Effect of 2-Chloroethanephosphonic Acid (Ethrel) on Health,Dormancy, and Flower and Corm Yield of Gladioli

2-Chloroethanephosphonic acid (Ethrel), an ethylene releasing compound, was used on gladiolus corms as a 30-minute dip treatment in various concentrations and at various times during storage.

The most important effect of Ethrel was the marked increase in health and survival of treated plants infected with latent Fusarium.

Ethrel at 1000 ppm enhanced sprouting when corms were stored at high temperatures or stored for a short period at 5 °C. Treatment of cold-stored corms at high concentrations delayed sprouting.

Ethrel increased corm splitting, delayed flowering and slightly shortened flower stems. The size of harvested corms was reduced, but the yield of cormels was greatly increased by Ethrel.     

The mode of action of ethephon in increasing health of gladiolus corms

Gladiolus corms and cormels were treated with various combinations of ethephon and the fungicides methylethyl mercury benzoate, benomyl, thiobendazole and methylmercury dicyandiamide either before or after storage at 10 °C and 30 °C for 6 weeks. The treated corms were examined for germination, splitting and rot symptoms caused by Fusarium oxysporum f. sp. gladioli.

Ethephon increased corm splitting in all treatments; it also increased germination in corms stored at 30 °C, and it increased the proportion of corms showing typical Fusarium rot symptoms by stimulating the growth of latent internal Fusarium. The effectiveness of the fungicides tested against F. oxysporum f. sp. gladioli was enhanced by the addition of ethephon. Permeability of corms to methylethyl mercury benzoate was increased by ethephon, and it is concluded that ethephon improves the efficiency of this fungicide, and probably of other fungicides as well, by increasing their penetration into gladiolus corms.     

脂氧合酶对唐菖蒲籽球形成和膨大的影响

为探讨脂氧合酶(LOX-1)对唐菖蒲籽球形成和膨大的影响,以'Rose Supreme'和'Advanced Red'两个品种为试材,研究了籽球的生长发育与LOX-1活性,内源茉梨酸甲酯(MJ)、蔗糖、淀粉和纤维素含量变化之间的关系。结果表明,唐菖蒲叶片中测不到LOX-1活性,匍匐茎中LOX-1活性和内源MJ含量最高,籽球数量较多的品种'Rose Supreme'LOX-1活性和MJ含量显著高于'Advanced Red',说明LOX-1在唐菖蒲籽球形成和膨大过程中起着重要作用,其作用途径可能是通过影响茉莉酸类化合物(JAs)的生物合成对籽球的发生和生长进行调控。在唐菖蒲籽球生长发育过程中,新球和籽球中蔗糖、淀粉和纤维素含量都不同程度升高,并且与LOX-1活性呈正相关,说明蔗糖、淀粉和纤维素对唐菖蒲新球和籽球的形成和膨大起着重要作用。     

Effects of various gaseous compounds and respiratory inhibitors on breaking dormancy of freesia corms

The exposure of freesia corms to an atmosphere containing 1 ml/l C₂H₄ strongly promoted sprouting of the corms when the treatment was applied at a high temperature (28–31°C), but the response was weak at temperatures below 20°C. Repeated treatments with C₂H₄ did not enhance sprouting, i.e. was not more effective than a single treatment. Exposure to an atmosphere containing CO of concentrations over 1 ml/l accelerated sprouting. The maximum effect of CO was obtained with 10 ml/l at 28–31°C.The effect of C₂H₄ combined with CO was similar to that of a single treatment with each separately. Soaking corms in solutions of 10^?1 M potassium cyanide and 30 g/l calcium cyanamide effectively promoted sprouting, but similar treatments with slaked lime and thiourea had no effect.Treatments with C₂H₄, CO, KCN and CaCN₂ did not stimulate C₂H₄-evolution in dormant corms. Respiration of the corms was increased by C₂H₄ and CO, and decreased by KCN and CaCN₂.     

Cytokinins in citrus. I. Fluctuations in the leaves during seasonal and developmental changes

Leaves of Citrus sinensis (L.) Osbeck, cultivar ‘Valencia’, were analysed for cytokinin activity on a seasonal and developmental basis. In spring, high levels of polar and low levels of non-polar cytokinins were detected in the mature leaves. This situation was reversed in early summer, when the polar cytokinins in these leaves became almost undetectable and the non-polar cytokinins, which co-chromatographed with zeatin and ribosylzeatin, increased. This apparent interconversion was followed by a decrease in the overall cytokinin content of the mature leaves, so that low levels were detected from mid-summer until late autumn. In developing leaves, particularly those expanding rapidly, low levels of cytokinin activity that co-chromatographed with zeatin and ribosylzeatin were detected. Once leaves were fully expanded, the activity associated with these cytokinins, as well as the polar derivatives, increased markedly. It is suggested that cytokinins are utilised during periods of active shoot growth, particularly when rapid leaf-expansion is taking place. In this respect, the mature leaves may play an important role in evergreen citrus. Cytokinin remobilisation and utilisation or export to the new shoot may occur from mature leaves following quiescent periods.     

Cytokinins in citrus. II. Fluctuations during growth in juvenile and adult plants

Juvenile and adult plants of ‘Pickstone Valencia’ orange (Citrus sinensis (L.) Osbeck) were compared for differences in shoot and root growth and for endogenous cytokinins in a synchronized growth flush. Dry-mass accumulation in both shoots and roots of juvenile-budded plants was significantly greater than in adult plants. Cytokinins extracted from leaves and roots of plants removed from the dormancy-induction environment, and subsequently during active growth, were mostly of the non-polar type. Buds of juvenile scions appeared to accumulate higher levels of polar cytokinins during dormancy than adult scion buds. In both plant categories, the level of polar cytokinins decreased once growth was stimulated by higher temperatures. However, cytokinin levels in buds were markedly higher than in new shoot, leaf or root material. Polar cytokinins were present in particularly low concentrations in the developing new shoots, and non-polar cytokinins only increased after the extent of shoot enlargement reached a maximum at about 50 days after warm-temperature incubation.The possible involvement of cytokinins in growth differences between adult and juvenile plants seems to be at the stage of bud activation, prior to breaking of dormancy. At this stage, polar cytokinins reached a much higher level of activity in juvenile buds, and this may have resulted in the greater scion growth of juvenile plants.     

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.     

Cloning,characterization and expression analysis of a 9-lipoxygenase gene in Gladiolus hybridus

Plant lipoxygenases (LOXs) is a functionally diverse class of dioxygenases involved in multiple physiological processes such as growth, senescence, and stress-related responses. Previously, based on the analysis of LOX1 activity and corm formation, it was depicted that LOX1 increased jasmonic acid (JA) synthesis and induced enlargement at top of stolon branches, forming cormels in Gladiolus hybridus. Here, LOX gene (GhLOX1) in full length was isolated from developing corms in G. hybridus. Sequence analysis showed that GhLOX1 was a novel LOX1 gene encoding 9-LOX. Transient expression analysis determined GhLOX1 to be a cytoplasm protein. Real time RT-PCR showed that the mRNA level of GhLOX1 gene correlated positively with LOX activity and was highest in cormels. GhLOX1 mRNA level, LOX activity and endogenous methyl jasmonate (MJ) content in corms increased steadily with a MJ gradient from 0.1 mmol/L to 0.5 mmol/L. Conversely, GhLOX1 mRNA level, LOX activity, and endogenous MJ content in corms steadily decreased with the increasing concentration of Salicylhydroxamic acid (SHAM). At the same time, we observed that MJ and SHAM treatments effected both LOX1 mRNA level and LOX activity, leading to promotion and inhibition of corm formation and enlargement, respectively. These data reveal that GhLOX1 is a novel LOX1 gene encoding a cytoplasm 9-LOX protein and its expression would contribute to LOX activity which plays an important role in corm formation and enlargement. In general, GhLOX1 is an ideal candidate for the promotion of corm formation and enlargement by gene manipulation in G. hybridus.     

Effect of pollination on cell division,cell enlargement,and endogenous hormones in fruit development in a gynoecious cucumber

To study the effect of pollination on fruit development in gynoecious and parthenocarpic cucumbers (Cucumis sativus L. cv. NK × AN8), the number of cells, cell size, mitotic index, histone H4 gene expression, and concentrations of endogenous cytokinins and auxin were compared in fruits that had developed from pollinated and non-pollinated flowers. Fresh weight was more in the pollinated group 4–12 days after anthesis (DAA) in both winter and spring, and 2–6 DAA in the summer. In winter, mitotic index increased from anthesis to 2 DAA and then decreased gradually in the pollinated group but immediately after anthesis in the non-pollinated group. Histone H4 gene in the pericarp zone was expressed more strongly during the period from pre-anthesis to 2 DAA in the pollinated group in summer. Concentrations of zeatin, isopentenyladenine, and indole-3-acetic acid (IAA) were higher in the non-pollinated group 2 and 4 DAA and peaked 4 DAA in spring whereas isopentenyladenine and IAA showed no distinct peaks in the pollinated group. These results are incompatible with the idea that pollination activates cell division by stimulating the synthesis of cytokinins and auxin in cucumber fruits.     

Influence of the Cytokinin, 6-Benzylamino-9-(Tetrahydropyran-2-yl)-9H-Purine,on the Growth and Development of Some Ornamental Crops

Foliar sprays of the synthetic cytokin, 6-benzylamino-9-(tetrahydropyran-2-yl)-9H-purine (PBA), increased branching in carnation, chrysanthemum, poinsettia, petunia and fuchsia, which showed varying levels of tolerance. In no instance did PBA reduce plant height. Applications of PBA to carnation and chrysanthemum stimulated branching in both intact and pinched plants. Treatment a few days prior to pinching produced more uniform development of new laterals. Response to the compound was most favourable under optimum growing conditions. Under relatively poor light intensity the laterals exhibited a reluctance for continued elongation and showed marked chlorosis. Application of PBA to flower buds at an early stage of development increased both the diameter and the fresh weight of carnation flowers or chrysanthemum inflorescences when fully open. Response to the compound decreased with age of the bud at the time of treatment. In carnation the effects on size were accompanied by an increase in petal area together with an increase in the number of primary petals produced. Relatively high concentrations also induced the formation of secondary growing centres from which varying numbers of additional petals were produced. Relatively large numbers of these secondary centres within a flower resulted in an increased incidence of calyx splitting. These centres were not observed in chrysanthemum. The formation of secondary growing centres could also be induced by GA₃ and IAA. However, while these growth substances increased the diameter and fresh weight of carnation flowers, unlike cytokinins they had no apparent effect on the number of primary petals formed. Finally PBA was also observed to increase the longevity of cut flowers of carnation. This was particularly apparent at relatively low temperatures.     

Temperature effects on flower formation in saffron (Crocus sativus L.)

The temperature conditions for shoot growth and flower formation were characterised for saffron (Crocus sativus L.). Leaf withering occurred during late winter or spring depending on location, and coincided with a rise in temperature. No growth was detectable in the buds during the first 30 days after leaf withering, neither in underground corms nor in lifted corms incubated in the laboratory under controlled conditions. Flower initiation occurred during the first growth stages of the buds. The optimal temperature for flower formation was in the range from 23 to 27 °C, 23 °C temperature being marginally better. To ensure the formation of a maximum number of flowers, the incubation at these temperatures should exceed 50 days, although incubation longer than 150 days resulted in flower abortion. Flower emergence required the transfer of the corms from the conditions of flower formation to a markedly lower temperature (17 °C). Incubation of the corms after lifting at a higher temperature (30 °C), reduced flower initiation and caused the abortion of some of the initiated flowers. No flowers formed in corms incubated at 9 °C. A variable proportion (20–100%) of the corms forced directly at 17 °C without a previous incubation at 23–27 °C formed a single flower. The wide differences in the timing of the phenological stages in different locations we found in this study seemed related to the ambient temperature. Leaf withering was followed shortly by flower initiation, which occurred during late spring or early summer as the rising temperature reached 20 °C. A long hot summer delayed flower emergence which occurred in late autumn as the temperature fell to the range of 15–17 °C.     

Florogenesis of the Mediterranean geophyte Narcissus tazetta and temperature requirements for flower initiation and differentiation

Plant florogenesis is determined by the interaction between the genetics of the individual plant and environmental factors. Flower initiation and development of many studied plant species require low temperatures. However, some geophytes form flowers within the bulb during the summer quiescence period and do not require low temperatures for florogenesis. Narcissus tazetta was employed to study, in detail, the stages of flower development during the summer period, with special emphasis on the effect of temperature on inflorescence initiation. The sequence of morphological processes occurring during floral initiation and development was observed by SEM. During 3 years, the bulbs were subjected to different storage temperatures during the summer, and records were taken of the percentage of apical meristems that shifted from vegetative to reproductive development. Flowering and inflorescence quality were recorded after planting. It was concluded that, under natural conditions, the temperature increase in June, during the growth of the mother plant, leads to the transition of the apical meristem to the reproductive stage. Floral initiation and reproductive development in N. tazetta is promoted by high temperatures with an optimum of 25 °C. Sub- and supra-optimal temperatures (20 and 30 °C) delayed differentiation, while lower temperatures (12 °C) inhibited florogenesis completely.     

Chemical composition of nine edible aroid cultivars of Bangladesh

Leaf blades, petioles, corms and cormels of 9 cultivars of edible aroids were analyzed to determine the content of protein, carbohydrate, crude fibre, ether extract, ash, carotene, thiamine, riboflavin, ascorbic acid, iron, calcium and phosphorus. The cultivars represent the genera Colocasia, Xanthosoma, Alocasia and Amorphophallus. Wide differences among the cultivars in respect of almost all of the components of analysis were observed.     

Response of gladiolus (Gladiolus spp) plants after exposure corms to chitosan and hot water treatments

The state of Morelos, Mexico has gradually become an important producer of gladiolus. Some preconditioning treatments of corms are empirically done causing uneven emergence and low quality of flowers. In this investigation, before planting, gladiolus corms var. ‘Blanca Borrego’ were dipped in chitosan (chitosan reagent and commercial chitosan Biorend^®), in hot water at various temperatures and in treatments combined with Biorend^® at 1.5% and hot water. Results indicated that the most influenced variables were corm germination, number of flowers per spike, number of cormlets and vase life. Overall, the commercial product Biorend^® at 1.5% accelerated corm emergence in approximately 4 days, the number of flowers increased by 2–7 and the vase life extended for 3 days. The number of cormlets was also duplicated. Corms dipped in the commercial chitosan Biorend^® at 1.5% at different intervals of time were not greatly affected except for the emergence and number of cormlets. However, for this experiment there were significant effects on the number of leaves and flowers because of the interactions between chitosan and the immersion time. The temperature of 55 °C affected plant development because emergence was delayed by 6 days; and there were less number of leaves, flowers and cormlets. On the other hand, the incidence of Fusarium oxysporum in naturally infected corms was 0% at temperatures of 55 °C and 50 °C. Immersion times (0, 10, 15 and 20 min) in hot water at 50 °C did not show significant effects on plant development and vase life. Corms dipped in Biorend^® at 1.5% and hot water at 50 °C accelerated their emergence for about 1–7 days, the number of flowers increased by two, extended the storage life for 1–3 days and increased the number of cormlets. The integration of these two treatments -Biorend^® and hot water- might be a good option for increasing the gladiolus plant quality and vase life.     

Effect of low temperature on breaking dormancy and flowering of Arisaema sikokianum (Araceae)

Arisaema sikokianum (Araceae) native to Japan is classified as a vulnerable species in the Red Data Book of Japan. Control of dormancy is essential for efficient corm production and forcing culture. Sprouting of both vegetative and reproductive corms was enhanced by exposure to low temperature. Vegetative corms exposed to low temperatures at 5 °C longer sprouted faster when grown at 20 °C. Effective temperatures for breaking dormancy was 5 °C. Reproductive corms treated at 5 °C longer showed shorter days to flower. Successful forcing culture was achieved; corms treated at 5 °C from November for 30 days flowered on 5th February.     

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.     

Storage conditions and ripening of the custard apple Annona squamosa L.

Annona squamosa is a climateric fruit in which maximal carbon dioxide production preceeds that of ethylene during post-harvest storage. Normal ripening occurred at temperatures between 15 and 30° C, although the fruits were susceptible to fungal attack at temperatures above 25° C. Storage temperatures below 15° C caused chilling-injuries. Ripening was enhanced by removal of carbon dioxide and by addition of oxygen to the storage atmosphere, and delayed by the addition of carbon dioxide or removal of oxygen. Ethylene had no apparent effect on ripening. Fruits maintained under low relative humidities ripened faster than those stored under high-humidity conditions. Dipping the fruits in a solution of indole acetic acid at concentrations between 10^?4 and 10^?2 M accelerated ripening. Levels of both ascorbic acid and glucose increased to a maximum at the climacteric, but decreased as the fruits became over ripe. The stage of “eating” ripeness occurred at the climacteric. Recommended conditions for storing custard apple are: temperatures between 15 and 20° C, low oxygen and ethylene tensions coupled with 10% carbon dioxide and a relative humidity of 85%–90% in the storage atmosphere.     

Temperature effects on corm dormancy and growth of Zephyra elegans D.Don

Experiments were performed with the Chilean geophyte Zephyra elegans, a potential cut flower, to evaluate the effect of corm weight and storage temperature on corm dormancy, and to determine the effect of day and night growing temperatures on its growth and flowering. Z. elegans has a deciduous and synanthous growth habit and the corm is replaced annually. Dormant corms were stored at different constant temperatures or temperature combinations from 20 to 40 °C. Corms released from their dormancy were grown at 15/10, 20/15, or 25/20 °C day/night temperatures. Corms of various weights were planted at the same date after being stored dry at 25 °C for 22 weeks. They all emerged 19–38 days after planting, showing that dormancy release was not affected by corm weight. A 20-week corm storage treatment at a constant 25 °C resulted in the most rapid corm sprouting. Sprouting percentage was reduced at higher or lower storage temperatures. Temperature also affected plant growth. When plants were grown at 15/10 or 20/15 °C they emerged and flowered more rapidly than when they were grown at 25/20 °C. The latter growing temperature also resulted in poor flower quality.     

The Development of Adventitious Roots on Hardwood Cuttings of Gooseberries

Changes in percentage dry weight and in carbohydrate levels and distribution were followed in Golden Brown Lockyer onion bulbs for three months at storage temperatures of 4°, 15°, 25° and 37°C. The percentage dry weight within the bulbs increased from the outer to the inner leaf bases. Storage temperature and length of storage did not influence water loss. Sucrose concentrations increased from the outer leaf bases to become highest in the inner leaf bases, and in all leaf bases were higher at higher temperatures. Glucose and fructose levels also tended to increase from outer to inner leaf bases. After eight weeks fructose levels increased rapidly at the lower storage temperatures and this is attributed to low-temperature hydrolysis of fructans. The only fructan detected was the trisaccharide fraction, which was barely detectable in outer leaf bases and maximal in the inner ones. Trisaccharide levels were generally lower at the lower temperatures, thus supporting the suggestion of low-temperature hydrolysis of fructans. No information was obtained regarding storage temperature effects on fructans having a higher degree of polymerization than the trisaccharide. The results are discussed relative to temperature and time and the development of storage rots.