Summer Pruning Research Articles

Evaluation of carbon balance and carbohydrate reserves from forced (Vitis vinifera L.) cv. Tempranillo vines.

Elevated temperatures during berry ripening have been shown to affect grape quality. The crop forcing technique (summer pruning that 'force' the vine to start a new cycle) has been shown to improve berry quality by delaying the harvest date. However, yield is typically reduced on forced vines, which is attributed to vine low carbon availability soon after forcing and likely incomplete inflorescence formation. The present study aims to estimate the carbon balance of forced vines and evaluate vine responses to changes in carbon patterns due to forcing. Three treatments were studied on Tempranillo cultivar: non-forced vines (Control), vines forced shortly after fruit set (CFearly) and vines forced one month later at the beginning of bunch closure (CFlate). Whole canopy net carbon exchange was modelled and validated using two whole canopy gas exchange chambers. In addition, non-structural carbohydrate reserves at budburst, forcing date and harvest, were analysed. Yield, yield components and vegetative growth were also evaluated. Harvest date was delayed by one and two months in the CFearly and CFlate, respectively, which increased must acidity. However, yield was lower in the forced treatments compared to the Control (49% lower for CFearly and 82% for CFlate). In the second year, at the time when CFearly and CFlate dormant buds were unlocked (forced budburst), forced vines had significantly lower non-structural carbohydrates than Control vines at budburst. Although the time elapsed from budburst to reach maximum net carbon exchange was longer for the Control treatment (80 days) than for the forced treatments (about 40 days), average daily net carbon exchange until harvest was comparable between Control (60.9 g CO2/vine/day) and CFearly (55.9 g CO2/vine/day), but not for CFlate (38.7 g CO2/vine/day). In addition, the time elapsed from budburst to harvest was shorter in forced treatments (about 124 days) than for the Control (172 days). As a result, the cumulative net carbon exchange until harvest was reduced by 35% (CFearly) and 55% (CFlate) in the forced treatments. However, no differences in carbon reserves at harvest were observed between treatments partly helped by the higher source:sink ratio observed in forced than Control vines.

Current trends and future perspectives towards sustainable and economically viable peach training systems

• Intensification of peach planting systems aims at facilitating mechanization and reduce labor cost. • High-density 2-D walls are recommended for intensive and highly mechanized systems with limited accessible labor. • Medium-density 3-D small open vases are recommended for low frost-risk areas and farms with fully available labor. • The employment of multifunctional net protection on high-density orchards can counteract the adverse effects of climate change. • Soil conservative management is suggested towards environmentally sustainable peach orchards through augmentation of carbon sequestration. Considering the limited areas suitable for peach cultivation, the short life cycle of the orchards, as well as aspects regarding appropriate rootstock availability and soil properties due to replant conditions, the sustainable intensification became increasingly necessary on peach production systems. Based on the local environment and labor availability, two new training systems have been introduced and are being widely adopted towards efficient small canopies for high- and medium-density orchards, respectively. The so-called two-dimensional (2-D) fruiting wall is an intensive, highly-mechanized/high-density training system and is commonly accompanied by multifunctional net protection in order to counteract the adverse effects of climate change. On the other hand, the medium-density three dimensional (3-D) small open vase is suitable for low frost-risk areas and farms with fully available manpower. In both cases, the decisions taken during the orchard establishment and the first years regarding soil fertility and orchard mechanization have strategic importance to guarantee a sustainable peach production system on both quantitative and qualitative terms. The employment of both spring and summer pruning increases work efficiency and improves fruit quality, as well as fruit thinning, management efficiency and mechanization. Sustainable intensification not only reshapes the use of chemicals and irrigation, but also weed control and soil amendment with organic matter to support the complexity and heterogeneity of the agroecosystem with the circular economy.

Reducing the Losses of Three Local Grape Varieties (Vitis vinifera L.) by Cool Storage Period.

Three local varieties of grapevine (Vitis vinifera L. Jnoby, Sulaimana- Rash and Zaitony); were taken from a private vineyard in Sian village, Dinarta, Duhok, Kurdistan region-Iraq after the distinctive signs of maturity appeared for each variety from healthy grapevines of 6-years old which planted at 2×3 m spacing and irrigated by drip irrigation system for study the effect of storage periods (0, 20, 40 and 60 days at 2±1 °C and 83-88% RH) on chemical and physical characteristics plus the loss of grape berries and clusters. The vines received conventional cultivation practices with regular winter and summer pruning, weed and diseases control. Berry shattering, spoilage, weight loss, total loss and rachis condition for the varieties were estimated as a function to storage in this study. Results showed that the maximum berry shattering (1.71%) was recorded in Sulaimana-Rash variety showing a significant difference with Jnoby variety (0.48%). The highest values of percent spoilage and total loss were recorded in variety Zaitony (20.17 and 26.36%) respectively. The maximum weight loss (10.24 %) was recorded in variety Jnoby which was significantly higher than the other two varieties (Sulaimana-Rash and Zaitony). Spoilage percentage, weight loss and total loss significantly increased with increasing storage periods (23.48, 12.13 and 32.83%) respectively. There were significant interaction effects on weight loss and total weight loss percentages among the varieties, the storage periods showed a maximum value was started after 60 days of the beginning of storage (14.33%) in Jnoby variety, while highest total loss (60.25%) was recorded in Zaitony.

Pear Tree Growth Simulation and Soil Moisture Assessment Considering Pruning

Few studies deal with the application of crop growth models to fruit trees. This research focuses on simulating the growth process, yield and soil moisture assessment of pear trees, considering pruning with a modified WOrld FOod Studies (WOFOST) model. Field trials (eight pruning treatments) were conducted in pear orchards in Alaer and Awat in Xinjiang, China and data were measured to calibrate and evaluate the modified model. In two pear orchards, the simulated total dry weight of storage organs (TWSO) and leaf area index (LAI) were in good agreement with the field measurements of each pruning intensity treatment, indicating that the R2 values of TWSO ranged from 0.899 to 0.976, and the R2 values of LAI ranged from 0.849 to 0.924. The modified model also showed high accuracy, with a normalized root mean square error (NRMSE) ranging from 12.19% to 26.11% for TWSO, and the NRMSE values for LAI were less than 10%. The modified model also had a good simulation performance for the soil moisture (SM) under all eight pruning intensity treatments, showing good agreement (0.703 ≤ R2 ≤ 0.878) and low error (NRMSE ≤ 7.47%). The measured and simulated results of different pruning intensities showed that the highest yield of pear trees was achieved when the pruning intensity was about 20%, and the yield increased and then decreased with the increase in pruning intensity. In conclusion, the modified WOFOST model can better describe the effects of summer pruning on pear tree growth, yield and soil moisture than the unmodified model, providing a promising quantitative analysis method for the numerical simulation and soil moisture assessment of fruit tree growth.

Summer pruning on seedless barberry: preliminary results on alternate bearing behavior

Summer pruning on seedless barberry: preliminary results on alternate bearing behavior

Responses of soil respiration and microbial community structure to fertilizer and irrigation regimes over 2 years in temperate vineyards in North China

Fertilizer and irrigation regimes can profoundly affect soil carbon (C) emissions, which influence soil organic carbon (SOC) storage. However, information regarding the effects of fertilizer and irrigation management on the components of soil respiration (Rs) and the underlying microbial community characteristics in vineyard ecosystems remains limited. Therefore, a 2-year field experiment was conducted in a wine-grape vineyard (WGV) and a table-grape vineyard (TGV). Each vineyard included two fertilizer and irrigation regimes: farmers' practice (FP) and recommended practice (RP). The trenching method was employed to separate Rs into heterotrophic respiration (Rh) and autotrophic respiration (Ra). Additionally, the SOC storage and soil microbial community structure at 0–20 cm soil depth were determined after the 2-year experiment. The results showed that the fertilizer and irrigation regimes caused no effect on Ra. Compared with the FP treatment in WGV and TGV, the RP treatment significantly (P < 0.05) decreased the average daily Rh by 15.13 % and 17.11 %, which contributed to the annual Rs values at the whole-vineyard scale decreased by 8.93 % and 11.78 %, respectively. Besides, compared with the initial value, the SOC storage under RP treatment were effectively increased by 6.39 % and 6.33 % in WGV and TGV, respectively. Low annual total Rh was partially ascribed to the significant (P < 0.05) decline in Proteobacteria and Bacteroidetes relative abundance, thus reducing the decomposition rate of SOC. Compared with WGV, the fertilizer and water input was higher in the TGV, which resulted in the annual total Rs and Rh values at the whole-vineyard scale was increased by 11.53 % and 15.74 %, respectively, while the annual total Ra was decreased by 18.83 % due to the lower grapevine density and more frequent summer pruning. Overall, RP treatment was found to be a suitable strategy for reducing soil C emissions and benefiting SOC storage in vineyards around North China.

Long-term summer pruning in peach trees: is it an advisable cultural practice?

Long-term summer pruning in peach trees: is it an advisable cultural practice?

Changes of Vine Water Status and Growth Parameters Under Different Canopy Managements on cv. Merlot (Vitis vinifera L.)

The climate is the dominant regulator that determines the cultivation in a viticulture region as it strongly controls vine physiology, vine growth, canopy microclimate, berry quality and finally wine components. However, the effects of climate change force vine producers to find solutions that will facilitate their adaptation processes. The importance of water management in vineyards is becoming more important every day for sustainable viticulture and winemaking. Efficient use of water in vineyards is an important issue to control the yield and to provide the targeted berry quality at the desired level. This experiment was carried out during the 2013-2014 and 2015 growing seasons to evaluate the effects of green pruning practices on water leaf potentials of 12-14 years old grapevines of cv. Merlot (Vitis vinifera L.) grafted onto Kober 5BB in the experimental vineyard of Tekirdag Viticulture Research Institute in Turkey. A completely randomized block design was used: LRMS1, LRMS2, LRMS3 represent three levels of leaf removal treatments on main shoots and LRLS1, LRLS2, LRLS3 represent three levels of leaf removal treatments on lateral shoots. Due to the relatively high soil moisture in vineyard conditions, no extreme and high-water stress levels was observed in experiment years. The main factor controlling the water status in cv. Merlot vines was largely dependent on the meso-climatic conditions and soil water availability during the growing season. However it was observed that increasing of main shoot length give rise to tendency to water stress. It was determined that leaf removal treatments on lateral shoots caused changes in shoot weight, pruning weight and Ravaz index (RI), especially in 2014 whereas the leaf removal treatments on main shoots caused changes in mentioned parameters in 2015. In conclusion, the results show that plant water condition can be managed with summer pruning taking into account of different climatic conditions and different phenological stages. Planning of canopy management practices should be done by considering long- and medium-term meteorological evaluations while short-term planning within vegetation period should be done in relation to weekly and monthly meteorological data.

Effect of Sustainable Preharvest and Postharvest Techniques on Quality and Storability of High-Acidity ‘Reinette du Canada’ Apple

Consumers are more disposed towards paying price premiums for sustainable food products. This fact is especially important for products with a PDO (Protected Designation of Origin) label, such as the high-acidity apple cultivar ‘Reinette du Canada’. However, ‘Reinette du Canada’ apple fruit is affected by two of the main post-harvest disorders in apple cultivars, bitter pit and senescent breakdown. As a means to achieve sustainable production of this high-quality apple cultivar, the effect of a sustainable preharvest technique, summer pruning, in combination with a zero-residue postharvest treatment allowed in organic farming on calcium-related disorders and quality in global terms in this PDO-labelled apple cultivar was assessed during storage. The combination of the two sustainable practices was an effective tool in diminishing senescent breakdown from 43% to 17% and to decrease bitter pit incidence by up to 21% (from 36% to 15%) throughout storage, especially in fruit with high susceptibility to this disorder during storage. Moreover, the overall acceptability was kept high (values of more than 3 on a 5-point scale) when applying this environment-friendly sustainable horticulture practice, which will not only reduce the synthetic pesticide input in the apple agroecosystem, but also contribute to producing fruit with zero residues.

Late summer pruning improves the quality and increases the content of functional compounds in Fuji apples

The objective of this paper was to evaluate the effect of the time of summer pruning on the quality of Fuji apples, on the red color and functional properties, at harvest and after 3.5 months of cold storage. The treatments evaluated consisted of the control (without summer pruning) and summer pruning in December, January, and February. The percentage of fruit with more than 50% red color on the skin was 20.5% higher when summer pruning was performed later than when performed early. In general, summer pruning in January and February provided fruit with a relatively high content of anthocyanins (19 and 25.1 mg cyaniding 3-glycoside·100 g-1 FW, respectively), relatively high values of total phenolic compounds (370.1 and 438.7 mg EAG·100 g-1 FW, respectively) and total antioxidant activity by the 2,2-diphenyl-1-picrylhydrazyl (DPPH) method (8,097.5 and 8,089.2 µMol Trolox·100 g-1 FW, respectively) in the 2017/18 season. Summer pruning did not affect fruit quality after cold storage. Summer pruning performed in January or February increased functional compounds content and improved red color, while in February it increased flesh firmness.

High-density ‘Spadona’ pear orchard shows reduced tree sensitivity to fire blight damage due to decreased tree vigour

Fire blight, caused by Erwinia amylovora, is a severe disease of pear (Pyrus communis). Highly vigorous trees are more sensitive to E. amylovora damage after summer pruning. Trees grown in high-density orchards have lower vigour than those in low-density orchards, reducing required inputs for pruning and tying, and increasing per hectare yields orchard profitability. Tree damage due to fire blight was assessed in high-density pear orchards vs. the common Israeli low-density orchards. Pear trees were planted at high densities using the spindle system (2500 trees ha-1 for ‘Spadona’ and 1250 trees ha-1 for ‘Coscia’), or at low density (1000 trees ha-1) using palmeta (’Spadona’) or open vase (‘Coscia’) systems. Four years after planting, both orchards were similarly infected with fire blight (11–50 infected blossoms per tree), but 1 year after infection, trees in the high density orchard had blossoms infections in the main limbs or trunk bases compared to the low-density orchard. At 3 years after initial infection, no trees had died in the high density orchard, whereas in the low density ‘Spadona’ orchard, 10% of the trees were wilted. For the more tolerant ‘Coscia’, infection did not progress at either orchard density. These results indicate that in fire blight-susceptible pear cultivars, a high density planting system, associated with reduced tree vigour, presents a decreased risk of fire blight damage.

Summer Pruning, an Eco-Friendly Approach to Controlling Bitter Pit and Preserving Sensory Quality in Highly Vigorous Apple cv. ‘Reinette du Canada’

Summer pruning reduces vegetative growth in apple trees, but it could have an impact on fruit quality. This study analyzed the effects of summer pruning as an eco-friendly pre-harvest alternative to chemical growth regulation inputs on instrumental and sensory quality of highly vigorous apple cv. ‘Reinette du Canada’, which has been awarded with a Protected Designation of Origin label in two environments. The results showed that summer pruning affected the mineral content of the fruit. Summer pruning reduced bitter pit, but it did not negatively affect fruit weight nor any other instrumental characteristic during storage. Moreover, sensory quality or degree of liking were not affected by summer pruning. Thus, summer pruning could be an eco-friendly pre-harvest alternative to chemical treatments to improve quality in global terms of ‘Reinette du Canada’ apple cultivar, regardless of the location. This technique contributed to the decrease of bitter pit incidence, but did not decrease sensory quality nor degree of liking.

Assessment of Nutritional and Quality Properties of Leaves and Musts in Three Local Spanish Grapevine Varieties Undergoing Controlled Climate Change Scenarios.

The market demand together with the need for alternatives to withstand climate change led to the recovery of autochthonous grapevine varieties. Under climate change, the summer pruning of vineyards may lead to an increase of vegetative residuals of nutritional and medicinal interest. The objectives of our study were (1) to evaluate the nutritional properties of the leaves of three local Spanish grapevines (Tinto Velasco, TV, Pasera, PAS, and Ambrosina, AMB) when grown under climate change conditions, and (2) to test the potentiality of these grapevines as suitable candidates to be cultivated under climate change scenarios based on the quality of their must. Experimental assays were performed with fruit-bearing cuttings grown in temperature gradient greenhouses that simulate rising CO2 (700 μmol mol−1) and warming (ambient temperature +4 °C), either acting alone or in combination. TV and AMB were the most and the least affected by air temperature and CO2 concentration, respectively. The interaction of elevated CO2 with high temperature induced the accumulation of proteins and phenolic compounds in leaves of TV, thus enhancing their nutritional properties. In PAS, the negative effect of high temperature on protein contents was compensated for by elevated CO2. Warming was the most threatening scenario for maintaining the must quality in the three varieties, but elevated CO2 exerted a beneficial effect when acting alone and compensated for the negative effects of high temperatures. While TV may be a candidate to be cultivated in not very warm areas (higher altitudes or colder latitudes), PAS behaved as the most stable genotype under different environmental scenarios, making it the most versatile candidate for cultivation in areas affected by climate change.

Actinidia (Mini Kiwi) Fruit Quality in Relation to Summer Cutting

Recently, there has been a trend towards healthy food. Consumers are looking for products that have health-promoting properties in addition to their taste. Actinidia fruit, apart from being tasty, contains valuable macro and micronutrients, vitamins, polyphenols and pectins. Tested cultivar Sientiabrskaja belong to Actinidia arguta and cultivars Geneva, Issai and Ken’s Red to A. kolomitka. They well tolerate conditions of moderate climate with negative temperatures in winter. To improve fruit quality, an additional summer pruning of the plants was performed at the time of ripening. After the second additional cutting of Actinidia shoots, an increase in the content of N, P and K in fruit was observed. The additional pruning also had a beneficial effect on the change in fruit color. The fruits were darker, especially in the cultivars Geneva and Ken’s Red. This is related to the ripening of fruit and an increase in anthocyanin content. Additional summer pruning caused changes in the polyphenol content-the amount of phenolic acid and flavan-3 ols decreased, while the level of anthocyanins increased. The antioxidant capacity also increased as well as fruit size, dry matter, pectin and Soluble Solid Content (SSC) content. The acidity of the fruit also decreased which positively affects the taste of the fruit. The highest content of polyphenols and L-ascorbic acid was found in ‘Sientiabrskaja’ fruit; but the highest antioxidant activity (determined Free Radical Diphenylpicrylhydrazyl-DPPH•, ABTS•+ and Ferric Antioxidant Power-FRAP) was found in fruit with red skin coloring and anthocyanins-‘Issai’ and ‘Ken’s Red’.

Exploring fungicides and sealants for management of Cytospora plurivora infections in western Colorado peach production systems

Cytospora plurivora, in western Colorado, is a limiting factor to peach production. The pathogen requires a wound, and entry points can be ubiquitous on peach trees depending on the season because of the need for tree cultural management (eg. dormant and/or summer pruning) and annual winter damage. Our study is focused on preventive control of the pathogen through wound protection. Fungicides and sealants were either evaluated in vitro, for antifungal activity, or selected from the present and previous trials to be evaluated in the field. Ten fungicide/sealant combinations were evaluated in the field for pathogen control during spring of 2018 and 2019 in western Colorado. Treatments included combinations of thiophanate-methyl, lime sulfur, VitiSeal (alone and in combination with other chemicals), with sealants (latex paint, paraffinic oil, and Nu-film 17). The fungicides/sealants that were most effective in reducing C. plurivora pathogen viability in branches and canker sizes was thiophanate-methyl alone, combined with VitiSeal, and combined with latex paint at 50 and 70% and VitiSeal combined with lime sulfur. The sealants Nu-film 17 and paraffinic oil, when combined with lime sulfur, were ineffective in all trials. Further, fungicides which showed evidence of efficacy in these studies and in previous studies were analyzed for their half maximum effective concentration rates (EC50) for an understanding of pathogen dose sensitivity.

Summer pruning improves the branch growth and tea quality of tea trees (Camellia sinensis)

At present, twice-a-year pruning is usually adopted for the tea garden, in which only spring tea is picked. Effects of different times and heights of summer pruning on tea trees are unknown. Here the effects of summer pruning on ‘Jin Guan Yin’ oolong mature tea trees were studied. The results showed that pruning at 30 cm (summer pruning at 30 cm above the cut surface of spring pruning) on Jul 25 could benefit to the growth of lateral branches, whereas two pruning treatments in August reduced their growth vigor. Pruning at 30 cm could also provide a benefit by decreasing the ratio of total tea polyphenols to free amino acids (TP/AA), an important factor in tea quality. Pruning at 30 cm and two pruning in August all significantly enhanced the contents of ester catechins [‘(−)-epigallocatechin gallate (EGCG) + (−)-epicatechin gallate (ECG)’] as compared to conventional summer pruning. Pruning on Aug 15 (summer pruning at 20 cm on Aug 15) had the lowest (EGCG + ECG)%. In addition, enhanced AA content induced by pruning at 30 cm was significantly associated with enhanced transcription of glutamine synthetase (CsGS) or glutamine:2-oxoglutarate aminotransferase (CsGOGAT). In a word, the summer pruning at 30 cm on Jul 25 was best to benefit the growth of lateral branches and spring tea yield and quality, whereas pruning on Aug 15 had the worst comprehensive effects.

Spatio-Temporal Distribution and Fixed-Precision Sampling Plan of Scirtothrips dorsalis (Thysanoptera: Thripidae) in Florida Blueberry.

Simple SummaryScirtothrips dorsalis, chilli thrips, is an invasive insect species in Florida and an important foliar pest of blueberry. Sound knowledge of insect distribution within the field is needed to formulate accurate sampling methods. Fourteen blueberry fields were systematically sampled for chilli thrips during the summers of 2017 and 2018. Field counts were modeled in various spatial models and determined chilli thrips had temporally stable aggregated distribution. A fixed-precision sampling plan was developed for summer sampling, requiring seven and three sampling units (sampling unit = 10 young blueberry shoots) to estimate a nominal mean density of 20 chilli thrips with a precision of 25% and 40%, respectively. The sampling plan can be used to improve the timing of control measures and assess the effectiveness of these control measures.Scirtothrips dorsalis Hood is an invasive and foliar pest of Florida blueberry that reduces plant growth by feeding on new leaf growth. A sampling plan is needed to make informed control decisions for S. dorsalis in blueberry. Fourteen blueberry fields in central Florida were surveyed in 2017 and 2018 after summer pruning to determine the spatial and temporal distribution of S. dorsalis and to develop a fixed-precision sampling plan. A sampling unit of ten blueberry shoots (with four to five leaves each) was collected from one blueberry bush at each point along a 40 × 40 m grid. Field counts of S. dorsalis varied largely ranging from zero to 1122 adults and larvae per sampling unit. Scirtothrips dorsalis had aggregated distribution that was consistent within fields and temporally stable between summers, according to Taylor’s power law (TPL) (aggregation parameter, b = 1.57), probability distributions (56 out of 70 sampling occasions fit the negative binomial distribution), Lloyd’s index (b > 1 in 94% occasions), and Spatial Analysis by Distance IndicEs (31% had significant clusters). The newly developed fixed-precision sampling plan required 167, 42, seven, or three sampling units to estimate a nominal mean density of 20 S. dorsalis per sampling unit with a precision of 5%, 10%, 25%, or 40%, respectively. New knowledge on S. dorsalis distribution will aid in evaluating the timing and effectiveness of control measures.

Use of a growth regulator (prohexadione-Ca) and summer pruning as post symptom rescue treatments following a fire blight infection during bloom

Fire blight of apples (Erwinia amylovora) can be a serious disease depending on production area and year. Bloom is the most frequent starting point for infection and the primary focus for sprays which can prevent infection, or of growth regulators such as prohexadione-Ca (ProCa) to limit spread. Because of the sporadic cases, many growers opt to forego bloom sprays when disease pressure is low. When symptoms do appear, quickly pruning out affected branches is currently the most effective control measure. Our goal was to determine if ProCa applied when symptoms appear, instead of during bloom when infection risks are predicted, could be used to limit disease spread, and if this would interact with summer symptom removal. The study was carried out in 2018 and 2019 at the IRDA orchard in Saint-Bruno-de-Montarville, Quebec. Plots inoculated during bloom were allocated to treatments in which diseased branches were either pruned during summer or only in winter, and trees sprayed with ProCa starting at bloom, when symptoms appeared, or not. Potential for disease progression was assessed by inoculating shoots and rating them for disease severity and ooze production. Significantly less wood was removed from trees pruned during the summer as opposed to winter, but total yield was reduced. ProCa had no effect on the amount of dead wood pruned, but still reduced disease severity. We found that ProCa reduced ooze on inoculated shoots and that post symptom timing was as effective as the bloom spray. Delaying sprays until symptoms appear could become an alternative strategy to reduce summer spread of fire blight.

The Influence of Agrotechnological Tools on cv. Rubin Apples Quality

With the growing demand for quality food in the world, there is a new ambition to produce high-quality apples seeking reduced cultivation costs. The aim of this study was to evaluate the influence of agrotechnological tools on the quality of cv. Rubin apples during the harvest. The apple tree (Malus domestica Borkh.) cv. Rubin was grafted on dwarfing rootstocks P60, planted in single rows spaced 1.25 m between trees and 3.5 m between rows. Six agrotechnological tools were used—hand pruning, mechanical pruning, trunk incision, calcium-prohexadione, summer pruning and mechanical pruning one side, changing sides annually. The agrotechnical tools had no significant effect on accumulation of most sugars and elements, malic, folic and succinic acids in the fruits. Mechanical pruning resulted in significant accumulation of phenolic compounds, antioxidants, ascorbic acid, but reduced the amount of glucose compared to hand pruning. However, the trunk incision or spraying with ca-prohexadione together with mechanical pruning had no significant effect on sugar content but resulted in significantly higher amounts of phenols, antioxidants, ascorbic acid, Fe and Mn and reduced starch and citric acid.

Nitrogen Partitioning in Young “Julyprince” Peach Trees Grown with Different Irrigation and Fertilization Practices in the Southeastern United States

Fertilizer recommendations for peach cultivation in the southeastern United States were developed decades ago and may not reflect the peach trees’ needs under current cultivation practices. Adequate fertilization for young peach trees induces a balanced vegetative/reproductive growth, ensures efficient resource use, and is environmentally sound. Droughts in the region are becoming more common. Supplemental irrigation for peaches from the time of field establishment serves as insurance in case drought conditions occur and can increase/advance the yield of young peach trees. Our objective was to determine the influence of different fertilizer levels (25, 50, 100, and 200% of the recommended rate), irrigation levels (irrigated vs. non-irrigated), and irrigation systems (drip vs. micro-sprinkler) on nitrogen partitioning and concentration in different organs of young peach trees. The cumulative nitrogen (N) removal per tree was not affected by the different fertilizer levels. Most of the N allocation was accounted for by summer pruning and defoliation (68% of the total N removed). Irrigated trees had higher cumulative N removal after three years than non-irrigated trees, with differences between irrigated vs. non-irrigated trees in most vegetative removal events (winter and summer pruning, and defoliation). Drip-irrigated trees had higher cumulative N removal after three years than micro-sprinkler-irrigated tress, with differences in N removal found in vegetative and reproductive removal events. Differences in N removal were mainly driven by differences in dry weight rather than the N concentration of the organs. These results suggest that different fertilizer levels did not alter the N partitioning in young peach trees, indicating that reduction in fertilizer applications can be done without negative effects. Furthermore, irrigation induced greater vegetative growth, especially under drought conditions, which may result in greater canopy volume and fruit yield compared to non-irrigated trees. Differences between irrigation systems are not consistent; however, drip is more efficient than micro-sprinkler irrigation, with ~38% water savings.