APS_July2023

Volume 77

JULY 2023

Number 3

AMERICAN POMOLOGICAL SOCIETY F ounded in 1848 I ncorporated in 1887 in M assachusetts

2022-2023

PRESIDENT K. GASIC

FIRST VICE PRESIDENT P. CONNER

SECOND VICE PRESIDENT M. OLMSTEAD

TREASURER A. ATUCHA

EDITOR R. P. MARINI

SECRETARY L. DEVETTER

RESIDENT AGENT MASSACHUSETTS W. R. AUTIO

EXECUTIVE BOARD

N. BASSIL Past President

N. BASSIL President

P. CONNER 1 st Vice President

M. OLMSTEAD 2 nd Vice President

L. DEVETTER Secretary

TOM KON ('19 - '23)

GINA FERNANDEZ ('21 - '24)

DAVID KARP ('22 - '25)

ADVISORY COMMITTEE 2020-2023 B. BYERS M. DOSSETT A. PLOTTO E. VINSON D. WARD 2021-2024 J. SAMTANI D. TRINKA S. MEHLENBACHER M. FARCUH G. BRAR 2022-2025 C. LUBY M. MUEHLBAUER L. REINHOLD A. WALLIS S. YAO

CHAIRS OF STANDING COMMITTEES

Editorial R. PERKINS-VEAZIE Wilder Medal Awards B. BLACK

Shepard Award F. TAKEDA Nominations M. PRITTS

Membership M. PRITTS

U. P. Hedrick Award E. FALLAHI

Website M. OLMSTEAD

Registration of New Fruit and Nut Cultivars J. PREECE, K. GASIC, D. KARP

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July 2023

Number 3

Volume 77

CONTENTS

Published by THE AMERICAN POMOLOGICAL SOCIETY Journal of the American Pomological Society (ISSN 1527-3741) is published by the American Pomological Society as an annual volume of 4 issues, in January, April, July and October. Membership in the Society includes a volume of the Journal. Most back issues are available at various rates. Paid renewals not received in the office of the Business Manager by January 1 will be temporarily suspended until payment is received. For current membership rates, please consult the Business Manager. Editorial Office: Manuscripts and correspondence concerning editorial matters should be addressed to the Editor: Richard Marini, 203 Tyson Building, Department of Plant Science, University Park, PA 16802-4200 USA; Email: richmarini1@gmail.com. Manuscripts submitted for publication in Journal of the American Pomological Society are accepted after recommendation of at least two editorial reviewers. Guidelines for manuscript preparation are the same as those outlined in the style manual published by the American Society for Horticultural Science for HortScience, found at https://cdn.ymaws.com/ashs.org/resource/resmgr/publications/ashspubsstylemanual.pdf Postmaster: Send accepted changes to the Business office. Business Office : Correspondence regarding subscriptions, advertising, back issues, and Society membership should be addressed to the Business Office, C/O Heather Hilko, ASHS, 1018 Duke St., Alexandria, VA 22314; Tel 703-836 4606; Email: ashs@ashs.org Page Charges : A charge of $50.00 per page for members and $65.00 per page ($32.00 per half page) will be made to authors. In addition to the page charge, there will be a charge of $40.00 per page for tables, figures and photographs. Society Affairs : Matters relating to the general operation of the society, awards, committee activities, and meetings should be addressed to Michele Warmund, 1-31 Agriculture Building, Division of Plant Sciences, University of Missouri, Columbia MO 65211; Email:warmundm@missouri.edu. Society Web Site : http://americanpomological.org The Role of Silicon in Strawberry production – Erich Griffin, Lailiang Cheng, and Marvin Pritts............................................................................................................................130 Effects of Different Trellis Systems on Fruit-zone Microclimate, Berry Quality and Anthocyanins of ‘Xinyu’ Grape ( Vitis vinifera L.) – S.J. Bai, J.G. Hu, M. Zheng, J.Y. Wu, J.S. Cai, G. Chen, R.H. Zhao, J.F. Meng .................................................................................136 About the Cover - Velvet apple ( Diospyros blancoi )..............................................................149 Genetic and Molecular Disease Management of Powdery Mildew, Bacterial Canker, and X Disease in US Pacific Northwest Sweet Cherry: Current Obstacles and Future Opportunities – Alexandra M. Johnson, Lyndon D. Porter, Gary Grove, Scott J. Harper, and Cameron P. Peace.............................................................................................................150 Beach Plum: a Fruit for the Future – Erich Griffin and Marvin Pritts . ...................................165 Anthocyanin Profiles of Two Subtropical Vaccinium Species and ‘O’Neal’ Southern Highbush Blueberry – Todd W. Anderson, Robert W. Durst, Scott W. Leonard, Kim E. Hummer, Claire Luby, and Nahla V. Bassil (U.P. Hedrick Award – First Place) .................................... 176 Instructions to Authors............................................................................................................186

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Journal of the American Pomological Society 77(3): 130-135 2023

The Role of Silicon in Strawberry Production E rich G riffin , L ailiang C heng and M arvin P ritts 1 Additional index words: silicic acid, powdery mildew, drought tolerance, cell wall integrity Abstract Silicon (Si) is among the most abundant elements in the Earth’s crust, although most of it is in an insoluble form. Si is regarded as a beneficial nutrient for its ability to alleviate abiotic and biotic stress. Soluble Si plays a role in improving strawberry ( Fragaria x ananassa ) water use efficiency, activating defense enzymes, releasing volatile compounds, and developing resistance to powdery mildew and mite feeding. Si has also been implicated in the regulation of stomata closure, enhancement of drought tolerance, and mitigation of harmful reactive oxygen spe cies produced under stress. Si fertilization has resulted in higher yield and fruit quality. Despite the documented role of Si in plant functioning defense and the existence of several genes involved in uptake and efflux, Si is not considered an essential element. However, as growers attempt to better control the growing environment through hydroponics, greenhouses, and enclosed structures, increased attention to this element is warranted.

Silicon is the second most abundant ele ment in the Earth’s crust. It is most readily available to plants via. the soil solution as a silicic acid—Si(OH) 4 (Epstein, 1994). Silicic acid is an uncharged monomeric molecule that is most readily assimilated by plants when the soil pH is below 9 (Ma and Yamaji, 2006). In most plants, including strawberry, Si travels to the Casparian strip through the roots (Naseer et al., 2012). Within the Cas parian strip of the exodermis and endodermis, the complementary gene types Lsi 1 (an NIP2 aquaporin homolog) and Lsi 2 (an Ars-B com plex) are responsible for the influx and efflux of Si(OH) 4 , respectively (Ma and Yamaii, 2006; Wang et al., 2021). Both Lsi1 and Lsi2 were recently identified in strawberry (Ouel lette et al., 2017). Lsi 1 encodes a membrane protein which performs similarly to aquapo rins and allows for Si(OH) 4 to enter the sym plast via the plasma membrane. The protein encoded by Lsi 2 is located on the proximal side of root cells. In the exodermis, Lsi 2 fa cilitates Si movement into the apoplast from the symplast with active transport (Yamaji and Ma, 2011; Coskun et al., 2021). Expression of Lsi1 and Lsi2 is depen

dent on the amount of internal soluble Si in the plant and externally on the soil solution (Ma and Yamaii, 2006). Once the Si passes through the Casparian strip, it is loaded into the xylem for transport throughout the plant as silicic acid. Upon reaching the shoots vas cular tissue, the silicic acid is converted to a colloidal silic gel, and then to silica gel (SiO2 • nH2O) before it reaches the leaves (Ma and Yamaji, 2006). The recent identification of the transport gene Lsi6 controls the move ment of Si into the leaves from the xylem (Wang et al., 2021). Si is dependent on the xylem for movement in the plant, but is in dependent of transpirational flow (Gao et al., 2006). Si movement in the phloem is heavily constrained, however (Raven, 1983). Functions of Si in plants Si is involved in activating defense-related enzymes and regulating the complex network of signal pathways (Wang et al., 2017). It is responsible for controlling phytohormone ho meostasis during stress, as well as priming the plant defenses to induce resistance (Wang et al., 2017). These are vital processes for plants to acclimate to a new environment by medi-

1 School of Integrative Plant Science, Horticulture section, Cornell University, Ithaca, NY 14853, gje28@cornell.edu

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ating growth, development, source/sink por tioning and nutrient allocation (Fahad et al., 2015, Wang et al., 2017). Si influences powdery mildew resistance . While all strawberry growers face pressure from powdery mildew (PM) ( Podosphaera aphanis ), greenhouse and high tunnel straw berry producers are at an even higher risk than those producing in the field (Pertot et al., 2007). While PM is most prominent outdoors in the field during the late summer/early fall for ever-bearing (day neutral) strawberries, the fungus presents a year-round problem for greenhouse producers (Ouellette et al., 2017). Without proper management, PM has the po tential to decrease photosynthesis by disrupt ing the Calvin cycle along with chlorophyll synthesis, as evident in barley and cucumber (Scholes et al., 1994; Abo-Foul et al., 1996). Si is responsible for the activation of plant defenses and is thought to impede the in oculation of fungi by one of the following mechanisms: 1) Si is mechanically depos ited beneath the leaf cuticle or on the tissue surface as a mechanical barrier to inhibit the systemic penetration of fungal spores through the leaf (Samuels et al., 1991) and/or 2) Si activates several defense compounds, such as lignin, phenolic (secondary) compounds and phytoalexins (Ma and Yamaii, 2006), in ad dition to kinases, peroxidases and pathogen esis-related transcripts (Zargar et al., 2019). The exact mechanism between soluble Si and plant biochemical pathways related to disease resistance remains unknown (Ma and Yamaii, 2006). Recent studies have explored the use of Si as a method to control PM in strawberries. Liu et al. (2020) reported that strawberries grown on a commercial farm in raised beds that were amended with Si via fertigation had less severe incidence of PM relative to the un treated control. Given Si’s role in activating plant defenses, the researchers found that Si applications benefitted the strawberry plants to a greater extent when the severity of the disease was greater, and the most effective suppression of the disease came when Si was

amended with a commercial fungicide. Kanto et al. (2006) obtained similar results when they treated field-grown strawberries with a potassium silicate fertilizer and observed that Si was most effective in reducing the overall severity of the PM infections as opposed to preventing their incidence completely. Ouellette et al. (2017) found that applica tions of soluble Si fertilizers in a high tun nel setting greatly increased the Si content of strawberries. Generally, the Si content of strawberries is approximately 0.3% dry weight (Moradtalab et al., 2019) but Ouelette et al. (2017) reported much higher levels. The uptake of Si made the berries highly resistant to PM in high tunnels. Kanto et al. (2004) found that strawberries grown hydroponically in 25 mg . l -1 K 2 SiO 3 had greatly reduced severity of PM infections, and strawberries grown in 50 mg . l -1 were completely free of PM. The researchers spec ulate that the decrease in the infection inci dence is due to an increase in leaf thickening with increasing levels of Si application. Wang and Galletta (1998) observed similar results when they foliarly applied potassium silicate to strawberries and measured decreased lev els of PM. Variation in response to Si applica tion by cultivar or species would be expected since leaf characteristics vary among geno types. F. chiloensis , for example, has a much thicker cuticle than F. ovalis which is associ ated with a far greater resistance to PM infec tion (Kanto et al., 2004), and cultivars vary in the amount of F. chiloensis in their ancestry. Si can reduce impacts from pests . There is some evidence that Si applications are ef fective against two spotted spider mites ( Tet ranychus urticae, TSSM). TSSM feed on over 1,100 plant species worldwide and can be problematic for strawberry growers (Ben soussan et al., 2016). The arthropod tends to interfere with plant growth and develop ment by spinning webs over the leaf surface and reducing the photosynthetic capacity of the plant and crop yield (Livinali et al., 2014). Ribeiro et al. (2021) found the paren tal generation of TSSM had a shorter pre-

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oviposition, oviposition, and longevity when strawberry plants were treated with K 2 SiO 3 . In the F1 generation, the duration of the egg phase was longer in plants treated with nano silicate particles relative to those treated with K 2 SiO 3 , and the larva phase duration was also longer in nano-silica plants in relation to the control. The delay of the pest’s development could potentially be due to the increased leaf thickening and decreased palatability from Si application (Moraes et al., 2005). This would delay TSSM feeding ability and result in the increased larval stages. Liu et al. (2020) also reported decreased incidence of TSSM in plants fertigated with 70-80% (w/v) tetra ethyl silicate. The average number of TSSM per strawberry leaf was two to three times greater in the untreated control than in the Si treatments in 2014 and more than three times greater in 2015. Si also impacts plant-herbivore relation ships through the modification of herbivore induced plant volatiles where the parasitoids Trathala flavo-orbitalis and Microplitis me diator were more attracted to Si-treated rice ( Oryza sativa ) (Liu et al., 2017), suggesting that Si applications may have indirect benefits for plant production. Another report suggests that Si supplementation has proved effective in reducing the presence of fall armyworm [ Spodoptera frugiperda (J. E. Smith)], caus ing high rates of mortality in the early stage of larvae (Ul Haq et al., 2022). Nevertheless, more research is required to understand the mechanism of Si in predator-prey dynamics as Si could be an environmentally friendly application in field settings (Deshmukh et al., 2017). Si can mitigate the effects of abiotic stress . Strawberries under water stress often have decreased leaf area, chlorophyll content, net photosynthesis rate, and stomatal conduc tance, but foliar application of K 2 SiO 3 can mitigate the transpiration rate and improve the water use efficiency (Dehghanipoodeh et al., 2018). Applying Si, along with inoculating the strawberry plants with arbuscular-mycorrhi

zal fungi (AMF), improved the relative water content in leaves by increasing the capacity for water uptake that, in turn, allowed the maintenance of a high stomatal conductance and photosynthetic capacity for supporting growth and dry matter production (Moradta lab et al., 2019). Roots amended with both Si and AMF had increased levels of organic os molytes, suggesting that this combination led to an increased influx of water into the root system (Moradtalab et al., 2019). Si can increase salinity tolerance . Si plays a crucial role in alleviating salinity stress in strawberries. High levels of NaCl exposure caused necrosis, leaf burn and nutritional im balances in strawberry leaves, resulting in de creased fruit yield and quality and increased rates of plant mortality (Avestan et al., 2019). The epicuticular wax layer (EWL) on straw berry leaves prevents water loss and serves as a barrier to abiotic stress (Jenks and Ashworth, 2010; González and Ayerbe, 2010). Since Si was linked with EWL formation, foliar appli cation of the element as a nanoparticle has the potential to reduce salinity stress (Avestan et al., 2019). Strawberry plants growing in Si amended soil had greater EWL than controls; the largest difference occurred at 100 mg . L -1 SiO 2 before flowering and 50 mg · L -1 after the flowering stage. Si nanoparticles reduced the relative water loss and improved the mem brane stability index of strawberries grown under salinity stress, linking Si to improved water use efficiency in strawberry. The re inforcement of the cuticle layer is thought to lead to decreased leaf transpiration as the silica layers form a physical blockade through cell thickening (Wang et al., 2021). Proline is often used as an indicator of sa linity stress because it accumulates when the stress is applied (Hayat et al ., 2012). Strawber ries amended with Si had lower proline levels relative to the control plants; there was also a negative correlation between proline and the EWL. Root growth improved in strawberries amended with Si nanoparticles and this also contributed to improved water use efficiency (Avestan et al., 2019). The application of Si

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nanoparticles enhanced strawberry fruit set and yield as well. Strawberry plants amended with 100 mg · L -1 SiO 2 before flowering and 50 mg · L -1 after the flowering stage displayed the highest fruit set, and strawberry plants treated with SiO 2 nanoparticles had higher yields than the control (Avestan et al., 2019). Si affects antioxidants. Reactive oxygen species (ROS) produced in plant leaves under stress have the potential to negatively impact plant metabolism (Muneer et al., 2017). Si application, in the form of K 2 SiO 3 has been shown to activate enzymes involved in the antioxidant system such as superoxide dis mutase, which effectively converts superox ide to hydrogen peroxide (H 2 O 2 ) and then to water by ascorbate peroxidase and catalase (Muneer et al., 2017). Si is most effective when applied foliarly as K 2 SiO 3 or when it is integrated into the dripline to scavenge ROS during extreme temperature stress. Park et al. (2018) found that the application of Si in creased the expression of two superoxide dis mutase isozymes during the plant’s exposure to salt stress. They also confirmed that K 2 SiO 3 is the most effective form of Si fertilizer. Catalase enzymes also were up-regulated in the presence of salinity-stressed strawberries amended with Si (Park et al., 2018). Si fertilization can enhance yield and fruit quality . Foliar forms of supplemental Si in creased the marketable yield, fruit size and firmness of strawberries (Weber et al., 2018; Ouellette et al., 2017). Potassium silicate applications in hydroponic solutions also increased yield and fruit firmness (Miyake and Takashi, 1986). Strawberries (cv. Paros) subject to Si-fertilization regimes showed in creased levels of phenolic compounds. Path ways that synthesize phenolic acids–gallic acid, caffeic acid, chlorogenic acid, and ellag ic acid–and pathways that produce flavonols and flavanols were both upregulated in plants amended with Si (Hajiboland et al., 2018). When plants were exposed to heat stress, the total sugar and anthocyanin concentration of Si-fertilized plants was higher than those not treated with Si (Weber et al., 2018). While

Si supplementation can help strawberry cul tivars reach their genetic potential, major changes in carbohydrate, enzyme activity, and secondary metabolite profiles are dictated by genotype (Topcu et al., 2022). Despite some of the clear benefits associat ed with supplementing strawberry fertilizers with Si, some abnormalities have been report ed, particularly the induction of albinism. Al binism was reported when the rate of soluble Si in the water source or nutrient solution was high (Lieten et al., 2002). Whether this is due directly to Si or an artifact of increased K and/ or N is disputed. In albino fruit, the N:Ca ratio and K:Ca ratio tends to be higher relative to normal fruit (Sharma et al., 2006). Jun et al. (2006) also reported incidence of albino fruit in hydroponic solution when they applied over 200 mg . l -1 of K 2 SiO 3 . While considering these claims, Ouellette et al. (2017) refuted the notion that Si supplementation could di rectly result in albino fruit in strawberry. If growers use supplemental Si fertilizers, care should be used to avoid the induction of albi nism from imbalances in nutrients. Conclusion Evidence suggests that Si is a critical el ement for optimal functioning of strawberry plants. Si fertilization can directly impact fruit size and quality, and indirectly enhance yield by mitigating abiotic and biotic stress. Both hydroponic and field-grown strawberry plants can benefit from regulated applications of Si, especially as it relates to the control of powdery mildew. Optimal application rates of appropriate forms of Si need to be determined for different production systems and the culti vars involved. Several associated underlying molecular mechanisms of Si functioning re main to be elucidated. Literature Cited Abo-Foul, S., V. I. Raskin, A. Sztejinberg, and J. B. Marder. 1996. Disruption of chlorophyll organi zation and function in powdery mildew-diseased cucumber leaves and its control by the hyperpara site Ampelomyces quisqualis . Phytopathol. 86(2): 195–199 .

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Journal of the American Pomological Society 77(3): 136-149 2023

Abstract In 2021, this study investigated the effects of three different trellis systems on the fruit-zone microclimate, berry quality and anthocyanins of ‘Xinyu’ grape in Shanshan, Xinjiang, China. The results showed that the light and heat energy of fruit-zone microenvironment were higher for inclined ingle dragon trunk shaping + Horizontal leaf curtain (ISDTS-H) and inclined single dragon trunk shaping + V and Horizontal leaf curtain (ISDTS-VH) than for single dragon trunk shaping + Horizontal leaf curtain (SDTS-H). SDTS-H was more susceptible to low humidity than ISDTS-VH. The canopy area and leaf area index around the fruit were increased and canopy closure was in creased with ISDTS-VH compared to SDTS-H. ISDTS-VH increased berry weight, total soluble solids (TSS) and yield. Delphinidin concentration and total delphinidin proportion with SDTS-H were higher than that with ISDTS VH and SDTS-H, respectively. In general, ‘Xinyu’ grape grown with the ISDTS-VH trellis system achieved high quality under the local environmental conditions. These results provide a reference for the trellis systems selection and optimization of the ‘Xinyu’ grape cultivar. S.J. B ai 1 , J.G. H u 1 , M. Z heng 2 , J.Y. W u 3 , J.S. C ai 1 , G. C hen 1 , R.H. Z hao 1 , J.F. M eng 4 Additional index words : anthocyanin content; berry quality; micro environment; table grape; trellis system Effects of Different Trellis Systems on Fruit-zone Microclimate, Berry Quality and Anthocyanins of ‘Xinyu’ Grape ( Vitis vinifera L.)

Grapevines are typically supported with trellises, but grape regions choose different training systems that are best suited to them (Tian et al., 2022). The present-day global diversity of grapevine training systems has arisen from differences between grape spe cies and cultivars with respect to growth habit and cropping capacity, as well as from envi ronmental and economic constraints on vine yard management (Wolf et al., 2003). A good training system can optimize canopy struc ture, which could improve microclimate con ditions and affect overall canopy photosyn thetic productivity (Liu et al., 2018; Araujo et al., 2008), influence vine performance and berry quality composition under protected cultivation. Vines trained on the SAYM (per

gola trellis and closing Y shaped trellis) trellis system had a large leaf area index (LAI) (Yin et al., 2022). It also contributed to total leaf area, the percentage of leaf well-exposed to light, and the percentage of leaves located in the interior of the canopy (Katerji et al., 1994; Reynolds and Heuvel, 2009; Schultz, 1995). Trellis systems can influence berry weight, and fruit soluble solids, and color (Ezzahoua ni and Williams, 2003; Sanchez-Rodriguez and Spósito, 2019), C 6 volatile compounds and C 9 compounds (Xu et al., 2015). Trellis systems may influence the concentration of monoterpenes, such as specifically geraniol (Ji et al., 2008), as well as berry dry matter (30%) and yield (9-11%) (Sanchez-Rodri guez and Spósito, 2019; Salvi et al., 2021),

1 Grapes and Melons Research Institution of Xinjiang Uighur Autonomous Region, Shanshan, Xinjiang 838200, China 2 Xinjiang Water Resource and Hydropower Research Institute, Urumqi, Xinjiang 830049, China 3 Turpan Research institute of Agricultural Sciences, Xinjiang Academy of Agricultural Sciences, Turpan, Xinjiang 838000, China 4 College of Enonogy, Northwest A&F University,Yangling, Shaanxi 712100, China Corresponding author: Ming Zheng, Jiangfei Meng, Junshe Cai. E-mail address: xjzhengming@126.com, mjfwine@nwsuaf.edu.cn, abc8303099@126.com

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and primary and secondary metabolites, such as soluble solids, acidity, and phenolic pro files of grapes (Azuma et al., 2012). Although training system effects on yield and fruit composition have been extensively evaluated in cool climates (Carbonneau and Huglin, 1982; Reynolds et al., 1995), less work has been done in warm to hot climates, where the mean January (or July) temperature (MJT) is greater than 21°C (Smart et al., 1985). Some studies also indicate that berry weight, length and diameter, and total soluble solids were not significantly different among the trellis systems (Kim et al., 2014). Ezzahouani and Williams (2003) also found that yield per vine was not affected by any of the trellis treat ments. Berry skin color is one of the most impor tant fruit traits selected for with red grape cul tivars. It is mainly determined by the quality and composition of anthocyanins (Azuma et al., 2015). There are six main anthocyanins in plants, which are cyanidin, delphinidin, pel argonidin, peonidin, malvidin, and petunidin (Wang et al., 2021). Anthocyanins accumu late in berry skins during ripening, and sev eral agroecological factors, such as cultivar, climate, soil conditions, canopy management, crop level, irrigation, ripening, and tempera ture have been related to anthocyanin ac cumulation in red grape skins (Jackson and Lombard., 1993; Esteban et al., 2001). The ‘Xinyu’ table grape ( Vitis vinifera L.) was bred from a cross between the natural hybrid single ‘Red Globe’ plant E-42-6 (fe male parent) and ‘Rizamat’ (male parent) at the Grapes and Melons Research Institute of Xinjiang Uighur Autonomous Region and registered by Xinjiang Uygur Autonomous Region Crop Variety Registration Commit tee in 2005. Its berries are oval with dark red/ violet skin, a slightly crisp texture, and sour sweet flavor as well as good storage, transpor tation, and adaptability characteristics (Luo et al., 2007). At present, ‘Xinyu’ is widely culti vated in Xinjiang, Yunnan, Shaanxi, and other provinces in China. Grapes were previously cultivated on small trellis systems in the Tur

pan region that provided a good windproof effect while requiring a minimal amount of material. However, these systems were also low to the ground and not amenable to mech anized cultivation and management. There are a multitude of trellis systems for grape vines in different parts of China. Each system has it peculiarities, which may be related to the characteristics of the region, such as the relief, climatic condition, technological level and cultural habit of grape grower (Sander et al., 2019). This research was conducted in the Turpan region of China, in 2021, and is a typical ex tremely arid area, with high temperatures and low humidity. During the fruit coloring, the air temperature is at its highest for the year, which can result in poor color or excessively dark coloration. To increase ‘Xinyu’ produc tion and to optimize fruit quality, it is very important to choose the appropriate trellis system to obtain light interception and pho tosynthetic radiation. Therefore, a new trellis system is required. To date there are still few studies aimed at the fruit quality and other characteristics of ‘Xinyu’ grown in a high temperature, low humidity, and strong light environment. The aim of this study was to in vestigate the effects of three different trellis systems on the fruit-zone microclimate, can opy structure, fruit quality, and anthocyanin concentration of ‘Xinyu’ grape cultivated in Turpan, Xinjiang, China, in order to provide a reference for the production of high-quality fruit. Materials and Methods Experimental site and treatments The own-rooted ‘Xinyu’ table grapes ( Vi tis vinifera L.) that had been planted in 2015 were sourced from Yuanyichang (42°91′N, 90°30′E), Shanshan county, Turpan, Xinji ang, China, in 2021. The experiment consisted of three treat ments: (1) single dragon trunk shaping and horizontal leaf curtain (SDTS-H, Figure 1), (2) inclined single dragon trunk shaping and horizontal leaf curtain (ISDTS-H, Figure 2.),

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Figure 1. Single dragon trunk shaping + Horizontal leaf curtain, SDTS-H

Figure 2. Inclined single dragon trunk shaping + Horizontal leaf curtain, ISDTS-H

(3) inclined single dragon trunk shaping with vertical and horizontal leaf curtains (ISDTS VH, Figure 3.). Both ISDTS-H and ISDTS VH vines were oriented in an east–west di rection with an angle of 15° to the west/east and were spaced at 2.0 m×3.5 m, the SDTS-H vines were spaced at 1.2 m×4.0 m and trunk was north-south. ISDTS-H and ISDTS-VH

treatments were applied to 42 grapevine ex perimental units, and SDTS-H treatment ap plied to 62 grapevine experimental units, each unit area was about 300 m 2 , and the treatments were replicated three times in a completely randomized design. Four grape vines at each end of the experiment plot were excluded to minimize the border effect.

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Figure 3. Inclined single dragon trunk shaping + V and Horizontal leaf curtain, ISDTS-VH

The vineyard was irrigated with a micro spray irrigation system. The total amount of irrigation water was about 15,000 m 3 ·ha –1 for each year. Organic fertilizer (sheep manure, 30 m 3 ·ha –1 ), diammonium phosphate (DAP, 900 kg·ha –1 ), carbamide (300 kg·ha –1 ), com pound fertilizer (15% N : 1.4% P : 6.55% K, 600 kg·ha –1 ) and potassium sulphate (300 kg·ha –1 ) were applied each year. Pest and dis ease management followed the standard pro cedure used in the production yard. Fruit-zone microclimate monitoring To measure the fruit-zone microclimate, a temperature-humidity recorder (EL-USB-2, Lascar, United Kingdom) was hung in the fruit zone during the fruit coloration period to monitor the fruit-zone temperature and hu midity. One sensor was applied to each ex perimental unit; there were 9 sensors. Values were recorded at 30-min intervals throughout each day from the early stage of veraison (5 June) to the fruit ripening stage (20 August). Grape sample collection and measurement Leaf curtain structure, branch growth, and leaves area index The length, width, and thickness of the leaf curtain were measured using a tape measure, seven days after secondary tips were trimmed

in early July. A plant canopy analyzer (LAI 2200C, LI-COR Biosciences, Lincoln, NE, USA) was used to measure leaf area index (LAI) for each replicate from 12 randomly selected sites in each plot. Berry quality and yield For each replicate, 1500 g of berries were collected and immediately transported to the laboratory to measure fruit quality. A subsample of 30 berries per replicate was weighted on an electronic balance (AL214, Sartorius, Germany), and berry longitudi nal diameter and transverse diameter were measured using Vernier calipers (DL3944, Deli Group Co. LTD, China). Berry shape in dex was calculated as longitudinal diameter (mm)/transverse diameter (mm). A portable refractometer (PAL-1, Atago, Tokyo, Japan) was used to determine the total soluble solids (TSS, °Brix). Titratable acid concentration (TA) was determined by titration with 0.05 mol·L −1 NaOH to an endpoint of pH 8.2, and was expressed as tartaric acid equivalents. Vitamin C (VC) concentration was determined according to food safety national standard Determina tion of total acid in foods (GB 12456-2021, 2021), total anthocyanins concentrations were determined utilizing the pH differential

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method (Stojanovic and Silva, 2007). Each measurement was repeated 3 times. When the berry was mature, clusters were picked and weighed to calculate the yield of each plot. Color measurement Berry color was determined around the equatorial belt of each berry for 20 berries per treatment. A chroma meter (CR-400, Atago, Tokyo, Japan) was used to measure L *, a *, and b * values. The values of a * and b * were used to calculate the chroma axis C * with the equation C *=[( a *) 2 + ( b *) 2 ] 0.5 . The hue angle ( h °) was calculated with the equation h °=tang −1 ( b */ a *). These values were used to calculate the color index for red grape (CIRG) with the equation CIRG=(180−h°)/(L*+C*) (Carreño et al., 1995), green-yellow (CIRG <2), pink (26) (Carreño et al., 1996). Detection of anthocyanin compounds in peel Chemicals and reagents . High-perfor mance liquid chromatography-grade methanol (MeOH) was purchased from Merck (Darm stadt, Germany). MilliQ water (Millipore, Bedford, MA, USA) was used in all experi ments. All of the standards were purchased from isoReag (Shanghai, China). Formic acid was purchased from Sigma-Aldrich (St. Louis, MO, USA). Hydrochloric acid was ob tained from Xinyang Chemical Reagent (Xin yang, China). Stock solutions of standards were prepared at a concentration of 1 mg/ml in 50% MeOH and stored at -20°C. Working solutions were prepared by diluting the stock solutions with 50% MeOH before use. Sample preparation and extraction . Sam ples were freeze-dried, ground into powder (30 Hz, 1.5 min), and stored at -80°C until use. The powder (50 mg) was extracted with 0.5 ml methanol/water/hydrochloric acid (500:500:1, v/v/v) and the extract was vor texed for 5 min, ultrasonicated for 5 min, and centrifuged at 12,000× g and 4°C for 3 min. The residue was re-extracted by repeating the above steps under the same conditions. The

supernatant was collected and passed through a membrane filter (0.22 μm; ANPEL Labora tory Technologies, Shanghai, China) before liquid chromatography–tandem mass spec trometry (LC–MS/MS) analysis. Ultrahigh-performance liquid chromatog raphy (UPLC) . Sample extracts were ana lyzed using a UPLC-electrospray ionization (ESI)–MS/MS system (ExionLC™ and Tri ple Quad 6500; AB Sciex, Framingham, MA, USA). The analytical conditions were as fol lows, ACQUITY BEH C18 (1.7 µm, 2.1×100 mm) (Waters, Milford, MA, USA); solvent system, water (0.1% formic acid):methanol (0.1% formic acid); gradient program, 95:5 v/v at 0 min, 50:50 v/v at 6 min, 5:95 v/v at 12 min, hold for 2 min, 95:5 v/v at 14 min, hold for 2 min; flow rate, 0.35 ml/min; tem perature, 40°C; and injection volume, 2 μL. ESI–MS/MS conditions . Linear ion trap and triple quadrupole scans were acquired on a triple quadrupole linear ion trap mass spec trometer (QTRAP6500+ LC–MS/MS system) equipped with an ESI turbo ion spray interface, operating in positive ion mode and controlled with Analyst v1.6.3 software (AB Sciex). The ESI source operation parameters were as fol lows: ion source, ESI+; source temperature, 550°C; ion spray voltage, 5500 V; and curtain gas, 35 psi. Anthocyanins were detected us ing scheduled multiple reaction monitoring (MRM). Analyst v1.6.3 software (AB Sciex) was used for data acquisition, and Multiquant v3.0.3 software (AB Sciex) was used to quan tify metabolites. MS parameters including the declustering potential (DP) and collision energy (CE) for individual MRM transitions were used with further DP and CE optimiza tion. A specific set of MRM transitions were monitored for each period according to the metabolites eluted within this period. Data analysis Excel 2007 software (Microsoft, Redmond, WA, USA) and SPSS v20.0 (IBM, Armonk, NY, USA) were used for statistical analyses. Statistically significant differences ( P <0.05) between groups were evaluated by 1-way

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analysis of variance and Duncan’s multiple range test for multiple comparisons. Figure 1 was produced with photoshop (CC2019, Adobe, America). Figure 2 was plotted using OriginLab OriPro 2021 (MicroLalab, USA). Results Fruit-zone microclimate The minimum and mean temperatures were higher for ISDTS-H and ISDTS-VH than those for SDTS-H. Means of the mini mum temperature and mean temperature were higher for ISDTS-H and ISDTS-VH than for SDTS-H, with differences of 2.77°C and 2.72°C, and 2.29°C and 2.24°C, respec tively (Figure 4). The maximum and mean humidities were

higher for SDTS-H than for ISDTS-H and ISDTS-VH, and ISDTS-VH was slighter higher than ISDTS-H. Compared with SDTS H, the maximum humidity and the minimum humidity for ISDTS-H and ISDTS-VH were

decreased (Figure 5). Leaf curtain structure

Canopy thickness was lower for ISDTS VH and ISDTS-H than for SDTS-H. Canopy length was significantly longer for SDTS-H than for the other systems, whereas SDTS-H and ISDTS-VH were not different. Canopy width was highest for ISDTS-VH and pro gressively lower for ISDTS-H and SDTS-H. Canopy height was the highest for ISDTS-H, followed by ISDTS-VH, SDTS-H, with sig

Figure 3. Inclined single dragon trunk shaping + V and Horizontal leaf curtain, ISDTS-VH

Figure 4. Daily average minimum, maximum and mean temperatures within the canopies of ‘Xinyu’ grape vines trained to three systems. Figure 4. Daily average minimum, maximum and mean temperatures within the canopies of ‘Xinyu’ grape vines trained to three systems.

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nificant differences among the three groups. For leaf area index (LAI), SDTS-H was the highest (5.84), followed by ISDTS-VH (5.25) and ISDTS-H (4.80), and differences among the trellis systems were significant (Table 1). Berry quality Berry weight, berry longitudinal diameter, and fruit shape index were significantly high er for ISDTS-VH than ISDTS-H and SDTS H, but the latter two treatments were not sig nificantly different. Berry transverse diameter was not affected by trellis system (Table 2). Total soluble solids and TSS/TA were sig nificantly higher for ISDTS-VH and ISDTS H than for SDTS-H, and titratable acid (TA) concentration was significantly lower for ISDTS-H and ISDTS-VH than for SDTS Table 1. Leaf curtain structure characteristics of ‘Xinyu’ grape vines trained to three different trellis systems. Canopy characteristic SDTS-H ISDTS-H ISDTS-VH Thickness (cm) 51.67±6.24 a 28.17±2.03 c 36.75±2.37 b Length (m) 4.06±0.13 a 2.13±0.06 b 2.11±0.07 b Width (m) 1.13±0.04 c 3.10±0.07 b 3.45±0.02 a Area (m 2 ) 4.59±0.15 c 6.60±0.12 b 7.28±0.08 a Height (m) 1.48±0.08 c 1.91±0.01 a 1.70±0.12 b Leaf area index 5.84±0.32 a 4.80±0.16 c 5.25±0.19 b z Values are means ± standard deviations of three replicates. Values within rows followed by common H. Vitamin C concentration was highest for ISDTS-VH, followed by ISDTS-H, and SDTS-H. Total anthocyanins concentration was highest for ISDTS-H, followed by IS DTS-VH, and SDTS-H. Number of clusters per ha and yield were significantly highest for SDTS-H, followed by ISDTS-VH and IS DTS-H. Berries on ISDTS-H ripened earliest (15 July), and fruit on SDTS-H ripened latest (10 August). Fruit color Compared to SDTS-H, values of L *, a *, b *, and C * were significantly lower for IS DTS-VH and ISDTS-H (Table 3). CIRG for SDTS-H was significantly lower than for ISDTS-VH and ISDTS-H. Figure 5. Daily average minimum, maximum and mean relative humidity measured within the canopies of ‘Xinyu’ grape vines trained to three systems. Figure 5. Daily average minimum, maximum and mean relative humidity measured within the canopies of ‘Xinyu’ grape vines trained to three systems.

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