Comparison of phenological characteristics for several woody plants in urban climates

Phenological properties of woody species were compared between two urban climates during 1997 and 1998. The study areas were Chungdam Park, Chungdam-dong, Kangnam-gu, Seoul (the urban center, 43 species) and Namhan-sansung Area, Sansung-ri, Joongbu-myon, Kwangju Gun, Kyonggi Province (the urban periphery, 16 species). Distance between these sites was 13.5 km. The differences of budding, foliation, and flowering times (1997 versus 1998) were 10.9, 3.2, and 7.4 days, respectively. Species that budded and flowered earlier were strongly influenced by Nuttonson’s Index (Tn) of February and March, but those with later dates were only weakly influenced. Unlike for budding and flowering times, foliation time was determined by air temperature or other factors in the leaf-growing season rather than by Tn. The Tn influence over phenology was stronger in shrubs and lianas than in trees. Phenophases in Chungdam Park appeared earlier than those in the Namhansansung area. The phenological differences between the two areas were 7.3 days in budding time, 8.3 days in foliation time, and 10.2 days in flowering time in mean values, with variations among species. Based on flowering-time data, the phenological variation between the two areas was equivalent to a 2.5° latitude difference. Budding time varied the most (20 days) inZelkova serrate, compared with only 3 days forPrunus padus. Differences in foliation time ranged from 15 days (inAlnus hirsute andStyrax obassia) to 0 days (P. padus). Flowering time differences were largest (24 days) inRhododendron mucronulatum and smallest (2 days) inP. padus. One can conclude that heat pollution in the urban center in Seoul severely changed phenology, and that sensitivity to that pollution differed among plant species.     

The Role of Hypocotyl and Roots in Photoperiodic Floral Induction of Chenopodium rubrum

Abstract: Hypocotyls and roots of Chenopodium rubrum were tested as possible receptors of photoperiodic signals inducing flowering. The hypocotyl was found to be responsive to such a signal. Its role as the locus of synthesis andjor the transport sys tem of a florigenic stimulus is discussed. The roots respond to light/dark conditions solely by changing their growth rate but they do not seem to be involved in induction of flowering.     

Changes in the polypeptide profiles during photoinduction of Xanthium strumarium

The polypeptides in the leaf blades, petioles and apices from photoinduced and noninduced Xanthium strumarium L. were compared by two dimensional gel-electrophoresis. A 15 kDa and a 16 kDa polypeptide were detected in gels of the leaf blade from noninduced, but not from induced, plants. Similarly, an acidic 9 kDa polypeptide was detected in the apices from noninduced plants, but not in apices from induced plants. Both the apices and petioles from noninduced plants showed a 34 kDa polypeptide which was absent in tissues from induced plants. Thus, the disappearence of identifiable polypeptides from photoinduced tissues may be associated with the photoinductive short-day treatment that leads to flowering.     

植物春化特性及春化作用机理

春化作用是某些高等植物成花转变的重要环节,被认为是植物在低温诱导下促使其相关基因的表达,从而导致生理状态转变的一种受遗传控制的生理过程.本文对植物春化反应特性、春化作用的生理生化特性及春化作用的分子生物学等方面的研究进展进行了概述,并对春化研究中的问题进行了分析和展望.     

花卉基因工程研究进展Ⅱ:花型、花期、货架期

近10年来,基因工程研究的机理,酶的纯化及基因分离等方面取得下很大的成就,这些成就已广泛用于花卉产业,并在花卉改良研究中取得突出的成效,本文详细介绍了基因工程用改善花型,花期和货架期等方面的研究进展。     

光照对蔺草生长和草茎开花率的影响

蔺草草茎长度和是否开过花是决定其品质的两个重要方面。试验表明,不同光周期及光照强度对蔺草的生长和草茎开花率会产生显著影响。生育前期,延长日照显著促进开花,遮光处理降低蔺草的分蘖、草茎长度、减少草茎开花率和每花序小花数。中后期对蔺草进行一定遮光处理后,草茎长度增加,开花率下降。试验表明,光照是造成蔺草开花逆转和影响草茎品质的重要生态因子之一。     

温度对植物成花的影响

温度对于植物成花的影响是多方面的 ,本文主要从低温、高温和昼夜温差三方面综述了温度影响成花之生理学方面的研究结果。认为温度处理的效果发生于成花启动之前和 /或成花启动进程中的较早步骤 ,其作用可能是间接的。     

喜树开花特性及繁育系统的研究

定位观测了喜树(Camptotheca acuminata Decne)花部构造、开花特性,用杂交指数(OCI)、花粉/胚珠比(P/O)、去雄、套袋、人工授粉等方法测定了喜树的繁育系统.结果表明:喜树花序为由4～6个头状花序组成的聚伞花序,聚伞花序上部的头状花序由两性花组成,下部的花序由雄花组成,两性花雌雄蕊发育正常,雄蕊10枚,雌蕊1枚,下位子房,一室,倒生胚珠;雄花雄蕊发育正常,雌蕊不发育.自然条件下,同一头状花序散粉后2 d,花粉活力最高;两性花在柱头外翻后3～4 d,柱头可受性最强,第6天失去可受性.喜树两性花为半同步雌雄蕊异熟类型,每个头状花序的所有小花同步开放,雄蕊先成熟,表现为雄性时期,雄蕊脱落后,雌蕊成熟,表现为雌性时期,上一级头状花序雌蕊成熟期与下一级头状花序雄蕊成熟期重合.繁育系统检测结果为部分自交和异交,需要传粉者活动才能完成授粉过程.