备难以精准贴合树干轮廓导致作业精度差、仿形效果不理想的关键问题,提出一种橡胶树树干轮廓曲线自动化提取方法。研制橡胶树树干轮廓点云数据自动采集平台,该平台由电源模块、控制模块、驱动模块、采集模块、数据传输模块以及数据记录处理模块组成,可实现树干外轮廓曲线点云数据的自动采集、传输、记录与处理。开展橡胶树树干轮廓曲线自动化提取试验,基于统计学方差分析法,通过曲线面积对比分析树干轮廓提取精度。结果表明,连续采集30组橡胶树树干轮廓点云数据,其轮廓特征有效识别度较高,轮廓特征点位置与实际位置基本符合;轮廓曲线重复提取变异系数为0.001 3;树干轮廓曲线提取精度不受树干位置和采集方向变化的影响,该技术方案具有较强可行性。

农机农艺融合的高效割胶技术优化设计与应用

割胶是橡胶树收获胶乳的重要途径,便携式机械化割胶是实现产业升级和节本增效的途径之一。为进一步提高机械割胶效果,根据采胶生理特殊性、割胶工况复杂多变性、橡胶树收获物胶乳黏弹特性、橡胶树生长差异性、割胶形式多样性等农机农艺融合问题对割胶机械的设计需求,优化设计便携式电动割胶装备的切割刀片、电子调速器、导向器等零部件。优化结果表明:采用刃高≥10 mm的刀片割胶,可以轻松切断旧胶线;电子调速器在电机转速为3 201~8 459 r/min区间调速时,灵敏度高,单次割胶轨迹连续平稳;导向器形状从“L”型优化为“T”型,减少旧胶线对割胶机械的干预。优化后的技术,提高便携式割胶机械对割胶农艺的适应性,降低操作技术难度和单株割胶时间,胶工更容易快速掌握。

橡胶树胶孢炭疽菌自噬相关基因ATG20的功能

胶孢炭疽菌(Colletotrichum gloeosporioides)是引起橡胶树炭疽病的优势小种,橡胶树感染后会大量减产。自噬现象是植物病原真菌中普遍存在的生理过程,自噬过程会受到多个自噬相关基因(ATG)的调控,在病原真菌对逆境的响应、生长发育和致病性方面具有重要作用。本研究克隆了橡胶树胶孢炭疽菌的ATG20同源基因CgATG20,构建了该基因的敲除突变株△CgATG20,并对其致病性、孢子产量、组织侵染情况和自噬情况等进行分析。结果显示,与野生型相比,△CgATG20的致病性、分生孢子产量和对植物的入侵率显著降低。在缺氮条件下,△CgATG20菌丝体中自噬小体的数量显著少于野生型。以上结果表明ATG20在胶孢炭疽菌的生长发育、致病性和自噬中发挥重要作用,这为寻找有效阻断病原真菌发育和侵染途径的防治策略提供了新的靶点。

枯草芽孢杆菌Czk1脂肽物质对橡胶树炭疽病和白粉病的抑制效果研究

白粉病和炭疽病是影响天然橡胶生产的重要病害。为明确枯草芽孢杆菌(Bacillus subtilis)Czk1脂肽物质对橡胶树炭疽病和白粉病的抑制作用,以橡胶种苗‘热研7-33-97’为试验材料,通过共培养法研究菌株Czk1脂肽粗提物对橡胶树炭疽病菌(Colletotrichum gloeosporioides)生长发育的影响,并采用脂肽粗提物和孢悬液法进行离体和盆栽试验评价其对橡胶树炭疽病和白粉病的抑制作用。结果表明,Czk1脂肽类粗提物可导致橡胶树炭疽病菌菌丝畸形和断裂,抑制病菌的最低质量浓度为40 mg·L^(-1),抑制其分生孢子萌发EC_(50)值为3.80 mg·L^(-1);40 mg·L^(-1)的Czk1脂肽类粗提物对橡胶树炭疽病菌孢子萌发抑制率达68.84%。脂肽粗提物质量浓度在1000 mg·L^(-1)时,可使盆栽和离体试验中炭疽病发病率降低43.40%和49.90%,同时亦使白粉病病情指数降低32.60和21.60,对橡胶树白粉病的防治效果为45.60%。由此表明,菌株Czk1脂肽物质能有效降低橡胶树炭疽病和白粉病发病率、抑制病菌生长并延缓病情的扩展,具有防治橡胶树叶部病害的良好生防潜力。

橡胶树割面涂施制剂载体黏度及其成膜性比较研究

针对现有橡胶树割面涂施制剂,其载体成膜粘附性不是很理想,存在容易被雨水冲刷、成膜不均匀、容易干裂等缺陷。选择聚乙烯醇(17-88)、聚乙烯醇(24-88)、聚乙烯醇(22-99H)、壳聚糖、海藻酸钠、聚甲基纤维素钠6种常见的胶体制剂载体,对其黏度及成膜性进行评价。评价结果表明,聚乙烯醇(17-88)、聚乙烯醇(24-88)、聚乙烯醇(22-99H)三种材料黏度及成膜性相对较好,适宜作为橡胶树割面涂施制剂载体,其中聚乙烯醇(24-88)载体最佳,其浓度为5%~10%适宜。聚乙烯醇(24-88)载体黏度适中,易于配制,成膜均匀,附着力强,耐折性好,机械性能稳定,是一种较理想的橡胶树割面涂施制剂载体。

大载荷植保无人机施药参数优选及不同药剂对橡胶树“两病”的飞防效果研究

本研究利用大载荷油动植保无人机(FBH300T)开展橡胶树白粉病和炭疽病(简称橡胶树“两病”)的飞防试验,分析飞行离冠层高度3、5、7 m和施药量60、90、105L/hm^(2)两个参数对橡胶树上、下层叶片雾滴沉积分布的影响。发现飞行高度和施药量对雾滴密度和雾滴覆盖率均表现出极显著的影响,筛选出飞行离冠层高度5 m、施药量90 L/hm^(2)、飞行速度5 m/s是该机型的最优施药参数。利用兼治橡胶树多种叶部病害的新型专用药剂19%保叶清微乳剂,以及60%硫磺粉悬浮剂、45%戊唑·咪酰胺水乳剂和50%硫磺·三唑酮悬浮剂等高效药剂与大载荷植保无人机配套施用,分析各药剂单独和两两混配施用对橡胶树“两病”的飞防效果。结果表明:4个单剂中对白粉病防效最好的是50%硫磺·三唑酮悬浮剂,其次是19%保叶清微乳剂;对炭疽病防效最好的是19%保叶清微乳剂,其次是45%戊唑·咪酰胺水乳剂。药剂两两混配施用下,19%保叶清微乳剂和60%硫磺粉悬浮剂按1∶1混配对白粉病和炭疽病的防效最好,其次是19%保叶清微乳剂和50%硫磺·三唑酮悬浮剂按1∶1混配。本研究结果可为橡胶树“两病”无人机飞防技术熟化和飞防专用药剂的选择提供参考依据。

橡胶狗尾草平脐蠕孢叶斑病病原菌鉴定及生物学特性研究

为明确采自西双版纳景洪地区疑似橡胶麻点病的病原菌,采用组织分离法进行病原菌分离,活体接种法进行致病性测定,通过形态学观察结合rDNA-ITS和GAPDH两个核苷酸片段序列分析,将病原菌确定为狗尾草平脐蠕孢Bipolaris setariae。通过单因子变量试验,对病原菌进行生物学特性研究,结果表明:菌丝生长最适温度为30℃,最适pH为7~8,最适培养基为PDA,菌丝致死温度为53℃,10 min。该病原菌能有效利用多种碳源和氮源,碳源以可溶性淀粉利用率最高,最适氮源为蛋白胨。24 h黑暗条件下培养更有利于菌丝生长。分生孢子萌发的最适温度为28~35℃,最适pH为7~8,28℃黑暗培养2 h后萌发率达到最大,为95.5%,分生孢子致死温度为60℃,10 min。

邻苯二甲酸对橡胶树RRIM600种子萌发和幼苗生长的影响

根系分泌物是植物自毒物质的重要来源之一,研究表明邻苯二甲酸是一种公认的自毒物质,也是橡胶树根系分泌物中含量较高的物质之一。为探究邻苯二甲酸对橡胶树自身是否具有自毒作用,考察不同浓度(0.05、0.50、1.00、2.00 mmol/L)邻苯二甲酸溶液对橡胶树RRIM600种子萌发、幼苗生长的影响。结果表明:(1)不同浓度邻苯二甲酸均推迟橡胶树种子的初始萌发时间,对种子发芽率、发芽速率和萌发整齐度均存在抑制作用,且浓度越高抑制作用越强,与对照相比,2.00 mmol/L邻苯二甲酸处理的发芽率、发芽指数、发芽速率、发芽势分别下降了23.60%、42.75%、37.18%、58.69%。(2)不同浓度邻苯二甲酸均抑制橡胶树芽长、芽粗、根粗的生长,减少了幼苗生物量的积累;在0.05~2.00 mmol/L浓度范围内,芽长、芽粗、根粗、芽重和根重分别下降了12.91%~40.70%、 20.05%~21.59%、 7.89%~34.13%、16.18%~26.47%、20.00%~36.00%。(3)随邻苯二甲酸浓度增加,橡胶树幼苗细胞膜脂过氧化程度逐渐加重,丙二醛(malonaldehyde,MDA)含量逐渐增加;游离脯氨酸和可溶性糖含量也逐渐增加。(4)橡胶树幼苗色素含量和过氧化氢酶(catalase,CAT)活性随邻苯二甲酸浓度增加呈现先增加后减少的趋势,而超氧化物歧化酶(superoxide dismutase,SOD)和过氧化物酶(peroxidase,POD)活性随邻苯二甲酸浓度增加而逐渐减少;0.05mmol/L的邻苯二甲酸促进幼苗叶绿素b的积累,降低了叶绿素a含量,并提高CAT活性,降低了POD和SOD活性;当浓度达到0.50 mmol/L时,叶绿素a、叶绿素总量和类胡萝卜素含量积累至最大,POD和SOD活性持续下降;在2.00mmol/L时,所有色素含量和3种抗氧化酶活性均降至最低。综上,邻苯二甲酸推迟了橡胶树RRIM600种子初始萌发时间,降低种子萌发率和萌发速率,导致橡胶树幼苗生理功能紊乱,并抑制生长发育。该研究结果可为客观评价邻苯二甲酸对橡胶树自毒作用提供基础数据支撑。

保水剂施用量对胶园土壤微生物和土壤酶活性及产量的影响

【目的】探明保水剂对胶园土壤生物活性及橡胶树产量的影响,探索适合开割橡胶树抗旱和高产的保水剂用量,为橡胶树抗旱高产栽培技术研究提供支持。【方法】以15割龄的橡胶树热研7-33-97为材料,采用田间试验,以不施用保水剂为对照(CK),比较不同保水剂施用量(T1:60 g/tree、T2:120 g/tree、T3:180 g/tree、T4:300 g/tree)对胶园土壤pH、水分、养分、微生物数量、酶活性以及橡胶树胶乳产量的影响。【结果】施用保水剂提高了胶园土壤含水量和速效养分含量,但对土壤pH无影响;同时还促进土壤细菌数量、放线菌数量和微生物总量增加,但未改变土壤中细菌、放线菌、真菌的总体比例,土壤微生物仍以细菌为主;不同处理土壤酶活性和橡胶树胶乳产量随着保水剂用量增加呈单峰曲线态势。细菌数量、放线菌数量、脲酶活性、转化酶活性、过氧化氢酶活性、氨态氮含量、速效磷含量、橡胶树干胶产量均随着保水用量增加呈先增后降趋势,且各处理中以T2用量对提高胶园土壤微生物数量和酶活性、增加橡胶树产量效果最佳;与CK相比,T2处理的土壤细菌与放线菌数量分别增加346.42%、191.48%,而土壤真菌数量减少15.31%,土壤脲酶、转化酶和过氧化氢酶活性分别提高40.01%、15.74%、31.44%,橡胶树干胶产量增加11.99%。【结论】在开割胶园施用保水剂,推荐施用120 g/tree,有利于提高土壤含水量,增加土壤微生物数量和养分含量,促进橡胶树胶增产。

海南橡胶树炭疽病调查及喀斯特炭疽病菌的鉴定

天然橡胶是四大工业原料中唯一的可再生资源,由炭疽病菌侵染引起的橡胶树炭疽病是当前我国橡胶生产上最为严重的两大叶部病害之一。本研究通过调查海南省主栽橡胶树品种(系)及监测炭疽病发生流行情况,调查发现PR107和RRIM600种植面积最大,分别占51.06%(102000 hm^(2))和43.39%(86700 hm^(2));在对橡胶树炭疽病的随机踏查和固定监测中发现,该病在实生苗、嫁接苗、增殖苗、各主栽品种幼龄树和成龄胶园中全年均可发生,3—4月为盛发期;海南省橡胶树种植面积大,且品种(系)单一,因此炭疽病在适宜发病条件下易暴发流行。通过形态观察、致病性测定和多基因系统发育分析发现,分离自琼中县阳江农场苗圃橡胶树叶片上的菌株HCkHNQZ1736为喀斯特炭疽菌(Colletotrichum karstii),这是首次在海南省橡胶树上发现该类病菌。致病力评价发现其对PR107、RRIM600、热研7-33-97和大丰95四个主推品种均有强致病力。杀菌剂敏感性测定结果表明,菌株HCkHNQZ1736和分离自云南保山的同种菌株MeCkYN1705对咪鲜胺锰盐差异不显著且不具抗药性,EC_(50)分别为0.0784μg/mL和0.0775μg/mL。HCkHNQZ1736对多菌灵表现出高抗药性,EC_(50)达1107.2654μg/mL,而MeCkYN1705的EC_(50)仅为0.0554μg/mL。