崖爬藤的生态生物学特征及其扦插繁殖技术

Ecological and biological characteristics and cutting propagation techniques of Tetrastigma obtectum

关键词:  崖爬藤, 园林绿化, 叶片形态结构, 光合生理, 扦插繁殖

Key words:  Tetrastigma obtectum, landscape greening, leaf morphology, photosynthetic physiology, cutting propagation

摘要:

崖爬藤为葡萄科常绿或半常绿藤本,具有重要园林绿化价值。该研究采用叶片离析法和石蜡切片法研究其叶片的形态结构。结果表明:崖爬藤平均叶面积(23.1 cm²)较大,单位叶面积干重(4.4 mg·cm^-2)较小,成熟叶厚约为195.5 μm,栅栏组织不发达,胞间隙大。利用便携式LI-6400光合测定仪、PAM-2100荧光测定仪对崖爬藤光合生理生态指标进行研究。结果表明:其PSII的最大光化学效率Fv/Fm(0.818)较高; 叶片的净光合速率日变化呈单峰型,没有明显的光合午休现象,最大净光合速率Pn为3.691 μmol·m^-2·s^-1,出现在14:00时,变化趋势与光合有效辐射Par、大气温度T、蒸腾速率Tr、气孔导度Gs等因子相同,与胞间CO₂浓度Ci相反,同时具有较高的水分利用效率(3.056 μmol·mmol^-1)。这都显示了崖爬藤喜阴湿环境,不耐寒且具有一定的耐旱特性,适合栽植于我国温度较高的南方地区。此外,以崖爬藤1～2年生老枝和当年生嫩枝为材料,经梯度溶液IBA处理进行扦插生根实验,结果表明,崖爬藤扦插繁殖迅速,生根率较高,以当年生嫩枝不经IBA处理直接扦插为最佳。该研究结果将为崖爬藤的栽培及开发利用提供重要的理论和技术指导。

Abstract:

Tetrastigma obtectum is an evergreen or half evergreen vine species of Vitaceae family with great potentials to be used for landscape greening. Leaf morphology in T. obtectum was comparatively studied using epidermal maceration and paraffin methods. The result indicated that T. obtectum had large average leaf area(23.1 cm²)and small leaf mass per area(4.4 mg·cm^-2). The blade thickness of it was about 195.5 μm, with underdeveloped palisade tissue. Large gaps between the cells of both palisade tissue and spongy tissue were good for T. obtectum to decrease the light transmission loss and improve the utilization of luminous energy, showing the suitability of shade and humid environment. With the aid of LI-6400 portable photosynthesis system and PAM-2100 portable chlorophyll fluorometer, the study on photosynthetic physiology was made. The maximal photochemical efficiency of PSII(0.818)was high, which was helpful for light-harvesting. At the same time, the high non-photochemical quenching could be favorable to dissipate excess light energy, which protected the photosynthetic tissue, and mitigated the effect of environment on photosynthesis. Its diurnal net photosynthetic rate in leaves showed a single peaked curve without midday depression. The peak value of net photosynthetic rate was 3.691 μmol·m^-2·s^-1 occurring at about 14:00, and changes were close to the variations of photosynthetic active radiation, air temperature, stomatal conductance, transpiration rate, but opposite to internal CO₂ concentration. With the increase of net photosynthetic rate, CO₂ consumption increased significantly leading to the decrease of internal CO₂ concentration. Meanwhile, the daily average value of instantaneous water use efficiency was 3.056 μmol·mmol^-1, fully embodied the strong utilization ability in water and weak light, and could keep high stomata aperture as well as high photosynthetic capacity. This showed that T. obtectum prefered to grow under shady and humid condition and had some tolerance to drought, without cold resistance. It was suitable to be planted in south China as urban climbing greenery plants. In addition, the 1-2 a hardwood cuttings and new born twigs of T. obtectum were used to do rooting experiments, treated with a series of IBA solution, which showed that the cutting age and IBA solution affected rooting rate obviously with rooting rate from 65% to 100%. Rooting rates of 1-2 a hardwood cuttings treated with 300 mg·L^-1 and 500 mg·L^-1 IBA were distinctively higher than the new born twigs at the same concentration. The highest rooting rate of 1-2 a hardwood cuttings reached 95% under treatment of 300 mg·L^-1 IBA, while the new born twigs without treatment by IBA was the best combination with 100% rooting rate. In a word, T. obtectum grew quickly with high rooting rate under cutting propagation, and this technique could speed the fine variety breeding of T. obtectum as well as the improvement of seedling quality. The results are very useful for cultivation, exploitation and utilization of T. obtectum in urban vertical green landscape.