The selective allelopathic interaction of a pasture-forest intercropping in Taiwan

An allelopathic interaction of a pasture-forest intercropping system was evaluated by field and greenhouse experiments and by laboratory assays. A study site was situated in the farm of Hoshe Forestry Experiment Station at Nantou County, Taiwan. After deforestation of Chinese fir (Cunninghamia lanceolata), a split plot design of 8 treatments was set up: open ground without planting as control, planted with kikuyu grass, planted with kikuyu grass andAlnus formosana, planted with kikuyu grass andZelkova formosana, planted with kikuyu grass andCinnamomum camphora, planted withA. formosana, planted withZ. formosana, and planted withC. camphora. Field measurements showed that weeds grew luxuriantly six months after treatment in plots which had not been planted with kikuyu grass. However, the growth of weeds was significantly retarded but that of woody plants was not affected when the plots were planted with kikuyu grass. As compared with the tap water control, the aqueous leachate of kikuyu grass stimulated the seedling growth ofC. camphora andA. formosana, but the extract stimulated the growth ofC. camphora and inhibited that ofA. formosana. In contrast, the aqueous extracts of three hardwood plants exhibited variable inhibition on the root initiation of kikuyu grass, and the extract ofZ. formosana revealed the highest phytotoxic effect. The aforementioned extracts and leachates were bioassayed against seed germination and radicle growth of four test plants, namely annual rye grass, perennial rye gras, tall fescue, and Chinese cabbage and against seedling growth ofMiscanthus floridulus. The extract ofZ. formosana revealed the highest phytotoxic effect on the test species while that of kikuyu grass showed the least effect. By means of paper chromatography and high performance liquid chromatography, phytotoxic phenolics were identified and the amount of phytotoxins present was highest in the extract ofZ. formosana but was lowest in that of kikuyu grass. The degree of phytotoxicity and amount of phytotoxins was in good correlation, indicating that a selective allelopathic effect was involved. The findings suggest that allelopathy may contribute benefits in the intercropping system to reduce the need for herbicides and to lessen the labour cost for weed control.Paper No. 346 of the Scientific Journal Series of the Institute of Botany, Academia Sinica, Taipei, Taiwan, Republic of China. This study was supported in part by grants of Academia Sinica, Taipei, and Council of Agriculture, Executive Yuan of the Republic of China.     

香樟凋落叶分解对辣椒及土壤氮营养的限制作用

香樟(Cinnamomum camphora)凋落叶分解能够明显干扰受体植物的生长、生殖、光合生理和活性氧代谢。该研究继续采用盆栽试验,探讨了不同量[0(对照)、25、50和100g]的香樟凋落叶添加到土壤(10kg/盆)中对受体植物辣椒(Capsicum annuum)及其土壤氮营养状况的影响,外源氮(尿素)输入对凋落叶分解的交互作用,以及凋落叶分解效应的产生是否因为其较高的C/N比而导致微生物争氮。结果显示:(1)各剂量(25~100g/盆)凋落叶处理下,辣椒幼苗硝态氮、可溶性蛋白和全氮含量均在至少2个月内大幅显著降低。(2)土壤硝态氮与辣椒硝态氮、全氮间均具有极显著的协同下降趋势;土壤微生物生物量氮则在总体上高于对照,而土壤全氮和铵态氮的响应较小。(3)施氮不仅使辣椒各氮组分和土壤硝态氮含量整体提升,还使凋落叶分解在这些指标上的抑制作用显著减弱。(4)香樟凋落叶的初始C/N为125.61±4.89,其在土壤中分解48~137d后的C/N始终远高于Hodge假说指出的可导致微生物争氮的临界值,但经过分解120d和135d的凋落叶添加到土壤中并不抑制辣椒的生长。研究认为,香樟凋落叶分解初期可能释放了不利于土壤硝化过程的物质,造成土壤硝态氮匮乏,以致受体植物的氮素吸收和积累减少,而凋落叶较高的C/N比及土壤微生物争氮并非主导因素。     

干旱胁迫及复水对香樟幼树生理特性及生长的影响

通过盆栽和持续干旱处理研究了轻度干旱(持续干旱2~4d)、中度干旱(持续干旱6~8d)和重度干旱胁迫(持续干旱10~16d)及复水对香樟(Cinnamomum camphora)幼树生理特性和生长的影响,为香樟育苗、造林及合理的水分管理提供理论依据。结果显示:(1)干旱胁迫下香樟幼树地径生长量(Zd)和树高生长量(Zh)受到了抑制;轻度、中度干旱处理(土壤体积含水量从正常状态下降到7%)下叶片相对含水量(LRWC)与对照差异不显著,重度干旱处理(土壤体积含水量下降到3%)下显著低于对照。(2)轻度、中度干旱处理的超氧阴离子和过氧化氢含量与对照无显著差异,重度干旱处理较对照显著上升。(3)在活性氧酶促清除系统中,超氧化物歧化酶(SOD)、过氧化物酶(POD)活性在轻度干旱时显著上升,而过氧化氢酶(CAT)活性在重度干旱时才显著上升,在复水48h后3种酶活性均恢复到对照水平。(4)在轻度、中度干旱处理中叶片丙二醛(MDA)含量无显著变化,而在重度干旱下显著升高,且复水48h后未见显著降低。(5)在渗透调节物质中,轻度干旱时可溶性蛋白(SP)含量开始显著升高,中度干旱时可溶性糖(SS)含量显著升高,重度干旱时脯氨酸(Pro)含量显著上升;复水48h后Pro含量显著降低,而可溶性蛋白和可溶性糖含量无显著变化。研究发现,香樟幼树在轻度干旱胁迫下能通过自身抗氧化酶系统和渗透调节物质维持正常生长,而在中度和重度干旱胁迫条件下,其水分生理状况变差,膜系统遭受伤害,酶活性受到抑制,最终导致其形态生长和地上部分生物量积累受限。     

不同种源樟树叶片形态特征及生长差异分析

为了解不同种源樟树叶片形态特征和生长差异,该文以30个种源樟树为研究对象,对其叶长、叶宽、叶柄长、周长、叶面积、长宽比、形态因子、株高、地径等指标进行测定和差异性分析.结果表明:(1)30个种源间叶片性状的变异系数为3.88％～16.14％,显示不同种源樟树叶片形态特征存在显著差异;叶长、叶宽、叶柄长、周长、面积、叶厚...     

New Resource Plants of Trans-Methyl Iso-eugenoI from Endemic Species to China

Both Cinnamomum septentrionale Hand. -Mazz. and Cinnamomum platyphyllum (Diels)Allen are endemic to China. The plant materials were collected from West Hubei In May-June, 1983. Both the essential oils, extracted from fresh leaves by steam distillation, were analysed in detail by means of capillary GC/MS/DS on Finnigan-4510 type. The result indicates that the major component of both essential oils s trans-methyl isoeugenol with the amount of 85.71% and 94.04% for C. septentrionale and C. platyphyllum respectively. The two species which are very rich in West Hubei are new important plant resources for transmethyl isoengenol.     

树冠位置对香樟叶形态性状和异速生长关系的影响

为深入了解树冠位置对植物叶形态性状的影响,在常绿乔木香樟树冠上下2层和东南西北4个方位开展调查取样,系统分析了不同树冠位置间叶形态性状(叶长、叶宽、叶厚、叶柄长、叶柄直径和叶形指数)及其异速生长关系的差异性。结果表明,叶形态性状在不同树冠方位间均差异显著,但上下2层变化趋势不完全一致。在树冠上层,除叶形指数和叶炳长外,其余4个性状均表现为东侧最大。在树冠下层,除叶形指数外,其余5个性状指标均表现为东侧最小。在同一方位上,叶形态性状在上下2层间也存在一定差异,其中叶形指数多为下层高于上层,而其他形态性状多呈相反趋势。此外,树冠层次和方位的交互作用对叶片长、叶片厚、叶柄长和叶柄直径有显著影响。各层次和各方位叶形态性状间多为异速生长关系(即异速生长指数不等于1),且多无显著差异。在所有树冠层次和树冠方位,叶宽与叶厚、叶宽与叶炳长、叶长与叶厚及叶长与叶柄长之间均呈异速生长关系。可见,树冠位置对香樟叶形态性状的影响较大,但形态性状间的异速生长关系相对稳定,这是香樟叶形态性状表型可塑性和内在关系稳定性的重要体现。     

川桂叶挥发油的化学成分与抗菌活性研究

采用ＧＣ－ＭＳ技术分析了川桂（Ｃｉｎｎａｍｏｍｕｍ ｗｉｌｓｏｎｉｉ）叶挥发油的化学组成,确定了２９种成分的化学结构与相对含量,其中,芳樟醇（３８．７１％）、反式柠檬醛（２２．６７％）和顺式柠檬醛（１８．５２％）为主要成分。体外对１４种真菌或细菌的药敏实验表明,该挥发油具有明显的抗菌活力,尤其对皮肤真菌和污染霉菌有效,其ＭＩＣ为０．１～２．０μｌ／ｍｌ。     

芳香樟精油毛细管色谱分析

采用弹性石英毛细管柱色谱法测定芳香樟精油中芳樟醇和桉叶油素含量.结果表明:采用40m石英毛细管柱,程序升温方式提升柱温,方法回收率平均达州94.2%以上,变异系数为3.21%以下,并认为该法是较好的测试方法。     

姜樟叶油的化学成份研究

姜樟鲜叶经水蒸汽蒸馏得到一种淡黄色的精油,得率为0.5-0.8％。我们应用气相色谱、红外光谱、气相色谱/质谱/计算机联用以及测定衍生物熔点等方法,对该精油进行成份分析、鉴定。共鉴定出α-,β-柠檬醛,香叶醇,柠檬烯,1,8-桉叶油素,芳樟醇,氧化芳樟醇,樟脑,龙脑,石竹烯等47个已知化合物,其中α-,β-柠檬醛含量高达64.11％。它们是香料工业和医药工业上的重要原料。     

毛桂和少花桂叶精油的化学成分

湖北省鄂西自治州产毛桂和少花桂叶精油,分别使用Finnigan-4510型毛细管气相色谱/质谱/电子计算机联用(GC/MS/DS)方法进行了化学成分分析。从毛桂叶精油中共检出61个成分,鉴定了其中21个化合物,占精油总量的76.39%,主要成分为1,8-桉叶油素(37.02%)和乙酸龙脑酯(16.24%)。从少花桂叶精油中共检出60余个成分,鉴定了其中33个成分,占全精油的77.85%,含量较高的有α-蒎烯(9.09%)、1,8-桉叶油素(8.27%)、香叶醇(6.03%),香叶醛(5.90%),乙酸香叶酯(4.94%)和黄樟油素(4.43%)等。