Bud Break Research Articles

Morphological characterization of different primary genotypes of mango (Mangifera indica L.) in Bihar

The morphological characterization of mango genotypes plays a significant role to understand their diversity, identifying distinct traits, and providing valuable insights into their classification and breeding. Hence, the experiment was conducted on 25 primary mango genotypes at Bihar Agricultural University, Sabour, Bihar during the years 2020–2021. The results showed that the genotypes G-06 and G-42 had the earliest bud break (4th February). While genotype G-23 had the maximum panicle length (36.75 cm). The genotype G-28 had the maximum canopy volume of 397.42 m3 with the maximum plant spread in both directions (7.35m in north-south and 7.35 m in east-west direction). Based on the above findings, it can be concluded that genotypes G-11, G-12, G-30, G-23, G-28, and G-29 performed better in respect of floral attributes and more canopy volume, which are important factors for maximization of yield.

Keiki induction by cytokinin on Phalaenopsis spp.

A Keiki is the product of asexual propagation which naturally develop at the node of a flower stalk or cane. Phalaenopsis produce Keiki along the middle to end nodes on the flower stalk. Although keikis are an inefficient way to propagate orchids on a commercial scale, it is interesting to study the cytokinin hormone Benzyl Aminopurine (BAP) effect to stimulate keikis on a node along the flower stalk. Two nodes of each flower stalk were used in this experiment. Cytokinin hormone (0 mg L−1 , 2 000 mg L−1 , 4 000 mg L−1 , 6 000 mg L−1 BAP) was only applied once to the second, third, fourth, and fifth nodes of the flower stalk base. The Keiki raised from the second and third nodes of the flower stalk while the flower spike raised from the fourth to sixth basal. BAP stimulated bud break on the node of the flower stalk and could produce either flower spike or keikis depending on node position from the basal node of the flower stalk.

Performance of different genotypes of pummelo (Citrus grandis L.) for softwood grafting success and growth parameters

Pummelo (Citrus grandis L.) is one of the important tropical fruit crops among the citrus group. Since pummelo is a monoembryonic and crosspollinated crop, vegetative propagation is critical for obtaining true-to-type plants. A study entitled “Performance of different genotypes of pummelo (Citrus grandis L.) for softwood grafting success and growth parameters” was carried out in the Department of Fruit Science, College of Horticulture Bengaluru in 2022. The experiment was laid out in a completely randomised design (CRD) with ten genotypes in three replications to know the response of softwood grafting success on locally gathered scions of elite Devanahalli pummelo genotypes was assessed. In February, they were grafted onto sixmonth-old rangpur lime rootstock. The results revealed that the genotype DSP-8 had recorded the significant minimum days (13) for bud breaking, the maximum graft success (96.67 %) and survivability (100.00 %). The genotype DSP-12 had a significantly maximum graft height at 30, 60, 90 and 120 days after grafting (DAG) (11.60, 14.73, 17.07 and 19.91 cm, respectively) and graft girth at 30, 60, 90 and 120 DAG (3.16, 3.95, 4.95, and 6.01 mm, respectively). Whereas the DSP-5 genotype had recorded significant maximum sprouts at 60, 90 and 120 DAG (3.67, 4.34 and 4.34, respectively) and the DSP-8 genotype had recorded the maximum number of leaves at 30, 60 and 120 DAG i.e., 7.67, 11.67 and 20.34. Among the different genotypes DSP-8 and DSP-12 recorded higher graft success, and these genotypes can be exploited for commercial production.

Review of designs of cultivators for agricultural care of forest crops

The article analyzes the designs of various types of cultivators, which are used to remove unwanted herbaceous and tree-shrub vegetation. Cultivators with disk, rotary, milling and tine working bodies are considered. It is shown that quite a lot of material resources are spent on carrying out agro technical care for valuable forest crops. It is noted that the mechanical method of soil care in the aisles and rows of forest crops has become widespread, despite the high costs. It was found that the rotary cultivators KRL-1M and KBL-1 during their movement cover seedlings up to 15 cm high with soil, and in plants 40-50 cm high and higher, when saddling a row, the apical bud breaks off, the bark is peeled off, side branches break. Damage to forest crops is about 8%. Damage and destruction of cultivated plants by the KRT-3 cultivator is 30%, and by the KFL-1.4 cultivator - 43%. Cultivator KRT-3 has low reliability. When meeting with stumps, the racks of the working bodies and wheels are deformed, and the paws are often broken. The milling cultivator KFL-1.4 also has low operational reliability.

Micropropagation of Hoya carnosa, H. kerrii, H. parasitica, and H. longifolia using tray-based floating and stationary hydroponic systems

Hoya is a wild ornamental plant with medicinal properties that have been extensively exploited from its natural habitat, causing a reduction at an alarming rate. The current study is aiming to fabricate an affordable and simple-to-use hydroponic system for the conservation and mass production of four Hoya species (H. carnosa, H. kerrii, H. parasitica, and H. longifolia). Tray-based floating and stationary hydroponic systems consist of Hoya plants (cuttings) inserted in a thermocol sheet and suspended in MS nutrient solution. Cuttings derived from mature plants were subjected to full MS (Murashige and Skoog), 1/2 MS, 1/3 MS, and 1/4 MS nutrient media for growth optimization. Subsequently, the ½ MS nutrient medium with explants was further augmented with different concentrations (0.5, 1.5, 2.5, 3.5, and 4.5 µM) of auxins like 1-naphthaleneacetic acid (NAA), indole-3-butyric acid (IBA), indole acetic acid (IAA) and IBA (2.5 µM) optimized for rooting. A combination of 1/2 MS + IBA (2.5 μM) proved to be the optimal medium for rooting in Hoya species when compared to all other treatments.Further, improvements in root number were recorded with augmentation of 25, 50, 100, 150, and 200 µM of Zinc Sulphate (ZnSO4). Half MS nutrient solution with 2.5 µM IBA and 100 μM ZnSO4 resulted a maximum of 15 roots in H. carnosa, 20 in H. parasitica, 38 in H. kerrii, and 19 in H. longifolia. The effect of 5.0 µM GA3 (Gibberellic acid) was also evaluated on bud break in rooted plants. Foliar spray of GA3 on acclimatized plants subsequently reduced the bud break time, and the highest reduction of time was observed from 21 d to 7 d in H. parasitica. Transfer of hydroponically raised plantlets was under stress during in vitro to field conditions. Stress markers (MDA, SOD, and CAT) for defense and photosynthetic pigments for better survival of hydroponically grown plants were monitored during acclimatization. MDA content was stable at 60 to 70 d while SOD and CAT activity was stabilized and influenced upon its peak on the same days under the poly-house condition in the propagated Hoya species. Photosynthetic pigments were gradually increased, and maximum values were recorded at 70 d of acclimatization. The present study proposed a reliable protocol for the conservation and mass propagation of most of the Hoya species.

In vitro Flowering and Production of Seeds in Oxalis corniculata L. - an Important Medicinal Plant

The multiple shoots (14.2) from Oxalis corniculata differentiated through bud breaking on MS medium with 2.0 mg/l BAP. The regenerated shoots were further sub-cultured on MS medium containing 1.0 mg/l BAP and 0.5 mg/l NAA. Vegetative to reproductive phase transition occurred in the cultures affected by plant growth regulators (PGRs), sucrose concentrations, strength of MS salts and light. Flower buds initiated from the regenerated shoots on half strength of MS salts with 1.0 mg/l Kn + 0.5 mg/l NAA and 3% sucrose. These flower buds opened under low light (10-15 μmol m-2 s-1) condition with 18h/6h photoperiod within 3 weeks of culture initiation. The shoots did not flower in the dark. Though smaller in size, the in vitro generated flowers were morphologically comparable to the natural flowers. Fruits were set in the cultures within 5 weeks. Plant Tissue Cult. & Biotech. 32(2): 193-203, 2022 (December)

Above- and belowground interplay: Canopy CO2 uptake, carbon and nitrogen allocation and isotope fractionation along the plant-ectomycorrhiza continuum.

In forests, mycorrhizal fungi regulate carbon (C) and nitrogen (N) dynamics. We evaluated the interplay among ectomycorrhizas (ECM), ecosystem C fluxes, tree productivity, C and N exchange and isotopic fractionation along the soil-ECM-plant continuum in a Mediterranean beech forest. From bud break to leaf shedding, we monitored: net ecosystem exchange (NEE, a measure of the net exchange of C between an ecosystem and the atmosphere), leaf area index, stem growth, N concentration, δ13 C and δ15 N in rhizosphere soil, ectomycorrhizal fine root tips (ERT), ECM-free fine root portions (NCR) and leaves. Seasonal changes in ERT relative biomass were strictly related to NEE and mimicked those detected in the radial growth. The analysis of δ13 C in ERT, leaves and NCR highlighted the impact of canopy photosynthesis on ERT development and an asynchronous seasonal C allocation strategy between ERT and NCR at the root tips level. Concerning N, δ15 N of leaves was negatively related to that of ERT and dependent on seasonal 15 N differences between ERT and NCR. Our results unravel a synchronous C allocation towards ERT and tree stem driven by the increasing NEE in spring-early summer. Moreover, they highlighted a phenology-dependent 15 N fractionation during N transfer from ECM to their hosts. This evidence, obtained in mature beech trees under natural conditions, may improve the knowledge of Mediterranean forests functionality.

Agave REVEILLE1 regulates the onset and release of seasonal dormancy in Populus.

Deciduous woody plants like poplar (Populus spp.) have seasonal bud dormancy. It has been challenging to simultaneously delay the onset of bud dormancy in the fall and advance bud break in the spring, as bud dormancy, and bud break were thought to be controlled by different genetic factors. Here, we demonstrate that heterologous expression of the REVEILLE1 gene (named AaRVE1) from Agave (Agave americana) not only delays the onset of bud dormancy but also accelerates bud break in poplar in field trials. AaRVE1 heterologous expression increases poplar biomass yield by 166% in the greenhouse. Furthermore, we reveal that heterologous expression of AaRVE1 increases cytokinin contents, represses multiple dormancy-related genes, and up-regulates bud break-related genes, and that AaRVE1 functions as a transcriptional repressor and regulates the activity of the DORMANCY-ASSOCIATED PROTEIN 1 (DRM1) promoter. Our findings demonstrate that AaRVE1 appears to function as a regulator of bud dormancy and bud break, which has important implications for extending the growing season of deciduous trees in frost-free temperate and subtropical regions to increase crop yield.

Earliness, Yield, and Fruit Quality Attributes of Low-Chilling Peach-Nectarine Cultivars with the Application of Low Biuret Urea and Calcium Nitrate

This study aimed to determine the effects of low biuret urea and calcium nitrate application on earliness, fruit set, yield, and fruit quality characteristics in ‘Astoria’, ‘Maya’ peaches, and ‘Garbaja’ nectarine cultivars. In the study, Bud Feed (low biuret urea 15%) and calcium nitrate (calcium oxide 12% and total nitrogen 7%) were applied 35 days before bud break. In this study, flowering and fruit set, harvest times, fruit yield, and quality characteristics were evaluated. The source of temperatures used to calculate chill accumulation (expressed as hours below 7°C and chill unit) and growing degree hours was investigated. Bud Feed application provided earliness of 2 days in ‘Astoria’ and ‘Garbaja’ cultivars and 3 days in ‘Maya’ cultivar. This application was showed positive effect on flowering and final fruit set in all cultivars compared to control plants. The application was more effective in increasing the yield per tree by 33.72% (‘Astoria’), 41.00% (‘Maya’), and 52.18% (‘Garbaja’). Bud Feed application was improved fruit size in ‘Garbaja’ and ‘Astoria’ cultivars, whereas provided more intense fruit skin color in ‘Maya’ and ‘Garbaja’ cultivars. These results showed that bud feed and calcium nitrate application can be used to prevent yield and fruit quality losses in peach-nectarines in warm winter under Mediterranean climate conditions.

The 'Candidatus Phytoplasma mali' effector protein SAP11CaPm interacts with MdTCP16, a class II CYC/TB1 transcription factor that is highly expressed during phytoplasma infection.

'Candidatus Phytoplasma mali', is a bacterial pathogen associated with the so-called apple proliferation disease in Malus × domestica. The pathogen manipulates its host with a set of effector proteins, among them SAP11CaPm, which shares similarity to SAP11AYWB from 'Candidatus Phytoplasma asteris'. SAP11AYWB interacts and destabilizes the class II CIN transcription factors of Arabidopsis thaliana, namely AtTCP4 and AtTCP13 as well as the class II CYC/TB1 transcription factor AtTCP18, also known as BRANCHED1 being an important factor for shoot branching. It has been shown that SAP11CaPm interacts with the Malus × domestica orthologues of AtTCP4 (MdTCP25) and AtTCP13 (MdTCP24), but an interaction with MdTCP16, the orthologue of AtTCP18, has never been proven. The aim of this study was to investigate this potential interaction and close a knowledge gap regarding the function of SAP11CaPm. A Yeast two-hybrid test and Bimolecular Fluorescence Complementation in planta revealed that SAP11CaPm interacts with MdTCP16. MdTCP16 is known to play a role in the control of the seasonal growth of perennial plants and an increase of MdTCP16 gene expression has been detected in apple leaves in autumn. In addition to this, MdTCP16 is highly expressed during phytoplasma infection. Binding of MdTCP16 by SAP11CaPm might lead to the induction of shoot proliferation and early bud break, both of which are characteristic symptoms of apple proliferation disease.

Cold Climate during Bud Break and Flowering and Excessive Nutrient Inputs Limit Apple Yields in Hebei Province, China

Apples have become a major source of income for smallholder farmers in Bohai Bay. However, the annual productivity of apples in the area is relatively low and the interannual yield gap varies drastically. Identifying the apple yield gap and interannual production constraints can potentially promote the sustainable development of apple production. Based on track monitoring data of 45 smallholder farmers from 2016 to 2018, the yield gap and constraint factors were determined by adopting boundary analysis methodology. The results showed that the yield potential of apples during 2016–2018 was 75, 108, and 87 t ha−1, and actual yields were 36.8, 52.3, and 35.2 t ha−1, respectively. The explainable yield gaps were 40.5, 56.9, and 55.1 t ha−1. Soil, management, and climatic factors limit apple yield improvement. Among these, low temperatures during the bud break and flowering periods can induce yield losses. Soil nutrient content and fertilizer management are also important limiting factors that have polynomial relationships with yield. Too much fertilizer and high levels of nutrients in the soil have already caused yield losses in some fields. Sound scientific guidance to help farmers adopt reasonable management techniques adapted to climate change is necessary to close the yield gap.

Higher spring phenological sensitivity to forcing temperatures of Asian compared to European tree species under low and high pre-chilling conditions

Winter chilling, spring forcing temperature and photoperiod are the most important drivers explaining the spatial and temporal variability of spring phenology in temperate trees. However, how these factors interact with each other on dormancy release and spring budburst date remains unclear and varies greatly depending on species. Our knowledge is also limited as to whether heat accumulation of forcing temperatures that trigger bud break in spring is a linear or non-linear process. Here, we aimed at experimentally quantifying the effect of chilling, forcing, photoperiod and their interactions on the budburst dates of nine different temperate tree species from East Asia (near Beijing, China) and Central Europe (near Zurich, Switzerland), including six phylogenetically related species (same genus). We conducted a full factorial experiment in climate chambers using two chilling (low and high, i.e., 0 vs. 56 days at 2°C after sampling at the end of December), four forcing (5, 10, 15, and 20°C), and two photoperiod (8 vs. 16 h) treatments simultaneously in Beijing and Zurich. We found that species growing near Beijing responded more readily to forcing conditions than species of the same genus growing near Zurich regardless of chilling treatment. Budburst timing of most species but European beech was marginally, if at all, affected by photoperiod. Furthermore, our results suggest that linear heat accumulation, as commonly used with the growing degree hours (GDH) model, could result in accurate prediction of budburst date depending on the temperature threshold used as a basis for heat accumulation. Our results also demonstrate the important role of chilling in shaping the sensitivity and rate of forcing accumulation to trigger budburst and suggest that species-specific sigmoid relationship for accumulating heat that accounts for prior chilling exposure may yield better predictions of budburst dates. Our results suggest that deciduous trees may have adapted their chilling and forcing requirements in regards to the predictability of winter-spring transition and late spring frosts. A less predictable winter-spring transition, as observed in Central Europe, could have driven species evolution towards higher chilling and forcing requirements compared to species growing in a more predictable climate of Northeastern Asia. Our cross-continental experiment therefore suggests that the spring phenology of East Asian species is tighter coupled to spring forcing temperature than Central European forests.

Evoluția fenofazelor de dezvoltare a unor specii de arbuști fructiferi în Republica Moldova

The paper presents the results of the study carried out regarding the development of the phenological phases of plant development of some species of fruit bushes in the Central area of the Republic of Moldova (the period of bud break, flowering and fruit ripening). It was established that the phenological phases of the studied species: raspberry (Rubus idaeus), black currant (Ribes nigrum), red currant (Ribes rubrum) and white currant (Ribes niveum), gooseberry (Ribes grossularia L.), Josta (Ribes x nidigrolaria), blackberry (Rubus caesius L.), sea buckthorn (Hippophae rhamnoides L.), honeysuckle (Lonicera kamtschatica), blueberry (Vaccinium corymbosum L.), dogwood (Viburnum opulus L.), chokeberry (Aronia melanocarpa Elliott), rose hip (Rosa rugosa Thunb), most of them having an early start in vegetation, which coincides with March, flowering takes place in April, and ripening – in June–July. Exceptions are: honeysuckle, with the earliest vegetation (03–09.03), flowering between 30.03 and 26.04 and ripening fruits in the second half of May (19–25.05); raspberries enter vegetation later (09–21.04), bloom on throughout May, and ripening takes place staggered in June, remontant raspberry varieties begin to bloom in July and ripens staggered in August; blackberry, with the latest onset of vegetation and the latest flowering (18.05–04.06), thus avoiding late spring frosts. Ripening takes place in stages at the beginning of July.

In vitro Propagation of Curcuma caesia Roxb. via Bud Culture Technique and ISSR Profiling of the Plantlets for Genetic Homogeneity

An in vitro propagation protocol has been developed for Curcuma caesia Roxb., an endangered medicinal plant by Foundation for Revitalisation of Local Health Traditions and Central Forest Department of India. The plant bears poorly germinated seeds and produces two-storage organs: rhizomes and multiple root tubers. Only rhizomes have medicinal-economic values. They serve as propagules too, which results in a shortage of planting material. Therefore, a complete one-year production cycle of C. caesia has been standardized through in vitro propagation including explants establishment (one month), subculture cycles (seven months), rooting (one month) followed by primary hardening (one month) and secondary hardening (two months). Dormant shoot buds on rhizome served as explants for culture initiation on Murashige and Skoog (MS) medium supplemented with different concentrations of 6-benzyladenine (BA) and kinetin (KIN) in combination with citric acid (CA), adenine sulfate (AdS) and indole- 3-acetic acid (IAA). Maximum bud break (70%) was obtained on MS with 8 mg L-1 BA, 8 mg L-1 KIN, 100 mg L-1 CA, 200 mg L-1 AdS and 2 mg L-1 IAA (standard medium). Shoot production potential continued on this medium during the subsequent seven-month-long subculture cycle. The in vitro raised shoots rooted best on ½-strength MS containing 1 mg L-1 indole-3-butyric acid. Plantlet survival rate was >95% after acclimatization. The genetic homogeneity of plantlets with the mother plant was analyzed using Inter Simple Sequence Repeats which generated a monomorphic banding pattern to confirm the uniformity of in vitro raised plantlets of C. caesia.

Antioxidant system: The hub of bud dormancy regulation in Prunus sp.

Global warming, through affecting the dormancy progression of temperate fruit trees, has a profound impact on bud break, flowering and fruiting performance. This may lead to economic losses in the production of the genus Prunus sp., which cultivation is common in temperate regions worldwide, producing edible drupes such as almond, apricot, cherry, plum, peach and nectarines. To overcome climate change-related fruit tree disorders, knowledge on the biochemical mechanisms governing bud dormancy and dormancy release is essential. In this review, we gather knowledge on the understanding of bud dormancy in Prunus. Herewith, the antioxidant system is situated in the hub of a process where metabolic, physiological, biochemical and molecular components are linked in a complex manner. Moreover, the knowledge on the use of oxidative stress-related compounds to regulate dormancy release in Prunus is summarized. Finally, future research directions in this field are outlined.

Contents of nitrogen compounds during bud break and peach tree performance in response to budburst-inducing products

The growth of peach orchards in subtropical regions depends on the minimal requirements for chilling accumulation, and crop loading requires sprays of chemical compounds to overcome dormancy, induce bud break, and allow adequate flowering and fruiting. The ability of hydrogen cyanamide, nitrogen fertilizer and calcium nitrate to break the dormancy of ‘BRS Kampai’ peach trees and their effects on nitrogen, tryptophan, and polyamine contents in buds were evaluated. Furthermore, budburst, flowering, fruit set percentage, flowering period, tree performance, and bioactive compound content in the fruits were assessed. The study was undertaken in São Paulo state, a subtropical region of southeast Brazil, and the field experiment was carried out in two crop seasons. Short flowering duration and higher percentages of budburst, flowering, and fruit setting were correlated with higher nitrogen content in vegetative buds and spermidine contents in flower buds. The better performance of hydrogen cynamide, compared with other treatments, was confirmed by the anticipation, patterning, and increase in budburst, flowering, and fruit setting, associated with high levels of spermidine in the flower buds. Hydrogen cyanamide also increases the concentration of antioxidant compounds in fruits. Hydrogen cyanamide and the combination of nitrogen fertilizer and calcium nitrate enhanced yield and production efficiency and are recommended for inducing budburst in subtropical regions.

Recommended resistant grape variety Traminette for quality winemaking

Тhe purpose of the variety study of the introduced white wine grape variety Traminette, originate at Cornell University, New York, USA in 1965, was to analyze the feasibility of its cultivation in the conditions of the northern zone of the industrial viticulture of the Russian Federation, for which the next objective were set: study in concrete soil and climatic conditions agrobiological and economically valuable characteristic and properties of the Traminette variety, such as yield, plasticity, resistance to biotic and abiotic environmental factors, as well as assess the quality of the resulting dry wine. To facilitate the identification of this variety, we made an ampelographic description according to the leading features. Тhe study was carried out in 2019-2021 according to the methods generally accepted in viticulture and winemaking in the grafted nursery of the Novocherkassk Experimental Field of the All-Russian Research Institute named after Ya.I. Potapenko for Viticulture and Winemaking – Branch of Federal State Budget Scientific Institution «FRARC» (Novocherkassk, Rostov Region). Тhe plantations are non-covered, non-irrigated, grafted, obtained by green grafting on the planted rootstock Oppenheim CO-4, planting scheme 3×1.5 m, medium-bole bush fan-shaped, medium pruning (4-6 buds left on the spoor). Тhe technology of cultivation of vineyards is standard and generally accepted. Тhe white wine variety Traminette of early-medium terms of grape ripeness, according to the variety study in the conditions of Novocherkassk, demonstrated winter hardiness sufficient for non-covering vineyards (the average long-term percentage of bud break is 79.8 %), high yield (10.2 t/ha), and increased resistance to fungal diseases (powdery mildew, downy mildew – 3.0, botrytis 1.5), excellent points for assessing dry wine material (8.7). All this makes the Traminette variety promising for use in industrial production in non-covering culture, with a decrease in the number of sprays compared to classical varieties, to obtain high quality wines.

A comparative proteomic analysis provides insight into the molecular mechanism of bud break in longan

BackgroundThe timing of bud break is very important for the flowering and fruiting of longan. To obtain new insights into the underlying regulatory mechanism of bud break in longan, a comparative analysis was conducted in three flower induction stages of two longan varieties with opposite flowering phenotypes by using isobaric tags for relative and absolute quantification (iTRAQ).ResultsIn total, 3180 unique proteins were identified in 18 samples, and 1101 differentially abundant proteins (DAPs) were identified. “SX” (“Shixia”), a common longan cultivated variety that needs an appropriate period of low temperatures to accumulate energy and nutrients for flower induction, had a strong primary inflorescence, had a strong axillary inflorescence, and contained high contents of sugars, and most DAPs during the bud break process were enriched in assimilates and energy metabolism. Combined with our previous transcriptome data, it was observed that sucrose synthase 6 (SS6) and granule-bound starch synthase 1 (GBSSI) might be the key DAPs for “SX” bud break. Compared to those of “SX”, the primary inflorescence, axillary inflorescence, floral primordium, bract, and prophyll of “SJ” (“Sijimi”) were weaker. In addition, light, rather than a high sugar content or chilling duration, might act as the key signal for triggering bud break. In addition, catalase isozyme 1, an important enzyme in the redox cycle, and RuBisCO, a key enzyme in the Calvin cycle of photosynthetic carbon assimilation, might be the key DAPs for SJ bud break.ConclusionOur results present a dynamic picture of the bud break of longan, not only revealing the temporal specific expression of key candidate genes and proteins but also providing a scientific basis for the genetic improvement of this fruit tree species.

Topophysis and Growth Regulators Effects on Buds and Zygotic Embryos Regeneration of African Bush Mango Tree Cultured In vitro

Background: African bush mango tree is an important fruit plant with high nutritional, medicinal, and commercial values. However, its seedling system remained a deep understanding. This study aimed to evaluate the effect of topophysis and growth regulators on the reactivity of different types of buds and zygotic embryos of wild mango.
 Methodology: Ripe fruits from two local varieties (Wossro and Sissro) were pulped. The nuts were extracted and dried for one week under greenhouse. Zygotic embryos were excised from nuts and disinfected with the bleach solution (NaClO 10% with 8% active chloride) for 10 min following by three successive rinsing using sterilized water. The second set of nuts was cultivated for under greenhouse in the polybags containing the sand. One month later, buds from different positions (apical, axillary and cotyledonary) were excised and disinfected with NaClO 10% for 10 min follow by the immersion in a mercuric chloride 0.1% added with two drops of Tween 20 especially for axillary and cotyledonary buds for 5 min while 0.01% of mercuric chloride was used for apical buds. The explants were cultured on ¼MS and ½WPM media supplemented with BAP, KIN at different concentrations (0.2 mg/L and 3.5 mg/L respectively) and NAA (0.05 mg/L).
 Results: The best sprouting rate was obtained with the variety Wossro which showed a high bud break rate (26.47%) against (9.88%) for the variety Sissro. The topophysis significantly influenced the response of the buds in tissue culture. 24.48% of axillary buds were sprouted on ¼ MS medium + 3.5 mg/L BAP+ 0.05mg/L NAA. The in vitro germination of embryos was significantly (p≤ 0.05) influenced by the genotype of the variety. 50.76% of buds were germinated for Wossro while 18.32% were germinated for Sissro. ¼ MS + 0.2 mg/L KIN has significant influenced the plants growth and development.
 Implication: The findings will help to improve the regeneration rate and plantlets production of African bush mango tree.

Adaptation of white spruce to climatic risk environments in spring: Implications for assisted migration

The timing of spring dormancy release and bud break in trees is an adaptive trait with potentially important management implications. Depending on how spring phenology is controlled, climate warming may disrupt the synchronization of bud break with the available growing season. Further, addressing climate change through human assisted migration in reforestation programs could cause additional problems if phenology triggers of source and target locations differ. Here, we assess how phenology is controlled by heat sum and chilling requirements for a widespread and commercially important boreal tree species, white spruce (Picea glauca) in a range-wide common garden experiment. We find significant genetic population differentiation in heat sum requirements ranging from 390 to 450 degree days among regions (±12 average SE), and from 375 to 500 (±16) degree days among populations within regions. The most northern populations showed the lowest heat sum requirements, which could be explained by frost avoidance or growth optimization strategies. Our data favors a frost avoidance hypothesis, although the explanations are not mutually exclusive. Chilling requirements in white spruce were also found (approx. 15 degree days), but they showed no geographic population differentiation. Due to generally low chilling requirements, we do not anticipate de-synchronization of spring phenology with the growing season under climate warming in spruce. Synthesizing results from this study and other research on additional growth and adaptive traits, we conclude that assisted migration northward, compensating for approximately 2° C warming, is safe and yields higher growth rates for white spruce.