Pollinizer influence on almond seed dormancy

Breaking seed dormancy is necessary for the completion of germination. Maternal tissues (integument and endocarp) appear to control seed germination, although the effect of the pollinizer has also been described. In this work, the influence of the pollinizer flowering time was studied on the stratification requirements of almond seed germination. Stratification requirements were determined in seeds (with and without endocarp) from crosses between a female progenitor and pollinizers of different flowering dates. The results showed an influence of the pollinizer in the stratification requirements of seeds with endocarp. However, no correlations were found between pollinizer flowering date and stratification requirements, which seem to be determined mainly by the female progenitor. In the case of seed stratification without endocarp, the results did not show any influence of pollinizer on stratification requirements. The observed variability within females (within or between crosses) could be due to differences in the shell characteristics, the different accumulation of inhibitors in the integument, or the genetic nature of the embryos.     

Methods to overcome seed dormancy in Echinacea angustifolia DC

Some factors (light, prechilling, gibberellic acid, ethylene) affecting germination of seeds of Echinacea angustifolia DC. were investigated. Without any pretreatment, the seeds germinated better in darkness than in light, however, percentages germination were low in both cases. GA₃ did not increase germination in light. Prechilling for 7–15 days in light or in darkness hardly affected percentage germination but significantly increased the rate of germination. Ethephon during prechilling resulted in a large increase of percentage and rate of germination in light, but had hardly any effect on germination in darkness. The results showed that a prechilling treatment for about 11 days at 5°C in a 1 mM ethephon solution in continuous light, followed by a 2-week germination period in light (24 h per day) at 20/30°C, can induce >90% seed germination in E. angustifolia. The prechilling treatment in ethephon also increased the rate of germination.     

Relationship between bolting-resistance and seed dormancy of different celery cultivars

A correlation between bolting-resistance and seed dormancy was established for 13 celery cultivars. Those cultivars which bolted early in response to a 4-week cold-treatment (7°C) given at the 5-leaf seedling stage had seeds which gave a high germination response to $\text{GA}{}_{\mathrm{<mtext>4</mtext><mtext>7</mtext>}}$ at 2 × 10^?4M in the dark at 22°C. Conversely, bolting-resistant cultivars showed a low germination response to $\text{GA}{}_{\mathrm{<mtext>4</mtext><mtext>7</mtext>}}$. A correlation coefficient (r) of 0.969 was calculated from these data, and values of r = 0.947 and r = 0.950 were obtained using data from field trials on celery bolting in 1974 and 1975, respectively.     

不同处理方法对解除杜梨种子休眠的影响

【目的】明确解除休眠的适宜方法及层积处理的最佳时间。【方法】以杜梨种子为材料,通过不同处理方法与不同层积(4℃)时间研究杜梨种子休眠。【结果】层积处理是解除休眠最有效的办法,处理后的杜梨种子发芽率高达67.00%,而-20℃低温冷冻和不同温度温水处理均不能有效解除杜梨休眠,生产上不宜使用。不同层积时间研究表明,40 d之前随层积时间的延长,发芽率逐渐升高,35 d以后各处理的发芽率变化差异不显著,40 d时种子发芽率最高。【结论】解除休眠的最适层积时间是35~40 d。     

Methods to break seed dormancy in Cyclocarya paliurus (Batal)Iljinskaja

Cyclocarya paliurus is native to China and is the sole species in its genus. However, the seeds remain deeply dormant for 2 years in their natural environment. We tested different pretreatments of chemical scarification and exogenous application of gibberellic acid (GA₃) for efficacy in breaking dormancy and speeding germination. In contrast to scarified seeds, non-scarified seed did not germinate, indicating that C. paliurus seeds have hard, impermeable seed coat dormancy. Exogenous application of GA₃ significantly enhanced germination of scarified seeds. Compared with seeds stratified in sand with water, the germination of seeds stratified in sand moistened with 400 ppm GA₃ for 60 days was significantly increased and germination rate was over 90% after 120 days. Analysis of variance indicated that both GA₃ concentration and stratification medium had significant effects on seed germination and final germination percentage. Germination was higher for longer stratification periods, but no significant difference in germination was observed after 90 days. These results suggested that C. paliurus seeds exhibit both exogenous and endogenous dormancy. A combination of chemical scarification and exogenous application of GA₃ alleviated seed dormancy in a relatively short period of time.     

Seed-coat anatomy and proanthocyanidins contribute to the dormancy of Rubus seed

Rubus seed has a deep double dormancy that restricts germination due to seed coat structure and chemical composition. Improved germination of diverse Rubus species required for breeding improved blackberry and raspberry cultivars is partly dependent on the seed coat structure. This study evaluated the seed coat structure of three species with thin (R. hoffmeisterianus Kunth & C. D. Bouché), medium (R. occidentalis L.) and thick (R. caesius L.) seed coats. The three species exhibited distinctive seed-coat cell composition. The very thin testa (0.086 mm) of R. hoffmeisterianus had little exotesta (surface) reticulation; with the meso- and endotesta composed of sclereids of homogenous shape and size. R. occidentalis had a thick testa (0.175 mm) and a highly reticulate exotesta; the meso- and endotesta were composed of several diverse types of sclereids. R. caesius had the thickest seed coat (0.185 mm) but only moderate exotesta reticulation; the meso- and endotesta were composed of large, irregular, loosely arranged sclereids. R. occidentalis, a medium size seed, was the most heavily lignified with seed-coat thickness similar to R. caesius, the largest seed. Proanthocyanidins (PAs) from dry seed of six Rubus species were extracted and quantified by high performance liquid chromatography. R. hoffmeisterianus, a thin only slightly hard seed, had half the PA (0.45 μg/seed) of R. occidentalis with a thick, extremely-hard seed coat and diverse sclereids (1.07 μg/seed). PA content and sclereid composition both appear contribute to seed coat hardness and resulting seed dormancy. The effectiveness of sulfuric acid for Rubus seed scarification is likely due to degradation of PAs in the testa.     

Levels of physiological dormancy and methods for improving seed germination of four rose species

Low seed germination is a major problem in commercial rose propagation and breeding and is species-dependent. The present work selected four rose species previously un-examined to explore effective methods for improving seed germination and the relevant dormancy mechanism and its levels in seven experiments. The results showed that both pulp and achenes from the four rose shrubs had chemical substances that significantly inhibited seed germination with the inhibitory effect was more pronounced in pulp extract than of achenes. Single treatments of H₂SO₄ scarification, short-term cold stratification (<16 weeks) or warm stratification were less effective in breaking dormancy as indicated by lower germination index than their combinations. Comprehensive comparisons showed that among the six treatments the most effective for breaking dormancy was H₂SO₄ scarification followed by warm plus cold stratification, then H₂SO₄ scarification followed by cold stratification and finally warm plus cold stratification. Scarification with H₂SO₄ for 2–4 h ordinal followed by warm stratification at 20 °C for 4 weeks and cold stratification at 5 °C for 8 weeks was the best pretreatment for increasing seed germination percentage for Rosa multibracteata (81.4 ± 2.9%), Rosa hugonis (13.1 ± 6.0%), and Rosa filipes (62.7 ± 5.7%); and H₂SO₄ scarification for 4 h followed by cold stratification at 5 °C for 12 weeks was the best pretreatment for Rosa sericea (46.7 ± 8.7%). Our results suggest that these four species have only physiological dormancy caused by integrative roles of pulp, pericarp and embryo. The level of physiological dormancy was ranked as R. hugonis > R. sericea > R. filipes > R. multibracteata.     

Effect of temperature on dormancy in strawberry

Early in autumn, at the end of September or at the beginning of October, strawberry plants of the cultivars ‘Glasa’ and ‘Tioga’ were transferred from outdoors to separate phytotron glasshouses at constant temperatures of 10° and 14°C. In November a number of these plants were chilled at 3°C for 0 to 4 weeks and subsequently forced; the rest remained at 10° and 14°C until June.The plants kept at 10°C and subsequently chilled and forced, grew faster and more vigorously than those pretreated at 14°C. The 14° plants showed more pronounced growth differences resulting from the length of the chilling treatments than did the 10° plants. Those remaining continuously at 10° developed vigorously from March onwards, while those at 14°C retained their flat appearance into June. These results showed that a continuous temperature as high as 10°C was still able to break dormancy in the strawberry plants, while 14°C was ineffective.     

AFLP-based genetic relationships in the Mediterranean myrtle (Myrtus communis L.)

Myrtle is an important plant species of the Mediterranean maquis, and is widely exploited for its aromatic properties. It is used in Italy for the production of a typical liqueur, for cut foliage and as an ornamental pot plant. We report the use of amplified fragment length polymorphism (AFLP) profiling to estimate genetic similarities within myrtle germplasm collected from six Italian regions, and from the Botanical Gardens of six other Mediterranean countries (including the outgroup Myrtus communis subsp. tarentina). Five AFLP primer combinations identified 122 polymorphic fragments analysing 92 individual samples, most of them (56%) were informative in discriminating among the populations. The AFLP patterns indicated that the majority of the variation occurs among rather than within populations (G_ST = 0.61). A neighbour-joining (NJ) tree separated the populations into two main branches: the first one grouped some of the Italian populations with those from Spain and Portugal; the second one included a Southern Italian subcluster together with samples from Greece, Israel, France and Croatia. A principal coordinate analysis supported the two major branches identified in the NJ analysis and showed the separation of Western and Eastern Mediterranean populations along the first axis. The Italian populations did not cluster in a single clade, but rather form distinct regional groups. The present analysis suggests that Italy represents a botanical transition zone between the Western and Eastern Mediterranean region in Myrtus communis.     

核果类果树种子休眠的机制及其解除方法研究进展

核果类植物是温带地区重要的果树资源,兼具良好的经济价值、生态价值及园林观赏价值。休眠是核果类果树种子为应对不良外界环境而产生的适应性进化,有利于保障种群的延续,但不利于苗木的规模化繁育。为了优化核果类植物繁育技术,提高苗木繁育效率,对核果类植物种子休眠与萌发机制的研究现状进行综述。本研究重点分析国内外相关研究进展,分别从果肉、内果皮、种皮、种胚4个方面对核果类果树种子休眠机制及休眠打破方法进行总结归纳,并基于综述结果对其研究前景进行展望,以期在阐明核果类果树种子休眠与萌发机制的基础上,为解决生产过程中种子休眠问题提供思路与方法,并为乡土植物资源保护、引种栽培提供科学依据。     

Abscisic acid relationships in dormancy of apple buds

When potted, dormant, leafless seedling of ‘Antonovka’ apple were held for 15 weeks at 4 or 24°C, the patterns of change for abscisic acid (ABA) in buds were similar. At both temperatures, ABA concentration had decreased to a low level by 6 weeks and remained at a fairly low level until Week 12. The ABA concentration showed a tendency to rise in both treatments by Week 15.When excised axillary buds of ‘Northern Spy’ seedings were placed on 10^?4 M ABA medium immediately after excision, their growth was inhibited substantially depending on the length of exposure to ABA. When similar axillary buds were first allowed to begin growth on ABA-free medium, and then subsequently transferred to 10^?4 M ABA medium, no inhibition of growth occurred, even though these buds contained about twice as much ABA as did the buds placed directly on ABA medium prior to the beginning of growth.Thus, growing buds responded much less to exogenous applications of ABA than did non-growing buds. Diminishing of bud reaction to ABA responded to emergence from dormancy after 18 weeks of chilling.     

Chemical changes during myrtle (Myrtus communis L.) fruit development and ripening

The chemical composition of fruit belonging to ‘Barbara’ and ‘Daniela’ myrtle cultivars was monitored during development from fruit-set to an over-ripe stage (July–January), with the aim to identify a reliable maturity index. Acidity, pH, reducing and total sugars, phenols, tannins, anthocyans, carbon dioxide and ethylene production rates were monitored over two different year seasons. Titratable acidity decreased during maturation, with significant differences due to cultivar and year of observation. Reducing sugars increased in both cultivars approximately sevenfold from fruit set to complete maturation. Total sugar content increased similarly ranging from 1.43% and 1.41% at fruit set to 8.28% and 7.56% at maturation for ‘Barbara’ and ‘Daniela’, respectively. Total phenols and tannins occurred at high levels after fruit set and declined during development. Anthocyans levels increased, in both cultivars, according to a sigmoid curve. The pattern of respiration rate showed a gradual decline in both cultivars ranging from 365.81 and 396.42 mg kg⁻¹ h⁻¹ to 79.98 and 52.27 mg kg⁻¹ h⁻¹, respectively for ‘Barbara’ and ‘Daniela’ in 2006. A peak of variable size was observed in October–November period. Small increases in ethylene production have been detected during fruit development ranging from 130.57 and 269.14 μL kg⁻¹ h⁻¹ measured at the onset of development to 13.04 and 19.36 μL kg⁻¹ h⁻¹ measured at harvest for ‘Barbara’ and ‘Daniela’, respectively.     

Effects of gaseous compounds in smoke on dormancy release in freesia corms

Exposing corms to smoke generated from smouldering plant materials (“smoke treatment”) releases freesia corms from dormancy. The smoke was found to contain some hydrocarbons, i.e. ethane, ethylene, (C₂H₄), and propylene at concentrations below 130 μl 1^?1, and carbon monoxide (CO) at 2000-400 μl 1^?1.Exogenous C₂H₄ at low levels of 100-1 μl/litre air strongly stimulated dormancy-release. In contrast, propylene and acetylene were required at a concentration much higher than that in the smoke to exert the dormancy-releasing effect: the application of 100 μl/litre air had little or no effect. Air containing $\text{1000 μ}\text{l CO}\text{litre}$ air produced some effect, which could be masked by co-existence of $\text{10 μ}\text{l C}{}_2\text{H}{}_4\text{litre}$ air. Acetaldehyde, which may occasionally be present in smoke, showed the dormancy release at ca. 1 mM but was phytotoxic. Corms exposed to smoke or C₂H₄ did not show an endogenous C₂H₄ rise, while non-treated corms showed it distinctly before dormancy release.These results suggest that a C₂H₄-stimulus is dominant in smoke treatment.     

单氰胺对温室甜樱桃休眠解除的影响

试验以温室栽培的红灯、美早和早大果3个甜樱桃品种为试材,研究了单氰胺对甜樱桃离体休眠芽休眠解除的影响及喷施单氰胺对树体萌芽及开花的影响。结果表明,涂抹2%单氰胺后,红灯离体休眠芽比对照可以提前10d解除休眠,而美早和早大果解除休眠的时间与对照相同。温室升温时喷施1%单氰胺可使树体的萌芽时间提前12-16d,开花时间提前15-17d,并且提高了树体的萌芽整齐度和开花整齐度。     

裸仁南瓜种皮发育研究进展

裸仁南瓜是南瓜中的一种自然突变类型,其种皮在发育过程中因缺乏木质素和纤维素逐渐退化成一层薄膜。裸仁南瓜营养丰富,方便食用和加工,是优异的种质资源,国内外市场需求旺盛,其种皮形成机制复杂,对其深入研究有助于解决生产难题和促进裸仁南瓜籽产业发展。笔者综述了近年来国内外裸仁南瓜种皮发育相关基础研究取得的最新进展与成果,包含南瓜籽主要营养成分研究、南瓜种皮分类、种皮形态学研究、相关酶分析、育种研究、种皮颜色研究、基因定位研究等。分析了目前裸仁南瓜种皮发育相关基础研究中存在的问题以及今后研究的重点和难点,以期为裸仁南瓜育种及种皮发育的深入研究提供理论和实践依据。     

大棚葡萄破眠剂应用试验

山东省蒙阴县大棚栽培葡萄已具一定的规模,大棚栽培的葡萄萌芽早、萌芽率高,这是其早成熟、早上市的关键.我们用石灰氮涂葡萄芽取得了较好的效果,但石灰氮涂芽存在着葡萄枝蔓发芽不整齐、费工、费时等缺点.2002年12月,我们在大棚栽培葡萄凤凰51上试用德国产破眠剂3%朵美滋,打破其休眠,促进提早萌芽、成熟,取得了较为满意的结果.     

落叶果树芽休眠相关基因的研究进展

落叶果树芽的休眠是一种十分复杂的生命现象,涉及到一系列复杂的生理生化反应(如光周期反应、温度反应、水分代谢、能量代谢、活性氧代谢、激素代谢等)和许多信号分子的转导,被称为"生命的隐蔽现象"。落叶果树芽休眠的诱导、维持和解除不是某单一基因作用的结果,参与休眠调控编码光敏色素、水通道蛋白、脱水素、腺苷三磷酸水解酶和抗氧化酶等主要结构基因和细胞周期调控基因已被分离,一个重要的转录因子MADS-box对休眠调控的功能已被初步鉴定。综述了这些休眠相关基因的表达和调控研究进展,以期为果树芽休眠的调控研究提供参考和借鉴。     

Effect of ethylene on breaking dormancy of freesia corms

Ethylene (C₂H₄) applied before chilling stimulated rooting and sprouting, and increased root number and length per corm. Only when corms experienced high temperature for a certain period before or after C₂H₄ treatment was a promotive effect on sprouting observed. When C₂H₄ was applied at the beginning of the high-temperature storage, the effect was greatest and all treated corms sprouted within 2 weeks of planting. Effects of ethephon on sprouting were slight.Shortening the dormant period with C₂H₄ could be useful for practical freesia forcing, since C₂H₄ has no adverse effects on the development of the root and the shoot.     

Carbohydrate changes in kiwifruit buds during the onset and release from dormancy

Carbohydrates were measured in axillary bud meristems from kiwifruit (Actinidia deliciosa (A.Chev.) C.F. Liang et A.R. Ferguson cultivar Hayward) to determine whether concentrations changed during winter dormancy. Buds were collected from kiwifruit vines growing in four sites, which spanned the climatic range that kiwifruit are grown in New Zealand, and from vines where the time of budbreak had been manipulated using hydrogen cyanamide. During winter, sugars comprised 78% of measured carbohydrates in meristems, with sucrose accounting for more than 86% of sugars detected (up to 200 mg g DW⁻¹). Starch concentrations in bud meristems showed little change during winter. Meristem sucrose and hexose concentrations increased rapidly from autumn until mid-winter, and this was correlated with leaf abscission. Sugar accumulation ceased in mid-winter and concentrations remained stable until spring, suggesting that bud meristem activity was low. Four weeks before visible bud movement, a marked decline in sucrose and increase in hexose concentrations, indicated activity in the meristems had increased prior to budbreak. The patterns of seasonal change and peak sucrose concentrations in meristems were similar at all sites. The only difference was in the timing of events, with changes in meristem sugars occurring earliest in vines growing at the coolest site, coinciding with their earlier cessation of and resumption of vine growth. Advancing budbreak, by applying hydrogen cyanamide to vines in late winter, also advanced changes in sugar concentrations within meristems. This work suggests that the concentration of sucrose in kiwifruit bud meristems has utility as an indicator of whether they are being induced into, maintained or released from winter dormancy.     

华光油桃解除休眠过程中几项生理指标的变化

研究了低温累积对华光油桃萌芽的影响以及花芽在自然休眠过程中几项生理指标的变化。结果显示,在低温诱导休眠解除的过程中,花芽内可溶性糖和淀粉含量在12月13日分别上升和下降,可溶性蛋白含量在此时出现谷值,游离脯氨酸含量休眠解除前由下降转为急剧上升,POD和SOD活性在12月13日分别出现高峰和低谷。表明这些参数可能与休眠解除有关。