Effects of Different Crop Loads on Physiological, Yield and Fruit Quality of ‘Joya<sup>TM</sup>’ Apple Trees: High Crop Load Decreases Maximum Daily Trunk Diameter and Does Not Affect Stem Water Potential

Atay, Ersin; Crété, Xavier; Loubet, Déborah; Lauri, Pierre‐Éric

doi:10.1080/15538362.2021.1951922

Cited by 10 publications

(4 citation statements)

References 33 publications

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“…With higher radiation and/or VPD, Ψ trunk was lower. However, our results from this study with an SVM model showed that the correlation between VPD and Ψ stem was not linear, which concurs with the results of De Swaef et al [21] and Atay et al [22]. Moreover, both of those studies showed that high VPD values above 2 and 3 kPa did not further reduce stem water potential, which concurs with the results of our SVM model.…”

Section: Discussionsupporting

confidence: 90%

Trunk Water Potential Measured with Microtensiometers for Managing Water Stress in “Gala” Apple Trees

González

Huber

Gao

et al. 2023

Plants

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The weather variations around the world are already having a profound impact on agricultural production. This impacts apple production and the quality of the product. Through agricultural precision, growers attempt to optimize both yield and fruit size and quality. Two experiments were conducted using field-grown “Gala” apple trees in Geneva, NY, USA, in 2021 and 2022. Mature apple trees (Malus × domestica Borkh. cv. Ultima “Gala”) grafted onto G.11 rootstock planted in 2015 were used for the experiment. Our goal was to establish a relationship between stem water potential (Ψtrunk), which was continuously measured using microtensiometers, and the growth rate of apple fruits, measured continuously using dendrometers throughout the growing season. The second objective was to develop thresholds for Ψtrunk to determine when to irrigate apple trees. The economic impacts of different irrigation regimes were evaluated. Three different water regimes were compared (full irrigation, rainfed and rain exclusion to induce water stress). Trees subjected the rain-exclusion treatment were not irrigated during the whole season, except in the spring (April and May; 126 mm in 2021 and 100 mm in 2022); that is, these trees did not receive water during June, July, August and half of September. Trees subjected to the rainfed treatment received only rainwater (515 mm in 2021 and 382 mm in 2022). The fully irrigated trees received rain but were also irrigated by drip irrigation (515 mm in 2021 and 565 mm in 2022). Moreover, all trees received the same amount of water out of season in autumn and winter (245 mm in 2021 and 283 mm in 2022). The microtensiometer sensors detected differences in Ψtrunk among our treatments over the entire growing season. In both years, experimental trees with the same trunk cross-section area (TCSA) were selected (23–25 cm−2 TCSA), and crop load was adjusted to 7 fruits·cm−2 TCSA in 2021 and 8.5 fruits·cm−2 TCSA in 2022. However, the irrigated trees showed the highest fruit growth rates and final fruit weight (157 g and 70 mm), followed by the rainfed only treatment (132 g and 66 mm), while the rain-exclusion treatment had the lowest fruit growth rate and final fruit size (107 g and 61 mm). The hourly fruit shrinking and swelling rate (mm·h−1) measured with dendrometers and the hourly Ψtrunk (bar) measured with microtensiometers were correlated. We developed a logistic model to correlate Ψtrunk and fruit growth rate (g·h−1), which suggested a critical value of −9.7 bars for Ψtrunk, above which there were no negative effects on fruit growth rate due to water stress in the relatively humid conditions of New York State. A support vector machine model and a multiple regression model were developed to predict daytime hourly Ψtrunk with radiation and VPD as input variables. Yield and fruit size were converted to crop value, which showed that managing water stress with irrigation during dry periods improved crop value in the humid climate of New York State.

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Section: Discussionsupporting

confidence: 90%

Trunk Water Potential Measured with Microtensiometers for Managing Water Stress in “Gala” Apple Trees

González

Huber

Gao

et al. 2023

Plants

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“…The loss of quality (flesh firmness, TSS, DMC, MA content, L/D ratio, and fruit color) with increasing crop load is in line with the findings of Bound [17] and Atay [41] and can be attributed to increased competition for resources with increasing crop load, while the low crop load trees had adequate availability of carbohydrate resources.…”

Section: Fruit Maturity and Qualitysupporting

confidence: 84%

“…This increase in fruit weight can be explained by the early removal of excess floral buds, which prevents wastage of resources, in combination with higher light interception through better fruit positioning contributing to increased carbohydrate production and improved partitioning to targeted fruits [17,30,34]. The reduction in fruit weight with increasing crop load was in line with the previously reported inverse relationship between the fruit number/tree and the final fruit weight [3,4,40,41].…”

Section: Fruit Weight and Yieldsupporting

confidence: 84%

Crop Load and Thinning Methods Impact Yield, Nutrient Content, Fruit Quality, and Physiological Disorders in ‘Scilate’ Apples

2022

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Most apple cultivars produce too many flowers to enable consistent yields of high-quality fruit, thus, crop load management (thinning) is an integral part of orchard management in modern apple cultivation. Crop load is managed by thinning excess flowers and/or fruit from a tree, however ideal targets vary between cultivars. In this two-year study, the effect of thinning methods at different levels of crop load on fruit quality and production, post-harvest storability and physiological disorders, and fruit and leaf nutrient content in ‘Scilate’ apples were investigated in southern Tasmania, Australia. Two thinning methods, artificial bud extinction (ABE) and hand thinning (HT), were compared at three levels of crop load: 3, 6, or 12 fruit cm−2 limb cross-sectional area (LCSA), described as low, medium, and high, respectively. During the second season, all the ABE and HT treatments received additional chemical thinning (CT). The results demonstrated that ABE consistently outperformed HT in terms of improved fruit set, return bloom, and fruit weight. The fruit quality parameters, such as flesh firmness, total soluble solids, dry matter content, malic acid content, and fruit shape, were also improved under the ABE regime, with these positive effects being the clearest in the second season. In general, high-quality fruits were obtained from the low and medium crop loads, while the fruit quality was poor for the high crop load trees, but the low crop load fruit had a slightly higher incidence of internal flesh browning (predominantly radial) and fruit softening after regular atmosphere storage. The crop load also impacted on the fruit and leaf mineral nutrient content, where fruit N, Ca, Mn, and Zn, and leaf N, Fe, Zn, and Cu content increased while fruit and leaf K declined with a higher crop load. High crop load, irrespective of the thinning regime, and HT with a medium crop load, induced severe biennial bearing, whereas, the fruit yield was relatively consistent with ABE, even with a medium crop load. We conclude that ABE with a medium crop load (around six fruit cm−2 LCSA) is an effective method of managing crop load and optimizing the fruit quality in ‘Scilate’ apples.

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“…These trees would be required to be adequately thinned to improve fruit quality for the current season but also yield a consistent crop load for the following season. Light crop load trees (“OFF”) are associated with bigger fruit sizes that can have storage disorders [ 5 ]. Both phases of the cycle cause a disruption in cropping levels resulting in serious economic losses for the apple industry and can cause significant financial strain on fruit growers.…”

Section: Introductionmentioning

confidence: 99%

Metabolic Pathways for Observed Impacts of Crop Load on Floral Induction in Apple

Reddy

Plozza

Ezernieks

et al. 2022

IJMS

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The triggers of biennial bearing are thought to coincide with embryonic development in apple and occurs within the first 70 days after full bloom (DAFB). Strong evidence suggests hormonal signals are perceived by vegetative apple spur buds to induce flowering. The hormonal response is typically referred to as the floral induction (FI) phase in bud meristem development. To determine the metabolic pathways activated in FI, young trees of the biennial bearing cultivar ‘Nicoter’ and the less susceptible cultivar ‘Rosy Glow’ were forced into an alternate cropping cycle over five years and an inverse relationship of crop load and return bloom was established. Buds were collected over a four-week duration within 70 DAFB from trees that had maintained a four-year biennial bearing cycle. Metabolomics profiling was undertaken to determine the differentially expressed pathways and key signalling molecules associated with biennial bearing. Marked metabolic differences were observed in trees with high and low crop load treatments. Significant effects were detected in members of the phenylpropanoid pathway comprising hydroxycinnamates, salicylates, salicylic acid biosynthetic pathway intermediates and flavanols. This study identifies plant hormones associated with FI in apples using functional metabolomics analysis.

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Effects of Different Crop Loads on Physiological, Yield and Fruit Quality of ‘Joya^TM’ Apple Trees: High Crop Load Decreases Maximum Daily Trunk Diameter and Does Not Affect Stem Water Potential

Cited by 10 publications

References 33 publications

Trunk Water Potential Measured with Microtensiometers for Managing Water Stress in “Gala” Apple Trees

Trunk Water Potential Measured with Microtensiometers for Managing Water Stress in “Gala” Apple Trees

Crop Load and Thinning Methods Impact Yield, Nutrient Content, Fruit Quality, and Physiological Disorders in ‘Scilate’ Apples

Metabolic Pathways for Observed Impacts of Crop Load on Floral Induction in Apple

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Effects of Different Crop Loads on Physiological, Yield and Fruit Quality of ‘JoyaTM’ Apple Trees: High Crop Load Decreases Maximum Daily Trunk Diameter and Does Not Affect Stem Water Potential

Cited by 10 publications

References 33 publications

Trunk Water Potential Measured with Microtensiometers for Managing Water Stress in “Gala” Apple Trees

Trunk Water Potential Measured with Microtensiometers for Managing Water Stress in “Gala” Apple Trees

Crop Load and Thinning Methods Impact Yield, Nutrient Content, Fruit Quality, and Physiological Disorders in ‘Scilate’ Apples

Metabolic Pathways for Observed Impacts of Crop Load on Floral Induction in Apple

Contact Info

Product

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Effects of Different Crop Loads on Physiological, Yield and Fruit Quality of ‘Joya^TM’ Apple Trees: High Crop Load Decreases Maximum Daily Trunk Diameter and Does Not Affect Stem Water Potential