NaCl胁迫对八棱海棠幼苗生长及其生理指标的影响

为明确八棱海棠的耐盐特性,为其在盐碱地区的园林绿化应用提供科学依据,采用砂基培养法,研究八棱海棠幼苗在不同浓度NaCl胁迫下的生长量和部分生理指标的变化过程。结果表明：随着NaCl浓度的升高,八棱海棠的株高、茎粗、叶片含水量、叶绿素含量呈减少趋势;MDA含量和可溶性糖含量呈上升趋势;脯氨酸呈先下降后上升趋势,变化平缓。通过对外观形态的观测以及生理指标的综合分析,推断出八棱海棠的耐盐阈值、存活阈值为0.6%。     

从化桉树、南洋楹速生丰产林的生长表现调查

本文通过对广州市北部山区从化市2年半生的桉树、南洋楹速生丰产林的生长表现进行调查,结果表明：在两个标准样地间,桉树、南洋楹的平均胸径以及南洋楹的平均分枝数无显著差异,而平均树高差异显著,说明桉树、南洋楹的胸径生长以及南洋楹的分枝数受遗传控制的程度较高,而树高生长受环境条件影响较大;桉树与南洋楹在平均胸径与平均树高两个性状上均达到极显著差异,并且这两个性状的变异系数,桉树均比南洋楹小,说明桉树的胸径生长和树高生长均比南洋楹稳定,受环境条件的影响较小,所能适应的立地条件和环境条件较南洋楹广泛。     

寄主植物对芒果壮铗普瘿蚊为害的生理效应

研究芒果壮铗普瘿蚊不同程度为害下寄主植物叶片中硝态氮、可溶性糖、可溶性蛋白质、叶绿素含量以及植物保护酶系——超氧化物歧化酶(SOD)、过氧化物酶(POD)和过氧化氢酶(CAT)活性的变化.将叶片受害程度划分为4个等级:1～50,51～100,101～200,＞200(每叶片虫瘿数),并以无虫瘿为害的叶片为对照组(CK).结果表明:可溶性糖与硝态氮含量在各个等级之间均没有显著的差异;可溶性蛋白和叶绿素a、叶绿素b含量各为害等级叶片均显著低于CK;而类胡萝卜素含量,高密度为害等级(101～200,＞200)显著高于其他各组及CK.植物保护酶系测定结果显示:CK组活力最低,＞200等级SOD,POD,CAT活力均高于其他各组;其中,51～100与＞200等级SOD活力显著高于其他等级;为害等级量重的(＞200)POD和CAT活力显著高于其他等级;而1～50等级显著低于其他等级.因此,人侵害虫芒果壮铗普瘿蚊的不同为害程度直接影响植物的光合作用及有关营养物质;随着为害等级的加重可导致植物保护酶系的活性增大.     

桉树人工林群落乔木层结构研究

通过对昆明市金殿旅游风景区桉树人工林乔木层结构的调查，结果表明：人工桉树林乔木层树种为单一的直杆桉；样地内直杆桉的胸径和冠幅、胸径和树高成极显著相关性，树高、冠幅和胸径之间有密切联系；树冠系数普遍达到0.12的水平，虽与0.2的水平有一定差距，但一定程度上反映出林地内乔木生长状况不良。     

八棱海棠MdPPO2B基因的克隆及降解苯酚研究

为了探索果树对酚类化合物的修复潜力,从八棱海棠中克隆获得多酚氧化酶基因Md PPO2B,并构建该基因植物超量表达载体,通过转化模式植物拟南芥研究该基因对酚类化合物的修复功能。结果表明,在平板、盆栽、液体3种试验中,不加入苯酚,转基因植株在生长状态和外部形态上和野生型相似;当苯酚浓度分别为0.1 m M和1 m M时,通过植物的根长、叶片鲜重等比较发现,转基因株系比野生型植株对苯酚的耐受性更强,其生长形态较为正常,而野生型植株的生长则受到了明显抑制。由此可见,Md PPO2B转基因植物的PPO活性在植物降解酚类化合物过程中起重要作用;使用果树来源的多酚氧化酶基因用于有机污染物修复,对环境治理具有较好的应用前景。     

八棱海棠一年生播种苗苗高年生长规律研究

以八棱海棠1 a生播种苗为研究时象,对其苗高生长规律和苗高与地径、生态因子的关系等进行研究.试验结果证明:Logistic方程可较好地反映苗高生长规律,苗高生长呈现"慢-快-慢-快-慢"的节律,并以此将苗高年生长过程划分为6个生长期.通过苗高生长规律与气象因子的相关分析,证明日平均气温是影响苗高生长的主要气象因子.     

Response of ethylene and chlorophyll in two eucalyptus clones during drought

A study was conducted with seven-month-old plantlets, of the clone 2814 of Eucalyptus grandis × E. camaldulensis Dehnh. hybrid and of the clone 2798 of E. grandis × E. robusta Sm., subjected to sublethal water stress. During the imposed drought, leaf water potentials and transpiration rates decreased, while ethylene production and leaf chlorophyll concentration increased to a maximum during the onset of water stress, and then declined. Stomatal closure coincided with or preceded maximum ethylene production. A saturation type relationship between ethylene production and chlorophyll concentration was observed. Genotypic differences in the response to water stress occurred between clones with clone 2814 appearing to be a drought avoider and clone 2798 a drought tolerator.     

Water use in a Grevillea robusta–maize overstorey agroforestry system in semi-arid Kenya

Novel approaches involving a combination of sap flow measurements of transpiration and allometric estimates of biomass production were used to determine seasonal water use by trees and crops in agroforestry systems. The results were used to test the hypothesis that agroforestry may improve productivity by capturing a greater proportion of annual rainfall than annual crops. Grevillea robusta A. Cunn., which is reputed to have a deep rooting habit, was grown in semi-arid Kenya either as sole stands or in combination with maize (Zea mays L.). Water use by individual trees and maize plants was determined using constant temperature heat balance gauges and scaled to provide stand-level estimates of transpiration based on linear relationships (r²>0.70) between sap flow and leaf area across a range of tree ages and environmental conditions. Maximum stand-level transpiration rates for grevillea ranged from 2.6 to 4.0 mm per day, consistent with previous studies in similar environments. Biomass production by grevillea was closely correlated with stand-level transpiration (r²>0.69–0.74), suggesting that non-destructive estimates of biomass increments can be used to provide reliable estimates of seasonal transpiration. Cumulative water use by grevillea over the 4.5-year observation period was comparable in the sole tree and agroforestry treatments, reaching a maximum utilisation of annual rainfall of 64–68% 3–4 years after planting. Approximately 25% of the water transpired by the trees was used during the dry season, indicating that they were able to utilise off-season rainfall, comprising 16% of the total annual rainfall, and residual water remaining in the soil profile after the cropping period. During the 1995 long rains, when 221 mm of rain was received, transpiration by sole maize was <50% of precipitation, compared to ca. 85% by the trees in the sole grevillea and agroforestry treatments. These results confirm that agroforestry systems may greatly increase rainfall utilisation compared to annual cropping systems. However, careful consideration of the tradeoffs between the loss of crop production and the additional value provided by tree products is essential.     

卧龙自然保护区拐棍竹地下茎结构特点研究

研究了卧龙自然保护区拐棍竹地下茎的数量特征、垂直分布结构、分岔习性和繁殖特点。结果表明,拐棍竹地下茎的密度大,193段.m-2,每段平均长为12.2 cm,地下茎总长2 169.8 cm.m-2,地下茎直径平均为1.1 cm,节间长平均为0.73 cm,平均每段地下茎具14节;随生长年龄递减,拐棍竹的地下茎直径、节间长、每段节数和每段长度递增,而地下茎段数和总长的变化则呈偏正态分布;拐棍竹地下茎主要分布在5~30 cm土层,并以"两侧单岔"为主要分岔类型,其次分别为"两侧多岔"和"一侧单岔","一侧多岔"很少;拐棍竹地下茎在土壤中延伸方向从坡面来看以"平行"方向延伸类型所占数量最多,为49.75%,从土壤剖面上来看拐棍竹地下茎在土壤中延伸方向则以"向上"类占优势,为53.19%,其次为"向下"类延伸方向,为39.12%。     

串珠镰刀菌侵染华棕的报道

对严重发生于漳州华棕(Washingtonis,filifera)上,造成大量华棕死亡的华棕立枯病的病原菌进行分离与鉴定.结果显示:从发病植株的病健交界处分离纯化得到2种具有离体和活体致病性的病原菌,其中1种菌的活体致病性更强;通过形态特征观察、不同培养基培养鉴定以及分子生物学技术鉴定,认定该病原菌为串珠镰刀菌(Fusarium moniliforme).