不同遮荫强度对几种苗木生长的影响

以黄金榕、花斑垂叶榕、乳斑榕的苗木为试验材料，来探讨不同遮荫强度苗木生长、水份利用及苗木生长环境的影响，试验表明：一层遮荫网处理的苗木比无遮荫网和二层遮荫网处理的苗木在株高、冠幅、根径以及叶片数目等方面均增长较快，苗木的地下部分、叶和茎含水量均较低。无遮荫处理利用较多水分，以及土壤温度在14：00点左右的时间明显高于所有的遮荫处理。     

垂叶榕瘿花发育特性的初步研究

研究榕属植物瘿花发育特性是理解榕树/榕小蜂协同进化内在机制的重要内容。本文解析了垂叶榕隐头花序伴随瘿花发育的 5 个发育时期，采用同工酶电泳的方法比较了瘿花与正常雌花同工酶（包括过氧化物酶、过氧化氢酶、淀粉酶和酯酶）谱带的差异，采用扫描电镜对比了瘿花壁与授粉后雌花子房壁的差异。结果表明，瘿花被榕小蜂产卵以后，至少启动了一个与消除过氧化物有关的酶；而且，瘿花子房壁结构疏松，内含物小而少，雌花子房壁结构致密且内含物多而大，说明瘿花发育所消耗的营养物质大于正常雌花发育的消耗。研究结果支持造瘿生物汇集营养与植物防御行为的互利假说。     

Comparison of HCl extraction versos total iron analysis for iron tissue analysis

Extraction of Fe from fresh leaves with 0.1 N HCl proved to be a better indicator of the Fe status of a variety of ornamental tropical foliage and flowering plants compared to total Fe, 0.1 N HCl‐ether, and IN HCl extraction. It consistently gave higher correlations (r = 0.73 to 0.95 depending on the species) with chlorophyll concentration than the other methods tested. However, even 0.1 N HCl extraction did not distinguish levels of Fe deficiency accurately when compared between species.     

榕管蓟马冷季种群动态及田间药效试验

对广州部分地区垂叶榕（Ficus benjamina Linn．）榕管蓟马（Gynaikothrips uzeliZimmermann）冷季种群动态及田间药效试验进行了研究．结果表明，冷季榕管蓟马种群的发生高峰为1月下旬，随后其种群数量迅速下降，在一个低水平的范围内波动，至4月上旬各虫态的数量慢慢恢复；榕管蓟马在垂叶榕东、南、西、北4个不同方位的虫口密度具有差异性，但对分布的方位没有明显的选择性；氯氰菊酯、氧化乐果、毒死蜱等3种药剂对榕管蓟马有很好的防治效果，药后3d的防治效果均达到95％以上．     

Diurnal Photosynthesis and Transpiration of Ficus benjamina L. as Affected by Length of Photoperiod,CO2 Concentration and Light Level

Abstract

The diurnal net photosynthesis of Ficus benjamina L., cultivar Cleo, was studied at different daylengths (12, 18 and 24 h day^?1), photosynthetic photon flux densities (40 and 120 μmol m^?2 s^?1 PPFD) and CO₂ concentrations (350 and 700 μmol mol^?1). Net photosynthesis increased to a maximum after 5–6 and 6–7h of light at 12 and 18h day^?1photoperiods, respectively, followed by a decrease towards the end of the photoperiod. At a photoperiod of 18 h day^?1 similar diurnal curves were found at 350 and 700 μmol mol^?1 CO₂, and at 40 and 120 μmol m^?2 s^?1 PPFD. Five days after the photoperiod was changed from 18 to a 24h day^?1the diurnal rhythm disappeared. Transpiration followed the same diurnal rhythm as that for photosynthesis. The water-use efficiency was enhanced by raising the CO2 concentration. A decrease in the CO₂ concentration from 700 to 350 μmol mol^?1after six days at high CO₂ first significantly decreased the photosynthesis, but three days later it reached the same level as that at high CO₂.     

Accumulation and utilization efficiency of potassium in ramie varieties

Difference in nutrient utilization efficiency of genotypes of crops is attracting more and more attention of plant nutrition and breeding scientists. This experiment was carried out to reveal whether genotypic variation of potassium (K.) utilization efficiency exists in ramie [Boehmeria nivea (L.) Gaud.], by measuring K concentrations and accumulations in different organs in relation to the dry matter and fiber productivity of six field growing ramie varieties with evident dissimilarity in growth vigor. Potassium concentration decreased in leaves, petioles and seeding organ, but increased in stem wood and in the raw fiber of high raw fiber yield (RFY) varieties at the late growth stage. For different parts, stem bark attained the largest K concentration, followed in order by petiole, stem wood, seeding organs, raw fiber and leaves. Potassium concentration of stem wood, bark and raw fiber, respectively, demonstrated positive and significant correlation with RFY. Potassium utilization efficiency declined by harvest time. The results suggested that the ramie varieties with high biomass and RFY and K consumption such as Xiyeqing can be planted under the condition of abundant K resource, while Nindu‐Ramie variety may be used as high K efficient genetic resource for its ratios of RFY (g) and biomass (g) to K consumption (g) are over 25 and 114, respectively, in spite of its low biomass and RFY.