以叶盘为外植体的白桦的再生

从不同的激素组成(BA, K T, 2, 4~D, NAA, GA₃)、基本培养基(MS, WP)、外植体放置的方向性进行了实验, 建立了以白桦叶盘为外植体的再生系统。当叶盘向轴面朝下放置在培养基上时, 三周后, 从叶盘边缘生出不定芽。不定芽的诱导率为64%, 平均每片叶盘可生出6 个不定芽。叶盘再生系统的建立为白桦的遗传转化提供了前提。     

陕北白桦个体生长过程的谐波分析

利用波谱分析方法中的谐波分析原理, 对陕北白桦个体生长过程进行了不同层次的分析。结果表明:白桦个体的树高、胸径和材积生长动态波动规律与Logistic 模型不完全相同, 树高在20 年后与Logistic 模型吻合, 胸径整个过程均不吻合, 但材积生长与Logistic 模型基本一致;应用波谱分析方法分析树木生长过程的动态规律, 比Logistic 模型更准确。     

采用BSLB(Brine Shrimp Letality Bioassay)法对元宝枫(Acer truncatum Bunge.)及同属植物活性部位的筛选

本文通过BSLB法对元宝枫及同属植物不同部位的水提物进行了活性试验,得知：元宝枫的幼技、种皮的水提物具一定的生物致死活性;同属植物青榨槭叶和种子,秦岭槭、权叶槭果翅的水提物也具一定的生物致死活性。本实验为元宝枫及同属植物进行进一步肿瘤细胞的体外培养试验及动物模型试验提供了科学依据。     

毛竹的无性系生长与立竹密度和叶龄结构的关系

毛竹为单轴型散生竹,属典型的无性系植物,原产我国亚热带地区。由于其个体高大、生长迅速、产量高、材质好、分布广,长期以来,一直是我国最为重要的经济竹种。本文应用无性系生长生理整合的理论,从种群统计学的角度,探讨了毛竹林立竹密度与叶龄结构对其无性系生长潜力的影响。结果表明：由于毛竹叶的生活期为两年,１龄新叶的光合能力比２龄老叶高,每样地的出笋数、活笋数与带１龄新叶的立竹数呈正相关,而与带２龄老叶的立竹数相关性不显著。另外,竹笋的死亡率是非密度制约的。本研究结果合理地解释了常见的毛竹林产量大小年交替变化的现象。     

温度和水分状况对几种不同类型植物叶片水势和延伸生长的影响

在田间条件下研究了温度、相对湿度、土壤水分对玉米、高粱、茄子、豇豆、河北杨和泡桐六种植物LER2)和ψWL3)日变化的影响。结果表明,ψWL日变化呈正弦曲线,即早晨、晚上高,中午低;土壤水分亏缺,中午大气ψWV4)愈低,ψWL降低愈多。在土壤供水良好的条件下,玉米、高粱、河北杨、泡桐叶片生长与温度密切相关,因此白天生长快,晚上生长慢;若中午ψWV太低,生长减慢,使叶片生长呈双峰曲线,即午前及18:00左右生长快。若土壤水分亏缺,白天ψWV太低,白天生长慢,晚上生长快。茄子和豇豆叶片生长对水分亏缺更敏感,晚上生长快,白天生长慢,干旱处理叶片在白天中午有收缩现象。     

Water Potential Modulates Extensibility of Rye Coleoptile Cell Walls

Extensibility of walls of frozen/thawed rye (Secale cereale) coleoptile segments as a function of the water potential of the incubation solution (Ψ₀) was analyzed employing the creep test method. Negative Ψ₀ exerts an inhibiting effect on extension of isolated walls. The lower the Ψ₀ of polyethylene glycol 6000 (PEG), the less the walls of frozen/thawed segments extended under load. This inhibiting effect of Ψ₀ on wall creep was reversible and independent of the preincubation temperature of the segments. An increase in Ψ₀ resulted in increased extension rate within 2–4 min, whereas a decrease in Ψ₀ resulted in gradually decreasing extension rate after 8–12 min. This finding implies that wall extension changes during growth induced by changes of Ψ₀ in vivo are not only due to changes of turgor pressure but also due to a direct influence by negative Ψ₀ on physical wall properties. The results are discussed with respect to the regulation of extension growth during conditions of water stress.     

The Role of the Epidermis in the Control of Elongation Growth in Stems and Coleoptiles

The peripheral cell wall(s) of stems and coleoptiles are 6 to 20 times thicker than the walls of the inner tissues. In coleoptiles, the outer wall of the outer epidermis shows a multilayered, helicoidal cellulose architecture, whereas the walls of the parenchyma and the outer wall of the inner epidermis are unilayered. In hypocotyls and epicotyls both the epidermal and some subepidermal walls are multilayered, helicoidal structures. The walls of the internal tissues (inner cortex, pith) are unilayered, with cellulose microfibrils oriented primarily transversely. Peeled inner tissues rapidly extend in water, whereas the outer cell layer(s) contract on isolation. This indicates that the peripheral walls limit elongation of the intact organ. Experiments with the pressure microprobe indicate that the entire organ can be viewed as a giant, turgid cell: the extensible inner tissues exert a pressure (turgor) on the peripheral wall(s), which bear the longitudinal wall stress of the epidermal and internal cells. Numerous studies have shown that auxin induces elongation of isolated, intact sections by loosening of the growth-limiting peripheral cell wall(s). Likewise, the effect of light on reduction of stem elongation and cell wall extensibility in etiolated seedlings is restricted to the peripheral cell layers of the organ. The extensible inner tissues provide the driving force (turgor pressure), whereas the rigid peripheral wall(s) limit, and hence control, the rate of organ elongation.     

RESPONSES OF PHENOLOGY AND GROWTH OF BETULA UTILIS AND ABIES FAXONIANA IN SUBALPINE TIMBERLINE ECOTONE TO SIMULATED GLOBAL WARMING, WESTERN SICHUAN, CHINA

 采用开顶式生长室(Open-top chamber, OTC)模拟增温对植被影响的研究方法, 研究了川西亚高山林线交错带糙皮桦(Betula utilis) 和岷江冷杉(Abies faxoniana)幼苗物候及生长特性对模拟增温的响应。结果表明, 温度升高使岷江冷杉幼苗芽开放时间显著提前(15.2 d); 糙 皮桦春季芽物候期变化不显著, 而落叶时间明显推迟(19.7 d), 叶寿命延长(22.8 d)。与对照(CK)相比, OTC内糙皮桦叶面积和岷江冷杉叶片长度及两者侧枝生长速率都显著加快。模拟增温对两物种基径相对生长速率都表现为正效应, 增温对两物种枝叶特性及分布格局表现为不同程度 的正效应、负效应或无影响。不同功能型两物种对模拟增温响应方式存在一定程度差异。     

东北槭属的种子表皮雕纹及其在分类上的意义

借助于扫描电子显微镜,对我国东北地区槭属（Ａｃｅ）的１１种变种的种皮雕纹进行了扫描观察,并拍制了电镜照片。从种皮的雕纹类型看,槭树属的种皮可以概括为四种类型：（１）嵌合型;（２）穴状条纹型;（３）条纹型;（４）网格型;雕纹的形态也支持了色木槭和元宝械作为两个独立种的处理意见;以及小果紫花槭作为紫花槭（Ａｃｅｒｐｓｅｕｄｏ－ｓｉｅｂｏｌｉｄｉａｎｕｍ（Ｐａｘ．）Ｋｏｍ）的种下等级变种（ｖａｒ．ｋｏｒ     

白桦种群的稳定性与火干扰关系的研究

从种群生态学和干扰生态学的角度出发,在火史重建的基础上,采用种群世代划分的方法,研究了大兴安岭北部白桦群的稳定性与火干扰的关系,结果表明：白桦种群的耐火力与自我恢复力都较差,主要依靠很强的火后恢复力维持其稳定性,种群耐火力与长期火状况密切相关,表现为：低频类〈中频类〈高频类。高强类〈中强类〈低强类。火后恢复力与自我恢复力和最近一次火烧强度及距今时间密切相关,火后恢复力与自我恢复力都以低强类〉高强类     

淹涝胁迫对水稻叶鞘和叶片中淀粉粒分布的影响

淹涝是世界上当前所面临的最严重自然灾害之一,尤其是近几年来,淹涝给我国的农业生产带来了巨大损失,全国平均每年受涝面积814万hm2,其中成灾面积448万hm2,损失粮食约28亿kg〔1〕。水稻是我国的主要粮食作物,并且分布于淹涝易发生的南方多雨潮湿地区和北方低洼地带,淹涝对水稻产量影响极大,因此,研究淹涝胁迫对水稻的伤害及水稻的耐淹机制越来越受到人们的重视〔2〕。淹涝对植物的伤害并非是因为水分过多而造成的直接伤害,而是由于淹涝造成的次生胁迫,其中最严重的是缺氧。在缺氧条件下,细胞中的碳水化合物代谢途径改变,对植物的生长和发育…     

Auxin increases elastic wall-properties in rye coleoptiles: implications for the mechanism of wall loosening

Auxin-induced changes of wall-rheological properties during different growth rates of rye coleoptile segments (Secale cereale L.) were investigated. In addition, changes of osmotic concentration and turgor pressure were measured. Decrease of turgor and of osmotic concentration followed a synchronous time course. Auxin-incubated segments exhibited a faster decrease and eventually lower values of both parameters. Creep test extensibility measurements demonstrate that apparent plastic as well as elastic extensibility of distilled-water-incubated segments strongly decreased during 24 h. In auxin-incubated segments apparent plastic as well as elastic extensibilities were strongly increased, even in the absence of growth due to insufficient turgor pressure. The increasing effect of auxin on elastic wall properties is also reflected by an increase in relative reversible length (part of segment length by which segments shrink after freezing/thawing as referred to total length) and a complementary decrease of relative irreversible length (remaining length after turgor elimination as referred to turgid length); again the effects were independent of growth rate and turgor pressure. Cellulose synthesis inhibition of approx. 80% by dichlorobenzonitrile (DCB) had no significant effect either on growth or on wall-rheological properties. Independent of whether the changed rheological wall behaviour of auxin-incubated segments is causally related to the mechanism of auxin-induced wall loosening, it indicates changes of wall polymer properties and/or interactions which are conserved when no actual length increase occurs due to insufficient turgor pressure. The results suggest that IAA-induced wall loosening may be primarily mediated by cell wall changes other than cleavage of covalent, load-bearing bonds as hypothesized in various wall loosening models.     

人生长激素和转移的人生长激素基因对去垂体鱼的生长代偿效应

通过显微注射技术,将小鼠重金属螯合蛋白(MT-1)基因启动顺序与人生长激素基因顺序的重组体pMThGH注入鲤鱼(Cyprinus carpio)的受精卵内,由此发育的转基因鱼及其后代F1和F2均显示出快速生长效应。去垂体后,转基因鲤鱼F2持续生长,而非转基因鲤鱼和鲫鱼(Carassius auratus)的生长停止。给去垂体的鲫鱼腹腔注射生物合成的人生长激素(hGH),可恢复其生长。实验结果表明,转基因鱼体内表达和体外生物合成的hGH均能代偿鲤鱼和鲫鱼的内源生长激素并刺激去垂体鱼的生长。