Hydrogen Cyanamide Application Research Articles

Enhancing Uniform Sprouting, Yield, and Quality in Grapevines: The Impact of Hydrogen Cyanamide (50% S.L) Treatment

Grape (Vitis vinifera L.) is considered as one of the most important commercial fruit crops in temperate, tropical and subtropical regions of the world. In India grape cultivation in tropical and subtropical regions assumes great significance, but one of the biggest issues preventing grapes from being produced in warm climates has been the lack of or insufficient winter chilling. Under these circumstances, there is uneven bud bursting, flowering, and delayed fruit development. The most crucial component of grape development is, consistent bud breaking is required to increase grape quality and maturity. Many plant growth regulators are used to promote bud burst and increase the proportion of bud break. Several locations across the world utilize plant growth regulators to intentionally cause bud break. The application of Hydrogen Cyanamide (H2CN2) during pruning time of grapes, helps to enhance growth uniformity, encourage earlier and more even bud break, raises the proportion of fruit buds, berry set, number of clusters per vine, weight of clusters, and dimensions of clusters. It also gives positive response to various metabolic activities; maximize yield and Maturity, Fruit quality, as well as production efficiency. In grape orchards, it is commonly used to promote consistent and improved bud burst, shortened flowering period, and boost output.

Hydrogen Cyanamide Application Accelerates Vegetative Bud Break and Causes Earlier Yield in ‘Optimus’ and ‘Colossus’ Southern Highbush Blueberry

Southern highbush blueberry (Vaccinium corymbosum interspecific hybrid) cultivation is a major industry in subtropical regions where low winter temperatures are infrequent and inconsistent. In Florida and other subtropical areas, growers use hydrogen cyanamide (HC) applications during endodormancy to mitigate the negative effects of low chill accumulation. Hydrogen cyanamide is a synthetic plant growth regulator that increases and expediates dormancy release and budbreak. However, southern highbush blueberry cultivars differ in their sensitivity to HC. Optimus and Colossus are two recently released cultivars from the University of Florida blueberry breeding program. The effects of HC in these cultivars are unknown. This research aimed to describe responses to HC applications at different rates for these new varieties. Experiments took place in a commercial farm in Waldo, FL, on 3- to 4-year-old deciduous blueberry bushes. HC was applied at rates of 3.8 g·L−1 (0.38%), 5.1 g·L−1 (0.50%), and 6.4 g g·L−1 (0.63%) in ‘Optimus’ and 3.8 g·L−1 (0.38%), 5.1 g·L−1 (0.50%), 6.4 g·L−1 (0.63%), and 7.7 g·L−1 (0.75%) in ‘Colossus’. In both cultivars, the control treatment was not sprayed. Vegetative bud count, and flower bud development, flower bud mortality, and yield were determined. HC application thinned reproductive buds and increased vegetative budbreak. Although seasonal yield was not increased, HC advanced fruit ripening early in the season.

Cianamida hidrogenada na brotação da macieira ‘Eva’ em região de inverno ameno

Abstract This study was carried aiming to evaluate different hydrogen cyanamide concentrations (0.00%; 0.26%; 0.52% 0.78% and 1.04%) associated with (3%) mineral oil on the bud growth of the ‘Eva’ apple tree in a high-altitude tropical climate region in the state of Minas Gerais. Sprouting percentage, fruit set: ratio between number of fruits and number of flowers (%), number of fruits per plant and flowering phenology were evaluated during the 2020 and 2021 production cycles. Even not being submitted to temperatures below 7.2°C, the ‘Eva ‘ cultivar completed its production cycle in two subsequent years. Hydrogen cyanamide application combined with mineral oil promoted increased budbreak and flowering uniformity, in addition to anticipating the beginning of flowering of the ‘Eva’ apple cultivar.

Effect of time of pruning and hydrogen cyanamide application on harvesting time and fruit quality in grapes (Vitis vinifera L.)

An experiment was conducted to ascertain the effect of pruning time and hydrogen cyanamide application on bud burst, maturity and fruit quality of Flame Seedless grapes. The plants were pruned at six different intervals and foliar application of hydrogen cyanamide @ 2% was given to the vines immediately after each pruning interval. These were compared with the vines kept untreated at each pruning interval. The study revealed that bud burst was 12–23 days earlier in vines treated with hydrogen cyanamide as compared to untreated vines. Amongst the hydrogen cyanamide treated vines, bud burst was the earliest when pruning was done in last week of December. In case of untreated vines, bud burst occurred during the month of March. The application of hydrogen cyanamide immediately after pruning advanced the time of flowering and ripening by 5–9 days and 4–5 days, respectively, as compared to untreated vines. The pruning time of first week of January registered more yield (31.4 kg/vine), while the overall yield (28.6 and 28.8 kg/vine) and bunch weight (378.1 and 378.4 g) were at par among the for treated and untreated vines, respectively. The fruit quality in terms of higher soluble solids content (18.8°Brix), total sugar, (15.62%) and lower acidity (0.5%) was also significantly achieved in treated vines. The study provides useful insight into improving the fruit quality and enhancing the marketability in grapes through advancement of budburst and ripening with the application of hydrogen cyanamide.

Effect of a Late Spring Application of Hydrogen Cyanamide on High-Chill Peaches

Due to a record low chilling accumulation in the winter of 2016–2017, many high-chill peach cultivars displayed almost no budbreak by mid-April of 2017 in central Georgia, USA, where budbreak usually occurs around mid-March. In this study, nine of these peach cultivars were used to study the effect of a late spring Dormex spray application (April 13, 2017) on subsequent budbreak, year-end cumulative vegetative growth, and following-season yield. Dormex was found to have strong stimulating effects on lateral budbreak, but little effect on terminal and floral budbreak. It also had apparent phytotoxic effects on lateral, terminal and floral buds, and growth. The effects varied among genotypes, tree ages, and shoot types. The peak of the effects occurred two weeks post-application. Most floral buds abscised before they swelled. Between Dormex-sprayed trees and unsprayed controls, there was no significant difference in the number and average length of the new lateral shoots by the end of 2017, nor in the number and weight of the fruit harvested in 2018. In conclusion, our data showed a late spring Dormex spray application stimulated earlier lateral budbreak and caused some level of phytotoxicity to all types of buds and new growth, but had little impact on flower budbreak, fruit set, year-end vegetative growth, or following-season yield. These findings provide useful information for growers, considering the need for spraying dormancy-breaking compounds when faced with insufficient chilling.

Drift measurements for conditions of hydrogen cyanamide spraying in kiwifruit

Kiwifruit are sprayed in late winter with hydrogen cyanamide to enhance with bud burst. The trellis layout of kiwifruit vines in combination with the canopy dormancy at that time of year means that a higher portion of the spray is able to drift away from the canopy. A spray application field study was conducted in a kiwifruit orchard to investigate spray drift potential, with particular focus for conditions relevant to hydrogen cyanamide applications. Spray application with conventional airblast-sprayer hollow-cone nozzles/adjuvant was compared with air-induction (AI) nozzles/drift-reducing adjuvant. Spray was applied every second row in the orchard with spray drift sampling conducted by measuring vertical distribution of spray deposition on both sides of the downwind shelterbelt. The trial showed that airborne drift carried to a height of at least 15 m to the downwind edge of the orchard, which was the height of the vertical sampling towers. The air-induction nozzle/drift-reducing adjuvant system reduced the drift intercepted at 15 m height on the downwind side of the shelterbelt by approximately 78% compared to the standard nozzle/adjuvant system.

Increasing the Efficacy of GA3 Sprays in Cluster Elongation and Berry Thinning in Tas-A-Ganesh Grape (Vitis vinifera L.) in Tropical Viticulture

In view of the stage specificity for the efficacy of blanket sprays of GA3 for berry thinning, a field trial was laid out to achieve uniform flowering in Tas-A-Ganesh grapevines subjected to chemical defoliation prior to and hydrogen cyanamide application at fruit pruning in the double pruning and single cropping system during 2013-14 and 2014-15 fruiting seasons in growers’ vineyards around Nashik, Maharashtra by removing the un-uniformly thick canes. GA3 at different doses was sprayed two or three times to address the variation in uniform flowering, if any in cluster elongation and reducing the berry number/cluster. Cane regulation and GA3 sprays were used to achieve uniformity in bud break and flowering. Cluster compactness was derived by multiplying the number of berries/ cm length of rachis with berry diameter. Regression analysis of the variation has revealed that the cane diameter, through uniformity in bud break, influenced the uniformity in flowering which in turn influenced the cluster compactness through increased efficacy of blanket GA3 sprays in reducing the berry number/ cluster. Based on the optimum values of the contributory factors to cluster compactness, cane removal coupled with two blanket sprays of GA3 @ 30 g a.i./ha or retention of all canes coupled with three blanket sprays of GA3 @ 20 g a.i./ha was found to be ideal to obtain loose to well filled clusters. Taking together into account the effect of treatments on cluster compactness, yield and quality, retention of all canes coupled with three sprays of GA3 @ 20 g a.i./ha was considered appropriate for table grape production in Tas-A-Ganesh cv. of grapes.

Increasing the Efficacy of GA3 Sprays in Cluster Elongation and Berry Thinning in Tas-A-Ganesh Grape (Vitis vinifera L.) in Tropical Viticulture

In view of the stage specificity for the efficacy of blanket sprays of GA3 for berry thinning, a field trial was laid out to achieve uniform flowering in Tas-A-Ganesh grapevines subjected to chemical defoliation prior to and hydrogen cyanamide application at fruit pruning in the double pruning and single cropping system during 2013-14 and 2014-15 fruiting seasons in growers’ vineyards around Nashik, Maharashtra by removing the un-uniformly thick canes. GA3 at different doses was sprayed two or three times to address the variation in uniform flowering, if any in cluster elongation and reducing the berry number/cluster. Cane regulation and GA3 sprays were used to achieve uniformity in bud break and flowering. Cluster compactness was derived by multiplying the number of berries/ cm length of rachis with berry diameter. Regression analysis of the variation has revealed that the cane diameter, through uniformity in bud break, influenced the uniformity in flowering which in turn influenced the cluster compactness through increased efficacy of blanket GA3 sprays in reducing the berry number/ cluster. Based on the optimum values of the contributory factors to cluster compactness, cane removal coupled with two blanket sprays of GA3 @ 30 g a.i./ha or retention of all canes coupled with three blanket sprays of GA3 @ 20 g a.i./ha was found to be ideal to obtain loose to well filled clusters. Taking together into account the effect of treatments on cluster compactness, yield and quality, retention of all canes coupled with three sprays of GA3 @ 20 g a.i./ha was considered appropriate for table grape production in Tas-A-Ganesh cv. of grapes.

Responses of green kiwifruit grown in low-chill area to hydrogen cyanamide application

Responses of green kiwifruit grown in low-chill area to hydrogen cyanamide application

Effects of Pre-chilling Potassium Nitrate and Post-chilling Hydrogen Cyanamide Application on Carbohydrate and Water Dynamics of ‘Housui’ Japanese Pear Spur Buds During Dormancy Under Mild Winter Conditions

Japanese pear (Pyrus pyrifolia Nakai) trees were treated with potassium nitrate (KNO3) before the onset of chilling and hydrogen cyanamide (CH2N2) after the trees had accumulated 600 chilling hours (CH) to determine the effects on bud dormancy release, carbohydrate dynamics, and water content. For the carbohydrate and water content analyses, Japanese pear spur buds were collected after 0, 300, and 600 CH, and after the accumulation of 2000, 4000, 6000, and 8000 growing degree hours (GDH) during the dormancy period. Bud burst and flowering were hastened by both KNO3 and CH2N2 application, and both chemicals affected carbohydrate and water dynamics during dormancy. Sucrose concentration tended to increase during the chilling period, and to decrease under forcing conditions. Hexose concentrations increased in buds treated with KNO3, CH2N2, or both, and were associated with advances in bud burst. Sorbitol concentration decreased early in buds treated with CH2N2, suggesting rapid sorbitol catabolism. Water content gradually increased under forcing conditions in all buds, although those treated with both KNO3 and CH2N2 exhibited the highest values. Accordingly, we recommend the use of KNO3 and CH2N2, before and after chilling, respectively, to promote the release of bud dormancy and increase bud burst rate in ‘Housui’ Japanese pear grown in regions with mild winter conditions.

Impact of chilling accumulation and hydrogen cyanamide on floral organ development of sweet cherry in a warm region

The microscopic investigation of the floral development of sweet cherry (Prunus avium L. cv. Hongdeng) from a warm winter climate (Shanghai) and cold winter climate (Tai’an, Shandong Province, China) was conducted to explore the reason of low fruit set. The effect of hydrogen cyanamide (HCN) on floral development under warm winter conditions was also investigated. Trees grown in Shanghai with insufficient chilling accumulation exhibited little difference in the progression of microspore development compared to trees in Tai’an that accumulated adequate chilling, but showed substantial delays in ovule and embryo sac development. The growth of nucelli did not proceed beyond the macrospore mother cell and macrospore stages with abortion rates of 13, 15 and 45% by 6, 3 and 0 d before full bloom, respectively. These abnormalities in the ovule and embryo sac in the Shanghai-grown trees were eliminated by HCN application. These results suggest that chilling regulates the development of female floral organs in winter dormancy; therefore, insufficient chilling accumulation, causing abnormality of the female floral organs, restricts the cultivation of sweet cherry in warm winter regions. Interestingly, HCN application, which decreased the chilling requirements for Hongdeng, may be a potential strategy for sweet cherry cultivation in warm winter regions.

Timing of hydrogen cyanamide application to grapevine buds

One major factor limiting the application of hydrogen cyanamide (H 2 CN 2 ) is the difficulty in deciding when to apply, since mistiming may lead to bud and crop damage. Since an effective method for monitoring the developmental stage of dormant buds is not yet available, minimizing such a risk involves the regional evaluation of application timing. For three successive years, several H 2 CN 2 application dates were evaluated in cv. Perlette vineyards in the Jordan valley in Israel. The level and uniformity of bud break did not differ significantly among the application dates tested. However, major effects of the application date on cluster number, cluster size and yield were found. The sensitivity of the reproductive meristem to H 2 CN 2 is discussed.

EFFECTIVE HYDROGEN CYANAMIDE (DORMEX®) APPLICATION FOR BUD BREAK, FLOWERING AND NUT YIELD OF PISTACHIO TREES CV. MATEUR IN WARM GROWING AREAS

SUMMARYClimate change characterized by global warming is expected to have an incidence on fruit trees’ development and production. The severity of these effects depends on lack of chilling. The current study focused on the research of an optimal dose of hydrogen cyanamide (Dormex®) treatment which can advance the bud break of female pistachio trees (Pistacia veraL.) to ensure better blooming synchronization with pollinators. A field experiment was conducted in northern Tunisia (36°49′N, 9°48′E) on mature pistachio trees. Two hydrogen cyanamide treatments at 2% and 4% Dormex® were applied with reference to the control untreated trees. The flowering time, vegetative growth, starch content, productivity and nut characters were followed. Results show that 4% Dormex® advanced the normal bud break by 15 days and flowering by 11 days and improved natural pollination by synchronization of male and female flowers. Consequently, fresh yield and nut quality as split and blank rates and nut weight were improved. However, shoot growth, leaf area and starch content in current shoot seemed unaffected by hydrogen cyanamide applications. In conclusion, hydrogen cyanamide could be used as 4% Dormex® and sprayed 45 days before bud break to improve pistachio productivity and prevent anomalies of lack of chilling due to global warming that could be more frequent in the Mediterranean areas.

Caracterização fenológica de pereiras 'Housui' e 'Kousui' cultivadas sob clima semiárido no nordeste do Brasil

Observações fenológicas fornecem informações sensíveis para a determinação de como as espécies de plantas respondem às condições climáticas regionais, visando à produção de frutas em diferentes regiões. Assim, o experimento foi conduzido de setembro de 2010 a janeiro de 2011, com o objetivo de caracterizar os estádios fenológicos de pereiras 'Housui' e 'Kousui', cultivadas em clima semiárido do Nordeste do Brasil. Os dados fenológicos (fases) foram coletados no pomar, em observações diárias, desde a aplicação de cianamida hidrogenada (para a quebra de dormência) até o amadurecimento das frutas. Concluíu-se que, em clima semiárido, as pereiras 'Housui' e 'Kousui' concluem seus ciclos fenológicos em 128 dias e 115 dias, respectivamente. Novas pesquisas e mais alguns anos de avaliação serão necessários para gerar um sistema de produção de peras no semiárido nordestino.

Expression and genomic structure of the dormancy-associated MADS box genes MADS13 in Japanese pears (Pyrus pyrifolia Nakai) that differ in their chilling requirement for endodormancy release

We isolated three dormancy-associated MADS-box (DAM) genes (MADS13-1, MADS13-2 and MADS13-3) and showed regulated expression concomitant with endodormancy establishment and release in the leaf buds of Japanese pear 'Kosui'. Comparative analysis between 'Kosui' and Taiwanese pear TP-85-119 ('Hengshanli'), a less dormant pear cultivar, showed reduction of MADS13-1 expression level in 'Hengshanli' earlier than in 'Kosui' towards endodormancy release, suggesting the possible relationship between chilling requirement and MADS13-1 expression. Application of hydrogen cyanamide accelerated endodormancy release with a reduction in MADS13 expression, whereas heat treatment in autumn inhibited endodormancy establishment without induction of MADS13 expression, indicating a close relationship between the MADS13 expression pattern and endodormancy phase transitions. Moreover, both the cis-acting regulatory elements and the methylation status in the 5' upstream region of the MADS13-1 gene were not largely different between 'Kosui' and 'Hengshanli'. Genomic structures of MADS13-1 from 'Kosui' and 'Hengshanli' revealed a 3218 bp insertion in the first intron of 'Hengshanli' that might be ascribed to the lower expression of MADS13-1tw; however, this insertion was also found in pear genotypes with a high chilling requirement. These results indicated that the low expression of MADS13-1 in 'Hengshanli' towards endodormancy release could not be explained by the identified cis-acting regulatory elements, the methylation status of the putative promoter or by intron insertion.

Short Exposure to Sublethal Heat Shock Facilitates Dormancy Release in Grapevines

A wet heat shock (WHS) treatment in a water bath at 50°C for 1 hr is a powerful stimulus for grapevine budbreak. However, this treatment is not feasible as a horticultural practice in commercial vineyards. The development of an effective horticultural dormancy release practice favors a short, intense heat shock that combines convenient application and effective stimulation of budbreak. Thus, the influence of heat shock temperature and duration on dormancy release of grapevine buds was studied. Results suggested that in both WHS and dry heat shock (DHS) treatments, increased temperature can compensate for shortened shock duration. In addition, it appeared that buds better tolerate DHS than WHS. Based on these results, we analyzed the effect of short and intense heat shock on budbreak. A DHS of 10 to 30 sec at the sublethal temperature of 150°C served as a powerful stimulus of dormancy release. This short shock induced production of acetaldehyde and ethylene from the buds, as follows application of hydrogen cyanamide. This similarity suggests that analogous mechanisms are activated by the short, sublethal temperature pulse and the commercially used chemical stimulus. The efficiency of short and intense heat shock, which has not been previously documented, will aid the development of a feasible and practical treatment in commercial vineyards.

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.

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.

Evaluation of Flower Bud Removal Treatments on Growth of Young Blueberry Plants

The effects of flower bud removal treatments on growth of young rabbiteye (Vaccinium ashei Reade) and southern highbush (V. corymbosum hybrids) blueberry plants were evaluated. Treatments consisted of pruning, hand stripping, and hydrogen cyanamide applications. The growth index of rabbiteye plants after the first spring growth cycle was unaffected by any of the flower bud removal treatments. However, the effects of flower bud thinning were cultivar specific for southern highbush blueberry plants. ‘Misty’ plants showed increases in total plant dry weight and in root, leaf, and stem dry weights from hand thinning and hydrogen cyanamide sprays. Conversely, ‘Santa Fe’ showed no increased growth response from any of the flower bud removal treatments. Flower bud mortality increased as hydrogen cyanamide spray concentration increased and was greater when applications were delayed so that flower buds were more advanced. Hydrogen cyanamide may have potential as an alternative to labor-intense flower bud removal practices such as hand stripping or pruning on young blueberry plants during establishment.

Endogenous cytokinin levels of table grape vines during spring budburst as influenced by hydrogen cyanamide application and pruning

Abstract Cytokinins play an important role in budburst, flowering and fruit set in table grapes. Rest-breaking treatments with hydrogen cyanamide and pruning practices modify budburst and reproductive development in table grapes, especially in regions with low and often inadequate winter chilling. The effect of these treatments on the xylem sap and bud Zeatin riboside (ZR) content was determined during late winter and budburst in ‘Sultanina’, ‘Sunred Seedless’, and ‘Alphonse Lavallee’ canes in a total of nine trials conducted between 1997 and 2001. Bud ZR levels of hydrogen cyanamide treated ‘Sultanina’ canes showed an earlier and increased cytokinin peak, in particular in the distal buds. Large ZR peaks before budburst and noticeable differences between distal and proximal buds were absent on non-sprayed canes. The xylary ZR content of long pruned ‘Sultanina’, ‘Sunred Seedless’, and ‘Alphonse Lavalee’ canes showed a significantly higher and earlier cytokinin peak than in short pruned spurs. By contrast, the bud ZR content tended to be higher in spurs than canes. Pruning and rest-breaking treatments enhanced budburst and increased endogenous cytokinins in these experiments. Long pruning in ‘Sultanina’ and ‘Sunred Seedless’ (both parthenocarpic) is necessary for acceptable fruit set and yields. Possibly, in longer canes more cytokinin is available for reproductive development. ‘Alphonse Lavalee’ (seeded) is sufficiently fruitful and produces adequate yields following spur pruning.