Trunk Cross-sectional Area Research Articles

Plant growth regulators to increase fruit set and yield of ‘Rocha’ pear trees in Southern Brazil

The aim of this study was to evaluate the effect of different aminoethoxyvinilglycine (AVG), thidiazuron (TDZ) and prohexadione calcium (P-Ca) rates sprayed at different timings on fruit set, yield, and fruit quality of 'Rocha' pear trees in different climatic conditions of Southern Brazil. The study was performed in two commercial orchards located in São Joaquim, SC (2015/2016) and Antônio Prado, RS (2016/2017). Plant material consisted of 'Rocha' pear trees grafted onto Pyrus calleryana and quince rootstock 'BA29' in São Joaquim and Antônio Prado, respectively. Treatments consisted of AVG, TDZ and P-Ca sprayed at different rates and timings. Trunk cross-sectional area increase, fruit set, thinned fruit, fruit per tree, yield, average fruit weight, projected yield, yield efficiency, fruit length, fruit diameter, L/D ratio, seed number, flesh firmness, and soluble solids content were assessed. Fruit set and yield were consistently increased by AVG in all experiments. Fruit set was not affected by P-Ca and was significantly decreased by TDZ. However, yield was positively affected by P-Ca 100 mg L-1 sprayed at full bloom + 7 days after full bloom and TDZ 10 mg L-1 at full bloom. Fruit size was consistently increased by TDZ.

Influence of an Alternative Soil Management System to Herbicide Use on Tree Vigor, Yield, and Quality of Apple Fruit

The aim of this study was to investigate the effect of alternative soil maintenance systems in a ‘Gold Chief’ apple orchard to the herbicide strip on tree growth, yield, and optimal fruit quality during 2012–2016. We compared several floor management systems: organic mulch comprised of Miscanthus spp., mechanical cultivation, black polypropylene cover, and herbicide strip as the control, with particular emphasis on the suitability and effectiveness of the organic mulch. During this five-year experiment Miscanthus spp. mulched trees grew most vigorously and significantly more than trees from other systems. The increment of the trunk cross-sectional area was higher for Miscanthus spp. mulched trees when compared to both mechanical fallow and herbicide strip. On average, fruits from trees grown in Miscanthus spp. plots were significantly larger than fruits from mechanical fallow and black polypropylene cover plots. The cumulative yield from the entire experiment was not significantly different for organic mulch, herbicide strip, and black polypropylene cover and was significantly higher than the mechanical cultivation. Different floor management systems had a significant effect on the solid soluble content in fruit both directly after harvesting and after storage. Our study shows that organic mulch can be a good alternative for soil management in orchard production systems.

Tree growth, productivity, and fruit quality of ‘Fuyu’ persimmon trees onto different dwarfing rootstocks

To investigate the dwarfing effect of candidate rootstocks on persimmon (Diospyros kaki Thunb.), we compared the growth of ‘Fuyu’ scions grafted onto ‘Hourakudai’ and S22 clone dwarfing rootstocks with that on a standard D. kaki rootstock, ‘Aogaki’ seedlings, in unpruned and non-bearing trees. In addition, we compared the growth, fruit quality, and yield efficiency of ‘Fuyu’ scions grafted onto three candidate dwarfing rootstocks (‘Hourakudai’, No. 3, and S22 clones) with those of ‘Aogaki’ seedlings grown under conventional cultivation (pruned and fruited). In unpruned and non-bearing trees, grafts on S22 and ‘Hourakudai’ rootstocks reached about 75 % of the height of trees on the standard rootstock. Tree canopy volumes on the S22 and ‘Hourakudai’ rootstocks were about 67 % and 42 %, respectively, of those on the standard rootstock. The high positive correlation between TCSA and tree canopy volume was observed for not only between trees grown under unpruned and non-bearing but also trees grown under pruned and bearing. Tree canopy volume was a better indicator of dwarfing capacity of rootstocks than tree height or tree canopy area. In conventional cultivation, trees grafted on all three candidate dwarfing rootstocks had smaller canopy area and canopy volume than those grafted onto the standard rootstock, from 2 to 11 years after planting. Although differences in tree growth between the three dwarf rootstocks were observed, the differences tended to decrease as tree age advanced. The quality of fruit produced (fruit weight, soluble solids content, and skin color) by trees on dwarf rootstocks did not differ from that produced on standard rootstocks, although annual variations occurred. Trees on S22 rootstock had the lowest yield owing to decreased vigor. Trees on ‘Hourakudai’ rootstock had the highest yield efficiency per trunk cross-sectional area of scions and per tree canopy volume. ‘Hourakudai’ softwood cuttings showed the highest rooting rate (80 %). These results identify ‘Hourakudai’ as a promising new rootstock for growing dwarfed ‘Fuyu’ trees, owing to the high yield efficiency without a decrease in fruit quality.

Cracking in Sweet Cherry Cultivars Early Bigi and Lapins: Correlation with Quality Attributes.

Fruit cracking is one of the main concerns in sweet cherry production and is caused by a heavy rainfall before and during the harvest. This physiological disorder leads to severe economic losses, which can be more or less effective depending on the cracked region of the fruit: in the cheeks (side cracks), in the stylar scar region, or in the stem cavity region. Sweet cherry cracking can be affected by several factors such as cultivar, growing conditions, rootstock, fruit size, flesh osmotic potential, cuticular characteristics of the skin, and stage of fruit development. In this sense, the objective of this work was to evaluate the cracking incidence in two sweet cherry cultivars (Early Bigi and Lapins grafted on “Saint Lucie 64” rootstock) and correlate the cracking index with other quality parameters. Fruits were harvested on 2 May (cv. Early Bigi) and on 27 May (cv. Lapins) 2019 at their commercial ripening stage. In the field, the total yield and the trunk cross-sectional area were determined for each tree in order to calculate the yield efficiency. In the laboratory, the cracking index was determined in 150 fruits without visual defects. In addition, fruit size and weight, wax content, flesh firmness, epidermis rupture force, total soluble solids, pH, titratable acidity, and maturity index of 30 fruits were also evaluated. In general, all the analyzed quality parameters were influenced by the cultivar, being that cv. Lapins presented larger, heavier, firmer, and sweeter fruits, with more acidity and higher maturation index. However, cv. Lapins also presented higher cracking index, which was positively correlated with all the parameters above-mentioned and negatively correlated with the wax content. In fact, cv. Early Bigi presented a high wax content and simultaneously a low cracking index. The stylar scar region cracks were the most prevalent in both cultivars. These results allowed us to conclude that, in the North Portugal region, the Lapins cherries presented better quality attributes than the Early Bigi cherries. However, the latter are still very valuable to the region due to its early ripening. Additionally, it was also possible to conclude that bigger, firmer, more mature, and with lower wax content cherries were more sensitive to cracking than the smaller fruits, soft-fleshed, less mature, and with higher wax content.

Sustainable Cornelian Cherry Production in Montenegro: Importance of Local Genetic Resources

Cornelian cherries has been grown Balkan peninsula no apparent disease and pest problems for centuries. The most important pomological and technological properties of cornelian cherry genetic resources (eleven local and introduced varieties and selections) in Gornje Polimlje, Montenegro were studied in four-year periods. Fruit weight, stone weight, and mesocarp/stone ratio shows great variation and varied between 1.89 to 6.16 g, 0.32 to 0.64 g and between 76.66 and 90.59%, respectively. Genotypes significantly differed each other in terms of yield determined as per trunk cross section area (TCSA). For better visualization of the agronomical traits important to the yield, i.e., yield per TCSA and fruit weight data is presented in combination as measured in the years of study. The best promising genotypes are Vladimirskiy, Chisinau yellow, and Krupnoplodni NS, which had consistently higher yield and large fruits for sustainable fruit production. Dry matter, total sugars, reducing sugars, sucrose, total acidity, Ca–pectate, vitamin C, total anthocyanins, total polyphenols, and ash content of cornelian cherry cultivars and selections were found between 19.81–24.46%, 10.94–14.47%, 10.44–13.09%, 0.24–1.23%, 1.92–2.51%, 2.76–4.43%, 41.09–101.27 mg/100 g, 0–157.06 mg/100 g, 183.91–307.9 mg/100 g, and 0.89–1.16%, respectively. The amount of potassium, which predominates in percentage of minerals in the ash, ranged from 2888 to 3574 mg/kg. The extensiveness of the study leads, therefore, to several clear conclusions and recommendations. Consistently, the best balance of biochemical elements in combination with good yield and fruit size measurements is found in selection Krupnoplodi NS. If consider fruit size and yield efficiency are priority, Vladimirskiy, Chisinau yellow, Kosten 3, and Krupnoplodni NS have clear advantage over the other genotypes. The study highlights the importance of local cornelian cherry selections for sustainable cornelian cherry production in Montenegro.

Integrated Weed Management in High Density Fruit Orchards

Despite the productivity, achieving long-term sustainability and maintaining plant biodiversity have become the pivotal goals in orchard floor management, especially along tree rows. Thus, the paradigm of eradicating weeds in the tree row using chemical herbicide or repeated soil tillage needs to be substituted with more sustainable alternatives. This study was conducted in two commercial apple and peach orchards in Marche region (Italy). Two integrated mechanical approaches, integrated mowing (mower and brush or disc) and integrated tillage (blade weeder and integrated mowing), were compared with the standard herbicide system in a 2-year trial. Weed species diversity, soil coverage, and weed biomass production, including, gas exchange parameters, trunk cross-sectional area (TCSA), fruit yield and quality were measured. Overall, both integrated practices demonstrated approximately 82%, 91% and 113% more species diversity, soil coverage, and weed biomass production, respectively, than herbicide systems. No significant differences were found in terms of tree gas exchange parameters, growth and fruit yield. However, a few fruit quality parameters such as fruit firmness, soluble solids content (SSC) and dry matter content responded positively to the integrated practices. These results suggest that the integrated mechanical approaches of weed management increased orchard biodiversity, and had no adverse effects on tree growth, fruit yield, and quality. The average costs per hectare associated with chemical weed control were 66.5% and 72% lower, respectively, compared to integrated tillage and integrated mowing. However, the government subsidies provided to the orchardists to encourage sustainable management practices were able to offset such additional costs.

Long-term Performance of ‘Delicious’ Apple Trees Grafted on Geneva® Rootstocks and Trained to Four High-density Systems under New York State Climatic Conditions

We conducted a large (0.8 ha) field experiment of system × rootstock, using Super Chief Delicious apple as cultivar at Yonder farm in Hudson, NY, between 2007 and 2017. In this study, we compared six Geneva® rootstocks (‘G.11’, ‘G.16’, ‘G.210’, ‘G.30’, ‘G.41’, and ‘G.935’) with one Budagovsky (‘B.118’) and three Malling rootstocks (‘M.7EMLA’, ‘M.9T337’ and ‘M.26EMLA’). Trees on each rootstock were trained to four high-density systems: Super Spindle (SS) (5382 apple trees/ha), Tall Spindle (TS) (3262 apple trees/ha), Triple Axis Spindle (TAS) (2243 apple trees/ha), and Vertical Axis (VA) (1656 apple trees/ha). Rootstock and training system interacted to influence growth, production, and fruit quality. When comparing systems, SS trees were the least vigorous but much more productive on a per hectare basis. Among the rootstocks we evaluated, ‘B.118’ had the largest trunk cross-sectional area (TCSA), followed by ‘G.30’ and ‘M.7EMLA’, which were similar in size but they did not differ statistically from ‘G.935’. ‘M.9T337’ was the smallest and was significantly smaller than most of the other rootstocks but it did not differ statistically from ‘G.11’, ‘G.16’, ‘G.210’, ‘G.41’, and ‘M.26EMLA’. Although ‘B.118’ trees were the largest, they had low productivity, whereas the second largest rootstock ‘G.30’ was the most productive on a per hectare basis. ‘M.9’ was the smallest rootstock and failed to adequately fill the space in all systems except the SS, and had low cumulative yield. The highest values for cumulative yield efficiency (CYE) were with ‘G.210’ for all training systems except for VA, where ‘M.9T337’ had the highest value. The lowest values were for all training systems with ‘B.118’ and ‘M.7EMLA’. Regardless of the training system, ‘M.7EMLA’ trees had the highest number of root suckers. Some fruit quality traits were affected by training system, rootstock or system × rootstock combination.

Determination of the Optimum Mulch-Irrigation Program Combination for Young Apple Trees

The gradual increase demand for water resources, the interest for growing techniques provides irrigation water saving in agricultural production and have no undesired impacts on yield, crop quality, growth and development. This study determined the effects of different mulch materials (black textile, rose oil processing wastes, wheat straw, and no mulch) and irrigation programs on growth of in an orchard for Fuji apple variety grafted on MM106 rootstock on irrigation water, water consumption, shoot number, shoot diameter, shoot length, leaf area index and trunk cross-sectional area. The highest vegetative development was obtained at mulch treatments and frequently irrigated 1st irrigation program. 1st irrigation program was determined as recommended irrigation when the available water resources are sufficient and also 2nd irrigation program together with mulch materials when available water resources are scarce. Each mulch treatment saved water compared to control as 22.0-31.3%, 21.2-28.7% and 17.8-23.5% in 2009, 2010 and 2011, respectively. Black textile was determined the most suitable mulch material for young apple trees according to results of water saving and vegetative development. Rose oil processing wastes and straw also can be used as mulch materials.

Improving Survival and Orchard Performance of “Costata” Persimmon Seedlings by K-NAA and IBA Applications

The present investigation was conducted during the 2018 and 2019 growing seasons on one-year-old persimmon seedlings cv. “Costata” grafted on “Seedy” and “Tarabouls” rootstocks in order to improve its survival percent and orchard perfoprmance. The Seedlings were treated with K-NAA or IBA either by dipping at 3000 mg l-1 for 5 seconds or soaking at 500 mg l-1 for 24 hours. Obtained results generally showed significant increase in vegetative growth, root biomass and leaf chlorophyll and mineral content by all K-NAA and IBA applications compared to the water treated ones. A highest values of sprouting buds percent (during April, June and August), average shoots number, trunk cross-sectional area, leaf area and canopy volume were recorded with the K-NAA soaking at 500 mg l-1for 24 h. Leaf chlorophyll content was highest with K-NAA and IBA soaking in the first season, while K-NAA soaking at 500 mg l-1 for 24 h gave the highest values of leaf N, P, K, Fe, Mn and Zn in both seasons. Also, the K-NAA soaking or dipping applications recorded the highest values of average shoot length, increment percnts of shoot length and stem diameter and highest seedlings survival in both seasons. The K-NAA soaking at 500 mg l-1 for 24 h gave the highest significant values of root biomass in the first season. Results also showed that seedlings on “Seedy” rootstock surpassed the ones on “Tarabouls” rootstock in all vegetative growth parameters and root biomass, but contained lower leaf N, P, Mn and Zn.

Soil Nitrogen Fertilization Increases Yeast Assimilable Nitrogen Concentrations in ‘Golden Russet’ and ‘Medaille d’Or’ Apples Used for Cider Production

The recent growth in the U.S. hard-cider industry has increased the demand for cider apples (Malus ×domestica Borkh.), but little is known about how to manage orchard soil fertility best to optimize horticultural performance and juice characteristics for these cultivars. To assess whether nitrogen fertilizer applied to the soil can improve apple juice and cider quality, calcium nitrate (CaNO3) fertilizer was applied at different rates to the soil beneath ‘Golden Russet’ and ‘Medaille d’Or’ trees over the course of three growing seasons. The experiment started when the trees were in their second leaf. The trees were cropped in their third and fourth leaf. At the end of the first growing season of the experiment, the greatest fertilizer rate increased tree trunk cross-sectional area (TCSA) by 82% relative to the control, but this difference did not persist through to the end of the study. Yield and crop load were unaffected by the nitrogen fertilization treatments. Increasing the nitrogen fertilizer rate correlated positively with more advanced harvest maturity in ‘Golden Russet’ fruit, which resulted in greater soluble solid concentration (SSC). Fruit from the greatest fertilizer rate treatment had an average starch pattern index (SPI) that was 1 U greater than in the control, and an SSC that was 3% greater than the control. The fertilizer treatments did not affect juice pH, titratable acidity (TA), or total polyphenol concentrations. Yeast assimilable nitrogen (YAN) concentrations were increased by nitrogen fertilization for both cultivars in both harvest years. The greatest fertilizer treatment increased juice primary amino nitrogen by 103% relative to the control. Greater nitrogen fertilization rates correlated positively with less hydrogen sulfide production during the fermentation of ‘Golden Russet’ juice from the first, but not the second, harvest. During the first year, cumulative hydrogen sulfide production for the ‘Golden Russet’ control treatment was 29.6 μg·L–1 compared with the ‘Golden Russet’ high treatment, which cumulatively produced 0.1 μg·L–1. Greater maximum fermentation rates and shorter fermentation durations correlated positively with increased fertilization rate for both cultivars after the second harvest. High treatment fermentations had maximum fermentation rates 110% greater, and fermentation durations 30% shorter than the control. Other horticultural and juice-quality parameters were not affected negatively by the CaNO3 treatments. In orchards producing apples specifically for the hard-cider industry, nitrogen fertilizer could increase juice YAN, thus reducing the need for exogenous additions during cider production.

Effect of N, P, K and Mg fertilizers on some vegetative and generative parameters of a sweet cherry cultivar

This two-year-study was aimed to provide results on the effect of nitrogen, phosphorus, potassium and magnesium fertilizer treatments (control, NP, NPK, NPKMg) on vegetative and generative features of the sweet cherry cultivar ‘Carmen’. Examinations were performed in an orchard planted in 2012 on Prunus mahaleb rootstock with spacing of 5 x 2.5 m. All treatments improved the vegetative features of the sweet cherry trees in both years of 2016 and 2017. Fertilizer treated trees increased trunk cross section area (TCSA) with 51.3-63.1%, while control trees showed 48.3% trunk growth increase. Yields of control trees were lower in both years (5.9-7.2 kg/tree), than that of the fertilized trees (7.8-11.3 kg/tree). Treatments also increased the phosphorus (16-22%), magnesium (12-20%) and potassium content (3.5-18%) of the fruits compared to control treatments.

Rootstock and Interstock Effects on Plum cv. ‘Čačanska Lepotica’ Young Tree Performance and Fruit Quality Traits

Extensive plum production in Serbia has led to a reduction in yield, quality and economic profitability, a transition to intensive production is necessary. The aim of the present study was to investigate the effects of different generative (Prunus cerasifera, Prunus cerasifera +Prunus spinosa) and vegetative (WaVit, WeiWa) rootstocks in a dense planting system (4 m × 2 m). The experiment was conducted on early high-quality domestic cultivar ‘Cacanska Lepotica’ characterised by high adaptive ability in different agro-climatic conditions. The orchard was established in 2012 at the Experimental Field for Fruit Growing of the Faculty of Agriculture Novi Sad at Rimski Sancevi, and the experiment was conducted from 2013 to 2017. Based on the research findings, Prunus cerasifera rootstock induced higher tree trunk cross-section area, while also enhancing the total soluble solids content in the fruit. Trees grafted on Prunus spinosa interstock with Prunus cerasifera as the rootstock exhibited the smallest vigour, cumulative yield and titratable acidity. On the other hand, vegetative rootstocks increased the fruit yield, weight and size.

Waterlogging tolerance in apple trees grafted on rootstocks from G, CG, and M series

This study was performed to evaluate the waterlogging tolerance of Cornell-Geneva (G11, G202, G214, G935, CG4814, and CG5087), M26, and M9 apple rootstocks. After grafting ‘Fuji’ scions on each type of rootstock, grafted trees were planted in 17-L pots and grown in a greenhouse under well-irrigated conditions. Sixteen weeks after planting, grown trees were divided into two groups: one group was drip-irrigated daily with 2 L of water (control treatment, CT), and the other group was waterlogged by repeating flooding and drainage at 1- to 3-day intervals for 4 weeks (waterlogging treatment, WT). After the cessation of flooding, trees were irrigated as in CT for 18 days. Trees grafted on G202, G214, and M9 had markedly lower leaf water potential than CT trees on the 27th day of flooding; predawn leaf water potential was − 1.26 to − 1.45 MPa in WT trees and − 0.30 to − 0.32 MPa in CT trees, and midday leaf water potential was − 2.85 to − 3.03 MPa in WT trees and − 1.83 to − 1.87 MPa in CT trees. This difference persisted until the 18th day after the cessation of flooding. The net photosynthetic rate and stomatal conductance of trees grafted on these rootstocks were also extremely low in WT trees, and they did not recover to the corresponding levels in CT trees until the 18th day after the cessation of flooding. Among WT trees, the height, trunk cross-sectional area, and dry weight of G202, G214, and M9 trees were markedly lower than those of trees grafted on other rootstocks, whereas CG4814 trees showed the least reduction in these parameters. The defoliation percentages of G202, G214, and M9 trees were 22%, 23%, and 35%, respectively, in WT trees, whereas trees grafted on other rootstocks had 4 to 9% defoliation. Thus, G202 and G214 trees showed similar sensitivity levels as M9 trees, whereas CG4814 trees were more resistant to flooding than M26 trees, and G11, G935, and CG5087 trees showed a waterlogging tolerance comparable to M26 trees.

Crop Load Influences Growth and Hormone Changes in the Roots of "Red Fuji" Apple.

Crop load has a substantial impact on growth of the aerial and belowground parts of apple trees. Here, we examined the effects of different crop loads on growth and hormone levels in apple roots. A crop load of 1.5 (T1.5) fruits per cm2 trunk cross-sectional area (TCSA) treatment resulted in lower root growth vigor, while non-fruiting (T0) and T0.4 conditions showed higher root growth vigor. In all treatments, dead roots increased in length 90 days after full bloom (DAFB), whereas live roots were more abundant at about 50 and 170 DAFB, showing a bimodal curve. During each root growth peak, levels of cytokinins (CTKs), indole acetic acid (IAA), and gibberellic acid (GA3) were higher. Moreover, hormone levels gradually decreased with increasing crop load within each peak. Root turnover tended to decrease with decreasing crop load. These findings indicate that root growth and hormone contents were positively correlated during the fruit growth phase, and that the negative impact of crop load on root growth may have been caused by hormone level decreases.

Spring deficit irrigation in olive (cv. Genovesa) growing under arid continental climate: Effects on vegetative growth and productive parameters

This study was aimed to evaluate the effect of regulated deficit irrigation (RDI), applied from mid-spring to early summer, on physiological parameters, vegetative growth and productivity in an intensive hedgerow olive orchard located in a non-traditional (marked winter-spring water-deficit) olive growing region. The experiments were carried out during three crop seasons by using four years old (7 m × 3.5 m) ‘Genovesa’ olive trees. Three RDI treatments (T25, T50 and T75) were applied as a percentage of crop evapotranspiration (25, 50 and 75% ETc, respectively) during the period from fruit set to pit hardening. Also, a control treatment was irrigated at 100% ETc during the whole crop season. Under the analyzed environmental conditions, stomatal conductance was less sensitive in young leaves than in mature leaves against changes in water availability. This fact should be considered when being used as benchmarks in olives trees submitted to water deprivation during periods with marked water constraint. Regarding vegetative parameters, significant reductions in apical vegetative shoot growth, trunk cross-sectional area and canopy volume were found in less irrigated treatments (T25 and T50) with respect to most irrigated ones (T75 and T100). Moreover, the strongest effects of deficit irrigation were observed when pruning was applied at the end of the second crop season evaluated. Both fruit and oil yields were barely affected by water availability. Although in the first crop season evaluated the fruit yield was greater in the full-irrigation treatment – which could be due to the age of the olive trees -, at the end of the whole experimental period (three crop years) the mean values from this yield component did not present significant differences among all irrigation treatments. Similarly, water availability did not affect oil yield (kg/ha); no significant differences were found among irrigation treatments in any of the crop seasons analyzed. The effects of water availability on productive parameters were more evident when analyzed as an estimated productive response; the total water productivity, calculated on both fruit weight and oil weight bases, gave the highest values in the most restrictive irrigation treatment. Overall, findings from this study could be of interest for olive cultivation in regions with dry spring period and for intensive hedgerow orchards suited to over-row harvesters. Imposing water restriction during this period could be suitable for achieving sustainable fruit and oil productivity while saving considerable amount of irrigation water.

Performance of ‘William’s’ pear grafted onto three rootstocks

ABSTRACT Pears are the most imported fruit from Brazil and thus, being an important opportunity to Brazilian growers. However, there are still some problems that restrict pear production, such as the lack of suitable rootstocks. The aim of this study was to assess growth, yield efficiency and fruit quality of ‘William’s’ pear grafted on quinces ‘Champion’ and ‘Melliforme’ and P. calleryana. The experiment was performed during 2009/2010 growing season at the Centro Agropecuario da Palma, FAEM/UFPel. The experimental design was a completely randomized block with three replications per treatment. The assessed parameters were trunk cross sectional area, shoot length, yield efficiency, number of fruit per tree, soluble solids, flesh firmness, fruit weight and fruit size. It was found that ‘William’s’ pear is more efficient and less vigorous when grafted on ‘Champion’ quince, thus being a potential scion x rootstock combination for commercial pear planting at medium densities. Moreover, fruit of trees grafted on quince rootstocks accumulated higher amount of soluble solids.

Long-term evaluation of rootstock effects on cropping and tree parameters of selected sweet cherry cultivars

The cropping of six sweet cherry cultivars that originated in the Research and Breeding Institute of Pomology at Holovousy, and a standard one, ‘Burlat’, were evaluated on three rootstocks in the period of 2007–2017. Trees planted in a spacing of 1.5 m × 5.0 m were trained as tall spindle axes utilising their natural tendency to develop a central leader. On the standard rootstock, P-TU-2, ‘Tim’ was the most productive with a mean total harvest of 47.6 kg per tree. ‘Sandra’ yielded the most on the PHLC rootstock with 56.2 kg per tree and ‘Helga’ yielded the most on Gisela 5 with a mean total harvest of 55.9 kg per tree. The mean impact of the rootstock on the tree vigour, measured upon the trunk cross section area, ranged from 148.4 cm2 on the standard rootstock P-TU-2 to 114.1 cm2 on the PHLC and 125.2 cm2 on Gisela 5 . On the standard rootstock P-TU-2, the most vigorous one according to this criterion was ‘Jacinta’ (178.0 cm2) whereas ‘Justyna’ (109.7 cm2) was the least vigorous. On the PHLC, the most vigorous was ‘Sandra’ (147.2 cm2) and the least was ‘Amid’ (94.0 cm2). The other tree characteristics were mainly dependant on the cultivar and minimally, or not at all, influenced by the rootstock vigour.

Branch Configuration Impacts on Production, Fruit Quality, and Leaf Minerals of ‘Aztec Fuji’ Apple Trees in an Upright Single Row High-Density Orchard System Over Five Years

Tree architectures play a critical role in the productivity of high-density orchards, but limited information is available in this subject. We studied effects of three branch configurations on tree growth, yield components, fruit quality and leaf mineral nutrients in ‘Aztec Fuji’ apple (Malus domestica Bork.) in a single row upright high-density system under southwest Idaho, USA conditions over 2012-2016. This study revealed that trees trained into a Tall Spindle (TS) had larger trunk cross sectional area (TCSA) than those with an Overlapped Arm (OA) system. Trees trained into a TS had higher number of fruit and yield per tree, three years after planting in 2012, than those with a Tipping Arm (TA) or OA system. However, in 2013, trees with a TA system had higher yield than those with a TS or OA configuration due to trees’ biennial bearing habit and higher spur formation in trees with a TA system. Trees receiving a TA training had lower biennial bearing index between all consecutive years. Trees with an OA training had smaller fruit than those with either a TA or TS training in all years between 2012-2016. Training systems did not have any effect on fruit color, soluble solids concentration, or starch degradation pattern at harvest. However, fruit from trees with an OA training had higher firmness and lower water core than those from trees with a TS or TA training. Leaves from trees receiving a TA training had greater leaf area, fresh weight, and potassium (K) and magnesium (Mn) concentrations than those with other trainings. Leaves from trees receiving an OA training had higher leaf iron (Fe), zinc (Zn), and copper (Cu) than those with a TS training. In this study, we concluded that training trees into a TA configuration rather than an OA system is recommended if the management and operation of apple production mandate the use of an “upright wall” structure to facilitate mechanical harvesting.

Evaluation of different deficit irrigation strategies in the late-maturing Japanese plum cultivar 'Angeleno'

In stone fruits, the pit hardening period is usually one of slow fruit growth that is considered relatively insensitive to an imposed moderate water stress. For this reason, this period is commonly employed for a first phase of reduced water input in regulated deficit irrigation (RDI) strategies. However, in previous studies with the Japanese plum cv. 'Angeleno', the identification of a period of slow growth just before harvest suggested the need to reconsider the most suitable RDI strategy for this cultivar. In this 3-year study (2014, 2015 and 2016) three irrigation strategies were compared: Control (CON) designed to meet tree water requirements throughout the season; Regulated Deficit Irrigation (RDI) with two separate periods of water deficit, one preharvest with no irrigation inputs during an intermediate period of fruit growth (pit hardening period), and the other postharvest with a 30 % reduction of the CON inputs; and Preharvest + Regulated Deficit Irrigation (RDP) with a single period of deficit irrigation initiated before harvesting and extended until the end of the irrigation campaign. Both deficit irrigation treatments were found to be effective at controlling tree vigor, with lower trunk cross-sectional area growth and pruned wood weight than in the CON treatment. Average water savings with the RDI and RDP strategies over the three years of the study were 24 % and 18 %, respectively, compared to CON, with no impact on yield and no carry-over effect. Fruit size in the RDP treatment was similar to the CON. The differences in fruit firmness, soluble solids concentration (SSC), acidity, lightness (L), hue (ho) and chroma (C*) of the skin were only slight or inconsistent over the three years. Our results confirm the suitability of moderate pre- and postharvest water stress (RDP strategy) in this cultivar, with greater water productivity than the traditional RDI strategy.

Determining water requirements for young peach trees in a humid subtropical climate

In the southern USA, low soil water holding capacity and erratic rainfall patterns create scenarios where plant water stress may occur, reducing early peach tree growth. Therefore, irrigation management is a key component to ensure adequate water supply during early tree growth stages. The objective of this study was to determine water requirements and crop coefficient (Kc) of young peach trees grown in a subtropical climate. A study was conducted in central Florida using young peach trees ‘TropicBeauty’ grafted onto ‘Flordaguard’. Daily actual evapotranspiration (ETA) was determined using weighing lysimeters. The highest daily peach water demand was recorded during the shoot development stage (23.7 L) between August and October, whereas the lowest daily ETA was 0.71 L, during dormancy in December and January. Year-round Kc values for young peach trees were obtained and ranged from 0.20 to 0.68. There was a significant correlation between plant water consumption with trunk cross-sectional area (TCSA) and projected canopy area (PCA), which can be used to estimate ETA. Peach irrigation water demand for 1–3 years old trees, expressed as daily ETA, can be estimated using daily reference evapotranspiration and PCA. The accurate determination of crop water demand allows the seasonal adjustment of irrigation scheduling avoiding water stress, or over-irrigation of young peach trees.