End Of Dormancy Research Articles

Effect of Menthol Treatment on the Sprouting and Quality of Potato Tuber

This study used Dutch potatoes at the end of dormancy as a material to explore the impact of menthol (0.2 and 0.5 g/kg based on potato mass) treatment on sprouting inhibition and potato quality. The findings revealed that a menthol concentration of 0.5 g/kg effectively inhibited potato tuber sprouting and significantly reduced glucoside alkaloid production. After a storage period of 15 days, the sprouting percentage and glucoside alkaloid content of potatoes treated with 0.5 g/kg menthol were observed to be significantly lower at 4.17% and 68.63 mg/kg, respectively, compared to the control group which exhibited values of 100% and 282.01 mg/kg, respectively (p < 0.05). Throughout the storage period, 0.5 g/kg of menthol promoted respiration, reduced malondialdehyde production in potatoes, inhibited polyphenol oxidase activity, and slowed down tissue browning. Additionally, it mitigated the decline in starch and soluble protein content, inhibiting the accumulation of reducing sugars.

Chilling requirement of four peach cultivars estimated by changes in flower bud weights

The adaptation of temperate fruit crops is a challenge being increased by the global warming. Chilling requirement is a key factor for adaptation. The objective of this study was to estimate the chilling requirement of peach cultivars BRS Bonão, Esmeralda, Granada and Eragil, using the Tabuenca test. Chilling accumulation was computed using four different chilling hour (≤ 7.2 ºC and ≤ 11 ºC) models; and chill units using the Low Chill model and the Taiwan model. The fresh bud weight and bud water contents were also evaluated. The Tabuenca test (based on differences in bud´s dry weight) showed a fairly good efficiency for estimating the end of dormancy in peach. However, under mild winter conditions, it is better to use fresh bud weights. Either one of three chilling accumulation computation models (temperature ≤ 7.2 °C, ≤ 11°C, or Taiwan model) is suitable to classify comparatively different cultivars, but none is accurate enough to conclude on the adaptation of a given cultivar to a specific site. Using hours of temperatures ≤ 11 ºC: ‘BRS Bonão’ needed around 180 hours for dormancy release; ‘Esmeralda’ around 250 hours; ‘Granada’ between 300 and 400 hours, and ‘Eragil’ more than 500 hours.

Graft survival of Pinus engelmannii Carr. in relation to two grafting techniques with dormant and sprouting buds.

Developing methods for successfully grafting forest species will be helpful for establishing asexual seed orchards and increasing the success of forest genetic improvement programs in Mexico. In this study we investigated the effects of two grafting techniques (side veneer and top cleft) and two phenological stages of the scion buds (end of latency and beginning of sprouting), in combination with other seven grafting variables, on the sprouting and survival of 120 intraspecific grafts of Pinus engelmannii Carr. The scions used for grafting were taken from a 5.5-year-old commercial forest plantation. The first grafting was performed on January 18 (buds at the end of dormancy) and the second on February 21 (buds at the beginning of sprouting). The data were examined by analysis of variance and a test of means and were fitted to two survival models (the Weibull’s accelerated failure time and the Cox’s proportional hazards model) and the respective hazard ratios were calculated. Survival was higher in the top cleft grafts made with buds at the end of latency, with 80% sprouting and an estimated average survival time of between 164 and 457 days after the end of the 6-month evaluation period. Four variables (grafting technique, phenological stage of the scion buds, scion diameter and rootstock height) significantly affected the risk of graft death in both survival models. Use of top cleft grafts with buds at the end of the latency stage, combined with scion diameters smaller than 11.4 mm and rootstock heights greater than 58.5 cm, was associated with a lower risk of death.

Dynamics of above- and belowground responses of silver birch saplings and soil gases to soil freezing and waterlogging during dormancy.

Winter precipitation and soil freeze–thaw events have been predicted to increase in boreal regions with climate change. This may expose tree roots to waterlogging (WL) and soil freezing (Fr) more than in the current climate and therefore affect tree growth and survival. Using a whole-tree approach, we studied the responses of silver birch (Betula pendula Roth.) saplings, growing in mineral soil, to 6-week Fr and WL in factorial combinations during dormancy, with accompanying changes in soil gas concentrations.Physiological activation (dark-acclimated chlorophyll fluorescence and chlorophyll content index) and growth of leaves and shoot elongation and stem diameter growth started earlier in Fr than NoFr (soil not frozen). The starch content of leaves was temporarily higher in Fr than NoFr in the latter part of the growing season. Short and long root production and longevity decreased, and mortality increased by soil Fr, while there were no significant effects of WL. Increased fine root damage was followed by increased compensatory root growth. At the beginning of the growing season, stem sap flow increased fastest in Fr + WL, with some delay in both NoWL (without WL) treatments. At the end of the follow-up growing season, the hydraulic conductance and impedance loss factor of roots were higher in Fr than in NoFr, but there were no differences in above- and belowground biomasses. The concentration of soil carbon dioxide increased and methane decreased by soil Fr at the end of dormancy. At the beginning of the growing season, the concentration of nitrous oxide was higher in WL than in NoWL and higher in Fr than in NoFr. In general, soil Fr had more consistent effects on soil greenhouse gas concentrations than WL. To conclude, winter-time WL alone is not as harmful for roots as WL during the growing season.

Comparison of Utah and Positive Utah models for determining of chilling and heat requirements of some olive cultivars

Determining of chilling and heat requirements of olive cultivars growing in Fars Province is important for the selection of cultivars that will exhibit satisfactory growth and development. The purposes of this study were determining the chilling and heat requirements of olive and comparison of Utah and Positive Utah Chill unit (PCU) models for determining the chilling requirements of olive cultivars. In this regard, chilling requirement of flower buds of ‘Fishomi’, ‘Dezful’, ‘Zard’, ‘Dehghan’ and ‘Shiraz’ cultivars were determined. Cuttings of these cultivars were taken during autumn when the mean temperature fell below 12oC. Cuttings were kept at 5 oC for periods of 0, 100, 200, 300, 400, 500, 600, 700, 800, 900, 1000, 1100, 1200, 1300, 1400, 1500, 1600, 1700 and 1800 h. Results indicated that the chilling requirements of ‘Fishomi’, ‘Dezful’, ‘Zard’, ‘Dehghan’ and ‘Shiraz’ were 900, 1000, 900-1000, 1000-1100 and 900 h, respectively. Results also showed that the PCU unit model was more efficient than the Utah for estimating chilling requirements under subtropical field conditions. Heat requirements from the end of dormancy to full bloom stage of these five olive cultivars were estimated as 199.2, 272.1, 245.2, 245.2, 321 growing degree days (GDDs), respectively. It was observed that ‘Fishomi’ had the lowest chilling requirement and ‘Dehghan’ obtained the highest one. Hence, ‘Fishomi’ can be recommended for cultivation in subtropical regions.

Changes in potato tuber sugar metabolism in response to natural sprout suppressive compounds

The increased demand for potato by the Brazilian processing industry requires long term refrigerated storage, but after a few months, natural dormancy ends, and sprouts start to grow. Thus, sprout inhibitors are necessary to reduce the rate of growth and allow further storage. The purpose of research described here was to determine the effects clove and menthol essential oils have on the inhibition of sprout growth in non-dormant ‘Asterix’ tubers. Both eugenol and menthol treatments reduced the rate of sprout growth during storage at 8oC for up to 50 days. Eugenol and menthol essential oils diminished the rate of accumulation of reducing sugar, which are responsible for browning of French fries. Color after frying was within acceptable levels when the tubers were treated with eugenol or menthol essential oils.

The Effect of Seasonal Humidity on Survival and Duration of Dormancy on Diverging Mexican Rhagoletis pomonella (Diptera: Tephritidae) Populations Inhabiting Different Environments.

Phytophagous insects synchronize emergence with plant phenology by engaging in dormancy during periods of host scarcity and environmental stress. Regulation of dormancy is achieved through response to seasonal cues. While temperature and photoperiod are important cues in temperate latitudes, seasonal humidity, such as the onset of rains, can be a reliable cue to for synchronization of emergence and affects survival of overwintering insects. We compared response of Mexican Rhagoletis pomonella (Walsh) (Diptera: Tephritidae) populations inhabiting subtropical environments differing in humidity patterns, to seasonal humidity regimes. Both populations emerged as adults in high proportions and suffered lower mortality under humidity regimes ending with a humid summer, but the effect was more pronounced for the Eje Volcanico Trans Mexicano (EVTM) population, which inhabits a dryer environment and undergoes longer dormancy. While there were no differences among pupae from the Sierra Madre Oriental (SMO) in percent of non-emerged pupae surviving and engaging in prolonged dormancy after a year, EVTM pupae exposed to an initial humid period engaged in prolonged dormancy in higher proportions than those exposed to other regimes. Seasonal humidity had little effect on the duration of dormancy, but EVTM pupae exposed to consecutive dry periods took longer to emerge than those exposed to other regimes. Our results suggest that rather than being used as a token stimulus, humidity affected survival of overwintering R. pomonella, especially at the end of dormancy when energy reserves are depleted and there is an increase in metabolic rate that renders EVTM pupae more susceptible to desiccation.

Some Factors Involved in the Success of Side Veneer Grafting of Pinus engelmannii Carr.

The establishment of clonal seed orchards is a viable option for the continuous production of improved seed of desired genotypes. Grafting is the main technique used to establish clonal seed orchards. The objective of this study was to examine how the geographic location and the age class of the donor trees of buds, the phenological status of the buds, and the anatomical characteristics of the scions and the rootstocks affect the survival and growth of Pinus engelmannii Carr. grafts. Scions were collected from two trees in each of three age classes (young, middle-aged, and old). Grafting was performed with buds in two physiological states (end of dormancy and beginning of sprouting). Cross-sections of the grafted organs were obtained for anatomical analysis. A Cox proportional hazards model was used to determine the effects of the variables that were considered. The age class of the scion donor trees, the total area of the cut surface of the scion, and the density of resin channels in the scions significantly affected (p < 0.05) survival of the grafts. By contrast, the physiological state of the buds and the other anatomical characteristics of the grafted organs did not significantly affect graft survival. In P. engelmannii, grafting was most effective when scions from middle-aged trees were used. Graft survival was enhanced by a small total area of the cut surface of the scion and low density of resin channels in the scions. The area of the cambium of the scions directly influenced growth of the grafts.

Role of Bark Color on Stem Temperature and Carbohydrate Management during Dormancy Break in Persian Walnut

Temperature is assumed to be the principal regulatory signal that determines the end of dormancy and resumption of growth. Indirect evidence that stem temperature interferes with phenology comes from the common orchard practice of painting stems to protect them from disease. This work studies the effects of application of white paint to the stems of persian walnut (Juglans regia) trees on winter stem temperature, carbohydrate content, and spring phenology. Painting bark resulted in the delay of budbreak by several days, higher nonstructural carbohydrate (NSC) concentrations in the bark and wood of painted extension shoots and changes in the spatial gradients of NSC during budbreak. The demands of maintenance respiration exceeded mobilization from local carbon pools during bud development suggesting a potential role of carbohydrate transport during spring budbreak in persian walnut. Painting provides an exciting perspective for mitigating effects of milder winter in orchards. The effect of reducing diurnal and spatial temperature variability limits early budbreak, NSC depletion associated with intense maintenance respiration, freeze–thaw cycles and frost dehardening.

Frost hardiness of flower buds of three plum (Prunus domestica L.) cultivars

Frost hardiness of flower buds of three plum (Prunus domestica L.) cultivars (‘Cacanska lepotica’, ‘Stanley’, ‘Besztercei’) was characterised by the LT50 values calculated from artificial freezing experiments conducted during eight dormancy periods between 2004 and 2016. Of the two variance components, the year effect was the strongest at the beginning of dormancy explaining around 60% of the phenotypic variation in LT50 values, while the effect of genotype started to increase from November and reached its maximum in the middle of January, when 81.2% of the variance in LT50 was due to the genotype. During the first part of winter the frost hardiness of the overwintering organs developed gradually in parallel to the decreasing ambient temperature. Flower buds were the most frost tolerant in the first half of January, when the maximum LT50 of ‘Cacanska lepotica’ was −22.8°C, for ‘Stanley’ −24.8°C and for ‘Besztercei’ it was −26.5°C, averaged over the 8 dormancy periods. From the end of dormancy the effect of year became much stronger over the genotypic differences from the second half of January. Milder days during this period resulted in faster flower bud development paralleled by a steeper and quicker decline in frost tolerance, which may significantly increase the probability of frost damages in flowers caused by late winter and spring frosts.

Increasing the frost resistance of ‘Golden Delicious’, ‘Gala’ and ‘Šampion’ apple cultivars

AbstractThe aim of this research was the evaluation of whether the application of 5-ALA, which has potential as a plant growth stimulating agent with indirect anti-stress activity, can limit the damage caused by low temperatures in winter. The research was conducted on frost-sensitive apple cultivars for three years in an orchard and in a laboratory. During the vegetative seasons of each year, the trees of three apple cultivars (‘Golden Delicious’, ‘Gala’ and ‘Šampion’) were subject to 5-ALA foliar application. Three times during each winter following the field application, apple shoots were taken to the laboratory and frozen at −20°C, −25°C and −30°C. After incubation, the damage to the sensitive parts of the shoots was evaluated. The application had a positive effect on the frost resistance of all cultivars, most often at the end of dormancy, which is especially noteworthy because frost damage occurs most frequently during this period. Positive effects of the application were found in most of the experiment combinations of cultivar, year, freezing date and shoot part. Additionally, the positive influence of 5-ALA application on frost resistance was found to increase with each year of the research.

C/N RATIO AND NUTRIENT CONTENT IN PEACH BARK RELATED TO PEACH TREE SHORT LIFE

ABSTRACT Peach Tree Short Life (PTSL) is a syndrome characterized by a plant collapse at the end of dormancy, which causes include several biotic and abiotic components. The aim of this study was to assess the C/N ratio and bark nutrients in symptomatic and asymptomatic short-life peach trees. Live tissue portions were removed from the bark of the main scaffolds of symptomatic and asymptomatic adjacent trees in nine commercial peach orchards located in Pelotas and Canguçu, state of Rio Grande do Sul, Brazil. In laboratory, carbon (C), nitrogen (N), phosphorus (P), potassium (K), calcium(Ca), magnesium (Mg), iron (Fe), manganese (Mn), zinc (Zn), copper (Cu), boron (B) contents and C/N ratio were determined. The main component analysis of the study variables did not allow the formation of different groups between symptomatic and asymptomatic short-life peach trees. Peach trees with visible PTSL symptoms had higher N, P and K contents and lower C/N ratio in the bark of the main scaffolds in the early sprouting season.

Performance of models for the beginning of sweet cherry blossom under current and changed climate conditions

Six phenological models, two simple forcing (F)-models and one sequential chilling/forcing (CF)-model, each with and without day length (DL)-term in the forcing approach were optimised (2001–2010) and validated (2011–2015) on very accurate blossoming data of an experimental sweet cherry orchard at Berlin-Dahlem (cultivar ‘Summit’). In parallel, in 3 seasons (2011/2012–2013/2014) climate chamber experiments were performed in order to determine the end of dormancy for ‘Summit’, which is usually an unknown or uncertain parameter in phenological modelling. Additionally, in the season 2013/2014 an in situ climate change experiment on three trees in the sweet cherry orchard were arranged, which was used to validate the phenological models for distinctly warmer climate conditions at the experimental site. On the basis of our climate chamber experiments we quantified the chilling requirement of ‘Summit’ trees. Thus, we were able to identify a CF-model for the beginning of sweet cherry blossom which is mostly physiologically based and works well for current and for future climate conditions at the experimental site. This paper also shows how phenological models can fail under warmer climates, if either the model is too simple or the model parameters are wrong. Additional, we confirmed that phenological models with DL-term in the forcing approach clearly surpassed the conventional phenological models without this parameter. The reason for this behaviour is extensively discussed.

A MORTE PRECOCE DO PESSEGUEIRO ASSOCIADA À FERTILIDADE DO SOLO

RESUMO A morte precoce do pessegueiro é uma síndrome caracterizada por um colapso das plantas ao final do período de dormência, cujas causas envolvem diversos fatores bióticos e abióticos. Objetivou-se avaliar a associação da morte precoce do pessegueiro com à fertilidade do solo. Amostraram-se a rizosfera, para análise química, sob a copa de plantas sintomáticas e assintomáticas, com idade entre dois e oito anos, em nove pomares comerciais localizados nos municípios de Pelotas e Canguçu, no Rio Grande do Sul, totalizando 108 amostras. De acordo com os resultados, a obtenção de uma função discriminante para classificar as plantas em duas categorias, como sintomáticas ou assintomáticas, não proporcionou resultado satisfatório, pois a taxa de classificação errônea superou 40%. A análise de variância individual mostrou que, univariadamente, não existe diferença significativa na fertilidade do solo entre os dois grupos de plantas amostradas. Embora a fertilidade do solo, na maioria dos pomares amostrados, esteja aquém do recomendado para a cultura do pessegueiro, a ocorrência da morte precoce do pessegueiro não apresentou relação com os atributos químicos de fertilidade do solo. O resultado sugere que outros fatores, como os aspectos físicos do solo e o uso de misturas varietais de cultivares-copa como porta-enxerto, possam estar envolvidos na ocorrência de morte precoce do pessegueiro.

Overwintering dormancy behaviour of the European eel (Anguilla anguilla L.) in a large lake

AbstractOverwintering dormancy behaviour was studied in female silver eels in Lake Mälaren in Sweden between 2008 and 2010. Depth choices and movements in relation to temperature were analysed from pressure and temperature records for 13 eels with implanted data storage tags, covering 17 overwintering periods and three intervening summer periods. Dormancy commenced in October–November as temperatures fell below 4–12 °C. Eels tended to remain motionless throughout the winter, with some short periods of activity signalled by small changes in depth distributions. During dormancy, the eel shows a clear avoidance of shallow areas <5 m in favour of the 10–25‐m‐depth interval. Activity tended to resume 4–6 months later in April–May as temperatures rose above 3–7 °C and ice cover broke, and eels spent more time at shallower depths of <5–10 m. The majority of the eels were assessed as being in the silver eel stage at the time of tagging. During the autumn months, the diving behaviour, with frequent and large vertical excursions and periods at the surface, was similar to that seen in migrating eels in the Baltic and Atlantic Ocean. In spring and summer, the behaviour differed, being dominated by more gradual depth variations, implying that the eels reverted from silver eel migration behaviour to yellow eel foraging behaviour. Body weight declined during dormancy, but other studies of starvation over comparable time periods showed significantly higher average specific weight losses, implying that the Mälaren silver eels must have fed between the end of dormancy and recapture.

Management practices impact vine carbohydrate status to a greater extent than vine productivity.

Light pruning and deficit irrigation regimes are practices which are widely used in high yielding commercial vineyards in the warm climate regions of Australia. Little information is available on their impacts on carbohydrate dynamics in vegetative organs within and between seasons, and on the resulting plant capacity to maintain productivity and ripen fruits. This study was conducted to address this gap in knowledge over five vintages on Vitis vinifera L. cv. Cabernet Franc, Shiraz, and Cabernet Sauvignon in the Sunraysia region of Victoria, Australia. Lighter pruning did not change the total carbohydrates concentration and composition in wood and roots within seasons in Cabernet Franc and Shiraz. However, the total carbohydrate pool (starch and soluble sugars) at the end of dormancy increased under lighter pruning, due to higher vine size, associated with retention and growth of old-wood (trunk and cordons). Water deficit negatively impacted trunk and leaf starch concentrations, over the day and within seasons in Cabernet Sauvignon. Soluble sugars concentrations in these tissues tended to be higher under limited water supply, possibly due to higher sugar mobilization as photosynthesis decreased. Trunk carbohydrate concentrations markedly varied within and between seasons, highlighting the importance of interactive factors such as crop load and climate on carbon status. The period between fruit-set and véraison was shown to be critical for its impact on the balance between carbon accretion and depletion, especially under water deficit. The lower leaf and trunk starch concentration under water deficit resulted in a decrease of yield components at harvest, while similar yields were reached for all pruning systems. The sugar allocated to berries at harvest remained remarkably stable for all practices and seasons, irrespective of vine yield and carbohydrate status in vegetative organs in Shiraz and Cabernet Sauvignon.

Observed changes in winter wheat phenology in the North China Plain for 1981–2009

Climate change in the last three decades could have major impacts on crop phenological development and subsequently on crop productivity. In this study, trends in winter wheat phenology are investigated in 36 agro-meteorological stations in the North China Plain (NCP) for the period 1981-2009. The study shows that the dates of sowing (BBCH 00), emergence (BBCH 10) and dormancy (start of dormancy) are delayed on the average by 1.5, 1.7 and 1.5 days/decade, respectively. On the contrary, the dates of greenup (end of dormancy), anthesis (BBCH 61) and maturity (BBCH 89) occur early on the average by 1.1, 2.7 and 1.4 days/decade, respectively. In most of the investigated stations, GP2 (dormancy to greenup), GP3 (greenup to anthesis) and GP0 (entire period from emergence to maturity) of winter wheat shortened during the period 1981-2009. Due, however, to early anthesis, grain-filling stage occurs at lower temperatures than before. This, along with shifts in cultivars, slightly prolongs GP4 (anthesis to maturity). Comparison of field-observed CERES (Crop Environment Resource Synthesis)-wheat model-simulated dates of anthesis and maturity suggests that climate warming is the main driver of the changes in winter wheat phenology in the NCP. The findings of this study further suggest that climate change impact studies should be strengthened to adequately account for the complex responses and adaptations of field crops to this global phenomenon.

STATUS OF POMEGRANATE (PUNICA GRANATUM L.) CULTIVATION IN AFGHANISTAN

Pomegranate is among the main exported fruits of Afghanistan that is exported to Pakistan, Russia and Arabic Countries. Most of the pomegranate growing areas in Afghanistan are situated between 700-1500 m above sea level, and it can be grown in such ranges commercially. In Afghanistan 48 cultivars of pomegranate are available. 20 cultivars are sweet, 17 cultivars medium sweet and 11 cultivars sour. Among all of them the seedless cultivar is very famous. The area of pomegranate orchards in Afghanistan is 2435 ha and the average yield is 9.5 t/ha. Generally Afghan pomegranate has 14-19% sugar content. Pomegranate is propagated by cuttings; the cuttings are taken at the end of winter and planted 20-30 days before the dormancy ends. Injuries to pomegranate due to low temperature are reported from Balkh province. Sun scald is one of the pomegranate problems in Afghanistan. Many growers prefer the multi trunk system wherever frost and sun scald are common features. Usually only one or two trunks are injured by these climatic factors. Single stem training is common in warm areas where there is no cold risk in winter. Fruit cracking is a main problem of pomegranate that is common in all pomegranate growing areas of Afghanistan. Producers use common rooms as store for pomegranate.

Changes of phenolic compounds in Carignan merithallus (Vitis vinifera L.) during bud dormancy and end of dormancy phase: correlation with rhizogenesis

The aim of the present study is to address the type of correlation that may exist between phenolic compounds and vine rhizogenetic potential by analyzing some phenolic compounds in the Carignan merithallus. Phenolic compounds were analyzed by HPLC in the young shoots (or merithallus) of Carignan vine (Vitis vinifera L.) and we established a correlation between the studied compounds and the rhizogenetic potential of shoots during the phases of bud dormancy and end of dormancy, taking into account the position effect on shoots. This work was carried out for the first time on this type of vine. Among the studied phenolic compounds, we observed a negative correlation between coumarin and rhizogenetic potential of Carignan vine. In contrast, positive correlations were found with naringin and syringic acid. Obtained results confirmed the fact that the action of phenolic compounds is complex and might be qualified as cofactors that interact with auxin on rhizogenesis.

Gibberellic Acid and Ethephon Alter Potato Minituber Bud Dormancy and Improve Seed Tuber Yield

While greenhouse production of minitubers has markedly improved production of disease free seed, minituber dormancy can be an issue. This study tested application of abscisic acid (ABA), ethylene (E), gibberellic acid (GA) and the combination of E+GA on release of dormancy in potato minitubers, sprout development, and subsequent effects on field plant growth and yield of seed tubers. Cultivars were categorized on the basis of known dormancy responses as follows: (1) one short dormancy cultivar, Silverton Russet, (2) three intermediate dormancy cultivars, Russet Norkotah (RNK), Sangre S-14 and Desiree, and (3) two long dormancy cultivars, Nooksack and Russet Norkotah Selection 3 (RNK-S3). Eighty eight to 93% of E+GA treated minitubers from cultivars in the long dormancy group developed sprouts signaling the end of dormancy within 5 weeks, while the control and ABA treated minitubers were totally dormant with 0% bud break. With the intermediate cultivars E+GA treated minitubers had 100% bud break compared to 37 to 55% bud break in the control minitubers. Treated long dormant minitubers also had 2.1 to 2.5 more sprouts per minituber and 1.6 to 2.4 cm longer sprouts. E+GA treated minitubers planted in field plot trials produced mature plants that were 19 to 36 cm per plant taller, with up to 3.9 to 8.8 more seed tubers per plant, and 1.9 to 4.2 kg per plot higher yields. The laboratory protocol developed to predict dormancy breaking attributes provided a reasonable estimate of cultivar dormancy under field conditions.