Flower bud dormancy in Coffea arabica L. II. Relation of cytokinins in xylem sap and flower buds to dormancy-release

Two cationic, butanol-soluble, cytokinin fractions were resolved from purified coffee flower bud and xylem sap extracts. Dormant buds yielded only the more polar fraction and xylem sap collected during drought the less polar fraction, levels of the latter fraction decreasing as drought proceeded. When bud dormancy was broken by irrigation or rainfall, a rapid increase occurred in the more polar cytokinin of the xylem sap. Activity of both cytokinin fractions increased in the buds also, but more slowly at first. The pattern of changes in both bud and sap cytokinin indicate that, when water stress in coffee trees is relieved, cytokinin, which may be required by the buds for further development to anthesis, is released from within the xylem. This, it is suggested, explains why water stress usually must be relieved before the buds can emerge from dormancy. Using thin-layer chromatography, the more polar cytokinin was found to be chromatographically indistinguishable from zeatin riboside in the six different solvent systems tried, while the mobility of the less polar one was similar, but not identical, to 6γγ (dimethylallyl) amino purine. A technique for the sequential extraction of gibberellins, abscisic acid and cytokinin is described.     

Effects of photoperiod on shoot elongation and endogenous gibberellins in the glasshouse carnation

Plants of glasshouse carnation were grown in photoperiodic cycles comprising 8 h natural daylight followed by either 16 h of darkness (short-day treatment) or by 16 h of low-intensity lighting from tungsten filament lamps (continuous-light treatment). When plants were transferred from short days to the continuous-light treatment, rates of shoot elongation were increased and flower initiation was promoted. Shoot tips of plants grown in continuous light yielded greater amounts of diffusible gibberellin-like substances than shoot tips of plants grown in short days. Yields of diffusible gibberellins increased with increases in the duration of the continuous light treatment up to 28 days, by which time flower initials were present. Application of GA₃ to the plants resulted in increased rates of shoot elongation, but no effect on flowering was observed.     

Effect of malformation on changes in endogenous gibberellins and cytokinins during floral development of mango

Patterns of gibberellin content of developing malformed mango inflorescences were very different from those in normal inflorescences. Cytokinin changes in healthy and malformed tissues followed a similar pattern, but cytokinin concentrations were always higher in the malformed inflorescences. Some qualitative differences were detected between chromatographs of cytokinins from malformed and healthy inflorescences.     

21世纪桃树次生木质部导管分子特征的观察

运用离析法和显微照相等技术,以晚熟桃21世纪桃为试材、典型的耐寒品种珲春桃为对照,研究比较了21世纪桃次生木质部导管分子的特征。结果表明,21世纪桃树干次生木质部导管分子中存在着许多不同的样式,迎风面导管分子的特征为多具尾性、长导管性、宽导管性、孔纹导管、单穿孔等,这些特征为21世纪桃在生长季节旺盛的水分需求提供了强有力的保证作用,同时,在风力强劲的冬季也可能使导管容易形成空穴和栓塞,水力结构破坏,致使输水系统受限,可能造成冬害。     

野生毛桃叶片愈伤组织诱导及不定芽再生

【目的】为了初步建立野生‘毛桃1号’叶片愈伤组织诱导、保存及不定芽再生技术体系,【方法】以野生‘毛桃1号’试管苗幼嫩叶片为外植体,探讨了基本培养基、激素配比等一系列因素对‘毛桃1号’叶片愈伤组织诱导和保存的影响及TDZ浓度对愈伤组织不定芽再生的影响。【结果】结果表明,适合‘毛桃1号’叶片愈伤组织诱导的培养基为LP+6-BA 1.0 mg.L-1+2,4-D 3.0 mg.L-1+AgNO30.5 mg.L-1+蔗糖30.0 g.L-1+琼脂6.0 g.L-1;保存的培养基为LP+2,4-D1.5 mg.L-1+CH 0.4 g.L-1+蔗糖30 g.L-1+CA 3.0 g.L-1或PVP 3.0 g.L-1+琼脂5.8 g.L-1,且采用持续暗培养保存,每28 d继代1次。愈伤组织在SH+TDZ 3.0 mg.L-1+NAA 0.3 mg.L-1+蔗糖30 g.L-1+琼脂6.0 g.L-1的培养基上可再生不定芽,再生率为6.83%。【结论】初步建立了‘毛桃1号’叶片愈伤组织诱导、保存及不定芽再生体系,为桃愈伤组织再生和遗传转化的研究奠定了基础。     

桃3种砧木次生木质部导管分子性状比较

为桃树抗寒砧木的选择提供参考依据,采用组织离析、显微照相与生物计量统计法,检测并比较了山桃(Prunus davidiana)(SP)、毛桃(P.persica)(MP)和珲春桃(P.persica cv.Hun-chun-tao)(HP)3种桃砧木根与茎导管分子形态和大小。结果表明,3种桃砧木导管分子性状相比较,根与茎导管分子侧壁次生增厚和木质化的方式、纹孔式、穿孔板类型以及其根一端具尾的导管分子比例基本相似,其茎导管分子均具有螺旋加厚现象,但是,两端具尾、一端具尾、两端无尾、两端倾斜、一端倾斜和两端水平的导管分子比例以及导管分子的长度与直径、根与茎导管分子长度与直径的比率均存在差异。     

Rooting response of shoot cuttings from three peach growth habits

Current year shoot cuttings were collected in October and August from three growth habits of peach (Compact, Pillar, and Standard) and treated with one of four concentrations of indole butyric acid (0, 250, 1250, and 2500 mg L⁻¹ IBA). Rooting response was measured after 5 weeks in the greenhouse. Little or no rooting occurred with cuttings from any growth habit that was collected in October or in August when treated with 0 and 2500 mg L⁻¹ IBA. In August, the number of shoots that rooted was greater in cuttings from Pillar (79 and 45%) than Compact (13 and 3%) treated with 250 and 1250 mg L⁻¹ IBA, respectively. Cuttings from Standard trees had intermediate rooting of 56 and 6% at 250 and 1250 mg L⁻¹ IBA, respectively. Pillar trees consistently grew more roots with greater root length per cutting than the other growth habits. It is proposed that differences in rooting response among the growth habits may be associated with differences in endogenous auxin concentration that had been found in previous studies. Within peach and possibly other fruit trees, the capacity of shoot cuttings to develop adventitious roots can vary by cultivar and successful root induction with exogenous plant growth regulators may depend, in part, on endogenous hormone levels.     

Phenotyping vigour control capacity of new peach rootstocks by xylem vessel analysis

In peach, xylem anatomical characteristics have been shown to be related to vigour of selected rootstocks. The goal of this research was to determine if xylem characteristics of a new set of rootstocks that exhibit a range of size-controlling potential and have a different genetic background from previously examined material would also exhibit similar differences in xylem characteristics. If so, then anatomical analysis of xylem may be a useful means of predicting the vigour control capacity of selected peach rootstock genotypes. Samples of xylem tissue were taken from roots, trunks and shoots of four new rootstocks that were derived from a genetic cross between ‘Harrow Blood’ and ‘Okinawa’ peaches and compared with tissue from ‘Nemaguard’, a vigorous control. Xylem samples were sectioned and analysed by optical microscope. The number and dimensions of vessels in recently developed xylem of each rootstock were measured and compared. The more dwarfing rootstocks had fewer large vessels and more small vessels than the more vigorous rootstocks. Weighted mean vessel diameter (Wm) and calculated hydraulic conductance (K_h) differed among rootstocks: more vigorous rootstocks had higher K_h and Wm than dwarfing rootstocks. Rootstock xylem vessel dimensions varied in relation to the vigour they imparted to a common scion cultivar (‘O’Henry’). After the ‘Nemaguard’ control, ‘HBOK 50’ was the most vigorous rootstock followed by ‘HBOK 10’, ‘HBOK 32’ and ‘HBOK 27’, respectively. Thus, as was seen in previous research with a separate set of rootstocks, the vigour-control capacity of this new series of peach rootstocks was strongly related to their xylem hydraulic characteristics and it appears likely that it would be possible to use xylem anatomical characteristics of shoots or roots of young trees to pre-select for size-controlling potential in a rootstock development program.     

一种测定葡萄新梢木质部水势的新方法

【目的】为了能够连续、即时测定葡萄新梢木质部水势,【方法】以无核白鸡心葡萄为试材,通过同时测定葡萄叶柄木质部导管平均流量和流速,应用变形的哈根-泊萧叶方程,研究了这种连续、即时测定葡萄新梢木质部水势的新方法。【结果】结果表明,在直径为4 mm的葡萄叶柄上,用此新方法测得的葡萄叶柄两端压力差与实际所加压力差吻合的很好,说明此新方法可用于连续、即时测定葡萄叶柄两端压力差。用此新方法在葡萄新梢上测定发现,葡萄新梢木质部水势日变化初步显现"倒双峰曲线",并且葡萄新梢木质部水势与叶水势之间成线性正相关。【结论】此新方法能够连续、即时测定葡萄新梢木质部水势。     

Effects of media,carbon sources and cytokinins on shoot organogenesis in the Christmas tree Scots pine (Pinus sylvestris L.)

Summary

Significant effects of seven basal media and three carbon sources (sucrose, glucose and fructose) on the induction of adventitious buds from embryos of Pinus sylvestris L. were observed. Moreover, hyperhydricity of expiants and shoot regenerants was observed on basal media containing fructose, especially with half-strength Murashige and Skoog (MS), MS, and woody plant medium (WPM). Expiants grown on a Gresshoff and Doy (GD) medium with sucrose produced the highest frequency of regeneration (81%) and with no hyperhydricity observed of developing adventitious shoots. Among three cytokinins tested including BA, BPA, and TDZ (at four concentrations each), 5 μM BA resulted in the highest regeneration frequency and mean number of adventitious shoots per embryo. Shoot régénérants were elongated after transfer to a GD medium containing 2 g-l_–1 activated charcoal and no growth regulators. After one month, rooting was induced on 10% of expiants.     

Influence of high concentrations of cytokinins on the production of somatic embryos by germinating seeds of tomato,aubergine and pepper

Summary

Somatic embryos of tomato, aubergine and pepper were initiated from intact seedlings when seeds were cultured on medium containing 6-benzylaminopurine (BAP) or thidiazuron (TDZ). The percentage of explants producing somatic embryos was highest for aubergine on media containing low concentrations of BAP, i.e. 0–10 mg l^–1, for tomato at 15–20 mg l^–1 and for pepper at 40–80 mg l^–1. Aubergine and tomato produced fewer somatic embryos per responsive seedling when cultured on medium containing TDZ, and pepper did not produce any somatic embryos on media containing 0–20 mg l^–1 1 TDZ. Morphogenesis of the seedlings producing somatic embryos was similar for all the genotypes, i.e. the seedlings were dwarf, only the cotyledons expanded, development of the apical meristem and the root were suppressed and a ring-like crown of nodular tissue developed at the base of the hypocotyl from which somatic embryos were initiated. Co-cultivation of tomato and aubergine seeds with seeds of pepper in media containing 0, 5, 10, 15 and 20 mg l^–1 BAP inhibited somatic embryogenesis in tomato and aubergine instead of assisting somatic embryogenesis in pepper. This is discussed in relation to the recent findings for the induction of somatic embyrogenesis in peanut (Arachis hypogea L.) and the role of BAP and TDZ.     

Girdling and summer pruning in apple increase soil respiration

The root system of plants derives all its energy from photosynthate translocated from the canopy to the root system. Canopy manipulations that alter either the rate of canopy photosynthesis or the translocation of photosynthate are expected to alter dry matter partitioning to the root system. Field studies were conducted to evaluate the effect of trunk girdling (2008 and 2009) and summer pruning (2009) on soil respiration, maximum quantum yield efficiency of photosystem II and leaf carbohydrate content. In apple trees, following trunk girdling there was increased soil respiration in association with a significant rainfall event suggesting rapid release of organic matter and subsequent microbial decomposition of the carbon. Soil respiration rates returned to baseline levels over time. Reduction in midday maximum quantum efficiency of photosystem II (RPSII) was increased by girdling when crop load was low and this reduction was not related to leaf carbohydrate levels. Girdling reduced leaf sucrose and sorbitol levels in both years, however, total leaf carbohydrates were not affected by girdling. Summer pruning increased soil respiration within 2 weeks of treatment in association with a significant rainfall event, also suggesting a release of organic matter and microbial decomposition of the carbon. Cultural practices that severely affect canopy sink source relationships such as girdling and summer pruning increase soil respiration, however these effects appear to be very short lived, 3–10 days, followed by recovery of the soil/root system to similar levels of soil carbon dioxide efflux. These cultural practices do not likely pose a long-term detrimental effect on root system efficiency because the effects are of short duration with apparent recovery.     

Girdling of ‘Fuerte’ avocado in subtropical Australia

Girdled limbs of ‘Fuerte’ avocado produced a bigger crop than controls for 3 consecutive years. Limbs girdled for 4 consecutive years yielded the same as the control, but healed slowly. Yield was maintained in the year after girdling was stopped. The number of seedless fruit was not increased by girdling.     

遮荫和环剥对荔枝枝梢生长和光合生理的影响

 以12年生‘黑叶’荔枝（Litchi chinensis Sonn.‘Heiye’）为研究材料,进行遮荫、环剥及遮荫 + 环剥处理,观测这些处理对新梢生长,以及叶片净光合速率、叶片光系统Ⅱ（PSⅡ）最大光量子效率（F_v/F_m）和淀粉含量的影响。结果表明：遮荫处理和环剥处理均能显著抑制枝梢生长,降低叶片的净光合速率,但两种处理抑制光合作用的机制各异。其中,环剥处理导致叶绿素含量降低,产生永久性光抑制,显示光系统Ⅱ（PSⅡ）受到破坏,因此,环剥处理导致光合作用的降低与光反应系统的破坏有关;遮荫下叶片最大光化学效率F_v/F_m维持正常,淀粉含量降低,但即使在相同的人工光源下,光合作用速率同样低于对照,可能主要与暗反应系统活性减弱有关;而遮荫可显著缓解环剥对光反应系统的破坏效应。     

螺旋环剥对早熟荔枝白蜡、白糖罂的效应

1　材料与方法　　试验于 1998～ 2 0 0 0年在广东省茂名市荔枝良种繁殖场进行 ,试材为 7～ 8年生早熟白蜡和白糖罂荔枝 (均为圈枝苗 )。 1998年和 1999年的 11月中旬分别进行螺旋环剥 ,在主干或主枝上进行 ,环剥宽度3ｍｍ ,螺距 12ｍｍ ,环剥 1 5圈 ,每品种处理 50株 ,完全随机排列 ,以不处理树为对照。观察成花情况 ,调查并统计成花枝率、花量、雌雄花比例和着果率等 ,果实成熟时进行果实性状分析。2　结果与分析2 1　对荔枝花量和花质的影响　环剥对改善白蜡和白糖罂花质的效果显著 ,对白蜡和小年白糖罂促花效果显著 ,但对大年白糖罂的…     

Mist propagation of peach and almond × peach hybrids

Several factors contributing to the successful rooting of stem cuttings of four peach clones and one almond × peach hybrid under intermittent mist were tested. With the almond × peach cross, leaf-bud cuttings were also tested.Severe cutting back of adult peach mother trees in winter favoured rooting of the cuttings, but less severe cutting back induced maximum roots per cutting.For short periods vermiculite was found to be a suitable medium. Sand alone or mixed with vermiculite or gravel gave poor results. Gravel alone or mixed with vermiculite was intermediate. For growing the rooted cuttings for a longer period, a mixture of perlite and peat was very suitable.A period of illumination of 3 h starting at midnight with incandescent light improved rooting of peach cuttings in August and October, but not in June.With cuttings obtained from old fruit-bearing peach trees highest rooting rates were obtained in July, but best root development occurred when rooting was carried out in October. In July rooting rate of basal cuttings was much higher than that of terminal ones. Success with leaf-bud cuttings (including a small branch piece) obtained from young mother trees of the almond × peach hybrid was only achieved at the end of May or in June.Dipping the base of peach cuttings in water before rooting was of advantage with one cultivar rooted in September, but of no advantage with another cultivar rooted in June.When the base of stem cuttings was dipped for a prolonged period in IBA solutions of various concentrations, highest rooting rates were obtained with 25–50 ppm IBA for peaches and with 200 ppm for the almond × peach hybrid. The addition of Phygon XL to this solution was of some advantage for peach cuttings. The concentration inducing maximum root development was higher than that required for maximum rooting and callusing. The optimal IBA concentration for rooting of almond × peach leaf-bud cuttings was 100 ppm.Penetration of the IBA into the leaf-bud cuttings reached a maximum 45 min a after floating them on a 100 ppm solution.Transplanting cuttings which had been rooted under mist was somewhat difficult; however, high rates of survival were obtained with cuttings planted in September which had developed a good root system.     

秋季枝干环剥对龙眼冬梢抽发及产量的效应初探

近几年来 ,由于全球气候变暖 ,加上果农栽培管理不当 ,龙眼大面积抽发冬梢 ,冬梢生长质量差 ,未充分老熟 ,无法成为良好的结果母枝。为此 ,笔者对乌龙岭龙眼进行了主干和主枝秋季环剥试验 ,探索其对控制冬梢抽发、促进龙眼成花及产量的效应。1　材料与方法试验于 1998年在莆田市科技开发中心龙眼园进行。选择立地条件相同、植株生长势相对一致的9年生乌龙岭龙眼树。试验 10月 2 3日在龙眼秋梢老熟后进行。设处理 1:主干螺旋环剥 ,螺旋环剥螺距 4～ 5cm ,上、下环剥口之间互相交叉约半圈 ;处理 2 :主枝环状环剥 ;处理 3:不环剥为对照。 3次重…     

AgNO_3对梨叶片不定梢再生过程中抗氧化酶活性的影响

为探讨AgNO3在离体培养物形态发生中的作用,以金水和金花梨组培苗为外植体,研究了不同质量浓度AgNO3对梨叶片再生不定梢过程中抗氧化酶活性的影响。结果表明,0.1mg/LAgNO3能明显提高金水叶片不定梢再生率和再生数;金花叶片不定梢再生有效促进的AgNO3为0.1～0.5mg/L。经AgNO3处理后,2品种抗氧化物酶活性与对照差异显著。在暗培养期间,叶片中过氧化氢酶(CAT)和过氧化物酶(POD)活性均有较大幅度变化,特别是经0.1mg/LAgNO3处理后,金花叶片中POD活性及金水叶片中CAT活性增幅均高于其余3个处理。叶片中O·2产生速率和H2O2含量也增加但上升幅度不及对照。在进入光培养阶段后,添加适当的AgNO3可提高叶片原有的超氧化物歧化酶(SOD)峰值,且H2O2含量和O·2产生速率随之下降,但较高含量AgNO3处理易引起H2O2含量和O·2产生速率回升。虽然品种间抗氧化物酶活性变化不完全一致,但通过比较发现0.1mg/LAgNO3对提高金花和金水叶片抗氧化物酶活性效果最佳。     

Endogenous gibberellins of mango shoot-tips and their significance in flowering

Eight gibberellin-like substances were isolated from mango shoot-tips. Factors X₂, X₃, X₄, X₅₍₂₎, X₆₍₁₎, X₇ and X₈ were tentatively identified as gibberellins A₁, A₇, A₉, A₄, A₃, A₅ and A₆, respectively, on the basis of their behaviour in column, paper and thin-layer chromatography. Factor X₁ could not be identified.The endogenous level of gibberellins X₁, X₂, X₃, X₄, X₅ and X₆ was higher in “off” year shoot-tips than in “on” year shoot-tips. This suggests that the failure of flowering in an “off” year may be accompanied by a higher level of gibberellins in the shoot-tips.     

桃粉蚜在郑州春季发生规律与桃及其近缘种抗性鉴定

【目的】探究郑州地区春季桃粉蚜发生规律和危害特点,鉴定不同桃及其近缘种对粉蚜的抗性,旨在为桃粉蚜的科学预防和桃抗粉蚜育种奠定基础。【方法】从2月下旬开始,每隔5 d对种植在郑州果树研究所抗性鉴定圃内的桃种质及其近缘种进行粉蚜发生、发展和危害调查;同时于粉蚜发生期采集发生粉蚜的桃树新梢和叶片,对圃内各种质材料进行过量接种,7 d后评价不同种质的抗粉蚜特性。【结果】郑州地区桃粉蚜一般在每年3月上中旬出现,6月下旬以后开始大量减少,集中危害发生在4月下旬至6月上旬,有时持续到6月中下旬;桃粉蚜大发生时,新梢、幼叶及成熟叶片均受危害,被害叶失绿并向叶背对合纵卷,覆有白色蜡粉。27份不同来源桃种质均表现感蚜,抗性等级为4级或5级;18份桃及其近缘种质群体中‘榆叶梅1号’群体高抗粉蚜,‘蒙古扁桃1号’群体和‘四道岭野生李’抗粉蚜,‘贵州毛桃4号’群体中抗粉蚜,甘肃桃、山桃、光核桃、西康扁桃等其他群体易感粉蚜。【结论】明确了郑州地区春季桃粉蚜发生和危害特点,拓展了对桃粉蚜寄主范围的认识,鉴定到‘榆叶梅1号’‘蒙古扁桃1号’‘四道岭野生李’和‘贵州毛桃4号’等抗粉蚜种质。