The Production and Maintenance of Virus-Free Raspberry Plants

Summary

Stubbed rhizomes of Curcuma alismatifolia Gagnep. were kept at room temperature with good ventilation during their dormant period and then were randomly sampled at different stages of dormancy, i.e. stage 1 (beginning of dormancy), stage 2 (middle of dormancy) and stage 3 (late in dormancy with the buds sprouting). Fresh and dry weights, water content, nitrogencontent and starch and total soluble sugar content decreased in the stubbed rhizome and storage roots during dormancy. Therhizome was the principal organ for N storage and the storage roots were the major organ for carbohydrate storage. Argin ne and glutamic acid were the predominant free amino acids in the rhizome and storage roots, respectively. Free abscisic acid in the rhizome increased from stage 1 to 2 and then decreased by stage 3, while the concentration in storage roots decreased continuously until buds sprouted.     

三种姜黄属花卉根茎贮藏对开花的影响

研究了贮藏温度和时间对广西莪术、南岭莪术、所罗门姜黄3种姜黄属根茎水养期间开花率、花枝寿命等指标的影响.结果表明:广西莪术根茎在15℃下贮藏60 d,南岭莪术根茎在15℃下贮藏30 d以上,所罗门姜黄根茎在15℃下贮藏0～60 d,均可提高开花率.3种姜黄属花卉在常温下贮藏均诱导叶芽分化,开花率均较低.     

苹果幼树秋季^14C同化物贮藏及再利用

本试验研究了苹果幼树不同形态~(14)C同化物的贮备特点、季节变化及再利用特性。结果表明,1.苹果碳素同化物贮藏形式有淀粉、糖、氨基酸和有机酸。淀粉秋季先在根中积累,贮备前期(9月)达到高峰,枝干木质部于休眠前(12月)、韧皮部于萌芽前分别达到高峰;糖和有机酸落叶前枝干中较多、休眠期以根系贮藏为主;氨基酸仲秋(9月)开始在根中积累、而不再上运;落叶回流氮化物主要贮藏在枝干中。2.萌芽展叶主要利用枝干贮藏营养,早春新根生长为根系贮藏营养第一个分配中心,枝叶旺盛生长为其第二分配中心。3.根系贮藏碳素营养春季极少以糖形式直接供应地上部,首先在根中转化成氨基酸,经木质部上运并在其中脱氨形成有机酸,大部分用于能量消耗,一部分再生成糖供新器官结构建造。     

The influence of fruiting on the bud sprouting and flower induction responses to chilling in Citrus

Summary

The effect of chilling temperatures on bud sprouting and flower formation was compared on fruiting and non-fruiting ‘Owari’ satsuma mandarin (Citrus unshiu Marc) trees. On non-fruiting trees, bud dormancy was weak, and a significant proportion of buds were able to sprout at high temperatures without being chilled. Separate effects of low temperatures on bud sprouting and flower induction were demonstrated. On fruiting trees these two effects of low temperatures were also demonstrated on summer-flush buds, but not on older (spring-flush) buds. The spring-flush buds from fruiting trees scarcely sprouted without being chilled. These buds required a longer chilling period for dormancy release than for flower induction, and it was not possible to separate the effect of low temperature on flower induction from the effect on dormancy release. The presence of fruit reduced flower formation by reducing bud sprouting. Furthermore, fruit had a direct inhibitive effect on vernalization which resulted in increased formation of vegetative shoots. The effect of fruit and low temperature on flowering was unrelated to carbohydrate accumulation in the leaves or the roots.     

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.     

Interactions between N,P and C mobilisations during spring growth of a semi-evergreen shrub (Ligustrum ovalifolium L.) grown in containers with different fertilisation schedules

Container-grown Ligustrum ovalifolium L. plants were used to determine the influence of nutrient availability on the mobilisation of carbon (C), nitrogen (N) and phosphorus (P) during spring growth. During the spring of the second growing season, plants either received no fertiliser, or were fertilised early (starting 17 days after bud break) or late (starting 3 months after bud break). Nutrient composition of different plant tissues was determined at several times during the second growing season from bud break to the end of elongation. Time of fertilisation did not influence aerial dry weight until flowering was completed. Plants that received no fertiliser or were fertilised late had greater root dry weight than plants that received fertiliser early. Fertilised plants had a second flush of growth after flowering completed. Nitrogen and phosphorus mobilisation occurred from bud break to the end of elongation (3 months). Nutrient mobilisation was effective in each perennial organ: root, trunk, ligneous stems and old leaves. However, the role of old leaves as storage organ was minor compared to evergreen tree leaves. Carbon mobilisation only occurred on the 1st month following bud break, before elongation. C-starch accumulation was observed in unfertilised plants even when the C-starch quantities in early fertilised plants were very low at the end of elongation, mainly in roots. In spite of fertilisation supplies, N and P quantities did not increase after elongation in the early fertilised plants, probably in relation to C insufficiency in roots to sustain N and P absorption and assimilation. By contrast, in late fertilised plants, high C quantities in roots were mobilised for N and P uptake and assimilation, which allowed both second growth flush and storage of N and P in perennial organs. The mobilisation of nutrients before and during elongation revealed the nutritional autonomy of shrubs, which could allow fertiliser use efficiency to be increased and environmental impacts to be minimised by delaying spring fertilisation. Nevertheless, the shrub ability to valorise fertilisation supplies for sustaining growth or nutrient storage restoration required sufficient C-starch quantities in roots. The starch accumulated in roots before late nutrient supply can be used for these objectives.     

Impact of Mononychellus progresivus and Oligonychus gossypii (Acari: Tetranychidae) on cassava growth and yield in Central Africa

Growth of cassava was investigated in Central Africa (Congo) on crops attacked by two phytophagous mites: Mononychellus progresivus and Oligonychus gossypii. Change and distribution of dry matter in leaves, stems and roots were monitored for the 24 month crop cycle on infested and mite-free plants. Leaf dry matter increased during the rainy season and decreased during the dry season. Stems contain the reserves used for initiating plant growth after the dry season. Dry matter increased in the roots which form true storage organs. At the start of the second year of cultivation, one third of the root biomass was used to support the recovery of plant growth and development. Mite densities fewer than 50 mobile forms per leaf (maximum number of mites) were not sufficient to cause significant loss of leaf, stem and root dry matter. Nevertheless the mites diverted part of the biomass allocated to the roots thereby reducing the efficiency of storage root production in the infested plot.     

The effect of gibberellic acid on sprouting and flowering of some tulip cultivars

The effect of gibberellic acid, GA₃, on breaking of dormancy, sprouting and flowering of 9 cultivars of tulips was investigated, using 4 cultivars recommended for forcing and 5 not suitable for forcing. GA₃ was applied to the basal plates of the bulbs in a lanolin paste before planting, or was injected into the bulbs prior to rooting or after 38 or 64 days of cold treatment. The application of GA₃ stimulated sprouting, growth of floral stalks and flowering in all investigated cultivars. Injection of GA₃ was more effective than topical application. The effect of GA₃ on sprouting and flowering of plants was especially effective after 38 or 64 days of cold treatment. The possibility of applying GA₃ in commercial horticulture is considered.     

云南省河口县蕉园香蕉植株中氮、磷营养分布特征

以云南河口县蕉园巴西香蕉为试验材料,分析了不同生长期(营养生长期、花芽分化期、现蕾开花期、果实生长期)不同器官(根、茎、叶)氮、磷含量及其变化规律.结果表明:香蕉植株根、茎、叶在整个生长期氮(N)含量分别在0.496％～0.675％、0.864％～0.923％和1.096％～1.457％之间.磷含量(P2O5)分别在0.088％～0.224％、0.123％～0.394％和0.157％～0.351％之间.从不同器官看,在整个生育期中,含氮量总体表现为叶＞茎＞根.含磷量在花芽分化期与现蕾开花期:叶与茎＞根;营养生长期:茎＞叶＞根;果实生长期:叶＞茎＞根.     

郁金香更新鳞茎发育的碳同化物积累与内源激素变化研究

 应用扫描电镜和¹⁴C同位素标记技术, 并结合内源激素测定, 考察郁金香更新鳞茎膨大发育与碳同化物积累、分配的关系。结果表明: 在鳞片细胞内观察到明显的淀粉颗粒, 并随鳞茎的发育进程充满整个细胞腔。在盛花期前, ¹⁴C同化物主要分配到地上部; 进入叶枯期后¹⁴ C同化物以向地下部运输为主,分配比例达66.01% , 其中更新鳞茎中¹⁴C同化物的分配占60.85% , 这时¹⁴C库活性表现为: 鳞茎>叶片>花茎>根系。在郁金香更新鳞茎发育进程中, 叶片中GA、IAA含量呈下降趋势, ABA含量则不断增高并在盛花期出现峰值, 达65.86 ng·g^{- 1} FM。比较不同生育期的GA₃ /ABA比值, 在发叶期的叶片和盛花期的更新鳞茎中均出现高比值, 表明内源激素的平衡可能是郁金香更新鳞茎发生和发育的调节因子。     

Patterns of 14C-sucrose translocation in egg plant (Solanum melongena L.)

Summary

Patterns of distribution of ¹⁴C-sucrose were determined in egg plant (Solanum melongena L.) cv. Arka Shirish at the vegetative, flowering and fruit development stages. 5 μCi of ¹⁴C-sucrose was fed to the fifth leaf from the top at each growth stage and the plants were harvested, 48 h after feeding or at later stages, and the distribution of ^l4C-sucrose determined. Results indicated bidirectional transport of assimilates to both apical and basal portions of the stem. Within 48 h ¹⁴C moved to all the plant parts; roots, stem and leaves appeared to be strong sinks until the fruit began to develop. In plants fed at the fruit development stage, the fruit below the fed leaf were a major sink, although considerable activity was traced in other plant parts also. Only at later stages of crop growth did the fruit become a strong sink. Even at the fruit development stage, about 5-8% of the activity was still found in the roots and no retranslocation to fruit was observed.     

Acclimatisation to mannitol-induced water deficit in miniature rose (Rosa hybrida) plantlets cultivated in vitro under autotrophic conditions

Summary

Miniature rose plantlets at the flower development stage were grown photo-autotrophically on MS medium and subsequently exposed to water deficits of –0.23, –0.32, –0.40, or –0.67 MPa osmotic potential ( _s) for 14 d. The _s in the culture medium was raised by increasing the concentration of mannitol, which caused abnormal floral development in terms of the flowering percentage and the number of flowers per plantlet, as well as delayed flowering. In vitro flowering and the number of flowers per plantlet declined significantly when miniature rose plantlets were exposed to water deficit stress at –0.40 MPa or –0.67 MPa. Reductions in growth, pigment degradation, chlorophyll a fluorescence, and net photosynthetic rate (Pn) were greatest in plantlets exposed to a water deficit stress of –0.67 MPa. This was particularly evident in the case of Pn, with a decline of 73.7% compared to non-stressed control plantlets. In contrast, proline levels increased in plantlets under water deficit stress, as proline performs a key role as an osmoprotectant under such conditions. The flowering stage in miniature rose plantlets is particularly susceptible to water deficit stress, which suppresses the development of reproductive organs. Knowledge of the responses to water deficit stress at the reproductive stage may be applied to identify effective indices for the selection of genotypes with increased tolerance to water deficit in miniature rose breeding programmes.     

Pre-harvest application of 2, 6-dichloroisonicotinic acid, -aminobutyric acid or benzothiadiazole to control post-harvest storage diseases of melons by inducing systemic acquired resistance (SAR)

Summary

Field-grown rockmelon plants were treated with -aminobutyric acid (BABA), 2,6-dichloroisonicotinic acid (INA), benzothiadiazole (BTH) or water during fruit development and evaluated for increased resistance against plant diseases or post-harvest pathogens. One experiment was conducted at Camden, NSW, Australia (INA, BABA or water). Two experiments were at Griffith, NSW, Australia (INA, BTH or water). Growing plants and harvested fruits were assessed for disease symptoms from natural infections and assayed for the accumulation of chitinase and peroxidase, two major pathogenesis-related (PR) proteins induced as a result of systemic acquired resistance (SAR). Harvested fruit from both BTH- or INA-treated plants showed a significant (P < 0.05) reduction in the severity and incidence of post-harvest storage diseases mainly caused by Fusarium, Alternaria and Rhizopus. However, there were no differences in disease severity and the incidence of rots between using four fortnightly foliar sprays of INA or BTH during flowering and fruit development, or a single spray of BTH, 2 weeks before harvest. Each approach showed an equivalent reduction in storage diseases. Plants treated with BABA showed less resistance against powdery mildew in the field and storage rots from natural inoculum, and lower increases in chitinase and peroxidase activities than those treated with INA. In all trials, an additional post-harvest dip with guazatine [0.05% (w/v)] gave a substantial reduction in melon storage rots. Pre-harvest application of INA or BTH reduced the occurrence of powdery mildew and downy mildew on the leaves. Over the three field-experiments, INA had a small phytotoxic effect causing lesion-like symptoms on leaves and affected plant growth, but not yield, at Camden, when applied during flowering and 2 weeks after flowering. However, INA did not produce any phytotoxic effects in the two experiments at Griffith when applied serially, four times to plants after flowering.     

The effect of various environmental factors on flowering of gladiolus. I. Light intensity

Light intensity is an important factor affecting the flowering of Gladiolus. Insufficient illumination from sprouting to the 4-leaf stage decreased flowering percentage. However, the inflorescences of those plants which did flower under conditions of low light intensity were normal and developed the full number of florets per spike. Plants at the 4–6 leaf stage were most sensitive to prevailing light conditions. Low light intensity during this period decreased both the percentage of flowering and the number of florets per spike. After this stage only the number of florets per spike was affected by insufficient light.     

The Effect of Cold Storage and Treatment with Gibberellic Acid on Flowering and Bulb Yields of Dutch Iris

Iris bulbs of the varieties Wedgewood and Prof. Blaauvv were injected with 50 or 500 μg. gibberellic acid (GA) before or after cold storage (10° C.) of 18 or 35 days. GA injection accelerated flowering by up to 19 days ; it had little or no effect on length of leaves or flower stem. It was most effective when applied at an early stage after flower initiation.

GA injection reduced bulb yield of Wedgiwood plants, and had no effect on, nor increased bulb yield of, Prof. Blaauw plants.

GA spraying (seven times at 10^-2M of GA) accelerated flowering and increased foliage growth in both varieties. It increased flower stem elongation and reduced bulb yield in Wedgfcwood plants.     

Effect of cold and drought stress on blueberry dehydrin accumulation

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.     

Floral induction in tropical fruit trees: Effects of temperature and water supply

Summary

Floral induction in tropical trees generally follows a check in vegetative growth. However, it is not easy to identify the environmental factors involved in flowering, which normally occurs during the dry season when temperatures are also often lower. The separate and combined effects of temperature and water supply on floral induction were investigated in ‘Hass’ avocado (Persea americana), ‘Lisbon’ lemon (Citrus limon). ‘Wai Chee’ litchi (Litchi chinensis) and ‘Sensation’ mango (Mangifera indica). Low temperatures (15°/10°C or 15°/10°C and 20°/15°C compared with 30°/25°C and 25°/20°C) generally decreased vegetative growth and induced flowering in well-watered avocado, litchi and mango. A pre-dawn leaf water potential (ψ_L) of ?1.7 to ?3.5 MPa compared with ?0.4 to ?0.7 MPa in control avocado and litchi, and a pre-dawn relative water content (R.W.C.) of 90-93% compared with 97% or above in control mango plants also reduced or eliminated vegetative growth, but did not induce flowering. Low temperatures (15°/10°C compared with 20°/5°C, 25°/20°C or 30°/25°C) and water stress (pre-dawn ψ_L of ?2.0 to ?3.5 MPa compared with ?0.7 to ?0.8 MPa in controls) reduced or eliminated vegetative growth in lemon. In contrast to the response in avocado, litchi and mango, flowering in lemon was very weak in the absence of water stress at 15°/10°C or outdoors in Brisbane in subtropical Australia (Lat. 28°S), and was greatest after a period of water stress. The number of flowers increased with the severity and duration of water stress (two, four or eight weeks) and was generally greater after constant rather than with cyclic water stress. In lemon and litchi, net photosynthesis declined with increasing water stress reaching zero with a midday ψ_L of ?3.5 to ?4.0 MPa. This decline in carbon assimilation appeared to be almost entirely due to stomatal closure. Despite the reduction in midday CO₂ assimilation, starch concentration increased during water stress, especially in the branches, trunk and roots of lemon. Leaf starch was uniformly low. The number of flowers per tree in lemon was strongly correlated with starch in the branches (r²=77%, P<0.01) and roots (r²=74%, P<0.001). In litchi, starch was lower than in lemon roots and was not related to flowering.

In separate experiments to test the interaction between temperature and water supply, low day/night temperatures (23°/18° and 18°/15°C compared with 29°/25°C) reduced vegetative growth and induced flowering in avocado, litchi and mango. None of these species flowered at 29°/25°C or as a result of water stress (ψ_L of ?1.5 MPa compared with ?0.3 MPa for avocado and ?2.0 MPa compared with ?0.5 MPa for litchi, and R.W.C, of 90-93% compared with 95-96% in mango). In contrast, in lemon, flowering was very weak (<10 flowers per tree) in the absence of water stress (pre-dawn ψ_L of ?2.0 MPa compared with ?0.5 MPa) and was only heavy (>35 flowers per tree) after stressed trees were rewatered. There were slightly more flowers at 18°/15°C than at 23°/18° and 29°/25°C in control plants, but no effect of temperature in stressed plants. Starch concentration in the roots of avocado, lemon, litchi and mango was generally higher at 18°/15°C and 23°/18°C than at 29°/25°C. Water stress increased the starch concentration in the roots of lemon and litchi and decreased it in avocado. There was no effect in mango. There was a weak relation (r²=57%, P<0.05) between the number of flowers per tree in lemon and the concentration of starch in the roots. In contrast, there was no significant relationship between flowering and starch levels under the various temperature and water regimes in the other species. In another experiment, only vegetative growth in litchi and mango occurred at 30°/25°C and only flowering at 15°/10°C. Six weeks of water stress (pre-dawn ψ_L of ?2.5 MPa compared with ?1.0 MPa or higher in litchi, and R.W.C, of 90-93% compared with 95% or higher in mango) in a heated glasshouse (30°C days/20°C night minimum) before these temperature treatments did not induce flowering.

Temperatures below 25°C for avocado and below 20°C for litchi and mango are essential for flowering and cannot be replaced by water stress. The control of flowering in lemon over the range of day temperatures from 18°C to 30°C differed from that of the other species in being mainly determined by water stress. Flowering was generally weak in well-watered plants even with days at 18°C. Starch did not appear to control flowering.     

The effect of ethephon on the growth and development of Liatris spicata

Summary

The first experiment studied the effect of applying ethylene biosynthesis regulating compounds (ethephon 1000 ppm, silver thiosulphate 0.4 mM and cobalt chloride 5 mM) on the growth and development of Liatris spicata cv. Callilepis. The results pointed to the important growth retardant properties of ethephon and the increased number of flowering stems per corm which could be obtained by pre-planting application. A second experiment aimed to optimize ethephon treatment in Liatris by applying the growth retardant in different concentrations (100, 700, 1300, 1900 and 2500 ppm) at three stages of development: stage I (pre-planting), stage II (immediately after the formation of basal leaf rosette) and stage III (when the main shoot began its rapid longitudinal growth). Besides confirming the effects produced by ethephon in the first experiment, the results suggested that the application of high ethephon concentrations (1900 and 2500 ppm) during stage II of growth produced many miniature flowering stems coming from the principal or secondary shoot.     

Postharvest sprouting of onion bulbs grown in different temperature and C02 environments in the UK

Summary

The effects of different mean growing season temperatures and C0₂ concentrations during bulb production on postharvest bulb sprouting in a common storage environment at Reading, UK, was examined in two cultivars of the Rijnsburger type of onion (Allium cepa L.). Crops were grown in the field in temperature gradient tunnels maintained at either 374 or 532 ppm C0₂. At crop maturity, cohorts of bulbs were harvested, transferred to a constant temperature room (at an average of 11.6°C) and the subsequent duration to sprouting recorded. The duration to the onset of sprouting (expressed as days in storage until the first bulb sprouted) was not affected by cultivar, mean growing season temperature or CO₂ concentration, and was 165 d. The subsequent rate of sprouting (expressed as bulbs per day) was a positive linear function of mean growing season temperature, but no effects of CO₂ or cultivar were detected. Mean rate of sprouting increased from an average of 0.036 bulbs per day at 12.3°C to 0.093 bulbs per day at 18.6°C. Rapid sprouting in storage was associated with lower levels of total non-structural carbohydrate in the bulbs at the time of harvest. Thus, postharvest susceptibility of onion bulbs to sprouting in storage is expected to increase in warmer crop production temperatures.     

The influence of apical dominance on the in vitro multiplication of the rhizome of Alstroemeria

The effects of mechanical and chemical methods of removing or reducing apical dominance on the multiplication of Alstroemeria cultivars grown in vitro were assessed. Subculture of rhizome explants without aerial shoot or rhizome apices and of rhizome explants divided into single internodes with or without aerial shoots, significantly enhanced rhizome multiplication. Subculture of rhizome explants with only the aerial shoot or rhizome apices removed produced no significant differences. Addition of the plant growth regulators T1BA, thidiazuron, NAA, GA3 and paclobutrazol to culture media, with or without BAP, did not significantly change the numbers of lateral rhizomes, shoots or roots produced. Paclobutrazol, however, extensively changed explant morphology.