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1.
以1年生盆栽枳砧纽荷尔脐橙为试材,研究不同施氮水平对叶片氮含量,春梢、夏梢和秋梢落叶率,以及春梢、夏梢和秋梢叶绿素含量季节变化的影响。结果显示,施氮植株当年萌发的春梢和夏梢的落叶率在次年5月有减少的趋势,秋梢落叶率则有增加的趋势,其余时期施氮量与落叶率关系不明显;叶片氮含量与施氮量极显著正相关(r=0.97);施氮在大多数时期可显著或极显著提高不同枝梢叶片的叶绿素含量,在整个测定时期内保持较为稳定,在单株施氮量6.5g范围内这种效应随施氮量增加而显著增强,对照(不施氮)植株不同枝梢叶片的叶绿素含量从当年10月开始明显下降且次年4月锐降。由此可见,充足的氮肥不仅可提高纽荷尔脐橙叶片叶绿素含量且可减少其季节性变化幅度。  相似文献   

2.
干旱胁迫对杏脂氧合酶活性的影响   总被引：1，自引：0，他引：1  
为了研究脂氧合酶(LOX)在植物干旱反应中的作用,以抗旱的山杏和抗旱性弱的龙王帽实生苗为试材,观察了自然干旱过程中叶片的生长状况以及测定了土壤含水量、新叶生长率、叶片脱落率、根和叶片的LOX活性。结果表明,在自然干旱过程中随着土壤含水量的降低,山杏和龙王帽的新叶增长率也下降。干旱后期山杏比龙王帽的新叶增长速率下降快、生长停止早。干旱使山杏比龙王帽叶片早脱落,而且落叶比率明显高于龙王帽。自然干旱时杏的LOX活性表现为叶片升高,在根中变化不大。而且山杏叶片的LOX活性增加幅度比龙王帽大,峰值出现比龙王帽早。因此,干旱条件下抗旱的山杏叶片脂氧合酶活性比龙王帽提早增加而且叶片易早脱落。山杏叶片LOX活性急剧升高出现在叶片萎蔫衰老之前,推测LOX活性增强可能与引发衰老有关。  相似文献   

3.
In one-node stem cuttings of Eucalyptus granáis the absence of leaves was fatal. The optimum leaf area per leaf for rooting was 2-5 cm2, and in this range rooting was higher in one-leaf than in two-leaf cuttings. Axillary shoots started to develop soon after the cuttings were set and their growth was promoted by the presence of the subtending leaf. Thus, in one-leaf cuttings the shoot in the leafy axil grew, at the expense of the shoot in the defoliated axil, while in two-leaf cuttings the shoot in the upper (sub-opposite) axil tended to grow more quickly. Axillary shoots were also vigorous in cuttings from decapitated and disbudded mother plants. Rapid shoot growth was associated with low rates of abscission of the subtending leaf and relatively high rooting ability. Removing axillary shoots from cuttings accelerated leaf abscission and reduced rooting. The stem of the cutting often swelled and discoloured from the base, apparently due to the demand of the cutting for water. Additional leaf wounds had no effect on rooting (but increased mortality), while immersing cuttings in water before setting, or leaving them in a loose heap on the propagation bench, promoted rooting.  相似文献   

4.

Background  

Abscission is the regulated dropping of plant organs, such as leaves or flower petals. This process involves a break down of the cell wall between layers of cells in the abscission zone, causing the organ to become detached. The model plant Arabidopsis thaliana undergoes floral organ abscission. Various experimental methods have been used to study Arabidopsis floral organ abscission, including measuring the petal breakstrength, or the amount of force required to pull a petal from the receptacle. Petal breakstrength provides a quantitative insight into the physical integrity of the petal abscission zone.  相似文献   

5.
Summary

The effects of ε-aminocaproic acid (EACA) on self-incompatibility was tested in a Phaseolus coccineus line which failed to form pods in controlled pollinations. Scanning electron microscope (SEM) and fluorescence miscroscopy confirmed problems in pollen-germination and pollen-tube growth but EACA-treated self- pollinations resulted in fairly normal pollen germination and pollen tube growth. In a few cases, pollen tubes were seen entering the embryo sac and occasionally pods were formed. Incongruity barriers also exist in crosses of P. coccineus × P. vulgaris, P. acutifolius × P. coccineus and their reciprocals. Effects of EACA on flower abscission, pod development and pod abscission were studied. Increased pod formation was observed in EACA treated materials, except in P. acutifolius × P. coccineus and P. coccineus × P. vulgaris cv. Jacobs Cattle. EACA seems to act at the stigmatic and stylar levels, thereby enhancing pollen germination and pollen tube growth and delaying flower abscission. The net result is fertilization and delayed senescence which permit the pod to grow for a longer period of time.  相似文献   

6.
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7.
Exogenous growth substances (GA4+7, IAA, PBA, and ABA) alone and in combination were applied as leaf dips to young ‘Golden Delicious’ apple trees in a growth room at 21 °C. All treatments containing GA4+7 accelerated the incidence of physiological leaf spot over treatments without GA4+7, ABA alone delayed the appearance of leaf spot. PBA, PBA + GA4+7, and PBA + GA4+7 + IAA retarded the abscission of spotted leaves.GA4+7 and GA4+7 + PBA also accelerated leaf spot development in bearing ‘Golden Delicious’ trees in the orchard.Fumigation of apple trees with ethylene at 2, 10, and 20 ppm had no influence on the occurrence of leaf spot or premature abscission.  相似文献   

8.
Summary

Changes in carbohydrate content of inflorescent buds of fruiting and defruited branches of the same tree were measured in 1994 and 1995 in the period before and during bud abscission in pistachio (Pistacia vera L. cv. Aegenes) to investigate its relationship to inflorescent bud abscission. HPLC was used for soluble sugar analysis, while starch was hydrolyzed to glucose enzymatically and the amount of glucose was then determined using the glucose oxidaseperoxidase method. The effect of fruit on leaf net photosynthesis (Pn), chlorophyll a and b (Chl (a+b)) in leaves and specific leaf weight (SLW) was also investigated in 1995. Starch concentration was initially similar in buds of fruiting and defruited branches but became greater in buds of defruited branches from early June 1994 (57 d after full bloom (AFB)) and 20 June 1995 (61 dAFB), resulting in higher starch contents. Glucose and fructose concentrations were similar in flower buds throughout the whole period of measurement; inositol and sucrose (the most abundant sugar in flower buds) both became much lower in fruiting branches from early July 1994 (83 dAFB) and mid July 1995 (88 dAFB). The rapid decrease in sucrose concentration coincided with rapid seed growth and the greatest period of bud abscission in fruiting branches. During the same period, total sugar and total carbohydrate concentrations and contents were greater in buds of defruited branches. The presence of fruit increased Chl (a+b) content in leaves while decreasing SLW between 43 and 61 dAFB. During this same period, leaf Pn rates were greater in fruiting shoots than in defruited ones.  相似文献   

9.
春季干旱对金冠苹果不同部位叶片衰老和脱落的影响   总被引：1，自引：0，他引：1  
春季不同部位叶片发育差异大.而且呈明显规律性.轻度干旱促进各类叶片成熟;严重干旱使长枝基部叶和短枝叶急剧衰老、游离氨基酸积累、内源乙烯大量释放、叶片脱落,但对长枝中部叶的发育影响不大;能促进长枝上部叶的成熟.可见,春季干旱落叶是衰老的结果.春季干旱,对不同部位叶片衰老和脱落的影响与其自身发育的差异有关,因此形成了春季干旱落叶的局部性.  相似文献   

10.
Summary

Two ethylene experiments were designed to show the reaction of the pot plant Capsicum annuum ‘Janne’ to ethylene and to define the critical level of ethylene exposure. The ethylene exposure consisted of 72 h of darkness at 19°C, an ethylene duration of 6–72 h and ethylene concentrations of 0.05–5.0 µl l?1. After the plants had been exposed to ethylene they were placed in a post-production evaluation room. The response of capsicum to ethylene, as expressed by leaf and fruit abscission, was dependent on developmental stage, duration of ethylene exposure and ethylene concentration. Leaves were the most ethylene-sensitive plant parts, followed by the green and maroon fruits. Ethylene did not affect the rate of development into red fruits. The most developed plants were less sensitive to ethylene. Capsicum is very sensitive to ethylene, e.g. there was significant abscission of leaves after exposure to an ethylene concentration of 1.0 µl l?1 for 12 h and a significant abscission of leaves and green fruit after exposure to 0.05 µl?1 for 72 h. A critical ethylene exposure is suggested, dependent on plant sensitivity, duration of ethylene exposure and ethylene concentration.  相似文献   

11.
Summary

Dehydrins are a group of plant proteins which respond to any type of stress that causes dehydration at the cellular level, such as cold and drought stress. Previously, three dehydrins of 65, 60, and 14.kDa were identified as the predominant proteins present in cold acclimated blueberry (Vaccinium corymbosumLinn.) floral buds. Levels were shown to increase with cold acclimation and decrease with deacclimation and resumption of growth. In the present study, to determine if dehydrins are induced in other organs in response to low temperature treatment (48C) and in response to drought, accumulation of dehydrins was examined in leaves, stems, and roots of two cultivars and one wild selection (a V. corymbosum cultivar, a V. ashei Reade cultivar, and a V. darrowi Camp selection) of blueberry by SDS-polyacrylamide gel electrophoresis (SDS-PAGE) followed by immunoblotting. Cold treatment involved placing plants in a cold room maintained at 48C for five weeks; drought stress was imposed by withholding water from potted, greenhouse-grown plants for 34.d. Relative water content (RWC) of shoots was determined periodically throughout the drought treatment. Dehydrins accumulated with both cold and drought stress but their molecular masses varied depending upon blueberry species. Dehydrins accumulated to higher levels in stems and roots than in leaves with cold stress and to higher levels in stems than in either roots or leaves with drought stress. Furthermore, cold treatment combined with dark treatment induced higher levels of dehydrins than cold treatment combined with a 10.h light/14.h dark photoperiod, suggesting that dehydrins may be responsive to changes in photoperiod as well. In the cold-stress experiment, the level of dehydrin accumulation was correlated with expected level of plant cold hardiness in the three genotypes. In the drought stress experiment, dehydrins accumulated prior to significant changes in RWC, and dehydrin levels did not appear to be closely correlated with RWC either among or within genotypes.  相似文献   

12.
 以8年生‘砂糖橘’（Citrus reticulata Blanco）为试材,研究了夏梢生长对果实糖代谢及脱落的影响。结果表明,夏梢生长诱导果实大量脱落及抑制果实的生长,夏梢萌发生长6 d后落果剧增,9 d时出现落果高峰,相对落果率为7.63% · d-1,18 d后累积落果率高达94.05%,比去梢对照增加1.58倍。夏梢生长6 d后,果实的蔗糖、还原糖含量加速下降,但18 d后糖含量恢复到去梢果实的水平。随着夏梢的生长,果实中酸性转化酶（AI）、中性转化酶（NI）的活性得到增强,淀粉酶、蔗糖磷酸合成酶（SPS）活性则被抑制,而蔗糖合成酶（SS）活性受影响不明显。因此认为,夏梢生长促进果实蔗糖分解方向的酶活性增加,加速了果实蔗糖的分解,是导致果实脱落的原因之一。  相似文献   

13.
The effect of temperature on the ability of 2-chloroethylphosphonic acid (ethephon), when applied at 20 mm stage of fruit development, to induce ethylene evolution of fruit and leaves and abscission of fruit and leaves was determined using 9-year-old root-bagged ‘Golden Delicious’/M.27 apple (Malus domestica Borkh.) trees in environment-controlled growth rooms. Ethephon at 400 μL L−1 effectively thinned apples, and its thinning effect was not affected by increasing day/night temperature from 21.1/10 to 32.2/21.1 °C. Fruit ethylene evolution was enhanced by application of ethephon. Peak fruit ethylene evolution occurred 1 day after application of ethephon when day/night temperature was 32.2/21.1 °C whereas it occurred 2 days after application of ethephon at a day/night temperature of 21.1/10 or 26.7/15.6 °C. Ethephon increased leaf ethylene evolution drastically but it did not induce leaf abscission regardless of temperature.  相似文献   

14.
由于一些侵染性病害的影响,浙江省主要梨产区出现早期落叶严重的现象,严重影响了砂梨产业的发展。通过对浙江省杭州市商业梨园主栽品种的田间调查发现,不同品种对病菌的抵抗能力不同。圆黄为黑斑病的易感品种,但对炭疽病的抗性较强;黄花和翠冠较抗黑斑病,但黄花炭疽病的发病率较高;3个品种的锈病发病率没有显著差异。病菌侵染和落叶时间的相关性分析表明,病菌侵染后翠冠和圆黄落叶较黄花早;受黑斑病菌侵染的叶片最易脱落,而梨炭疽病菌和梨锈病菌不易引起落叶,仅在后期形成穿孔。总体上圆黄早期落叶现象最为严重。受梨黑斑病菌侵染后,叶片诱导POD活性的增加来抵御病原菌的侵染。  相似文献   

15.
Black currant bushes of nine varieties were graft-inoculated with reversion virus and compared with healthy bushes in a field trial of eight years’ duration. Two virulent and one relatively avirulent strain caused similar flower and leaf symptoms of differing severity.

The first symptoms appeared in the year after inoculation, when they were restricted to a few shoots and yields were unaffected. Thereafter yields declined as symptoms spread to all shoots within four or five years. The characteristically glabrous flowers borne by virus-affected shoots usually developed abnormally early in spring and many abscissed prematurely. Ultimately infection with the virulent strains caused bushes to become virtually barren. Fruits that did develop were small with few seeds, many of which were abnormal. One virulent strain had little effect·on bushes previously infected with the avirulent strain, which alone halved yield and caused slight symptoms that spread slowly.

Annually the first-formed leaves subtending the flowers of virus-affected shoots were few, small and pale. Later vegetative growth was abnormally vigorous with many, short axillary shoots. Infection decreased susceptibility to the leaf-spot fungus (Pseudopeziza ribis Kleb.) and delayed leaf abscission.  相似文献   

16.
Summary

1-Aminocyclopropane carboxylic acid (ACC) was applied to apple (Malus × domestica Borkh.) trees or to individual fruiting spurs between full bloom (FB) and 31 d after full bloom (DAFB; mean fruit diameter of 20 mm) to determine the effects of ACC on the ethylene released from detached spurs and on fruit abscission. The rate of ethylene release from detached fruiting spurs increased 1 d after applying 50 mg l–1 ACC at full bloom or 16 DAFB (mean fruit diameter of 10 mm), but ACC had a reduced effect on the rate of ethylene release when it was applied 31 DAFB (mean fruit diameter of 20 mm). ACC reduced fruit set in ‘GoldRush’ apple in a concentration-dependent manner in 2009 and in 2010, but had no thinning activity on ‘Pink Lady’ in 2010. ACC at 200 mg l–1 resulted in the yellowing and abscission of ‘GoldRush’ spur leaves in 2009, but not in 2010. The effects of combining ACC and 5 mg l–1 naphthaleneacetic acid on fruit set in ‘GoldRush’ apple were additive. The application of 200 mg l–1 ACC when fruit are ca. 10 mm in diameter may therefore be a useful chemical thinning treatment for apple fruit.  相似文献   

17.
Summary

We examined changes in leaf growth and chemical composition, including chlorophyll content, ribulose bisphosphate carboxylase-oxygenase (RuBisCO), and glycine betaine (GB) in relation to photosynthesis and transpiration responses to salt stress in Amaranthus tricolor leaves. To induce salt stress, plants were transferred to a growth medium containing 300 mM NaCl for 7 d followed by 7 d of relief from salinity. A decrease in leaf enlargement began 3 d after salt stress, and leaves subsequently showed the same degree of regrowth as controls after relief in non-salt medium. Chlorophyll content expressed on a leaf-area basis increased under conditions of salinity due to a reduction in leaf tissue water content. The decrease in chlorophyll content continued throughout the 7 d of relief from salinity. The RuBisCO and soluble protein contents when expressed on a leaf dry-weight basis decreased in response to salinity, and then gradually increased during the relief period. GB content increased slightly up to 3 d of salt stress, and showed typical accumulation during salt stress. GB content decreased sharply immediately after plants were transferred to non-stress medium, but remained at a higher level throughout the relief period. A decrease in photosynthetic activity and transpiration rate preceded any changes in leaf area, RuBisCO or GB content. During relief from salinity, photosynthesis and transpiration rates gradually recovered to control levels with restoration of stomatal conductance. The above findings suggest that the increase in GB content is important in adaptation to salt stress in Amaranthus plants, although photosynthesis and transpiration responses occurred immediately after salt-stress.  相似文献   

18.
Summary

Attempts to micropropagate Annona squamosa L. (sugar apple) from nodal expiants have been hindered by complete leaf abscission during establishment in culture. Absorbents and inhibitors of ethylene biosynthesis and action were tested in order to control leaf drop. The inhibitors of ethylene action, silver thiosulphate and 2,5- norbornadiene, were more effective in avoiding leaf abscission than absorbents of ethylene, activated charcoal, mercuric Perchlorate and potassium permanganate, or inhibitors of ethylene biosynthesis, aminoethoxyvinylglycine, aminooxyacetic acid and cobalt chloride. The results suggest that silver compounds can be used as effective inhibitors of leaf abscission in the establishment of Annona squamosa in culture.  相似文献   

19.
柑橘幼果发育期碳水化合物代谢及其与生长发育的关系   总被引：1，自引：0，他引：1  
温州蜜柑幼果在盛花后逐渐生长 盛花后6 d开始大量脱落 日本甜夏橙幼果在盛花后12 d内重量未增加，一直处于急剧落果期。甜夏橙幼果中蔗糖含量高出温州蜜柑20多倍，种间还原糖含量变化趋势略有不同。两种柑橘的淀粉含量变化也不同，但它们的淀粉含量与淀粉酶活性、幼果相对脱落率均呈负相关。对幼果碳水化合物代谢与生长、脱落的关系作了讨论。  相似文献   

20.
Summary

Overhead irrigation is a common irrigation practice in nurseries, yet it can be wasteful of water and nutrients. We compared the water use, fertilizer use and growth of ‘Top Gun’ lettuce (Lactuca sativa L.) and ‘Grosse Lisse’ tomato (Lycopersicon esculentum Mill.) seedlings in sub and overhead irrigation systems. Five rates of controlled release fertilizer were used – 0.625, 1.25, 2.5, 5 and 10 kg m–3. Sub-irrigation used 86% less water than overhead irrigation. Irrigation type had a significant effect on some growth measurements by final harvest, 43 d after sowing. The sub-irrigated lettuce seedlings were significantly taller. The overhead irrigated lettuce seedlings had a higher dry weight and more leaves. The sub-irrigated tomato seedlings were taller, had longer leaves, a larger leaf area and more leaves. Increasing levels of controlled release fertilizer produced quadratic type responses over time for shoot dry weight, with 10 kg m–3 producing tomato and lettuce transplants with a higher biomass in a shorter time than lower levels of fertilizer.  相似文献   

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