The purpose of this study was to establish the relationship between the chilling resistance of rubber trees and the bark-bleeding characteristics caused by chilling stress, considering physiological indicators in rubber tree bark, cell wall chemical components, fiber morphologies, and tensile properties. This offered a unique perspective for examining the underlying mechanisms of latex bleeding and chilling stress in Hevea brasiliensis. One-year-old seedlings and two-year-old twig segments in five- and twenty-one-year-old rubber trees (5YB and 21YB) were used to compare the age-mediation differences in their various parameters. Meanwhile, the LT50 values were calculated with Logistic regression analysis of relative electrical conductivity (REC) data under gradient low temperatures. Subsequently, changes in corresponding parameters of 1-year-old seedling stem bark at different ages were determined, and the bark-bleeding characteristics of seedlings and twig segments were analyzed under artificially simulated chilling stress, respectively. A correlation analysis between semi-lethal temperature (LT50) values, relative water content (RWC) values, bark-bleeding characteristics, cell-wall chemical component contents, fiber dimensions, and tensile property parameters was implemented to estimate interrelationships among them. The LT50 values ranged from −2.0387 °C to −0.8695 °C. The results showed that the chilling resistance order of rubber trees at different ages was as follows: 21YB (2-year-old twig bark from 21-year-old rubber trees) > 5YB (2-year-old twig bark from 5-year-old rubber trees) > SLB (semi-lignification bark in 1-year-old seedlings) > GB (green bark in 1-year-old seedlings). The chilling resistance of seedlings and twig segments in rubber trees was highly positively (p < 0.001) related to fiber morphologies. Chilling-induced bark-bleeding characteristics were significantly correlated (p < 0.001) with fiber morphologies, bark tensile properties, and cell-wall components. The analysis data in this study contribute towards building a comprehensive understanding of the mechanisms of chilling-induced bark bleeding needed not only in rubber tree cultivation but also in sustainable rubber production.

The Camellia nitidissima C.W. Chi, a globally endangered species, is classified as a first-class protected plant in China. Given the potential impact of climate change on the distribution of species on a larger scale, it is crucial to understand the responses of C. nitidissima to this phenomenon for resource protection and sustainable utilization. Based on the existing records of C. nitidissima and multi-source remote sensing data, the optimal MaxEnt model was used to predict the potential habitat of C. nitidissima in both current and future periods. The results indicate that November average maximum temperature(Tx11) is the dominant factor. Under current climate conditions, the potential habitat of C. nitidissima is primarily located in the humid and hot coastal areas of southern China. Under future climate scenarios, the distribution range of C. nitidissima will initially increase, then decrease and finally increase again in correlation with radiation intensity. Comprehensive analysis reveals that under the background of global climate change, there remain significant challenges for the survival and reproduction of C. nitidissima in China. Appropriate protection and utilization measures can be implemented based on its migration trends to ensure the continuity of C. nitidissima habitats.

The rubber tree (Hevea brasiliensis), extensively cultivated in tropical regions, is a primary source of natural rubber. With increasing global demand for natural rubber, precise monitoring of cultivation dynamics of rubber plantations is crucial for regional economic development and ecosystem assessment. However, the significant spatial variability in rubber plantation phenology, interference from non-rubber deciduous forests, and cloud-free optical imagery limitations create considerable uncertainty in applying existing monitoring methods across varying latitudes. This study leverages extensive field surveys and over 30 years of Landsat/Sentinel-2 data to analyze the land use changes, growth processes in rubber seedling stages, and phenological changes during mature stages of rubber plantations. We developed a novel, high-precision identification and stand age estimation algorithm for rubber plantations on the Google Earth Engine (GEE) cloud platform, integrating multi-temporal remote sensing data, machine learning, and advanced algorithm optimization. Applications of this algorithm in countries with complex terrain and climate, such as Vietnam, Laos, Cambodia, and Myanmar, demonstrate higher robustness and accuracy. Ground data validation shows that the overall classification accuracy exceeds 95%, with an average stand age estimation error of less than two years. Spatial statistical analysis at 30-meter resolution aligns closely with data from authoritative sources like the Association of Natural Rubber Producing Countries (ANRPC), underscoring our method's effectiveness and reliability. Beyond mapping distribution and stand age structures of rubber plantations, this research supports future natural rubber production forecasts, environmental impact assessments, and sustainable policy development. Moreover, this study paves the way for novel applications of remote sensing in the monitoring of agriculture and forestry in tropical areas, setting a foundation for future advancements and innovations in these domains. Keywords: Rubber plantations, classification, Landsat, Sentinel-2, Google Earth Engine

Rubber trees (Hevea brasiliensis) serve as the primary source of natural rubber. Their native habitat is characterized by warm and humid conditions, so they are particularly sensitive to low temperatures. Under such stress, latex burst can cause severe damage to rubber trees, which is due to the uniqueness of their economically productive parts. In order to establish a correlation between young and mature rubber trees and provide a novel prospective for investigating the mechanisms of latex burst and chilling resistance in rubber trees, the chlorophyll contents, photosynthesis, and chlorophyll fluorescence parameters in four varieties of one-year-old rubber tree seedlings were analyzed under artificially simulated chilling stress. The latex burst characteristics were subsequently recorded. A comprehensive statistical analysis of the chilling-resistance rank was conducted using the membership function method and the combination weighting method. Meanwhile, chemical compositions and tensile properties of barks from two-year-old twigs of mature rubber trees were ascertained. A correlation analysis between chilling resistance, chemical compositions, and tensile properties was performed to identify any interrelationships among them. The results showed that the number and the total area of latex-burst positions in variety Reken628 seedlings were greater than those in other varieties, and the lowest number and total area of latex-burst positions were observed in variety RRIM600 and variety PR107, respectively. With the exception of variety GT1, nectar secretion was noted in all other varieties of rubber tree seedlings under chilling stress. The chilling resistance of the four varieties decreased in the following order: variety GT1 > variety RRIM600 > variety PR107 > variety Reken628. The chilling resistance was strongly (p < 0.001) negatively correlated with cellulose content and acid-insoluble lignin content, respectively. The total area of latex burst was significantly (p < 0.001) and positively correlated with holocellulose content and maximum load, respectively. Furthermore, this study also provides new insights into the mechanism of nectar secretion induced by low temperatures and its association with the chilling resistance of rubber trees.

Aluminum (Al) toxicity severely restricts crop growth and productivity in acidic soils. The rubber tree is one of the most economically important crops in tropical regions, which is tolerant to high concentrations of Al in sand or hydroponic culture conditions compared with other plants that have been reported. However, the mechanisms of Al tolerance in rubber trees remain unknown. In this study, we conducted a transcriptome and metabolome analysis for rubber tree sapling roots treated with 200 mM Al for 0 (CK), 2 or 5 days, respectively. Compared with the CK, a total of 9534 differentially expressed genes (DEGs) and 3821 differentially expressed metabolites (DEMs) were identified in 2 d of Al treatment. There were 10,373 DEGs and 4636 DEMs after 5 d of Al treatment, and 1626 DEGs and 1674 DEMs between 2 and 5 d of Al treatment. The DEGs mainly concentrated in transporters, transcription factors (TFs), cell wall biosynthesis and antioxidant systems, and the DEMs were mainly focused on lipids and lipid-like molecules, organic acids and derivatives, organic oxygen compounds, phenylpropanoids and polyketides. The combined transcriptome and metabolome analysis indicated DEGs and DEMs involved in ABC transporters, glutathione metabolism, flavonoid biosynthesis and phenylalanine metabolic pathways were identified to be closely associated with the Al tolerance of rubber trees. Our study elucidated the mechanism of rubber trees’ tolerance to Al at the transcriptional and metabolic levels, which provides a theoretical basis for the study of Al tolerance both for rubber trees and other woody plants.

为探索不同品种橡胶树幼龄树耐寒性与成龄树枝条韧皮部纤维形态、树皮抗拉伸性能之间的关系,分析不同品种橡胶树耐寒性与其相应生理、生物力学指标的相关性,从而比较不同品种橡胶树耐寒性的差异,以期建立不同品种橡胶树幼龄树茎段与成龄树枝条树皮相应指标之间的联系,并从细胞结构及树皮生物力学角度研究橡胶树耐寒性机理.以热研7-33-97、PB86、IAN873、大丰95、云研77-2等5个橡胶树品种1年生芽接苗茎段及相应品种成龄树2年生枝条树皮为材料,测定低温梯度下茎段韧皮部电导率及枝条韧皮部纤维形态、树皮抗拉伸性能指标,利用Logistic方程确定其低温半致死温度(LT50)的大小,得出不同品种耐寒性,并采用Spearman相关性分析法,得出LT50与韧皮部纤维形态指标、树皮抗拉伸性能之间的相关性.结果表明,5个橡胶树品种韧皮部相对电导率呈"S"形曲线变化,相对电导率与胁迫温度之间呈极显著负相关,5个品种LT50分别为-2.075℃、-2.240℃、-1.923℃、-1.900℃、-2.186℃;5个品种纤维长度在2921.013～4799.438μm,宽度在21.717～23.908μm,双壁厚度分别为11.504、10.271、10.873、12.715、10.401μm,腔直径分别为0.900、1.423、0.922、1.298、0.915μm,PB86的纤维双壁厚最小,腔直径最大;5个品种树皮厚度分别为0.709、0.564、0.886、0.935、0.774 mm,PB86的树皮厚度与其他品种的差异达到了显著水平(P<0.05),5个品种拉伸破坏荷载在4.935～11.064 N,PB86的抗拉伸强度与最大拉伸位移均为5个品种最大,分别为3.629 MPa、1.360 mm;1年生茎段韧皮部LT50与成龄树2年生枝条韧皮部纤维双壁厚呈显著性正相关,与2年生树皮厚度、抗拉强度分别呈显著性正相关和显著性负相关.从细胞尺度与组织生物力学角度研究橡胶树耐寒性,以此搭建橡胶树幼龄树与成龄树联系的纽带,是橡胶树耐寒机理研究的有效途径.

Secretion and efflux of oxalic acid from roots is an important aluminum detoxification mechanism for various plants; however, how this process is completed remains unclear. In this study, the candidate oxalate transporter gene AtOT, encoding 287 amino acids, was cloned and identified from Arabidopsis thaliana. AtOT was upregulated in response to aluminum stress at the transcriptional level, which was closely related to aluminum treatment concentration and time. The root growth of Arabidopsis was inhibited after knocking out AtOT, and this effect was amplified by aluminum stress. Yeast cells expressing AtOT enhanced oxalic acid resistance and aluminum tolerance, which was closely correlated with the secretion of oxalic acid by membrane vesicle transport. Collectively, these results underline an external exclusion mechanism of oxalate involving AtOT to enhance oxalic acid resistance and aluminum tolerance.

为探究拟南芥种子进行 1/2MS培养基筛选的最适潮霉素浓度,将野生型拟南芥种子灭菌后,点播在含 0,20,30,40,50 mg/L潮霉素的 1/2MS培养基上进行培养(分别记为 M0、M1、M2、M3、M4),观察潮霉素对种子萌发、幼苗生长形态变化的影响,统计种子萌发率、第 3 天萌发势、第 13 天幼苗失绿死亡率,测定第 7 天幼苗鲜重、干重、相对含水率、主根长度,结合逆向思维的变异系数-熵权组合赋权的TOPSIS方法得出不同浓度潮霉素处理效果的综合排序.结果表明,潮霉素对拟南芥种子萌发和幼苗生长均有明显的抑制作用;变异系数-熵权组合赋权的 TOPSIS方法得出不同处理对拟南芥种子萌发和幼苗生长抑制效果的排序为:M4>M3>M2>M1>M0,M2 的接近度为 0.531 5,约为 0.5,最接近抑制效果的 50％;综合实验结果可知,拟南芥种子进行 1/2MS 培养基筛选的适宜潮霉素浓度为 30 mg/L,种子点播的第 7～10天为幼苗移栽的适宜时期.

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;0.05 mmol/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 2.00 mmol/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.

Rubber (Hevea brasiliensis Muell.) plantations are among the most critical agricultural ecosystems in tropical regions, playing a vital role in regional carbon balance. Accurate large-scale biomass estimation for these plantations remains a challenging task due to the severe signal saturation problem. Recent advances in remote sensing big data, cloud platforms, and machine learning have facilitated the precise acquisition of key physiological variables, such as stand age (A) and canopy height (H), which are critical parameters for biomass estimation but have been underutilized in prior studies. Using Hainan Island—the second-largest rubber planting base in China—as a case study, we integrated extensive ground surveys, maps of stand age and canopy height, remote sensing indicators (RSIs), and geographical and climate indicators (ECIs) to ascertain the optimal method for estimating rubber plantation biomass. We compared different inputs and estimation approaches (direct and indirect) using the random forest algorithm and analyzed the spatiotemporal characteristics of rubber plantation biomass on Hainan Island. The results indicated that the traditional model (RSIs + ECIs) had low accuracy and significant estimation bias (R2 = 0.24, RMSE = 38.36 mg/ha). The addition of either stand age or canopy height considerably enhance model accuracy (R2 = 0.77, RMSE ≈ 21.12 mg/ha). Moreover, incorporating the DBH obtained through indirect inversion yielded even greater predictive accuracy (R2 = 0.97, RMSE = 7.73 mg/ha), outperforming estimates derived from an allometric equation model input with the DBH (R2 = 0.67, RMSE = 25.43 mg/ha). However, augmenting the model with stand age, canopy height, or their combination based on RSIs, ECIs, and DBH only marginally improved the accuracy. Consequently, it is not recommended in scenarios with limited data and computing resources. Employing the optimal model, we generated biomass maps of rubber plantations on Hainan Island for 2016 and 2020, revealing that the spatiotemporal distribution pattern of the biomass is closely associated with the establishment year of the rubber plantations. While average biomass in a few areas has undergone slight decreases, total biomass has exhibited significant growth, reaching 5.46 × 107 mg by the end of 2020, underscoring its considerable value as a carbon sink.

Understanding the status and changes of plant diversity in rubber (Hevea brasiliensis) plantations is essential for sustainable plantation management in the context of rapid rubber expansion in the tropics, but remains very limited at the continental scale. In this study, we investigated plant diversity from 10-meter quadrats in 240 different rubber plantations in the six countries of the Great Mekong Subregion (GMS)-where nearly half of the world's rubber plantations are located-and analyzed the influence of original land cover types and stand age on plant diversity using Landsat and Sentinel-2 satellite imagery since the late 1980s. The results indicate that the average plant species richness of rubber plantations is 28.69 ± 7.35 (1061 species in total, of which 11.22 % are invasive), approximating half the species richness of tropical forests but roughly double that of the intensively managed croplands. Time-series satellite imagery analysis revealed that rubber plantations were primarily established in place of cropland (RPC, 37.72 %), old rubber plantations (RPORP, 27.63 %), and tropical forests (RPTF, 24.12 %). Plant species richness in RPTF (34.02 ± 7.62) was significantly (p < 0.001) higher than that in RPORP (26.41 ± 7.02) and RPC (26.34 ± 5.37). More importantly, species richness can be maintained for the duration of the 30-year economic cycle, and the number of invasive species decreases as the stand ages. Given diverse land conversions and changes in stand age, the total loss of species richness due to rapid rubber expansion in the GMS was 7.29 %, which is far below the traditional estimates that only consider tropical forest conversion. In general, maintaining higher species richness at the earliest stages of cultivation has significant implications for biodiversity conservation in rubber plantations.

为了缩短橡胶树非生产期,加快橡胶树生长,在查阅文献资料和总结多年研究结果的基础上,提出了 1套橡胶树抗旱定植和速生管理技术,包括品种选择、苗木选择、挖穴与基肥、定植时间、抗旱定植、修芽与补换植、根圈覆盖、扩穴与挖肥穴、压青、追肥、病虫害防治等,旨在为橡胶树的定植与速生管理提供参考.

橡胶林下间作可提高林下土地资源的利用效率,促进胶园生产多元化,增加产值,但因成龄橡胶林下荫蔽度大,可间作作物种类较少、产品市场容量小,价格和效益不稳定,目前大多数成龄橡胶林下空间并未被充分利用.通过对橡胶林下资源环境特点及金花茶生活习性、价值、金花茶组研究、栽培历史、林下间作研究现状等分析,结合近2年引种栽培结果得出在海南橡胶林下间作金花茶可行的结论,该模式具有较好的发展潜力和前景,为成龄橡胶林下间作提供了新的途径.

为了计算和测定橡胶树的需水量,利用海南省儋州市1954—2020年的气候资料,采用CROPWAT模型,研究了不同水文年橡胶树的需水量及其与有效降水量的耦合度.结果表明:(1)橡胶树年均需水量为1069.8 mm,该区橡胶树年均有效降水量为1048.3 mm.(2)以旱季即11月至翌年4月的降水量为依据可较好划分当地水文年型,依此得到海南儋州地区橡胶树多雨年、正常年、旱年和特旱年需水量分别为1060.7、1072.0、1069.3和1156.6 mm.6～10月有效降水量最多;1～4月因降水量较小,有效降水量不能满足橡胶树蒸散需水量,因此,容易造成旱害.

[目的]探讨4个橡胶树品种耐寒能力及低温所致爆皮流胶情况的差异,以期了解品种耐寒性与爆皮流胶的关系及爆皮流胶的机制,为完善橡胶树耐寒评价提供参考,也为橡胶树抗寒栽培技术及产品研发提供理论基础.[方法]人工模拟低温下,以热研7-33-97、热研7-20-59、湛试327-13、93-114等4个橡胶树品种一年生芽接苗为试材,测定其叶片的相对电导率(REC)、丙二醛(MDA)含量、可溶性糖(SS)含量、可溶性蛋白(SP)含量、超氧化物歧化酶(SOD)活性、叶绿素a(Chl-a)含量、叶绿素b(Chl-b)含量(Chl-T)、叶绿素总量、PSII最大光化学效率(Fv/Fm)等生理生化指标及统计低温胁迫所致植株爆皮流胶情况,分别利用隶属函数法和主成分分析法综合比较4个橡胶树品种耐寒性与爆皮流胶耐受性的关系.[结果]4个橡胶树品种生理生化指标变化并不完全一致,4个品种的相对电导率(REC)、SOD活性均呈先升高后下降的趋势,Fv/Fm均呈逐步下降趋势,低温4～6 d的过程中,品种间SS含量差异达显著水平(P＜0.05);与对照相比,93-114的MDA含量、叶绿素a(Chl-a)含量、叶绿素总量变化幅度最大,低温第6天,仅93-114的SOD活性增加;与对照相比,热研7-20-59的可溶性蛋白(SP)含量均降低,Chl-a含量、Chl-b含量、叶绿素总量均低于其他3个品种.隶属函数法和主成分分析法得出的耐寒性顺序均为93-114＞湛试327-13＞热研7-33-97＞热研7-20-59,叶绿素含量、Fv/Fm、SS含量、SOD活性、REC、SP含量可作为橡胶树耐寒性评价的主要参考指标.[结论]橡胶树不同品种流胶个数与植株存活率与耐寒性保持一致,而流胶量与耐寒性并不一致.

P proteins encoded by SEOs (sieve element occlusion) have been shown to be associated with the blockage of sieve tubes after injury in many plants, but the presence of SEO genes and their association with rubber tree laticifer plugging and latex yield remain unclear. Through a systematic identification and analysis, seven SEO genes were identified from the rubber tree genome. The physicochemical properties of their proteins, gene structures, conserved domains, and locations on chromosomes were analyzed. According to their phylogenetic distance, HbSEOs were divided into two clusters. The transcript levels of HbSEO genes varied with tissues, in which HbSEO3 and HbSEO4 were most highly expressed in leaf, bark, and latex. HbSEOs could be induced by ethephon, methyl jasmonate, mechanical injury, and tapping; furthermore, they were highly expressed in trees with short flow duration, suggesting their possible association with rubber tree laticifer plugging and latex yield. To our knowledge, this is the first report of HbSEOs in rubber trees. It provides us with a better understanding of the mechanism of laticifer plugging.

橡胶树蜜具有丰富的矿物质及人体所需的多种微量元素,是较好抗氧化剂的来源,其生产可为橡胶树种植业带来更多经济效益,对胶园立体复合系统效益提升具有推动作用.但是,目前橡胶树蜜生产量有限,国内相关科学研究仅限于其生理生化指标的分析.从橡胶树泌蜜量影响因素入手,归纳了植胶区寒害与降雨、胶园立地环境、蜂群生产与繁殖、橡胶树白粉病防控、蜜蜂品种等与泌蜜量之间的关系,由此提出促进橡胶树泌蜜的各项栽培管理措施,以期为橡胶树蜜生产及应用研发提供一定的理论依据.

Secretion of oxalic acid from roots is an important aluminum detoxification mechanism for many plants such as Hevea brasiliensis (rubber tree). However, the underlying molecular mechanism and oxalate transporter genes in plants have not yet been reported. In this study, the oxalate transporter candidate genes HbOT1 and HbOT2 from the rubber tree were cloned and preliminarily identified. It was found that HbOT1 had a full length of 1163 bp with CDS size of 792 bp, encoding 263 amino acids, and HbOT2 had a full length of 1647 bp with a CDS region length of 840 bp, encoding 279 amino acid residues. HbOT1 and HbOT2 were both stable hydrophobic proteins with transmembrane structure and SNARE_assoc domains, possibly belonging to the SNARE_assoc subfamily proteins of the SNARE superfamily. qRT-PCR assays revealed that HbOT1 and HbOT2 were constitutively expressed in different tissues, with HbOT1 highly expressed in roots, stems, barks, and latex, while HbOT2 was highly expressed in latex. In addition, the expressions of HbOT1 and HbOT2 were up-regulated in response to aluminum stress, and they were inducible by metals, such as copper and manganese. Heterologous expression of HbOT1 and HbOT2 in the yeast mutant AD12345678 enhanced the tolerance to oxalic acid and high concentration aluminum stress, which was closely correlated with the secretion of oxalic acid. This study is the first report on oxalate transporter genes in plants, which provides a theoretical reference for the study on the molecular mechanism of oxalic acid secretion to relieve aluminum toxicity and on aluminum-tolerance genetic engineering breeding.

以橡胶树热研7-33-97芽接苗为材料,比较低温胁迫下市售、复配割面涂封剂处理对叶片叶绿素含量、光合作用及光化学效率的影响,以期为橡胶树新型割面涂封剂研发及抗寒机制研究提供理论依据.结果表明,低温胁迫导致叶片叶绿素含量、净光合速率(Pn)、气孔导度(Gs)、胞间二氧化碳浓度(Ci)、蒸腾速率(Tr)、PSⅡ最大光化学效率(Fv/Fm)下降,实际光化学效率(ΦPSⅡ)水平先升高后下降;低温胁迫1 d,以25 mg/L脱落酸、0.05 g/L壳聚糖、8.0 g/L CaCl2为主成分的复配割面涂封剂处理比市售割面涂封剂处理及对照的橡胶树叶片的 ΦPSⅡ分别高出37.90％、80.29％,差异达到极显著水平(P<0.01);低温胁迫4 d,复配涂封剂处理比市售割面涂封剂处理及对照的橡胶树叶片的叶绿素a含量、叶绿素b含量和叶绿素总量分别高出23.49％、21.78％、23.07％和29.91％、26.04％、28.96％,差异均达到极显著水平(P<0.01);低温胁迫7 d,复配涂封剂处理比市售割面涂封剂处理及对照的橡胶树叶片的Pn、Gs、Ci、Tr、Fv/Fm高出74.53％、847.41％、90.94％、1617.80％、6.57％和145.39％、7700.23％、229.02％、18009.72％、14.46％,差异达到显著或极显著水平.综合分析可知,复配割面涂封剂能够缓解由低温导致的橡胶树芽接苗叶片叶绿素含量、Pn、Gs、Ci、Tr、Fv/Fm及ΦPSⅡ的下降幅度,可以在一定程度上避免低温胁迫对光合系统的伤害,维持叶片光合能力及PSⅡ反应中心活性,有效缓解低温对橡胶树芽接苗的胁迫,提高其抗寒性.