枫杨种子休眠与萌发特性研究

为了确定枫杨种子的休眠原因及其打破休眠的方法,以枫杨成熟种子为材料,对种子透水性、种子浸提物的生物抑制作用、种子催芽处理效果以及种子在不同温度下的萌发能力进行研究。结果表明:枫杨种子种皮透水性良好,种子浸提液中存在发芽抑制物质,抑制物质的存在是造成种子休眠的主要原因。直接埋藏和混雪后埋藏解除枫杨种子休眠的效果不理想;低温层积解除种子休眠效果较好,层积时间达到120d时种子萌发率可以达到89%。温度显著影响枫杨种子的萌发,25℃的恒温条件下种子萌发能力显著高于其它温度条件。结论:枫杨种子不存在物理休眠,属于生理休眠类型,种子需要低温层积处理120d打破休眠,解除休眠种子的适宜萌发温度是25℃。     

短叶松种子发芽条件的研究

为适应扩大引种的需要,我们对短叶松种子通过层积时间、光照、温度等因子进行萌发效应的研究。优选出了短叶松种子发芽条件的规范。对短叶松种子的浸提液进行生物鉴定,并就其内外种皮对种子萌发的影响进行对比试验,结果表明短叶松种子有休眠期;休眠的主要原因是受胚的生理因素影响。试验表明:低温层积20—40天可解除休眠;在20/30℃变温加光照条件下也能解除休眠。从而为种子检验和场圃育苗提供了科学依据。     

低温解除牡丹芽休眠进程中内源激素的变化

以4～5年生牡丹'胡红'为试材,研究1～7周不同低温处理时间对其开花展叶的影响.根据花芽萌动和开花情况结合激素的变化动态,将低温解除花芽休眠进程划分为:低温累积期、休眠解除启动期、休眠基本解除期、休眠彻底解除期4个时期.分别测定低温处理期内和进入温室后内源GA,,ABA,CTK,IAA及其比值的变化.结果表明:低温期内GA,,ABA,CTK质量分数的增减和GA,/ABA比值的变化可明显地反映低温解除花芽休眠的进程.其中,GA,/ABA比值的变化与休眠的进程直接对应.进入温室后牡丹花芽内各激素的变化进一步证明GA3和CTK是解除休眠的促进物,ABA是解除休眠的抑制物.低温解除牡丹休眠是通过调节休眠解除的促进物和抑制物之间的平衡来实现的,是多因素综合作用的结果.     

贮藏板栗休眠与萌芽的温度调控

本文研究了板栗贮藏过程中呼吸作用变化和内源激素含量与贮藏温度的关系,确定了板栗的休眠时期,并探讨了通过贮藏温度调控板栗休眠和萌芽的措施。研究结果表明,板栗休眠期长短与贮藏温度有密切关系,在室温（２０℃～２２℃）贮藏条件下板栗的休眠期为２个月左右,在冷藏（０℃～２℃）条件下的休眠期为３个月左右。说明虽然冷藏较室温贮藏能延长板栗的休眠期,但不能完全控制休眠。板栗休眠解除后,在生理上表现为呼吸作用上升和内源激素（ＩＡＡ、ＧＡ３、ＺＲ）含量增加,外观上表现为胚芽萌动生根。冷藏板栗在休眠解除前将贮藏温度降至临界低温（－２℃～－４℃）,可有效地抑制呼吸回升和内源激素的合成,使休眠不被解除,从而在整个贮藏过程中不萌芽。经临界低温贮藏的板栗,仍较好地保持种子活力,出库后品质和萌芽正常,未造成低温伤害。     

牡丹优良品种"洛阳红"的促成栽培技术

以牡丹优良品种"洛阳红"为对象,研究了牡丹植株解除休眠的方法和促成栽培与环境因子的相关关系.结果表明用700 mg·kg-1赤霉素涂芽15 d可解除牡丹休眠;促成栽培时间与积温呈显著正相关,与日均温呈负相关;促成栽培适宜的日均光照13 h,空气相对湿度70%～80%,土壤含水率25%～50%,所需时间最短32 d,最长56 d.     

香椿生物学起点温度的研究

通过对香椿的休眠期、生物学起点温度及解除休眠的试验研究发现:香椿落叶后有17天的生理低温休眠期;生物学起点温度为8.3℃;顶芽解除休眠完成芽萌动需要的有效积温为234℃,从芽萌动到采芽需要的有效积温为165℃。根据这一结果进行栽培,可以提高香椿芽的产量。     

赤霉素对水曲柳种子解除休眠的作用

水曲柳(Fraxinus mandshurica Rupr.)是我国东北林区的一种优良珍贵用材树种。种子(实为果实)有很长的休眠期。为了解除它的休眠,一般需经8—10个月,即先在暖温(20℃)下4—5个月,再在低温(5℃)下4—5个月的层积,外施赤霉素(GA)可促进多种植物种子解除休眠。本文主要研究GA对水曲柳种子的解除休眠有无促进作用,同时对GA促进解除休眠的原因进行了初步分析。     

牡丹‘洛阳红’芽休眠低温解除中需冷量和生理生化动态变化

以4年生牡丹‘洛阳红’为试验材料,经历0～42 d低温处理观测其芽萌动成花情况,探讨上海地区牡丹花芽低温休眠解除过程中需冷量和生理生化指标的动态变化规律.结果表明:处理7d为低温累积期,处理14 d即可启动休眠解除但萌动率(52.8％)和成花率(27.8％)均较低;基本解除休眠需要21 d低温处理,萌动率可达90.3％,但成花率为51.6％;而彻底解除休眠则需要至少低温处理28 d,成花率急剧增加至71.8％.花芽中可溶性蛋白和可溶性糖的变化趋势类似:休眠完全解除前随着低温累积量的增加急速增加,彻底解除后随着需冷量的增加变化趋缓.花芽内源激素及其比值的动态变化表明,GA3和ABA的含量变化与花芽体眠解除的进程分别呈显著的正、负相关;在基本与彻底解除休眠区间内二者含量急剧变化,GA3/ABA的值可以直接显示花芽休眠的程度.进一步证明GA3是最为重要的促进休眠解除激素,而ABA则是休眠解除的主要拮抗物.     

天女花种子催芽方法研究初报

为了打破天女花种子休眠，对其种子催芽技术进行了研究。结果表明，种胚未完成发育是天女花种子休眠的主要因子，种皮的机械约束对种子萌发影响不大。用２５０μｇ／ｇ的ＧＡ浸种可加速种胚的分化、发育。不进行催芽处理，当年不能出苗。种子在催芽过程中，必须进行浸种，后经低温沙藏，再经变温或高温催芽，才能解除休眠。     

林木种子的休眠与解除

林木种子绝大多数都具有休眠现象，主要有生理发育不完全引起的生理休眠、外在不具备萌发基本条件而引起的强迫休眠等，文章叙述了种子休眠的原因及分类，休眠机理，解除种子休眠的多种措施，以及不同处理对不同树种的效应。     

Low temperature, but not photoperiod, controls growth cessation and dormancy induction and release in apple and pear

In contrast to most temperate woody species, apple and pear and some other woody species of the Rosaceae family are insensitive to photoperiod, and no alternative environmental seasonal signal is known to control their dormancy. We studied growth and dormancy induction in micropropagated plants of four apple (Malus pumila Mill.) and one pear (Pyrus communis L.) commercial rootstock cultivars in controlled environments. The results confirm that growth cessation and dormancy induction in apple and pear are not influenced by photoperiod, and demonstrate that low temperature (< 12 degrees C) consistently induces both processes, regardless of photoperiodic conditions. Successive stages of the autumn syndrome (growth cessation, formation of bud scales and winter buds, leaf senescence and abscission, and dormancy induction) occurred in response to low temperature. Long days increased internode length at higher temperatures, but had no significant effect on leaf production in any of the cultivars. Chilling at 6 or 9 degrees C for at least 6 weeks (about 1000 h) was required for dormancy release and growth resumption, whereas treatment at 12 degrees C was marginally effective, even after 14 weeks of exposure. We are thus faced with the paradox that the same low temperature conditions that induce dormancy are also required for dormancy release in these species.     

两种耐旱植物种子发芽特性及其比较分析

选择鬼针草和侧柏这两种广泛分布的植物进行种子发芽试验,目的是在掌握它们发芽特点的基础上,进一步比较、探讨木本植物与草本植物种子发芽的差异,为以后的研究和高速公路边坡植被恢复提供参考。试验分析表明:①鬼针草和侧柏种子的含水量分别为14.15%和9.59%。②鬼针草种子净度为91.83%,千粒重为1.64 g;侧柏种子净度为82.8%,千粒重为8.46 g。③侧柏种子具有休眠特性;鬼针草种子在冬季室温条件下也能发芽,即鬼针草种子没有休眠特性。④鬼针草种子发芽的温度为9℃以上;侧柏种子需要经过冬季低温休眠才能发芽,发芽温度为24.5~27.5℃。     

Effects of "near-lethal" stress on bud dormancy and stem cold hardiness in red-osier dogwood

We studied the effects of "near-lethal" (NL, 47 degrees C for 1 h) heat stress, applied to intact shoots of red-osier dogwood (Cornus sericea L.) during early (October), deep (November) or late (December) dormancy, on bud dormancy release and development of stem tissue cold hardiness under natural conditions and at a constant temperature of 0 or 23 degrees C in the dark. The NL heat-stress treatment overcame bud dormancy when applied during the early and late stages of dormancy. During October and December, all plants in the 23 degrees C + dark post-stress environment broke bud within 35 and 12 days, respectively, whereas the corresponding values for days to bud break in the control plants were more than 150 and 110 days, respectively. Application of NL heat stress during deep dormancy caused only slightly earlier bud break compared to the control plants. In the 0 degrees C + dark post-stress environment, all NL heat-treated plants died within 9 weeks. Under natural post-stress conditions, bud break in plants receiving NL heat stress during early and deep dormancy occurred at the same time as in control plants, whereas bud break of plants receiving NL heat stress during late dormancy occurred 55 days earlier than in control plants. Under both natural and 23 degrees C + dark post-stress conditions, cold hardiness of plants receiving NL heat stress during early dormancy was similar to that of controls. Application of NL heat stress during deep dormancy hastened the rate of deacclimation under the 23 degrees C + dark post-stress conditions but had no effect on deacclimation under natural post-stress conditions. Application of NL heat stress during late dormancy enhanced deacclimation of plants in both the 23 degrees C + dark and natural post-stress environments.     

Differential responses of silver birch (Betula pendula) ecotypes to short-day photoperiod and low temperature

We investigated interrelations of dormancy and freezing tolerance and the role of endogenous abscisic acid (ABA) in the development of silver birch (Betula pendula Roth) ecotypes in controlled environments. Short-day treatment induced growth cessation, bud set and dormancy development, as well as initiation of cold acclimation and an increase in freezing tolerance. Subsequent low temperature and short days (12-h photoperiod) resulted in a significant increase in freezing tolerance, whereas bud dormancy was gradually released. The concentration of ABA increased in response to short days and then remained high, but ABA concentrations fluctuated irregularly when the dormant plants were subsequently exposed to low temperature during short days. Although there was a parallel development of freezing tolerance and bud dormancy in response to short days, subsequent exposure to low temperature had opposite effects on these processes, enhancing freezing tolerance and releasing dormancy. Compared with the southern ecotype, the northern ecotype was more responsive to short days and low temperature, exhibiting earlier initiation of cold acclimation, growth cessation and an increase in ABA concentrations in short days, and higher freezing tolerance, faster dormancy release and greater alteration in ABA concentrations when subsequently exposed to low temperature during short days. The rates and extent of the increases in ABA concentration may be related to increases in freezing tolerance and dormancy development during short days, whereas the extent of the fluctuations in ABA concentration may play an important role in enhancing freezing tolerance and releasing dormancy during a subsequent exposure to low temperature during short days.     

Effects of ABA application on cessation of shoot elongation in long-day grown Norway spruce seedlings

Abscisic acid (ABA) was applied in lanolin to apical buds of Norway spruce (Picea abies (L.) Karst.) seedlings actively growing in a 24 h photoperiod. At a rate of 100 microg per plant, ABA suspended shoot elongation for about three weeks in the majority of plants but failed to induce normal winter buds. The role of ABA in the induction of dormancy is thus uncertain in conifers as well as in deciduous woody plants.     

Autumn temperature affects the induction of dormancy in first‐year seedlings of acer platanoides L.

First‐year seedlings of five latitudinal populations of Acer platanoides were subjected to decreasing photoperiod treatment under three different temperature regimes. The depth of the induced dormancy was quantified as the number of days to bud burst (DBB) under defined conditions favourable to growth. The results suggested a close relationship between autumn temperature and the strength of the induced dormancy, with high temperatures combined with short days leading to a deeper stage of dormancy. Northern and continental populations generally had bud burst earlier than southern. The results are discussed in relation to hypotheses for dormancy induction and release.     

The minimum temperature for budburst in Betula depends on the state of dormancy

Vegis has put forward the theory that the range of growth-promoting temperatures changes during the induction and the release of dormancy. We have tested the response of buds of Betula pubescens Ehrh. and B. pendula Roth. on temperature during the induction and release of dormancy. Betula seedlings were exposed to dormancy-inducing high-temperature and short-day conditions and subsequently to dormancy-releasing chilling conditions in darkness. To monitor the dormancy status of the seedlings, subsets of them were transferred to five forcing temperatures and their budburst was observed. The results show that the expression of dormancy was temperature dependent, so that the minimum temperature for 100% budburst rose during the induction and dropped during the release of dormancy. These responses may explain previous contradictions between experimental and modelling studies, but that needs to be verified with more extensive experiments, some of which are identified in this study. The results provide further evidence for the concept of gradual change in bud dormancy. They also suggest that global change studies modelling budburst phenology should address the changing expression of bud dormancy.     

我国木本植物体细胞胚胎发生研究进展

综述了我国木本植物组织培养体细胞胚胎发生研究领域的研究现状，分别从影响木本植物体细胞胚胎发生的主要因子、生理生化基础、遗传变异性等几个方面进行了评述，对我国木本植物体细胞胚胎发生研究领域提出了一些建议。     

氮、磷、钾对若干种木本植物离体培养繁殖的影响

本文通过培养基中三个主要营养元素氮、磷、钾对若干种木本植物(如杉木、北美红杉等)离体培养繁殖影响的研究,提出了较适合于这些木本植物离体培养的改良MS基本培养基(其中大量元素氮、磷、钾水平修改为:NH₄NO₃ 850mg/L,KNO₃ 2000mg/L,KH₂LO₄ 100mg/L)。在此基础上,讨论了工厂化组培繁殖木本植物特别是一些常规繁殖困难的林木树种的可能性,以及提高组培生产率和降低生产成本的有效措施。