Fruit Soluble Solids Content Research Articles

‘신고’ 배 과실 품질과 저장성에 미치는 지베렐린 페이스트들의 효과

This study evaluated the effects of four different gibberellin-pastes (GAP) on fruit quality and storability of niitaka pear in 2014 and 2015 consecutive years. Pear fruit stalks were treated with dongbu GA gold, nebaekeo, busa, and GA hyeophwa-pastes at 35 and 37 days after full bloom, respectively. After harvest time, the fruits were stored at 0°C for up to 180 days. In both years, fruit weight was 6.2-21.3% higher in GAP-treated fruits than the control fruits at harvest. In 2014 year, flesh firmness was higher in control (70.6 N) than the GAP-treated fruits (54.4-64.6 N) at harvest, but it was not different in all treatments in 2015 year. The titratable acidity (TA) at harvest was also higher in control than the GAP treated fruits in 2014 year. The soluble solids content (SSC) at harvest was slightly lower in control than the GAP treated fruits in both years. During cold storage, flesh firmness was decreased in all treatments, whereas the fruits treated with nebaekeo GAP had the lowest flesh firmness (39.4 N) after 135 days of the storage. TA was a slightly higher in control (0.19%) than the GAP-treated fruits (0.14-0.17%) after 180 days of storage. However, SSC was higher in the fruits treated with dongbu GA gold and GA hyeophwa-pastes than the control fruits during storage. Therefore, GAP-treatments increased fruit weight and SSC than control, but flesh firmness and TA of GAP-treated fruits were reduced after 180 days of the storage.

HKT1;1 and HKT1;2 Na+ Transporters from Solanum galapagense Play Different Roles in the Plant Na+ Distribution under Salinity.

Salt tolerance is a target trait in plant science and tomato breeding programs. Wild tomato accessions have been often explored for this purpose. Since shoot Na+/K+ is a key component of salt tolerance, RNAi-mediated knockdown isogenic lines obtained for Solanum galapagense alleles encoding both class I Na+ transporters HKT1;1 and HKT1;2 were used to investigate the silencing effects on the Na and K contents of the xylem sap, and source and sink organs of the scion, and their contribution to salt tolerance in all 16 rootstock/scion combinations of non-silenced and silenced lines, under two salinity treatments. The results show that SgHKT1;1 is operating differently from SgHKT1;2 regarding Na circulation in the tomato vascular system under salinity. A model was built to show that using silenced SgHKT1;1 line as rootstock would improve salt tolerance and fruit quality of varieties carrying the wild type SgHKT1;2 allele. Moreover, this increasing effect on both yield and fruit soluble solids content of silencing SgHKT1;1 could explain that a low expressing HKT1;1 variant was fixed in S. lycopersicum during domestication, and the paradox of increasing agronomic salt tolerance through silencing the HKT1;1 allele from S. galapagense, a salt adapted species.

Hyperspectral image information fusion-based detection of soluble solids content in red globe grapes

• Red globe grape are widely loved for their full grain, firm flesh, sweetness and high nutrient content. SSC is one of the important internal qualities of the fruit and is an important indicator of fruit ripeness. • The traditional method for testing SSC of fruits is to conduct destructive detecting, which is tedious and time-consuming, and only samples can be detected, and the experimental samples are completely damaged after detecting and cannot be sold and consumed. • In this paper, the hyperspectral images and spectral information of the samples were collected by hyperspectral imaging technology, and a PLSR model of SSC of red globe grape based on the fusion of spectral information, image information and hyperspectral image information was built. • After comparative analysis, an optimal detection model of SSC of red globe grape was determined, which provides a new method for the non-destructive detection of SSC of red globe grape. The Soluble Solids Content (SSC) of red globe grapes is an important indicator of internal quality. In this paper, 360 red globe grapes in the growing stage were collected as samples and the spectral information and images of the samples were extracted. The Raw spectral (RAW) information was extracted using the one-time dimensionality reduction algorithm (GA, CARS, SPA, UVE) and the combined dimensionality reduction algorithm (CARS-SPA, UVE-SPA) to build the PLSR model of the spectral information. The grey-scale co-occurrence matrix of the image was extracted as the texture feature information of the image and combined with the color information of the image (R, G, B, H, S, V, L, a, b) to form 19 image features to build the PLSR model of the image information. Thus, the PLSR model based on the fusion of hyperspectral image information was built by fusing the spectra extracted with the successive projection algorithm (SPA) feature wavelength and the image information after dimensionality reduction by the principal component analysis algorithm (PCA). The results showed that if only the spectral information was used for modelling, the SPA algorithm effectively extracted the characteristic wavelengths of the red globe grapes of SSC spectral information and improved the prediction performance of the model. If only image information was used for modelling, the PCA algorithm effectively improved the detection performance of the model by dimensionality reduction, but the improved performance was limited. The correlation coefficients of the calibration set and prediction set of the PLSR model were 0.9775 and 0.9762, and the detection effect and stability of the model were greatly improved compared with those built unilaterally based on spectral information or image information, and a new non-destructive detection method was found for the detection about SSC of red globe grapes.

Tolerance of southern highbush blueberry to 2,4-D choline postemergence-directed

AbstractField studies were conducted on southern highbush blueberry in Elizabethtown and Rocky Point, NC, in 2019, 2020, and 2021 to determine tolerance to 2,4-D choline as a postemergence-directed application. In separate trials for younger and older bearing blueberry bushes, both 2,4-D choline rates and application timing were evaluated. Treatments included 2,4-D choline at 0, 0.53, 1.06, 1.60, and 2.13 kg ae ha–1 applied alone in winter during dormancy, and sequential treatments at 0.53 kg ae ha–1 followed by (fb) 0.53, 1.06 fb 1.06, 1.6 fb 1.6, or 2.13 fb 2.13 kg ae ha–1. The first application of the sequential treatments was applied in winter followed by another application in spring during early green fruit. Injury to blueberry from 2,4-D choline treatments was not observed for either maturity stage, and fruit yield was not affected by any of the treatments. Differences among treatments were not observed for fruit soluble solid content (SSC) in older bushes, or for fruit pH, SSC, and titratable acidity (TA) in younger bushes. In older bushes, fruit pH and TA had rate-by-timing interactions, and TA had a farm-year interaction with differences at Rocky Point in 2019 and Elizabethtown in 2020, but biologically no pattern was observed from the treatments.

A bulked segregant analysis tool for out-crossing species (BSATOS) and QTL-based genomics-assisted prediction of complex traits in apple

IntroductionGenomic heterozygosity, self-incompatibility, and rich-in somatic mutations hinder the molecular breeding efficiency of outcrossing plants. ObjectivesWe attempted to develop an efficient integrated strategy to identify quantitative trait loci (QTLs) and trait-associated genes, to develop gene markers, and to construct genomics-assisted prediction (GAP) modes. MethodsA novel protocol, bulked segregant analysis tool for out-crossing species (BSATOS), is presented here, which is characterized by taking full advantage of all segregation patterns (including AB × AB markers) and haplotype information. To verify the effectiveness of the protocol in dealing with the complex traits of outbreeding species, three apple cross populations with 9,654 individuals were adopted. ResultsBy using BSATOS, 90, 60, and 77 significant QTLs were identified successfully and candidate genes were predicted for apple fruit weight (FW), fruit ripening date (FRD), and fruit soluble solid content (SSC), respectively. The gene-based markers were developed and genotyped for 1,396 individuals in a training population, including 145 Malus accessions and 1,251 F1 plants of the three full-sib families. GAP models were trained using marker genotype effect estimates of the training population. The prediction accuracy was 0.7658, 0.6455, and 0.3758 for FW, FRD, and SSC, respectively. ConclusionThe BSATOS and GAP models provided a convenient and efficient methodology for candidate gene mining and molecular breeding in out-crossing plant species. The BSATOS pipeline can be freely downloaded from: https://github.com/maypoleflyn/BSATOS.

Fruit quality prediction based on soil mineral element content in peach orchard.

Mineral nutrition of orchard soil is critical for the growth of fruit trees and improvement of fruit quality. In the present study, the effects of soil mineral nutrients on peach fruit quality were studied by using artificial neural network model. The results showed that the four established ANN models had the highest prediction accuracy (R 2 = .9735, .9607, .9036, and .9440, respectively). The results of prediction model sensitivity analysis showed that available B, Ca, N, and K in the soil had the greatest influence on the single fruit weight, available Fe, K, B, and Ca in the soil had the greatest effect on fruit soluble solid content, available Ca, N, B, and K in the soil had the greatest influence on the fruit titratable acid content, and available Ca, Fe, N, and Mn in the soil had the greatest effect on fruit edible rate. The response surface methodology analysis determined the optimal range of these mineral elements, which is critical for guiding precision fertilization in peach orchards and improving peach fruit quality.

A novel early maturing kiwifruit (Actinidia eriantha) cultivar

ABSTRACT The fruit of most wild Actinidia eriantha are late maturing, which greatly restrict their commercial development. Fortunately, our team found an early maturing genotype, ‘Ganlv 2', with excellent fruit quality traits at an altitude of 750 m in Nancheng County, Jiangxi Province, China. In order to clarify whether the early maturity trait is stable and provide evidence for new cultivar protection, we performed DUS (Distinctness, Uniformity and Stability) tests during 2017-2019 and used SSR technology to construct a molecular fingerprint. The results showed that ‘Ganlv 2' is a novel diploid genotype, and matures about 20 d earlier than other A. eriantha cultivars. The average fruit weight of ‘Ganlv 2' was 45 g, and the maximum was 58 g at harvest. The fruit shape was oval and the peelable skin were covered with dense white hair. The three-year average value was 15.2% for its fruit soluble solids concentration, 17.4% for dry matter, 9.3% for total sugar content, 1.0% for total acid content, and 466.24 mg/100 g FW for vitamin C. In conclusion, the early maturity trait of ‘Ganlv 2’ appears to be stable, and it provides a novel genotype for studying the mechanism of early fruit maturity in kiwifruit.

Combined effects of Aloe vera gel and modified atmosphere packaging treatments on fruit quality traits and bioactive compounds of jujube (Ziziphus jujuba Mill.) fruit during cold storage and shelf life

This study assessed Aloe vera gel (AV) and modified atmosphere packaging (MAP) treatments on weight loss, respiration rate, color, firmness, soluble solids content (SSC), titratable acidity, vitamin C, phenol, flavonoids and antioxidant activity of jujube (Ziziphus jujuba Mill. cv. 'Li') fruit during cold storage and shelf life. Fruit were stored at 0 ± 0.5 °C and 90 ± 5 % relative humidity (RH) for 35 d followed by 21 ± 1.0 °C and 65 ± 5 % to simulate shelf life for 4 d. During cold storage, weight loss and respiration rate were delayed by MAP. At the end of cold storage, higher firmness and acidity were measured in fruit treated with MAP compared to control. Also, L*, hue angle, vitamin C, total phenolics, and the antioxidant activity of jujube fruit treated with both AV and MAP were higher than control. However, lower chroma and SSC in fruit treated with MAP were determined. During shelf life storage, higher firmness, L*, hue angle and acidity in fruit treated with MAP were obtained compared to control and AV treatments, whereas lower chroma and SSC were observed. On the last day of shelf life measurement (35 + 4 d), vitamin C, total phenolics, total flavonoids and antioxidant activity (DPPH and FRAP assays) of fruit treated with both AV and MAP was higher than control. In conclusion, it was revealed that AV and MAP treatments could be an effective tool for retarding the losses that occurred in the fruit quality of jujube during cold storage and shelf life. The effect of MAP treatment in maintaining fruit quality was more pronounced.

Interactions of Linearly Polarized and Unpolarized Light on Kiwifruit Using Aquaphotomics.

Near infrared (NIR) spectroscopy is an important tool for predicting the internal qualities of fruits. Using aquaphotomics, spectral changes between linearly polarized and unpolarized light were assessed on 200 commercially grown yellow-fleshed kiwifruit (Actinidia chinensis var. chinensis ‘Zesy002’). Measurements were performed on different configurations of unpeeled (intact) and peeled (cut) kiwifruit using a commercial handheld NIR instrument. Absorbance after applying standard normal variate (SNV) and second derivative Savitzky–Golay filters produced different spectral features for all configurations. An aquagram depicting all configurations suggests that linearly polarized light activated more free water states and unpolarized light activated more bound water states. At depth (≥1 mm), after several scattering events, all radiation is expected to be fully depolarized and interactions for incident polarized or unpolarized light will be similar, so any observed differences are attributable to the surface layers of the fruit. Aquagrams generated in terms of the fruit soluble solids content (SSC) were similar for all configurations, suggesting the SSC in fruit is not a contributing factor here.

Wi-Fruit

People usually assess fruit qualities from external features such as color, shape, size, and texture. However, it is quite common that we select fruits with perfect appearances but rotten inside, especially for fruits with thick pericarps. Thus the accurate measurement is desirable to evaluate the internal conditions of fruits. As two key features of fruit internal qualities, existing methods on measuring fruit moisture and soluble solid contents (SSC) are either destructive or costly, limiting their adoption in daily life. In this paper, we propose Wi-Fruit, a non-destructive and low-cost fruit moisture and SSC measurement system leveraging Wi-Fi channel state information (CSI). First, to cope with the fruit structure dependency challenge, we propose a double-quotient model to pre-process CSI on adjacent antennas. Second, to address the fruit size and type dependency challenges, a lightweight artificial neural network (ANN) model with visual information fusion is proposed for fruit moisture and SSC estimations. Extensive evaluations are conducted on 6 types of fruits with both thick (i.e., watermelon and grapefruit) and thin pericarps (i.e., dragon fruit, apple, pear, and orange) over a month in either an empty laboratory room or a library with massive books. Results demonstrate that Wi-Fruit achieves an acceptable estimation accuracy (RMSE=0.319). It is independent of various fruit structures, sizes, and types, while also robust to time and environmental changes. The fruit internal sensing capabilities of Wi-Fruit can help fruit saving and safety in both pre-harvest and post-harvest applications.

Effect of ambient temperature on the model stability of handheld devices for predicting the apple soluble solids content

The soluble solids content (SSC) is an important factor for determining the harvest time and the optimal storage time of apple fruit. However, changes in environmental temperatures cause the apple spectrum to fluctuate, which affects the robustness and accuracy of the model for predicting the apple fruit SSC. A portable detection device applicable for different temperatures was developed using a micro-spectrometer and temperature sensor. The detection time for the device was less than 2 s. The circuit board for collecting and analysing the spectrum signal, the detection light path and the housing of the device were designed, and the optimal integration time (6 ms) and light source power (4.5 W) of the device were determined. A total of 420 apple samples were examined in three ambient temperature ranges (0–2, 10–13, and 19–24 °C). The results showed that the model built independently in a single temperature environment can make a good prediction of the samples in the same temperature range. The application of d-value curve method reduced the influence of temperature on model accuracy to a certain extent. The d-value curve is a variable selection method independent of the reference value y, which describes the characterisation ability of each wavelength to samples in different sampling environments. These results conform that removing temperature-sensitive wavelengths from the independent variables or adding temperature factors can both improve the prediction ability of the device in different temperature environments. The model established by incorporating the temperature factor produced the most accurate predictions, with a predicted correlation coefficient, root mean square error of prediction, and ratio of standard deviation to RMSEP of 0.871, 0.402%, and 2.038, respectively.

Interactive effect of irrigation and blend ratio of controlled release potassium chloride and potassium chloride on greenhouse tomato production in the Yellow River Basin of China

Soil water and fertilizer are two main factors affecting tomato yield and quality, and their optimization management is crucial for sustainable production. There are many studies about the response of tomato growth and fruit yield formation to irrigation level and potassium (K) fertilizer, but few studies have been conducted on the responses of irrigation level and controlled release potassium chloride (CRK), not to mention the different irrigation levels and CRK to KCl blending ratios. In this study, two consecutive growing seasons (2020–2021) tomato pot experiments were presented with three irrigation levels (W100, W80, and W60) and three blending ratios of CRK to KCl (100%, 80%/20%, 60%/40%) under the condition that the amount of potassium fertilizer was reduced by 40% compared with conventional application rate. The results revealed that under W80 water conditions, 80% CRK mixed with 20% KCl application led to a significant increase in tomato yield by 4.1–11.9% and 4.6–18.9%, K use efficiency by 11.5–34.2% and 6.1–32.3%, fruit vitamin C content by 9.3–25.3% and 5.6–28.3%, fruit soluble sugar content by 10.2–20.0% and 10.2–24.1% in 2020 and 2021, respectively, compared with the other K fertilization treatments. Meanwhile, the water use efficiency and fruit soluble solid content of W80K80 treatment were also maintained at a high level. Molecular analysis shows that the W80K80 treatment had a higher photosynthetic rate, rubisco content, cytokinin content, and osmotic regulation substances content, and lower abscisic acid (ABA), malondialdehyde (MDA), and hydrogen peroxide (H2O2) contents. Our results indicated that 80% irrigation level and 80% CRK-20% KCl blending ratio were the optimal water and K supply mode for tomato production in this study. The result provided useful information regarding greenhouse tomato production that would allow the achievement of higher fruit yield, quality and resource use efficiencies, and provided theoretical and technical support for greenhouse tomato irrigation and K fertilizer application technologies.

Easily Extractable Glomalin-Related Soil Protein as Foliar Spray Improves Nutritional Qualities of Late Ripening Sweet Oranges

The role of arbuscular mycorrhizal fungi in sweet oranges is well known, but the function of their secondary metabolite, especially the easily extractable glomalin-related soil protein (EE-GRSP), an active fraction of glomalin, is still unclear. The proposed study aimed to analyze the field response of foliar application of exogenous EE-GRSP on tree mycorrhizal development and fruit quality of two sweet orange (Citrus sinensis L. Osbeck) varieties viz., Lane Late Navel (LLN) and Rohde Red Valencia (RRV). Application of EE-GRSP significantly increased the root mycorrhizal colonization and soil mycorrhizal hyphal length in both the sweet orange varieties. The external quality of fruits (fruit weight, polar diameter, and equatorial diameter) also improved in response to foliar application of EE-GRSP in both sweet orange varieties. However, EE-GRSP treatment showed no change in fruit soluble solid content, while it increased the Vc content, solids-acid ratio, fructose, glucose, and sucrose content of sarcocarp in the two sweet oranges varieties. The LLN variety treated with EE-GRSP recorded significantly higher N, P, K, Fe, and Si content of sarcocarp as a mark of nutritional quality, while the RRV variety treated with EE-GRSP displayed a higher concentration of nutrients like Cu, Fe, Si, and Zn in the sarcocarp as compared with the corresponding non-treated control. To the best of our knowledge, this is the first report regarding the improvement in fruit quality of late-ripening sweet oranges (especially LLN) in response to foliar application of EE-GRSP as another potential biostimulant.

Seed-Propagated Summer Apples: Great Morphological and Biochemical Diversity

The northeastern Anatolia region of Turkey is one of the richest plant biodiversity areas in Turkey. This study describes some important tree and fruit characteristics of 20 seed-propagated summer apple genotypes from northeastern Anatolia using morphological and biochemical markers. The genotypes were evaluated morphologically for tree growth habit, ripening date, fruit weight, fruit firmness, fruit shape, fruit color, fruit taste, juiciness and aroma. The biochemical characteristics measured were organic acids, SSC (soluble solid content), titratable acidity, vitamin C, total phenolic content and antioxidant capacity. We found significant differences for most of the morphological and biochemical characteristics. The genotypes exhibited quite diverse harvest dates ranging from 4 July to 16 August. Summer apple genotypes had fruit weight between 101.9 g and 133.5 g. The genotypes had diverse fruit shapes, including round, conic and oblate, and over fruit colours such as pink, red, yellow and green. Genotypes GUM7 and GUM13 stood out for fruit weight, SSC, total phenolic and antioxidant capacity. GUM7 and GUM13 present dissimilarity from the other genotypes. While the first showed a lower average fruit weight, SSC, total phenolic content and antioxidant capacity, the second revealed higher average of fruit weight, total phenolic content, antioxidant capacity and higher SSC. Due to their favorable characteristics, GUM13 can be used for further crosses with genotypes of other groups, which also present favorable characteristics.

Pre-Harvest Oxalic Acid Application Improves Fruit Size at Harvest, Physico-Chemical and Sensory Attributes of ‘Red Flesh’ Apricot During Fruit Ripening

Apricot is a highly nutritive stone fruit which ripens quickly after harvest and exhibits rapid fruit quality deterioration at ambient conditions. The current research work was executed to evaluate the effect of pre-harvest application of oxalic acid (OA); (0, 0.5, 1, and 2mM) on fruit quality of ‘Red Flesh’ apricot during fruit ripening at shelf under ambient conditions (25±1 °C; 60-65% RH). Fruit size, average fruit weight, fruit juice percentage was determined at harvest. While, fruit weight loss, fruit colour, fruit firmness, titratable acidity (TA), soluble solid contents (SSC), ratio of SSC to TA, ascorbic acid, total phenolics content (TPC), anti-oxidative scavenging activity (ASA), superoxide dismutase (SOD), peroxidase (POD), catalase (CAT) enzymes activity were determined during fruit ripening. Fruit sensory attributes (fruit pulp colour, fruit taste, fruit flavour and overall acceptability were determined at fruit ripening. Pre-harvest application of 2mM-OA was found the most effective in improving fruit size, average fruit weight, juice percentage at harvest, about 5%, 6% and 15% higher than control, respectively. Additionally, pre-harvest application of 2mM-OA retained higher fruit firmness, ascorbic acid, TPC, ASA and activities of POD, CAT enzymes in apricot fruit during fruit ripening at ambient conditions. On day-5 of fruit ripening 2mM-OA-treated apricot fruit exhibited about 28%, 20%, 17%, 7%, 9% and 23% higher fruit firmness, ascorbic acid, TPC, ASA and activities of POD, CAT enzymes, respectively as compared to control. Moreover, significant lower fruit weight loss (35%), SSC (20%) and SSC:TA ratio (30%) were exhibited by the apricot fruit treated with 2mM-OA than unsprayed apricot fruit. However, fruit treated with 1 mM-OA exhibited better fruit sensory attributes compared to other treatments at fruit ripening. Conclusively, pre-harvest application of 2 mM-OA improved the fruit size, delayed fruit ripening, and retained higher fruit antioxidants of apricot at ambient conditions.

On-farm reduced irrigation and fertilizer doses, and arbuscular mycorrhizal fungal inoculation improve water productivity in tomato production

Viability of horticultural production requires high yields of high-value products, coupled with optimization of inputs. Rational fertilizer and water use are vital for the economic and environmental sustainability of vegetable production. Microbial resources are also used to increase yield, reduce inputs, and improve product quality. That includes arbuscular mycorrhizal fungi (AMF), symbionts associated with 80% of plant species, including many vegetable crops, such as tomato. To evaluate how AMF inoculation and reduced water and fertilizer affect tomato yield and quality, we carried out three independent experiments in commercial-production medium-technology (growth in soil, plastic cover, and no temperature control) greenhouses in Catalonia, Northern Spain. In the first experiment, AMF inoculation increased fruit number, total yield and improved fruit quality (soluble solids concentration or color) using lower fertilizer doses than those usually adopted on the farm. In a second assay, plants grew under three irrigation regimes: the farm usual regime, a managed-deficit regime (75% of the former), and an optimized dose using weather and plant-growth data. Deficit and optimized irrigation increased tomato yield and fruit size, but not fruit soluble solids concentration or color, and there was no effect of AMF inoculation. In the third experiment, fertigation was reduced by regulating irrigation doses according to soil moisture data. AM-inoculated plants sustained yield levels with 13% lower water and fertilizer rates. Reduced fertigation associated with AMF inoculation resulted in a 1.6% decrease in costs, which corresponds to at least six times the price of available commercial AMF inoculants. In all experiments, AMF inoculation was associated with increased water productivity, the ratio between product yield and the volume of irrigation water. Gains in input use efficiency, not only simple yield increase, should define commercial AMF inoculant use in vegetable production. We argue that researchers should estimate the financial incentive that AMF inoculation incurs so that farmers and inoculant producers have a base to test and adopt AMF inoculation technology.

Influences of open-central canopy on photosynthetic parameters and fruit quality of apples (Malus × domestica) in the Loess Plateau of China

Although open-central canopy (OCC) is popular in apple (Malus × domestica) orchards in Loess Plateau of China, its relevant photosynthetic mechanisms have not been elucidated. In this study, changes in photosynthetically active radiation (PAR), gas exchange, chlorophyll fluorescence quenching and fruit quality in apple trees were measured in OCC and compared with those in the conventional condensed round and large canopy (RLC). Results showed that light intercepted at different orientations was 44% higher by OCC than that by RLC. The improved light environment within OCC remarkably increased leaf maximum net photosynthetic rate (Pnmax) and significantly decreased stomatal limitation. Under high light, the ratio of photorespiratory rate to gross photosynthetic rate (Pr/Pg) in OCC was higher than that in RLC. Moreover, reversible component in non-photochemical quenching (r(qE)) was increased, while irreversible component (r(qI)) was decreased in OCC than in RLC. As a result, the fruit quality in OCC was greatly boosted as evidenced by the significantly increased single fruit weight, fruit flesh firmness and fruit soluble solid contents and the sharply decreased fruit titratable acid contents. PAR intercepted by the canopy and the fruit soluble solid contents, leaf Pnmax or single fruit weight were positively correlated, while PAR or Pnmax was negatively correlated with the fruit titratable acid contents. Accordingly, the improved crown light environment and the enhanced leaf photosynthetic performance and photoprotective capacity in OCC led to the boosted fruit quality.

High Levels of Shading as A Sustainable Application for Mitigating Drought, in Modern Apple Production

The sustainability of reducing light in apple orchards under well-watered (ww) and water stress (ws) conditions was evaluated for water relations, plant gas exchanges, fruit growth, yield determinants, and fruit quality over three years. A black (B) 28% shading net was compared with two different 50% shading nets: red (R) and white (W). Each net was combined with two irrigation regimes (ww and ws) based on plant water status. Under ww and ws conditions, increasing shade from 28% to 50% was not detrimental for plant gas exchanges, yield, or quality over three years. Higher shade improved plant water status regardless of irrigation regime. Higher shading could be considered sustainable in apple orchards over several seasons. Fruit quality was more sensitive to plant water status than to light reduction. ws increased fruit soluble solid content and relative dry matter, regardless of shading, and this was positively reflected in consumer’s preference. When water availability is limited, increasing shading to 50% can help save water and maintain high-quality yields associated with water stress. Given the likely reductions of water availability in agriculture, growers and consultants may consider shading apple orchards as a sustainable and safe horticultural technique to save water.

Higher Temperatures Decrease Fruit Size in Strawberry Growing in the Subtropics

Five strawberry (Fragaria × ananassa Duch.) cultivars were grown in Queensland, Australia to determine whether higher temperatures affect production. Transplants were planted on 29 April and data collected on growth, marketable yield, fruit weight and the incidence of small fruit less than 12 g until 28 October. Additional data were collected on fruit soluble solids content (SSC) and titratable acidity (TA) from 16 September to 28 October. Minimum temperatures were 2 °C to 4 °C higher than the long-term averages from 1965 to 1990. Changes in marketable yield followed a dose-logistic pattern (p < 0.001, R2s = 0.99). There was a strong negative relationship between fruit weight (marketable) and the average daily mean temperature in the four or seven weeks before harvest from 29 July to 28 October (p < 0.001, R2s = 0.90). There were no significant relationships between SSC and TA, and temperatures in the eight days before harvest from 16 September to 28 October (p > 0.05). The plants continued to produce a marketable crop towards the end of the season, but the fruit were small and more expensive to harvest. Higher temperatures in the future are likely to affect the economics of strawberry production in subtropical locations.

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

ABSTRACT This study aimed to evaluate the effects of different crop load levels on apple trees’ yield and physiological characteristics, emphasizing the relationship between stem water potential and crop load and the link between trunk diameter growth and crop load. It was conducted in 2014 at Station Expérimentale Fruits et Légumes (SUDEXPE-CEHM) in Southern France. The ‘JoyaTM’ apple on Pajam-1 rootstock was used as the plant material. Trees were subjected to hand thinning to obtain four final crop load levels as high (100%; 10 fruit/cm2 of branch cross-sectional area (BCSA)), medium-high (75%; 7.5 fruit/cm2 of BCSA), medium-low (50%; 5 fruit/cm2 of BCSA) and low (25%; 2.5 fruit/cm2 of BCSA). The four crop load levels were set up in a randomized block design with four replications, and each plot was formed of five uniform trees. Stem water potential was weakly affected by crop load but was mainly driven by vapor pressure deficit. The maximum daily trunk diameter, by and large, reduced while crop load level increased. The increase in crop load level was negatively related to fruit size, acidity and soluble solids content. Crop load did not affect bitter pit incidence. However, in parallel to the increasing crop load level, cumulative yield, yield efficiency and water productivity increased.