不同激素对锦绣杜鹃的催花作用

在加温、补光条件下,研究赤霉素(GA3)、萘乙酸(NAA)和吲哚乙酸(IAA)处理对锦绣杜鹃花蕾发育、开花期及开花质量等的影响。结果表明:锦绣杜鹃花蕾经0～3000mg.L-1GA3涂抹后,其催花效果随处理浓度增大呈先升后降趋势,并于2000mg.L-1浓度下达到最佳,表现在花蕾发育快、开花期提前及开花质量高等;而0～3000mg.L-1NAA和IAA对锦绣杜鹃催花效果均不明显。锦绣杜鹃花蕾大小(包括长度和宽度)与开花期提前时间和花径之间均呈极显著正相关,与花蕾期则呈极显著负相关;花蕾期与开花期提前时间之间呈极显著负相关(P<0.01)。     

乙烯丰和赤霉酸对桃开花的影响

春季发生霜害可能性大的地区,调节落叶果树开花的时间是重要的。秋季或春季在花芽膨大之前立即使用植物生长调节剂,已作为调节开花期既手段被提出来。Proebsting和Mills成功地采用乙烯丰延迟了樱桃开花。Webster发现秋季施用乙烯丰推迟李的开花时间3—13天。 据报道,赤霉酸会影响桃的开花期。Corgan和Widmoyer以及Painter和Stembridge的研究发现,秋季施用赤霉酸能阻碍翌年春季花芽的发育。然而,其他研究者却报道,采用乙烯丰和赤霉酸处理,其效果不明显或出现产量显著下降的副作用,故在商业上没有应用价值。本文介绍作者在新泽西州采用乙烯丰和赤霉酸调节‘Cresthaven’桃     

海南海岸青皮林繁殖物候特征

石梅湾海岸青皮林是海南岛重要的天然海防林及旅游区风景林,对其繁殖物候的研究有助于揭示青皮在贫瘠海岸沙滩成功定居及繁殖的生物学特性。采用种群、个体定位和小枝标记相结合的方法,连续3a对其开花物候进行观测,结果表明:青皮个体繁殖物候期约为101d,小枝平均花蕾数为133.3个,幼果坐果率为42.4%,结实率为4.4%;青皮种群为1a连续开花型,但集中开花模式明显,有2个高峰期且花量多,非集中开花期花量很少;个体间及个体中小枝间开花存在一定的不同步性;开花及种子丰年现象明显,歉年花量及种子雨量很少;开花物候期前1个月的降雨量对开花物候期无显著影响,但3、4月份平均气温分别高于24℃和26.4℃,开花期提前明显,低于此温度开花期推迟相对缓慢,即物候期的提前与推迟对温度的上升与下降的响应是非线性的。     

近20年青藏高原东北部禾本科牧草生育期变化特征

利用1988—2010年青藏高原东北部地区5个站点牧草生育期地面观测数据,分析了近20年代表性牧草返青、开花、黄枯期及生长季的变化趋势,并通过偏相关分析探讨了气温和降水对牧草生育期的关系。结果表明,近20年青藏高原东北部牧草生育期北部推迟南部提前的特征明显。南部的三江源区域返青、开花与黄枯期总体呈显著提前趋势,其中曲麻莱羊茅返青期提前的倾向率达到-4 d/10 a,开花期为-13 d/10 a,黄枯期达到-9 d/10 a,且均通过0.01的显著性检验水平。北部环青海湖区域的海北西北针茅生育期则表现出一定的推迟趋势。生长季长度北部地区延长,而南部除甘德(垂穗披碱草)外均呈明显缩短趋势。近20 a黄枯期的变化幅度明显大于返青期,使得生长季长度的变化更多地受黄枯期变化的影响。1月和3月气温是影响研究区牧草返青最主要的气候因子,气温增高返青提前。开花期南北差异明显,北部与同期气温呈明显负相关关系,南部则主要与开花前2—3个月的降水量密切相关,降水增多大部地区开花期提前。此外,降水也是各地牧草黄枯的主要影响因子。     

早春草本植物开花物候期对城市化进程的响应——以北京市为例

植物物候对城市化的响应是全球变化与城市生态环境效应研究的重要内容。2012年3月到6月,结合气象观测数据,对北京市西北向城市化梯度上7种早春草本植物开花物候期进行观测与研究,发现温度因子和早春草本植物开花物候期均随城市化梯度发生变化,即越靠近城市中心区,温度和积温累计值越高;早春草本植物开花物候期出现时间越早,平均提前2—4 d;但开花期持续时间与开花速率并不随城市化梯度发生明显变化。此外,研究发现北京市7种早春草本植物开花期对5℃积温变化响应最为敏感;开花期提前时间梯度变化显著性与生活型密切关联,多年生草本植物对城市化梯度变化的响应比一年生或一二年生草本植物明显。未来城市植物物候期研究中,应更关注城市化进程中土地利用/覆被变化与热岛效应对城市气候及植物生理生态特征的累积影响特征,以期进一步揭示植物物候期对城市化及气候变化的响应规律。     

中国温带旱柳物候期对气候变化的时空响应

为了揭示中国温带植物物候随时间变化和植物物候对气候变化响应的空间格局及其生态机制,利用52个站点1986—2005年的旱柳展叶始期、开花始期、果实成熟期、叶变色始期和落叶末期的物候数据,分析其时间序列的线性趋势,并通过建立基于最佳期间日均温的物候时间模型,确定物候发生日期对气温年际变化的响应。在研究的时段内,区域平均旱柳展叶始期、开花始期和果实成熟期的发生日期分别以-4.2 d/10 a、-3.8 d/10 a和-3.3 d/10 a的平均速率显著提前,而区域平均旱柳叶变色始期和落叶末期的发生日期则分别呈不显著推迟和以2.4 d/10 a的平均速率显著推迟的趋势。单站展叶始期、开花始期和果实成熟期发生日期的线性趋势以提前为主,显著提前的站点分别占40%、41%和29%;叶变色始期发生日期呈显著提前和显著推迟趋势的站点数相当,分别占17%和19%;落叶末期发生日期的线性趋势以推迟为主,显著推迟的站点占23%。各站展叶始期、开花始期和果实成熟期发生日期的线性趋势空间序列与相应的最佳期间日均温的线性趋势空间序列之间呈显著负相关,表明一个站点前期气温升高的速率越快,该站这些物候期发生日期提前的速率就越快。在物候期对气温年际变化的响应方面,区域平均春季最佳期间日均温每升高1℃,展叶始期、开花始期和果实成熟期的发生日期分别提前3.08 d、2.83 d和3.54 d;区域平均秋季最佳期间日均温每升高1℃,叶变色始期和落叶末期的发生日期分别推迟1.69 d和2.28 d。单站展叶始期和落叶末期发生日期对气温年际变化的响应表现出在温暖地区的站点比在寒冷地区的站点更为敏感的特点。总体上看,基于日均温的物候时间模型对春、夏季物候期的模拟精度明显高于对秋季物候期的模拟精度。建立了基于最佳期间日均温和日累积降水量的改进秋季物候模型,该模型使旱柳叶变色始期和落叶末期的模拟精度显著提高。由此可见,旱柳叶变色始期和落叶末期的发生日期受到前期气温和降水量的综合影响。     

濒危植物矮牡丹致濒原因分析

矮牡丹是我国特有种,为国家3级濒危保护植物。仅分布于山西南部(稷山和永济)和陕西中北部(华山、铜川和延安)。矮牡丹分布区的生态环境特征是：热量条件较好,降水量较少,立地条件较差。在落叶阔叶林和落叶阔叶灌丛中,矮牡丹往往多为伴生成分。偶尔可成为灌木层的优势种。矮牡丹濒危的主要原因有：(1)开花和结实率较低,产生的种子较少;(2)种子的特殊休眠特性导致萌发率较低;(3)生长发育缓慢;(4)竞争能力较弱和(5)人为干扰严重。此外。针对矮牡丹的濒危现状和原因,还提出了科学保护对策。     

乙烯利对番茄果实的催熟效应

我国长江流域种植春番茄,果实成熟多集中在六、七月份,影响市场均衡供应。采用催熟技术特别是应用乙烯利处理番茄的植株或果实,可使产品提前上市,这在生产上是可行的。我们于1977—1978年在本校及赭山公社,进行了影响乙烯利催熟番茄的因素的试验。现简报如下。     

太行山石质山地石榴中幼龄林林地蒸散规律研究

利用波文比-能量平衡方法测定了太行山石质山地石榴林地蒸散量的日变化和月变化,并且计算出各物候期的蒸散量．结果表明,石榴在中午关闭气孔,以减少生理蒸腾．石榴林地蒸散量与净辐射呈显著线性相关,回归方程为Y=0．0029X-0．1449,相关系数R为0．9．石榴林地从萌芽期到落叶期的总蒸散量为424．08mm．其中,开花-果实成熟期林地蒸散量最大,占生长季节总蒸散量的64．59％．石榴林地每年需要补充灌溉两次,一次在萌芽期,一次在开花前期．     

Ca2+调节剂在乙烯催花中对观赏凤梨CaM基因表达特性的调节作用

凤梨科植物乙烯催花技术自1930年代开始使用,效果显著。但凤梨科植物乙烯催花的机理尚不明确。鉴于Ca2+-CaM在多种植物开花过程中具有一定的调节作用,为了研究Ca2+-CaM系统在乙烯诱导凤梨科植物开花中的作用,本文以紫花擎天凤梨成株为试材,通过乙烯分别和Ca2+调节剂(Ca2+促进剂,Ca2+螯合剂和抑制剂)的组合处理植株后,利用RT-PCR和Northern技术分析了CaM基因表达特性的变化。结果表明,乙烯处理的同时,加入Ca2+促进剂,使CaM表达量峰值出现的时间由24h提前到了6h;而加入Ca2+螯合剂和抑制剂,使CaM基因表达量峰值出现的时间延迟到了48h以后。该结果与相应的开花时间进程一致,即加入Ca2+促进剂,使花器官出现的时间提前约5d,而加入Ca2+螯合剂和抑制剂,使花器官出现的时间有不同程度的延迟,表明Ca2+调节剂对CaM表达特性的调节作用对乙烯诱导凤梨开花也有一定的影响。     

The effect of LAB 173711 and ethephon on time of flowering and cold hardiness of peach flower buds

Peach flowers are often killed during bloom by spring frosts. LAB 173711, a compound with abscisic (ABA)-like activity, and ethephon delayed flowering in peach trees. In greenhouse experiments, LAB 173711, at concentrations of 10^?3–10^?2 M, was most effective in delaying bloom when applied after a 5°C cold storage period, rather than before the dormancy breaking treatment. In contrast, ethephon delayed bloom most effectively when applied before 5°C cold storage; ethephon caused flower bud abscission when treatments were made after the chilling requirement had been satisfied. In field experiments, ethephon delayed flowering by 6–7 days, which reduced bud injury after a spring frost during bloom. No flower bud injury was found on ethephon-treated trees after temperatures of ?4.3°C; whereas without ethephon 25% of the flower buds were frost damaged. LAB 173711 delayed the time to 50% bloom by 2–3 days. However, this was not long enough to avoid low-temperature injury to the flower buds.     

The effect of LAB 173711 and ethephon on time of flowering and cold hardiness of peach flower buds

Peach flowers are often killed during bloom by spring frosts. LAB 173711, a compound with abscisic (ABA)-like activity, and ethephon delayed flowering in peach trees. In greenhouse experiments, LAB 173711, at concentrations of 10^–3–10^–2 M, was most effective in delaying bloom when applied after a 5°C cold storage period, rather than before the dormancy breaking treatment. In contrast, ethephon delayed bloom most effectively when applied before 5°C cold storage; ethephon caused flower bud abscission when treatments were made after the chilling requirement had been satisfied. In field experiments, ethephon delayed flowering by 6–7 days, which reduced bud injury after a spring frost during bloom. No flower bud injury was found on ethephon-treated trees after temperatures of –4.3°C; whereas without ethephon 25% of the flower buds were frost damaged. LAB 173711 delayed the time to 50% bloom by 2–3 days. However, this was not long enough to avoid low-temperature injury to the flower buds.     

Dual effect of light on flowering and sprouting of rose shoots

Shade, caused by a dense leaf canopy in the light conditions of a normal greenhouse, reduced sprouting of the third axillary bud (from the top) on decapitated rose branches ( Rosa hybrida cv. Marimba) in comparison to less shaded buds on branches protruding above the canopy and sparsely spaced. Flowering of the third young shoot on shaded branches bearing 3 lateral shoots was totally inhibited. Mixed fluorescent and incandescent light in a growth chamber reduced sprouting of the third bud on decapitated rose branches in comparison to decapitated branches on rose plants held in fluorescent light of similar photon flux density. This was attributed to the higher R:FR ratio in fluorescent vs mixed light that reached the third bud, and in exposed vs shaded branches. Flowering of the third shoot was promoted by several factors: high photon flux density, 0.5 m M gibberellic acid (GA) or 0.2 m M benzyladenine (BA). BA was the most effective treatment. Treatments promoting flowering of the third shoot did not reduce growth or flowering of the upper shoots. However, spraying the uppermost shoot with BA suppressed the growth of the shoots below. It is concluded that light affects flowering in two ways. The effect on bud sprouting is related mainly to R:FR ratios, while the effect on flower development is related mainly to photon flux density. Cytokinins may substitute for the light effect on flower development.     

平阴玫瑰花芽分化期叶片内源激素的变化

对平阴玫瑰花芽分化期叶片甲醇提取物进行IAA、ZR、GA₃、ABA的分离、纯化和测定。结果发现,所测的几种激素均表现出明显的变化规律,其中IAA和GA₃在花芽分化期含量逐渐下降,且在分化临界期出现一低峰,而ZR和ABA则完全相反。同时经比较分析得出ABA/GA₃, ABA/IAA,ZR/GA₃,ZR/IAA也表现明显的变化规律,即比值总体趋势是逐渐提高,且均在分化临界期含量出现一飞跃,显然ABA/GA3,ABA/IAA,ZR/GA₃,ZR/IAA在平阴玫瑰的花芽分化过程中起着重要的调控作用,由此推测,增加植物体内的ABA、ZR的含量或降低IAA、GA₃的含量,都可以促进玫瑰的花芽分化;反之则抑制其花芽分化。     

Ethylene perception inhibitor 1-MCP decreases oxidative damage of leaves through enhanced antioxidant defense mechanisms in soybean plants grown under high temperature stress

Ethylene is a stress hormone involved in early senescence and abscission of vegetative and reproductive organs under stress conditions. Ethylene perception inhibitors can minimize the impact of ethylene-mediated stress. The effects of high temperature (HT) stress during flowering on ethylene production rate in leaf, flower and pod and the effects of ethylene inhibitor on ethylene production rate, oxidative damage and physiology of soybean are not understood. We hypothesize that HT stress induces ethylene production, which causes premature leaf senescence and flower and pod abscission, and that application of the ethylene perception inhibitor 1-Methyl cyclopropene (1-MCP) can minimize HT stress induced ethylene response in soybean. The objectives of this study were to (1) determine whether ethylene is produced in HT stress; (2) quantify the effects of HT stress and 1-MCP application on oxidative injury; and (3) evaluate the efficacy of 1-MCP at minimizing HT-stress-induced leaf senescence and flower abscission. Soybean plants were exposed to HT (38/28 °C) or optimum temperature (OT; 28/18 °C) for 14 d at flowering stage (R2). Plants at each temperature were treated with 1-MCP (1 μg L⁻¹) gas for 5 h or left untreated (control). High temperature stress increased rate of ethylene production in leaves, flowers and pods, production of reactive oxygen species (ROS), membrane damage, and total soluble carbohydrate content in leaves and decreased photosynthetic rate, sucrose content, F_v/F_m ratio and antioxidant enzyme activities compared with OT. Foliar spray of 1-MCP decreased rate of ethylene production and ROS and leaf senescence traits but enhanced antioxidant enzyme activities (e.g. superoxide dismutase and catalase). In conclusion, HT stress increased ethylene production rates, caused oxidative damage, decreased antioxidant enzyme activity, caused premature leaf senescence, increased flower abscission and decreased pod set percentage. Application of 1-MCP lowered ethylene and ROS production, enhanced antioxidant enzyme activity, increased membrane stability, delayed leaf senescence, decreased flower abscission and increased pod set percentage. The beneficial effects of 1-MCP were greater under HT stress compared to OT in terms of decreased ethylene production, decreased ROS production, increased antioxidant protection, decreased flower abscission and increased pod set percentage.     

The inhibitory effect of gibberellic acid on flowering in Citrus

The application of gibberellic acid (GA₃) at any time from early November until bud sprouting, resulted in a significant inhibition of flowering in the sweet orange [ C. sinensis (L.) Osbeck] and the Satsuma ( C. unshiu Marc.) and Clementine ( C. reticulata Blanco) mandarins. Two response peaks were evident: the first occurred when the application was timed to the translocation of an unknown flowering signal from the leaves to the buds. The second occurred during bud sprouting, at the time the flower primordia were differentiating. From the pattern of flowering, it appears that the mechanism of inhibition was similar irrespective of the timing of GA₃ application. There was an initial reduction in bud sprouting affecting selectively those buds originating leafless inflorescences. An additional inhibition resulted in a reduction in the number of leafy inflorescences with an increase in the number of vegetative shoots, suggesting the reversion of a floral to a vegetative apex. The inhibited buds sprouted readily in vitro but invariably vegetative shoots were formed. A continuous influence of the sustaining branch is necessary to keep the flowering commitment of the buds; irreversible commitment occurs when the petal primordia are well differentiated.     

Changes in carbohydrates and mineral elements in Citrus leaves during flowering and fruit set

Mineral elements and metabolizable carbohydrates in Citrus leaves [ Citrus sinensis (L.) Osbeck cv. Washington navel] have been determined from bud sprouting until the end of the June drop and related to fruitlet growth and abscission. Mineral elements in old leaves decreased during the spring flush of growth and reached minimum values at flower opening, coinciding with a peak in abscission. This was followed by a rapid recovery in potassium and nitrogen to the initial values, with little change afterwards. Old leaves accumulate carbohydrates until flowering, and lose them during post-anthesis at a constant rate for more than 4 months; this rate of export is unaltered by the presence of a nearby growing fruit. Inflorescence leaves accumulate carbohydrates and mineral elements during post-anthesis; during the June drop there is an interruption in the accumulation of nitrogen and a net loss of phosphorus, potassium and carbohydrates from these leaves, coinciding with the attainment of the maximum growth rate of the fruit.
The two main periods of abscission coincide with minima in the amount of reserves in leaves, suggesting that a limitation in metabolite supply may be the primary cause of drop. There is a closer relationship of the fruit with inflorescence leaves than with old mature ones; however, the regulation of carbohydrate levels in the inflorescence leaves cannot be simply explained in terms of source-sink relationships with the nearby growing fruit, and the smaller size of inflorescence leaves vs. vegetative ones is not due to the presence of the flower during leaf development.