桃树花芽分化期间枝叶细胞分裂素和赤霉素类物质的含量变化

本文报道了白凤花芽分化期间枝叶的细胞分裂素类物质(CTKs)和赤霉素类物质(GAs)的含量变化。用苋红合成法测定CTKs,大麦胚乳法测定GAs。结果如下:短枝和长枝中部的花芽分化开始期为7月27日,长枝上部为8月6日;枝叶生长期内源GAs含量高,快速生长期最高;枝叶停长后,内源GAs含量一直很低。梢尖和中部叶是GAs的主要分布场所。GAs为成花抑制物;花芽分化前30～40天所有样本均有一个CTKs含量高峰。CTKs来自根系并为成花促进物;叶芽可在枝叶生长、CTKs/GAs很低时活动并抽生二次枝。枝叶停长、CTKs/GAs上升后花芽开始活动。     

赤霉素对沙滩黄芩种子萌发的影响

采用不同浓度赤霉素溶液浸泡沙滩黄芩种子,观察比较其发芽率,从而确定出对种子萌发影响效果最佳的赤霉素浓度;同时研究了提前用蒸馏水浸泡与否及赤霉素不同浸泡时间对沙滩黄芩种子发芽率的影响。结果表明:赤霉素处理浓度在100~600mg/kg对种子发芽率均有明显提高且各处理间存在着一定的差异,其中以500mg/kg赤霉素处理效果最佳,发芽率最高,达到75%;在最佳浓度500mg/kg下,以处理72h的种子发芽率最高,可达84.7%。试验还表明,直接用赤霉素而不用蒸馏水浸泡处理种子发芽率更高。     

盐芥和拟南芥根系IAA与GAs应答高浓度NaCl胁迫的比较研究

【目的】比较近缘植物盐芥和拟南芥在高浓度NaCl胁迫下根的生长情况及根中内源赤霉素(GAs)及生长素吲哚乙酸(IAA)的含量变化,为进一步研究盐生植物的耐盐机制提供理论依据。【方法】选取在MS培养基上生长约1周,转接后根长相近的盐芥和拟南芥幼苗进行NaCl胁迫(NaCl浓度拟南芥为0,50,100,150,200,250,300mmol/L,盐芥为0,50,100,150,200,300,500mmol/L),测定高盐胁迫下2种植物根系的生长情况。选取在MS培养基上生长1周,移栽到蛭石/珍珠岩(体积比1∶1)的培养基上继续培养4周的拟南芥和盐芥进行高浓度NaCl胁迫(NaCl浓度为150和300mmol/L),分别于0(对照),1,4,7,10d取根样,采用酶联免疫吸附(ELISA)法测定2种植物根系内源激素GAs及IAA的含量。【结果】正常生长条件下,盐芥根系的生长速度低于拟南芥;高浓度NaCl胁迫下,盐芥与拟南芥根系的生长均受到抑制,但盐芥耐盐能力较强;高浓度NaCl胁迫下,盐芥和拟南芥根系IAA含量均呈现先下降后增加的变化趋势,而GAs含量则呈现不断增加趋势。【结论】盐芥和拟南芥均可通过积累内源IAA和GAs来应对高浓度NaCl胁迫,且盐芥在高浓度NaCl胁迫下IAA和GAs的积累量高于拟南芥。     

Floral induction in longan (Dimocarpus longan, Lour.) trees: IV. The essentiality of mature leaves for potassium chlorate induced floral induction and associated hormonal changes

This study was conducted to elucidate the function of leaves and their role in the alteration of plant hormone homeostasis during potassium chlorate (KClO₃) induced “off season” floral induction (FI) of longan. KClO₃ application had almost no effect on the concentration of gibberellins in receptive apical and lateral shoot meristems, whereas the auxin IAA initially decreased, but later remarkably increased. The most significant changes caused by KClO₃ treatments was an increase in zeatin/zeatin-riboside (Z/ZR) type cytokinins (CKs) 8 days after treatment in the shoot apical and close by lateral buds as well as in the tissue beneath these buds. The 6–7-fold increase in CK concentrations were greatly reduced in the absence of leaves (leaves removed between the apical bud and a girdle). A significant exception was a strong accumulation of isopentenyl adenine/isopentenyl adenosine (iP/iPA) type CKs in wood and bark beneath the bud of defoliated shoots that were isolated against the rest of functional leaves of the tree by a girdle. This accumulation of iP/iPA, the immediate precursors of Z/ZR, together with the strong increase of Z/ZR in the shoot apical bud (SAB) after KClO₃ application indicate that leaves may be involved in the biosynthesis of CKs. Overall, the results suggest that cytokinins play a significant role in KClO₃ induced “off season” floral induction in longan. This role may not be restricted to the biosynthesis of these hormones but also to their mobilization and accumulation in the SAB of newly flushing shoots.     

Floral induction (FI) in longan (Dimocarpus longan, Lour.) trees: Part I. Low temperature and potassium chlorate effects on FI and hormonal changes exerted in terminal buds and sub-apical tissue

Floral induction (FI) in longan (Dimocarpus longan, Lour.) trees was achieved in controlled greenhouse experiments by low temperature (LT) and by the application of potassium chlorate at high temperature (HT + KClO₃) during two consecutive seasons. The latter treatment was successful also at temperatures above 20 °C. The present experiment was conducted to investigate possible alterations in the concentrations of plant hormones exerted by these two methods and to relate them to the floral induction process. The following hormones were examined by radioimmunoassay in the shoot apical buds (SAB), and in sub-apical bark and wood: the auxin indole-3-acetic acid (IAA); gibberellins (GAs); and the cytokinins zeatin/zeatin riboside (Z/ZR) and isopentenyl-adenine/isopentenyl-adenosine (iP/iPA).     

柿(Diospyros kaki L.)果实发育及成熟过程中内源GAs活性和ABA含量的变化

利用生物学方法和气相色谱法分别对柿有代表性的早、中、晚熟品种果实中内源赤霉素类物质(GAs)活性及脱落酸(ABA)含量的变化进行了测定。GAs 活性和 ABA 含量在幼果初期都很高,以后随果实的发育而迅速降低,在果实生长速度缓慢的第二期变化不大。但自果实进入成熟期开始,GAs 活性再次迅速降低,而 ABA 含量却呈增加趋势。发生这种变化的时期,与果实的成熟期一致。讨论了内源值物生长调节物质的平衡与果实成熟的关系。     

赤霉素及烯效唑对大豆形态、光合生理及产量的影响

为了解赤霉素ＧＡ３和烯效唑的壮苗效果,采用ＧＡ３和烯效唑浸种处理大豆种子,调查大豆茎秆、节长、叶柄、叶片光合特性及产量的变化。两年结果显示,ＧＡ３ 和烯效唑对大豆株高有调控作用,但具有时效性。苗期,ＧＡ３处理增加株高,烯效唑抑制株高;盛花期、结荚期和鼓粒期处理与对照之间株高无显著差异;收获期ＧＡ３处理降低了第１、３、１０、１２、１３、１４节节长,从而显著降低大豆株高,烯效唑降低第１节节长,不影响株高。ＧＡ３和烯效唑 浸种处理均增加大豆茎粗,增强大豆抗倒伏性。ＧＡ３处理降低了８～１０节叶柄长度、增加了１４～１８节叶柄长度;烯效唑增加７～１２节叶柄长度。两种调节剂从节长和叶柄两个方面改变了大豆冠层结构,叶柄长度的变化量与同节位的产量贡献率的变化量显著相关,相关系数为０．６２２和０．５８５,Ｐ＜０．０５。烯效唑浸种处理能够增加７ｄ、１４ｄ叶绿素含量,１４ｄ光合速率,显著提高单株粒数、单株荚数和产量,两年平均增产１５．１４％。说明烯效唑处理可能通过改变大豆冠层结构和光合性质影响大豆产量。