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991.
GAO Jian PENG Zhen-hua 《林业研究》2006,17(4):269-272
Introduction Salinity is a major factor in inhibiting plant growth and decreasing forest productivity. Up to 1997, the total area affected by salinity in the world had amounted to 930 million hm2 (FAO), and is still increasing. A global study of land use … 相似文献
992.
地下滴灌条件下杨树速生丰产林生长与光合特性 总被引:13,自引:0,他引:13
研究了北京沿河沙地I 2 1 4杨树人工林地下滴灌和常规灌溉林地树木生长与光合特性 ,结果表明 :与常规灌溉相比 ,地下滴灌能大大增加树木的生长量 ,提高林地生产力。 2 0 0 0年 (栽植第 4年 ) ,地下滴灌区树木平均胸径、树高和单株材积分别达到 2 1 1 8cm、1 4 2 3m和 0 1 81 5m3,比常规灌溉增加了 5 4 5 %、36 9%和 2 4 7 6 % ;林地生产力达到 2 2 78~ 2 5 81m3·hm- 2 a- 1 ,比常规灌溉增加了 3 9~ 4 6倍。树木生长改善和林地生产力提高的生理机制是地下滴灌可促进树木光合作用和水分利用效率。地下滴灌区树木叶净光合速率在一天中几乎一直显著高于对照 ,幅度达 1 0 0 %~ 2 1 4 % ;从一个滴灌周期来看 ,滴灌区树木叶净光合速率显著高于对照 9 0 %~ 9 9% ;滴灌区树木水分利用效率也较对照区显著提高。通过相关分析表明 ,表层土壤 (1 5~ 2 5cm)水分含量在 5 %~ 8%时树木叶净光合速率能在长时间维持较高水平 ,而水分含量低于 4 % ,树木叶净光合速率将降低。建议在干旱半干旱和季节性干旱地区营造速生丰产用材林时应结合当地经济条件推广地下滴灌技术 ,这不仅有利于水资源的可持续利用 ,而且将大幅度提高林地生产力 ,使我国人工林生产力赶超世界先进水平。 相似文献
993.
Seedlings of three tree species (Acer pseudoplatanus L., Castanea sativa Miller. and Quercus frainetto Ten.) were planted on a field site in Northern Greece to investigate factors connected to planting failures. On several dates,
for the first two growing seasons after planting (1997 and 1998), leaf water potential, chlorophyll fluorescence, gas exchange
variables and seedling survival were determined. Q. frainetto seedlings exhibited the lowest values of leaf water potential (Ψ) for most of the season in both studied years. Seedlings of all species showed large reductions in Ψ the mid-summer in both years, with particularly low values in 1998. In both years, a sharp reduction in Ψ was observed at the beginning of July when all three species exhibited their lowest net CO2 assimilation (A) rate by the end of July. In 1997, A recovered after the July depression to values even higher than those recorded in June. However, in 1998, only Q. frainetto and to a lesser degree C. sativa recovered from a similar July depression in physiological values. Species reached their highest A rates by the end of August in 1997 and in June during 1998. In general, stomatal conductance and transpiration rates paralleled
the A patterns. In 1997, the seasonal course of effective quantum yield (ΔF/Fm), for all plant species followed a rise-and-fall pattern with a peak at the beginning of July. In 1998, ΔF/Fm values were relatively high in June, showed a deep depression during July and while Q. frainetto and C. sativa recovered afterwards, A. pseudoplatanus continued to exhibit very low values. This study showed that differences in mortality between species were due to differences
in tolerance to water stress and the superiority of Q. frainetto was probably related to the fact that it was the only species native and adapted to the planting site 相似文献
994.
CHEN Jun-wen CAO Kun-fang 《林业研究》2005,16(4):323-326
Plant leaves may emit a substantial amount of volatile organic compounds (VOCs) into the atmosphere, which include isoprene, terpene, alkanes, alkenes, alcohols, aldehydes, eters, esters and carboxylic acids. Furthermore, most of these compounds actively participate in tropospheric chemistry. Great progresses have been made in linking emission of these compounds to climate. However, the VOCs emission function in plant is still not clear. Recently, some evidence has emerged that the production and the emission of VOCs, such as isoprene and monoterpenes, which account for 80% of total VOCs, exhibit plant protection against high temperatures. These increases in VOCs emissions could contribule in a significant way to plant thermotolerance. This perspective summarizes some latest literatures regarding the VOCs emission-dependent thermoprotection in plant species subjected to high temperature stress, presents the achievement in studies concerning plant VOCs emission-dependent thermotolerance, and then exhibits the proposed mechanisms of such plant thermotolerance. Finally open questions regarding the plant VOCs emission were shown, and the future researches were proposed. 相似文献
995.
以香樟、白兰花和栀子花为试验材料,利用Li-6400型光合作用测定系统监测其叶片光合生理生态特性,并利用相关分析探讨了净光合速率和蒸腾速率与生理生态因子间的关系。结果表明:①白兰花叶片的净光合速率(Pn)、蒸腾速率(Tr)和气孔导度(Cd)的日变化均呈不对称双峰曲线,具有明显的光合"午休"现象;香樟叶片的蒸腾速率(Tr)和气孔导度(Cd)的日变化呈单峰曲线,而净光合速率(Pn)的日变化均呈双峰曲线;栀子花叶片的净光合速率(Pn)和气孔导度(Cd)的日变化均呈不对称双峰曲线,蒸腾速率(Tr)的日变化呈单峰曲线;香樟和栀子花的光合"午休"现象不太明显。②3种芳香植物Pn、Tr、Cd和Ci的峰值出现时间不同步。③3种芳香植物的净光合速率日均值、气孔导度的日均值和蒸腾速率的日均值依次为白兰花>栀子花>香樟,但种间差异不显著;胞间CO2日变化中利用的CO2体积分数日均值依次为栀子花>白兰花>香樟,由此可见栀子花和香樟适应环境的能力比白兰花较强,生长发育稳定且易成活,在植物配置中应多利用栀子花和香樟。 相似文献
996.
997.
The photosynthesis and transpiration characteristics ofAdenophora lobophylla andA. potaninii, as well as stomatal behavior such as stomatal size, stomatal density, stomatal open and stomatal conductivity were measured
at different altitudes. The relationship between the photosynthesis and transpiration characteristics and the stomatal behavior
was analysed by correlation coefficient and path coefficient analysis with altitude changes. The results showed that the influences
of stomatal behavior were not evident on the photosynthesis and transpiration characteristics ofA. Lobophylla, but evident on that ofA. potaninii.
This study is supported by the National Natural Science Foundation of China (No. 39391500).
Responsible editor: Zhu Hong 相似文献
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