Cyanamide Research Articles

DORMANCY RELEASE OF 'GALA' MUTATIONS APPLE TREES WITH GARLIC EXTRACT AND MINERAL OIL

This study aimed to examine the effects of garlic extract and mineral oil on the budbreak of 'Gala' mutations apple trees. In the first trial, 'Mondial Gala' apple trees were sprayed to drip point at dormant bud stage using an air blast, with the following treatments: 1) control (untreated); 2) H 2 CN 2 0.25% + 4% MO (mineral oil); 3) 0.5% GE (garlic extract) + 3% MO; 4) 1.0% GE + 3% MO; 5) 1.5% GE + 3% MO. In the second trial in a 'Royal Gala' commercial orchard, the following treatments were sprayed, using a hand driven sprayer: 1) control (untreated); 2) 3% MO (mineral oil); 3) 0.5% GE (garlic extract) + 3% MO; 4) 1.0% GE + 3% MO; 5) 1.5% GE + 3% MO. The same experiment was carried out using natural extract garlic obtained from cold-pressing of garlic cloves and filtering. The use of garlic extract 0.5% and mineral oil 3% was effective in bud dormancy release of 'Mondial Gala' and it was analogous to the standard treatment with hydrogen cyanamide. In 'Royal Gala' apple trees all treatments showed a very poor sprouting, basically due to an atypical warm winter in this region. But, any way, the treatment 0.5% GE + 3% MO advanced bud sprouting when using the commercial product Bioalho ® , although no differences were verified at 56 DAT. When natural garlic extract was used, no differences were observed between treatments.

MODELS FOR QUANTIFYING EFFECTIVE WINTER CHILL ON APPLE ENDODORMANCY

Under southern Uruguayan conditions (34°37'SL;56°11'O, 40 m) winter chilling requirements are not always satisfied for the main commercial apple (Malus domestica Borkh) cultivars. The use of chemical rest breaking agents (mineral oils and hydrogen Cyanamid) to compensate these requirements is widely used. Therefore winter chill quantification should be a relevant issue to adjust this technique. To do so, adequate models to represent the advances in the endodormancy process as a function of climatic conditions are necessary. The UTAH and CH models are usually applied, regardless of which species or cultivar is considered. Although these models have the advantage to be widely spread and incorporated to commercial production, there are evidences of the lack of adjustment to the phenologyc behaviour of the main cultivars. This work's goal was to quantify the occurrence of winter chill during the endodormancy period with six models, in four apple cultivars ('Red Chief', 'Granny Smith', 'Royal Gala' and 'Fuji') during 2005 and 2006. The models used were CH, UTAH, UTAH+, Dynamic Model, North Carolina Model and Model for Subtropical Conditions. The beginning of endodormancy release was determined when 50% of leaf fall was reached and the process finished when 50% of one-year-old shoot buds sprouted in a forcing chamber. All model quantifications were based on hourly temperature data, obtained from sensors located in the tree and at the nearest weather station. The greatest temperature amplitude registered at field conditions, compared to weather station conditions, modified up to 2.5 times, the quantifications performed by the same model, being the UTAH model, the most affected by this phenomenon. These results show differences among models and years, consequently, in order to determine the viability of them in southern Uruguayan conditions, a longer evaluating period is needed.

TIME OF ERGER APPLICATION FOR BUDBREAK INDUCTION IN APPLE TREES

More than 50% of the Southern Brazilian apple production is located in areas where chilling varies from 800 to 1.200 cold units by the North Carolina model, or from 400 to 600 hours of temperature below 7.2°C. This low chilling results in budbreak and blooming delay, which requires artificial budbreak induction. Erger, an inorganic nitrogen compound, combined with calcium nitrate, has a similar effect to that of hydrogen cyanamid, with the advantage of being less dangerous to the environment. Budbreaking products are influenced by environmental factors, but mainly by the temperature at the time of application or during the following days, which should be at least 20°C. The aim of this experiment was to evaluate the effects of time of Erger 5% + Calcium Nitrate 5% application on budbreak induction of 'Imperial Gala' and 'Suprema' apple trees. The experiment was carried out in Cacador, Brazil (lat. 26°46'31), in an RCB design with five treatments and six single tree replications. The treatments were a check and four fortnightly Erger applications. Phenology, axillary and terminal budbreak, fruit set, fruits per cluster and mean fruit weight were evaluated. In comparison with the check treatment, Erger 5% + calcium nitrate 5% anticipated up to 28 days the full bloom of 'Imperial Gala' when applied on August 15, but only up to 13 days if applied on September 15. The effect on 'Suprema' was at a lesser extent than on 'Imperial Gala'. The axillary's budburst of 'Imperial Gala' significantly increased when the plants were treated on August 1, differing from the check up to 60 days after application. The axillary's budbreak on 'Suprema' was greater than on the check trees except for the application on August 15 because of the low temperature that persisted also during the following days. The low temperature affected the response in both cultivars. Fruit set of 'Imperial Gala' was not affected by the time of treatment application, but it was reduced in 'Suprema' when applied on August 1. There was a tendency of mean fruit weight increase on treated plants, probably related to a longer bloom-ripening period.

HYDROGEN CYANAMIDE ON BUDBREAK AND YIELD OF 'O'NEAL' HIGHBUSH BLUEBERRY IN SOUTH URUGUAY

Southern Highbush Blueberry cultivars are becoming a high value crop in Uruguay since 2002. A rapid increase in surface area is due to the good prices of blueberries at the beginning of the off-season fresh market. The application of Hydrogen Cyanamide (Dormex, H 2 CN 2 ,) in our mild and variable winter is one of the cultural practices that may improve yields and advance harvest. This study was conducted in two commercial blueberry orchards in the south of Uruguay (34°44' south latitude). 'O'Neal' (V. corymbosum L. hybrid) plants were sprayed with 0, 1, 1.5 or 2% of Dormex (v/v) at two moments in (May and June). The experiments had a randomized complete block design with 6 plants per treatment with 3 replications in 2005 and 6 replications in 2006. Variables measured were: total length plant, nodes number per plant, reproductive and vegetative budbreak, fruit number and total fruit weight (picked up twice per week in harvest). June applications of H 2 CN 2 accelerated vegetative and reproductive budbreak in both evaluated years, advancing fruit ripening. Dormex, the H 2 CN 2 applied at 1%, increased by 13,2% and 8% the total kg/plant harvested in the first 10 days in 2005 and 2006 respectively. However, Dormex at the 2% H 2 CN 2 sprayed in June injured apical flower buds mainly at stages 2 and 3. This removal of the apical dominance stimulated growth of lateral vegetative buds one month earlier than the control. Even though the final number of vegetative budbreak was higher, the fruit weight was improved only on the first harvest date. The effect on fruit number and total harvest weight were influenced by Dormex treatment depending on the doses and chill hours accumulated at each date of application moment.

Brotação de gemas em macieiras 'Imperial Gala' e 'Fuji Suprema' pelo uso de Erger® e nitrato de cálcio

Apesar da alta eficiência de algumas substâncias químicas na indução da brotação de frutíferas de clima temperado, a elevada toxicidade apresentada por esses compostos é um dos principais problemas relacionados ao seu uso. Resultados preliminares indicam que Erger®, composto à base de nitrogênio, combinado com nitrato de cálcio, tem efeito similar à cianamida hidrogenada, com a vantagem de ser menos agressivo ao ambiente. Assim, o presente trabalho teve por objetivo avaliar a eficiência da combinação de Erger® e nitrato de cálcio como indutor de brotação em macieira. O experimento foi conduzido em Caçador-SC, no ano de 2007, sendo efetuada a aplicação de diferentes indutores de brotação em macieiras das cultivares 'Imperial Gala' e 'Fuji Suprema'. Os indutores de brotação testados foram Erger® a 3% + nitrato de cálcio a 3%, Erger® a 5% + nitrato de cálcio a 5%, Erger® a 7% + nitrato de cálcio a 7%, óleo mineral 3,2% + cianamida hidrogenada 0,34% e a testemunha (sem aplicação). Foram avaliadas as datas de ocorrência das fases de início, plena e fim de floração, brotação de gemas axilares e terminais, uniformidade da brotação de gemas axilares e frutificação efetiva. Os indutores de brotação aumentaram significativamente a brotação de gemas axilares e terminais, assim como aumentaram a uniformidade da brotação e a coincidência de florescimento das cultivares Imperial Gala e Fuji Suprema. As combinações de Erger® e nitrato de cálcio apresentaram desempenho similar à cianamida hidrogenada e ao óleo mineral na brotação de gemas e na uniformização da brotação, mostrando ser uma eficiente alternativa para a indução da brotação em macieira. Em função do efeito negativo sobre a frutificação efetiva em macieiras 'Imperial Gala', indica-se a utilização de Erger® e nitrato de cálcio em concentrações inferiores a 7%.

Similarities between natural and chemically induced bud-endodormancy release in grapevine Vitis vinifera L.

Bud-break in grapevines ( Vitis vinifera L) can be poor and uneven in locations that have warm winters with insufficient chilling. Growers in these regions use hydrogen cyanamide (HC), a dormancy-breaking compound, to increase and synchronise bud-break. Previous studies demonstrated that HC upregulates the expression of select genes encoding enzymes belonging to the ascorbate glutathione cycle (AGC) (glutathione reductase, VvGR) to the oxidative pentose phosphate pathway (oPPP) (glucose-6-phosphate dehydrogenase, VvG6PD) and a key enzyme for dormancy release (1,3-β-glucanase, VvβGLU). Here, the expression of these genes was studied in grapevine buds throughout the natural progression of endodormancy (ED) and under the effects of the dormancy-breaking compounds, HC and sodium azide. Although gene expression increased with the progression of ED until mid-May, in early-June they turned off transiently and reappeared in mid-July before bud-break. The upregulation of these genes under both natural and artificial conditions suggests that dormancy-breaking compounds activate the same metabolic pathways that are naturally activated during the bud-ED release process. However, in contrast with the effects of dormancy-breaking compounds, artificial chilling did not upregulate the above genes.

Hot Water Treatment Released Endodormancy but Reduced Number of Flowers in Potted Red Raspberry Plants

Partially released dormancy causes poor and uneven bud break in temperate plant species like red raspberry (Rubus idaeus L.). Insufficient chilling may be a problem when raspberries are grown at southern latitudes and in year-round production. Dormancy may be released by sublethal stress in many species. We studied the effect of sublethal stress on endodormancy in red raspberry ‘Glen Ample’ and ‘Ottawa’. Canes growing in pots were treated with either hot water (45 °C, 1 h) or the dormancy-breaking chemical, hydrogen cyanamide (1.04%), after accumulation of 0, 240, 480, 720, 960, or 1200 h of chilling at 1 °C. Bud break, vegetative growth, and number of flowers were recorded during 12 weeks of greenhouse forcing after the treatments. Chilling increased bud break, growth, and dry weight of lateral shoots and number of flowers in both cultivars. During deepest endodormancy (0 and 240 h of chilling), treatment with either hot water or hydrogen cyanamide enhanced bud break and lateral shoot growth but could not completely replace chilling. In ‘Ottawa’, hydrogen cyanamide was more effective than hot water during deepest endodormancy, but hot water treatment broke dormancy effectively when 720 h of chilling had accumulated. For ‘Glen Ample’, hot water was as effective as hydrogen cyanamide in breaking endodormancy. Hot water treatment reduced the number of flowers in ‘Glen Ample’ during late endodormancy (720, 960, and 1200 h of chilling). The chilling requirement for ‘Ottawa’ was fulfilled between 720 and 960 h of chilling. However, in ‘Glen Ample’, 1200 h of chilling was not enough to fully release bud dormancy; bud break remained low and it was increased by dormancy-breaking treatments. Hot water treatment can be used to release endodormancy in raspberries, but treatment conditions need to be optimized to preserve crop potential. Chemical name used: hydrogen cyanamide (Dormex, Hi-Cane, Morgrapes).

CALCIUM AND PH AS PARTS OF A COHERENT CONTROL STRATEGY FOR CLUBROOT DISEASE (PLASMODIOPHORA BRASSICAE)

Commercially sustainable and environmentally acceptable control of clubroot disease caused by Plasmodiophora brassicae can be achieved by integrating land management, crop husbandry, crop nutrition and where available pathogen resistant cultivars and agrochemicals when accepted by the regulatory authorities. Manipulation of supplies of calcium, boron, nitrogen and soil pH values is associated with advantageous changes to soil microbial populations and diminution of the efficiency of stages in the pathogen life cycle. These effects allow the host - pathogen relationship to be rebalanced in favour of the crop plant. Fertilisers of especial value in achieving rebalancing are calcium cyanamide and calcium nitrate. Examples of their effects are given.

EFFECTS OF HYDROGEN CYANAMID ON BUD BREAKING OF THE GRAPEVINE 'ITALIA' IN THE SÃO FRANCISCO RIVER VALLEY

Under tropical climate conditions, as in the Sao Francisco River Valley, Northeast Brazil, grapevine presents bud dormancy and high apical dominance. The present work aimed at evaluating the effects of hydrogen cyanamid, spreader-sticker and torsion of the canes on grapevine bud break, yield and fruit quality of the ‘Italia’ table grape cultivar, in the Sao Francisco River Valley. The experiment was carried out at Petrolina-PE, in the semi-arid region of Northeast Brazil, during two harvest seasons (2001–2002). The treatments were as follows: T1: control; T2: H2CN2 2.45%; T3: H2CN2 2.94%; T4: H2CN2 3.43%; T5: H2CN2 2.94% + BreakThru ® 0.03% and T6: H2CN2 2.45% + torsion of the canes, in a randomized complete block design with four repetitions. The results showed that hydrogen cyanamid, independent of the concentration, increased bud burst and bud fruitfulness, with increments of 68% and 84% in the yield per plant, respectively in the 1 st and 2 nd d harvest seasons. There was no significant effect on berry size, sugar and acidity content of the fruits and harvest anticipation. There was no answer to spreader-sticker. On the other hand, the practice of cane torsion presented a tendency to increase the effects of the hydrogen cyanamid.

Identification and sequence characterisation of molecular markers polymorphic between male kiwifruit (Actinidia chinensis var. deliciosa (A. Chev.) A. Chev.) accessions exhibiting different flowering time

Fruit set in kiwifruit is strongly dependent on pollination, which is limited by the lack of efficient male pollen donors, among other factors. We searched for molecular markers that could be polymorphic in relation to flowering time in order to classify male kiwifruit plants to discard those that are not likely to perform as efficient pollen donors. Random amplified polymorphic DNA (RAPD) and modified amplified fragment length polymorphism (AFLP) markers were generated using 41 male kiwifruit plants in two flowering groups, early- and late-flowering males (with respect to the female cultivar ‘Hayward’). One RAPD and nine modified-AFLP markers polymorphic between male plants exhibiting different flowering time were identified, sequenced and analysed in databases. Unweighted pair group method with arithmetic average (UPGMA) clustering and multidimensional scaling showed that these markers could be used to classify the male plants into flowering groups. Analysis of molecular variance (AMOVA) agreed with this classification, showing that most of the genetic variation is found between flowering groups. Sequence analysis based on a database search revealed that the polymorphism PolM contains a 7-nucleotide long element involved in the repression of the phytochrome A gene, that Pol4 is a partial sequence of a phytochrome B gene, and that sequences Pol3, Pol5, Pol7, and Pol9 show high identity with ESTs from kiwifruit buds treated with hydrogen cyanamide. Clustering analysis supported the previous classification of males into flowering groups, making it feasible to predict male plants’ flowering times with respect to the cultivar ‘Hayward’ based upon these molecular markers.

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

Abstract 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.

An FTIR study of the induction and release of kiwifruit buds from dormancy

Many deciduous, perennial fruit crops require winter chilling for adequate budbreak and flowering. Recent research has shown that changes in sugar and amino acid profiles are associated with the release of buds from dormancy. This paper uses FTIR spectrometry to provide an alternative mechanism for tracking metabolic changes in the meristems of kiwifruit buds during winter dormancy. The results suggest that the application of multivariate analysis to FTIR spectra has the potential to be a reliable and fast method for detecting structural and compositional changes in fruit crops. Ten wave numbers of the FTIR spectra are used to calculate a bud development function. This function has been validated using data from two seasons and four orchards, and by monitoring the effects of hydrogen cyanamide application, sugar concentrations and soil temperatures on this function. These wave numbers appear to be associated with carbohydrate, pectin and cellulose levels in the meristems. It is expected that this FTIR signature can be used to advance our understanding of the influence of the various environmental and physiological factors on the breaking of bud dormancy and shoot outgrowth, including the optimum timing and concentrations of applications of budbreak regulators, such as hydrogen cyanamide.

Organic Alternative for Breaking Dormancy in Table Grapes Grown in Hot Regions

Problem statement: In warm-winter regions, the need for intervention of chemical means to break bud rest becomes a dominant factor for maintaining economic production of table grapes. However, the problem is more acute when farmers want to grow organic table grapes in the absence of environmentally-friendly budbreak promoters. Approach: This study aimed to evaluate the effect of a mix of naturally occurring Garlic Compounds (GC) in comparison to the conventional use of hydrogen cyanamide to promote budbreak and its effects on cluster quality in four table grape cultivars field-grown in hot region (Sonora Desert). Results: Four cultivars responded to GC, the vines bursting bud about 3 weeks after application. Quality of fruit from 4 cultivars treated with GC was excellent. Clusters weigh and berry sizes were larger than other treatments. Conclusion: Ability of GC to break dormancy in table grape grown in Sonora Desert has significant implications for organic table grape production in hot regions.

Microbial properties of rhizosphere soils as affected by rotation, grafting, and soil sterilization in intensive vegetable production systems

The increased use of rotation, grafting, and soil sterilization has been documented to increase crop yield in intensive vegetable production systems in China. It is believed that these practices can promote changes in the rhizosphere that enhance early growth of plants. A 2-year greenhouse experiment on tomato double-cropping systems was conducted to investigate the effects of different agricultural treatments on microbial properties of rhizosphere soils and tomato fruit yield. The treatments included planting of welsh onion as a cover crop in the summer fallow (SF) period (CW), rotating vegetable chrysanthemum and tomato (CT), planting graft-tomato instead of auto-root tomato (GT), sterilizing soil with calcium cyanamide in the SF period (TC), and fallowing in the SF period (Control). Microbial population was analyzed by dilution plating. In general, microbial populations were higher in CT, GT and TC than in control. Fungal population was higher in TC whereas a high number of bacteria were found in CT. Soil microbial biomass C and N, total microbial population, organic C and total N showed significant positive correlations ( P ≤ 0.01) with each others, and tomato yield showed significant positive correlations ( P ≤ 0.05) with organic C, total N and total microbial population. In most treatments, CW, GT and TC significantly ( P ≤ 0.05) increased tomato yield by 8%, 21% and 19% in four growing seasons, respectively. CT significantly ( P ≤ 0.05) increased tomato yield by 26% in the spring season of 2007. These results suggested that rotation, grafting and soil sterilization could lead to changes in the microbial properties of plant rhizosphere and consequently increase plant yield. Additionally, the responses of plant yield were complex dependent on rhizosphere soil microbes in rotation-, grafting-, and soil sterilization-induced systems.

GROWING APPLE (MALUS DOMESTICA) UNDER TROPICAL MOUNTAIN CLIMATE CONDITIONS IN NORTHERN ETHIOPIA

SUMMARYLack of effective chilling during the dormant season is one of the major problems when apples are growing under a tropical climate. We evaluated the response of different apple cultivars (Golden Delicious, Gala, Fuji, Granny Smith and Jonagold) grown on M9 rootstock with different dormancy-management practices. The trials were carried out between 2004 and 2006 in a tropical mountain area (Tigray, Ethiopia), where chilling conditions are poor with the aim of improving and synchronizing the bud break and the blossoming period of these apple cultivars. Two-year-old well-feathered trees were planted in two experimental trial sites in a randomized complete block design. Trees were subjected to the following treatments in two sets of experiments: one defoliation per year only; two defoliations per year, one defoliation followed by 1% hydrogen cyanamide (Dormex) treatment; one defoliation followed by 2% Dormex treatment; one defoliation followed by 4% winter oil; one defoliation followed by 0.5% Dormex and 2% winter oil; and a control with no defoliation or dormancy breaking treatments. The results show positive effects of the dormancy breaking agents on the productivity of the trees after defoliation, with comparable results for the effectiveness of both Dormex and winter oil. There were no statistically significant differences between the Dormex doses. The defoliation treatment alone was not sufficient to break dormancy for the cultivars Golden Delicious, Granny Smith or Gala but showed promising results with dormancy breaking on Jonagold. Yields increased as a result of better flowering time synchronization within a tree but even with the dormancy treatments the length of the flowering period was still spread over five weeks, where under a more temperate climate it lasted two to three weeks. The average fruit weight of Jonagold and Granny Smith can be considered as a good fruit quality while the fruit of other diploid cultivars like Golden, Gala and Fuji were rather small, which indicates that fruit thinning by hand will be a necessity for these cultivars. Red colouration of the apples on the cultivars Gala and Jonagold was excellent and meets the standards necessary for commercialization of these fruits. The sugar concentration of the fruits and the fruit firmness at harvest was high. The results of these first trials indicate that it is possible to develop new apple production in the mountain region of Tigray, Ethiopia.

Época e princípios ativos para a quebra de dormência de caquizeiro cv. Fuyu

Este trabalho foi realizado com o objetivo de aumentar o período de oferta do caqui 'Fuyu' e buscar alternativas à falta de opções para estimular a brotação, avaliando-se épocas e diferentes princípios ativos na quebra de dormência dos frutos. Os tratamentos testados foram: óleo mineral (OM), cianamida hidrogenada (CH) e a mistura de macro e micronutrientes, em três épocas de aplicação, constituindo-se esquema fatorial com 5 tratamentos e 3 épocas de aplicação. Os tratamentos testados foram: T1-testemunha; T2- 0,5 % OM; T3-: 2 % CH + 0,5 % OM; T4- 1 % micronutrientes + 0,2 % macronutrientes + 0,5 % OM; T5- 2 % micronutrientes + 0,2 % macronutrientes + 0,5 % OM. Avaliaram-se o número de brotos por ramo, a porcentagem de gemas brotadas e o número de ramos com broto, o número e a produção de frutos por planta. A antecipação da época de quebra de dormência provocou a diminuição do número de frutos produzidos na região centro-sul do Paraná. A produção de frutos foi diretamente proporcional à porcentagem de gemas brotadas no primeiro surto de brotação. A aplicação de cianamida hidrogenada promoveu antecipação da brotação e aumento na produção de frutos de caquizeiro; no entanto, a mistura de micronutrientes e óleo mineral não influenciou na brotação e produção de frutos de caquizeiro.

Gene-expression profiling of grape bud response to two alternative dormancy-release stimuli expose possible links between impaired mitochondrial activity, hypoxia, ethylene-ABA interplay and cell enlargement

A grape-bud-oriented genomic platform was produced for a large-scale comparative analysis of bud responses to two stimuli of grape-bud dormancy release, hydrogen cyanamide (HC) and heat shock (HS). The results suggested considerable similarity in bud response to the stimuli, both in the repertoire of responding genes and in the temporary nature of the transcriptome reprogramming. Nevertheless, the bud response to HC was delayed, more condensed and stronger, as reflected by a higher number of regulated genes and a higher intensity of regulation compared to the response to HS. Integrating the changes occurring in response to both stimuli suggested perturbation of mitochondrial activity, development of oxidative stress and establishment of a situation that resembles hypoxia, which coincides with induction of glycolysis and fermentation, as well as changes in the interplay between ABA and ethylene metabolism. The latter is known to induce various growth responses in submerged plants and the possibility of a similar mechanism operating in the bud meristem during dormancy release is raised. The new link suggested between sub lethal stress, mitochondrial activity, hypoxic conditions, ethylene metabolism and cell enlargement during bud dormancy release may be instrumental in understanding the dormancy-release mechanism. Temporary increase of acetaldehyde, ethanol and ethylene in response to dormancy release stimuli demonstrated the predictive power of the working model, and its relevance to dormancy release was demonstrated by enhancement of bud break by exogenous ethylene and its inhibition by an ethylene signal inhibitor.

A rapid transcriptional activation is induced by the dormancy-breaking chemical hydrogen cyanamide in kiwifruit (Actinidia deliciosa) buds

Budbreak in kiwifruit (Actinidia deliciosa) can be poor in locations that have warm winters with insufficient winter chilling. Kiwifruit vines are often treated with the dormancy-breaking chemical hydrogen cyanamide (HC) to increase and synchronize budbreak. This treatment also offers a tool to understand the processes involved in budbreak. A genomics approach is presented here to increase our understanding of budbreak in kiwifruit. Most genes identified following HC application appear to be associated with responses to stress, but a number of genes appear to be associated with the reactivation of growth. Three patterns of gene expression were identified: Profile 1, an HC-induced transient activation; Profile 2, an HC-induced transient activation followed by a growth-related activation; and Profile 3, HC- and growth-repressed. One group of genes that was rapidly up-regulated in response to HC was the glutathione S-transferase (GST) class of genes, which have been associated with stress and signalling. Previous budbreak studies, in three other species, also report up-regulated GST expression. Phylogenetic analysis of these GSTs showed that they clustered into two sub-clades, suggesting a strong correlation between their expression and budbreak across species.

CHEMICAL ALTERNATIVES TO METHYL BROMIDE FOR STRAWBERRY IN THE AREA OF HUELVA (SPAIN): 2002-2007 RESULTS

The Spanish Methyl Bromide (MB) Alternatives Project (INIA) has carried out experiments over ten-years in Huelva for strawberry production. More than 20 soil fumigant treatments have been evaluated on cv. 'Camarosa'. The last series has been carried out in two locations of Eastern coastal Huelva (Moguer and Palos de la Fra.) from 2002-2003 until now. Treatments: MB + chloropicrin, 1,3-dichloropropene + chloropicrin (1,3D:CP), chloropicrin (CP) alone, metam sodium (MS), dimethyl disulphide (DMDS), ethanedinitrile (EDN), propylene oxide (PO), sodium tetrathiocarbamate (ENZ), methyl iodide + chloropicrin (MI), essential oils (EO), were shank-applied, or drip-irrigated such as sodium azide (SEP), furfural (FUR) under mulched (VIF film) pre-formed beds, or incorporated into the soil: dazomet (DAZ) and calcium cyanamide (CC). Treatments were applied in September and cultivation cycle was between October and the end of May every year. Black root rot complex and nematodes Meloidogyne hapla and Pratylenchus penetrans appear as the main phytosanitary problems related to soil. Our results supported feasible alternatives to MB with 1,3D:CP, CP alone or DMDS plus CP (DMDS:CP). In coastal Huelva, significant amounts of alternative fumigants have been applied to the strawberry crop since 2005, mainly 1,3D:CP, CP alone, DAZ:1,3D and MS. This activity has allowed 100% MB replacement rates in 2007. However some concerns remain due to the implementing of the Directive 91/414/EEC.

EXTRATO DE ALHO NA SUPERAÇÃO DA DORMÊNCIA DE PEREIRA ‘HOUSUI’

Com o objetivo de avaliar o efeito do extrato de alho na superação da dormência da pereira em condição de baixo acúmulo de frio foi instalado um experimento em um pomar comercial da cultivar Housui, em espaçamento 1,5 m x 4,0 m, com 7 anos de idade, no município de Campo Largo, PR. Os tratamentos foram aplicados quando as plantas estavam no estádio fenológico B (gema inchada), no dia 17/08/2007. O experimento foi realizado em delineamento inteiramente casualisado, com 3 repetições e 6 tratamentos: 1) Testemunha; 2) 4% Óleo Mineral (OM); 3) 0,52% Cianamida hidrogenada (CH) + 4% OM; 4) 1% Extrato de Alho (EA) + 4% OM; 5) 2,5% EA + 4% OM; e 6) 5% EA + 4% OM; 5). As avaliações foram realizadas 29, 36, 43, 50 e 57 dias após a aplicação. Observou-se que o extrato de alho teve influencia sobre a superação da dormência das gemas da pereira. O tratamento com 5% EA + 4% OM antecipou a brotação das gemas com resultado semelhante à aplicação de 0,52% CH + 4% OM. Nenhum tratamento apresentou efeito fitotóxico.