Fruit Soluble Solids Content Research Articles

Rapid and non-destructive determination of soluble solid content of crown pear by visible/near-infrared spectroscopy with deep learning regression

The development of rapid and non-destructive prediction technology for fruit quality after harvest could enhance market competitiveness and profitability. The soluble solids content (SSC) is an essential quality index of fruit. This study aims to predict the SSC of crown pear using visible/near-infrared (Vis/NIR) spectroscopy (397–1187 nm) with deep learning model MLP-CNN-TCN. Firstly, the spectral information of crown pears was collected, and Savitzky-Golay (SG) smoothing method and Standard normal variate (SNV) were used to preprocess the spectral data. Secondly, the Multi-layer perceptron (MLP) method was used to reduce the dimension of the preprocessed data, and the reduced data was input into a one-dimensional convolutional neural network (1D-CNN) to extract spectral features. Finally, a Temporal convolutional neural network (TCN) was used to establish a regression model to predict pear SSC. This method was also compared with feedforward neural network (FNN), MLP, 1D-CNN, partial least squares regression (PLSR), and support vector regression (SVR). The MLP-CNN-TCN model obtained better prediction performance, with a prediction determination coefficient (RP2) of 0.956 for SSC. This study demonstrated that the combination of Vis/NIR spectroscopy and MLP-CNN-TCN method could rapidly and non-destructively detect SSC of crown pear, and provide a new regression alternative for the prediction of fruit SSC.

Determination of watermelon soluble solids content based on visible/near infrared spectroscopy with convolutional neural network

The soluble solids content（SSC）of fruits is an essential indicator of fruit taste and flavor. The near-infrared spectroscopy (NIRS) is widely used in fruit SSC detection. A common method to deal with such predictive modelling is the partial least-squares (PLSR). Wavelength selection algorithms are often employed to eliminate redundant wavelengths before constructing the model. However, the wavelength selection algorithms can not only increase the model complexity but also may lose valuable information. In this work, 1D-CNN was used to improve the prediction model of the watermelon SSC. First, the best parameter combination for 1D-CNN was found. The root mean square error of prediction (RMSEP) was 0.21 and the determination coefficient of prediction (Rp2) was 0.97. Then, the performance of PLSR and backpropagation neural network (BPNN) are compared. The results show that the Rp2 of 1D-CNN is improved by 14.1% and 6.6%, respectively. Finally, a gradient-based method for visualizing features of CNN regression models, namely regression activation mapping (RAM), was proposed. The results show that the features of 1D-CNN are consistent with the feature peaks of the spectrum, while the features of the BPNN and PLSR are not obvious.

Influence of Mechanical Flower Thinning on Fruit Set and Quality of ‘Arisoo’ and ‘Fuji’ Apples

This study aimed to identify the efficiency of mechanical flower thinning (MFT) and its influence on apple fruit quality. In the first experiment, ‘Arisoo’ apple flowers were subjected to MFT with one hundred sixty-two (half) and three hundred twenty-four (full) strings at the same rotor (300 rpm) and tractor (6 km/h) speeds. Hand thinning was performed as a control. The number of removed flowers in each terminal and lateral flower cluster was slightly higher in MFT with full-strings than that of MFT with half-strings. The fruit set rate was lower in MFT with full-strings than that of MFT with half-strings. However, the use of full-strings during mechanical thinning increased the leaf damage rate compared to half-strings. Except a* value, MFT with full-strings improved flesh firmness, soluble solids content (SSC) and titratable acidity (TA), and reduced starch pattern index of fruits at harvest compared to the control. In the second experiment, ‘Fuji’ apple flowers were subjected to chemical thinning, MFT (300 rpm, 6 km/h), and MFT + chemical thinning treatments and compared with hand thinning (control). The thinning efficiency of MFT was similar to that of chemical thinning and MFT + chemical thinning treatments in terms of the removal of flowers and fruit set rates. Compared to the control, MFT, chemical thinning, and their combined treatments improved flesh firmness and SSC of fruits at harvest. TA was highest in the chemical thinning treatment compared to other thinning treatments. However, fruit size, weight, and a* value were unaffected by any treatment. In conclusion, the use of full-strings during MFT achieved optimal results in ‘Arisoo’ apples. In ‘Fuji’ apples, MFT treatment alone achieved effective results and the addition of chemical thinning after MFT had no supportive role in thinning efficiency and fruit quality.

Non-destructive determination of soluble solids content in intact apples using a self-made portable NIR diffuse reflectance instrument

The soluble solids content (SSC) is an important internal quality parameter of fruits that is monitored on the fruit market to meet different consumer demands. The aim of this study was to develop a self-made portable near-infrared (NIR) diffuse reflectance instrument to evaluate and monitor the SSC of intact apples. The visible and near-infrared (Vis-NIR) spectra of 118 ‘Fuji’ apples were collected using a Vis-NIR diffuse reflectance spectroscopic measurement system in the spectral range of 450–1100 nm. Savitzky-Golay convolution smoothing and first derivative methods were subsequently applied to eliminate noise interference and baseline shift. Successive projections algorithm (SPA) was performed to extract feature wavelengths from the pretreatment spectra, and the back-propagation artificial neural network (BP-ANN) and multivariate nonlinear regression (MNLR) models were employed to evaluate the predictive ability of the extracted and selected feature wavelengths for the SSC of apples. Seven wavelengths (881, 890, 901, 926, 941, 951, 978 nm) were selected as optimal feature wavelengths from the extracted feature wavelengths (18 wavelengths). The MNLR model (R2 = 0.953, RMSE = 0.391 %) exhibited a high prediction accuracy compared to the BP-ANN model (R2 = 0.865, RMSE = 0.754 %). Based on the results, NIR combined with the MNLR model could be applied in the self-made portable instrument to innovatively monitor the SSC of apples. Finally, a self-made portable NIR diffuse reflectance instrument was designed and developed, and the spectral information of 298 ‘Fuji’ apples was collected using the instrument. According to the results, the MNLR model could well predict the SSC of apples (R2 = 0.871, RMSE = 0.687 %). The overall results also revealed that the developed portable NIR instrument is a promising device for rapid non-destructive monitoring of fruit SSC, thereby meeting the practical application requirement of postharvest commercial processing systems. This instrument could also be beneficial to customers, growers, and producers.

Seaweed Extract as a Biostimulant Agent to Enhance the Fruit Growth, Yield, and Quality of Kiwifruit

The kiwifruit [Actinidia deliciosa (A. Chev.) C.F. Liang & A.R. Ferguson] has attained significant importance for commercial cultivation in the mid-Himalayan region of the Indian subcontinent during the last three decades. The fruit quality matching international standards has remained a concern. Keeping in mind the bio-stimulatory effects of seaweed extract, a marine bioactive component in horticultural crops, the current study conducted to elucidate the impact of seaweed extract on kiwifruit growth, yield, and quality was conducted in the Department of Fruit Science’s kiwifruit block at Dr. Yashwant Singh Parmar University of Horticulture and Forestry, Nauni, Himachal Pradesh, India. For the studies, nine-year-old Allison kiwi vines of uniform size and vigor were planted at a spacing of 4 m × 6 m. With 11 treatments, the experiment was set up in a randomized block design viz, T1: Spray treatment of 1000 ppm (seaweed extract) SWE at fruit set (FS); T2:Spray treatment of 2000 ppm SWE at FS; T3: Spray treatment of 3000 ppm SWE at FS; T4: Spray treatment of 1000 ppm SWE at FS and 10 days after Fruit set (FS); T5: Spray treatment of 2000 ppm SWE at FS and 10 days after FS (DAFS); T6: Spray treatment of 3000 ppm SWE at FS and 10 days after FS; T7: Fruit dip treatment of 1000 ppm SWE at 10 days after FS; T8: Fruit dip treatment @ 2000 ppm SWE at 10 days after FS; T9: Fruit dip treatment @3000 ppm SWE at 10 days after fruit set; T10: Fruit dip treatment @ 5 ppm CPPU at 10 days after fruit set; T11: Control. The current study compared several seaweed extract treatments, which were applied at various times and concentrations, to N-(2-chloro-4-pyridyl)-N-phenyl-urea (CPPU-5ppm) and untreated control. Seaweed extract (SWE) dip at 3000 ppm 10 days after the fruit set produced significant growth in fruit length and diameter in growing kiwifruit, which was non-significant with CPPU treatment and superior to control. The shape index, fruit weight, and total fruit yield were also found to be the highest with the same treatment. Fruit quality parameters, namely fruit soluble solids contents (SSC) and total sugars, were recorded at a maximum with the SWE Spray dose of 3000 ppm at FS and 10 DAFS. The SSC: Acid ratio and reducing sugars were recorded as the highest with an application of SWE dip at 3000 ppm 10 DAFS. The application of SWE dip at 2000 ppm 10 DAFS) was found to advance the harvesting maturity by 6 days and also exhibited the lowest physiological loss in weight (% PLW) with the highest ascorbic acid content. After 15 days of storage at ambient room temperature (25 ± 2 °C), the application of SWE dip at 3000 ppm 10 DAFS recorded the highest SSC acid ratio and the lowest titratable acidity. Thus, the application of seaweed extract dip at 3000 ppm 10 days after the fruit set can be recommended to the farmers as an appropriate alternative to the chemical treatment.

Construction of spectral detection models to evaluate soluble solids content and acidity in Dangshan pear using two different sensors

It is most desirable to have an reliable and effective nondestructive method to detect soluble solids content (SSC) and acidity (pH) in pear fruit for fruit quality evaluation. In this study, we used the non-imaging spectrometer PSR + 3500 and the imaging spectrometer SOC710E to collect the spectral data of SSC and pH in 'Dangshan' pear (Pyrus spp.) fruit. Their characteristic wavelengths were screened using Competitive Adaptive Reweighted Sampling (CARS) and Successive Projections Algorithm (SPA). Partial Least Squares (PLS) and Random Forest Regression (RFR) were used to establish different SSC and pH detection models. The effects of spectral range and use of the two sensors on the internal quality detection of pear fruit were compared and analyzed. The results show that the data processing process of the non-imaging spectrometer performed better. Taking the characteristic bands screened by CARS for SSC and pH as an input, the SSC and pH detection models, constructed by the RFR modeling method, had the highest accuracy, and the determination coefficients of calibration set and validation set were both above 0.9. The results of this study provide the important theoretical foundation for the development of real-time online fruit SSC and PH detection equipment.

The Stability of Important Fruit Traits in Strawberry in Queensland

Information was collected on yield and fruit quality in ‘Festival’, ‘Fortuna’, ‘Red Rhapsody’, ‘Fronteras’, ‘Grenada’ and ‘Petaluma’ strawberry (Fragaria × ananassa Duch.) in southern Queensland, Australia. Marketable yield was similar in the cultivars and ranged from 352 to 416 g/plant. Fruit were smaller in ‘Festival’ and ‘Grenada’ (21.3 or 23.7 g), intermediate in ‘Fortuna’ and ‘Red Rhapsody’ (25.0 or 24.7 g), and larger in ‘Fronteras’ and ‘Petaluma’ (27.6 or 27.8 g). Fruit soluble solids content (SSC) was lower in ‘Fronteras’, ‘Grenada’ and ‘Petaluma’ (6.9% to 7.2%) than in the other cultivars (7.4% to 8.3%). Fruit titratable acidity (TA) was lower in ‘Fortuna’ and ‘Fronteras’ (0.55% to 0.58%) than in the other cultivars (0.63% to 0.69%). The cultivars had similar estimates of stability for fruit weight (0.74 to 1.27) using the method of Finlay and Wilkinson (1963), where a cultivar with a value of one has average stability in a group. This suggests that the cultivars behaved similarly to changes in conditions over the season. The estimates of stability for SSC were lower than one or higher than one in some cultivars (0.45 to 1.75). The estimates of stability for TA were lower than one for some cultivars (0.33 to 1.33). None of the cultivars had high values of fruit quality and stable values of fruit quality for all the three traits. ‘Festival’ would be an acceptable parent in a breeding programme used to increase fruit SSC. In contrast, the other cultivars would be acceptable parents to increase fruit size. Efforts need to be made to develop cultivars with high and stable values of quality and that are suitable for production under global warming.

A 21-bp InDel in the promoter of STP1 selected during tomato improvement accounts for soluble solid content in fruits.

Domestication and improvement are important processes that generate the variation in genome and phonotypes underlying crop improvement. Unfortunately, during selection for certain attributes, other valuable traits may be inadvertently discarded. One example is the decline in fruit soluble solids content (SSC) during tomato breeding. Several genetic loci for SSC have been identified, but few reports on the underlying mechanisms are available. In this study we performed a genome-wide association study (GWAS) for SSC of the red-ripe fruits in a population consisting of 481 tomato accessions with large natural variations and found a new quantitative trait locus, STP1, encoding a sugar transporter protein. The causal variation of STP1, a 21-bp InDel located in the promoter region 1124bp upstream of the start codon, alters its expression. STP1 Insertion accessions with an 21-bp insertion have higher SSC than STP1 Deletion accessions with the 21-bp deletion. Knockout of STP1 in TS-23 with high SSC using CRISPR/Cas9 greatly decreased SSC in fruits. In vivo and in vitro assays demonstrated that ZAT10-LIKE, a zinc finger protein transcription factor (ZFP TF), can specifically bind to the promoter of STP1 Insertion to enhance STP1 expression, but not to the promoter of STP1 Deletion , leading to lower fruit SSC in modern tomatoes. Diversity analysis revealed that STP1 was selected during tomato improvement. Taking these results together, we identified a naturally occurring causal variation underlying SSC in tomato, and a new role for ZFP TFs in regulating sugar transporters. The findings enrich our understanding of tomato evolution and domestication, and provide a genetic basis for genome design for improving fruit taste.

Yield and Quality of Winter Jujube under Different Fertilizer Applications: A Field Investigation in the Yellow River Delta

Winter jujube (Ziziphus jujuba Mill. cv. Dongzao) is highly popular due to its attractive taste and flavor of fruits. However, its cultivation is facing a serious obstacle for the substantial decrease in fruit soluble solids contents. In this study, four commonly-used fertilization types, including organic manure application (OM), combined application of manure and NPK fertilizer (OC), NPK fertilizer application at high rate (HC) and NPK fertilizer application at low rate (LC) were selected to investigate their effects on soil and fruit properties. Results showed that fertilization influenced soil organic matter (SOM) and NPK contents. Fruit yield decreased as HC (3.37tha−1) > OC (2.81tha−1) > OM (2.14tha−1) > LC (1.92tha−1).Total soluble solids (TSS), protein contents, and the ratio of TSS to titratable acid (TA) were highest in OM, followed by OC, LC and HC. TSS and TSS/TA ratio in OM were 23.0% and 27.0% higher than those in HC. Fruit yield was significantly positively correlated with soil available N, vegetative shoot leaf N, and total topsoil P contents. TSS and TSS/TA ratio both significantly positively correlated with SOM of topsoil and leaf P contents. Combined application of organic and inorganic fertilizers should be the optimal mode for winter jujube production.

Prediction of Soluble Solids Content by Means of NIR Spectroscopy and Relation with Botrytis cinerea Tolerance in Strawberry Cultivars

Strawberry fruits are particularly appreciated by consumers for their sweet taste related to their soluble solids content (SSC). However, strawberries are characterized by a short shelf-life and high susceptibility to tissue infection, mainly by Botrytis cinerea. The SSC determination of strawberry fruit through traditional destructive techniques has some limitations related to the applicability, timing, and number of samples. The aims of this study are (i) to verify if any relation between SSC and B. cinerea susceptibility in the fruits of five strawberry cultivars occurs and (ii) to determine the SSC of strawberry fruits through near infrared spectroscopy (NIR). Principal component analysis was used to search for spectral differences among the strawberry genotypes. The partial least squares regression technique was computed in order to predict the SSC of the fruits collected during two harvesting seasons. Moreover, variable selection methods were tested in order to improve the models and get better predictions. The results demonstrated that there was a high correlation between SSC and B. cinerea susceptibility (R2 up to 0.87). The SSC was predicted with a standard error of 0.84 °Brix and R2p 0.75 (for the best model), which indicated the possibility to use the models for screening applications. NIR spectroscopy represents an important non-destructive alternative and finds remarkable applications in the agro-food market.

Yield, quality and physiological variation of strawberry in response to irrigation regimes and exogenous proline with a cost benefit analysis

Strawberry (Fragaria × ananassa Duch.) production is a major aspect of the agricultural economy in Turkey's Mediterranean region, offering high rates of employment and farm revenue. The effects of treatment of the exogenous amino acid on yield, quality, and physiological diversity for strawberry production was analyzed considering the economic aspects. To achieve this, 4 different irrigation regimes (IR (irrigation) 125, IR100, IR75, IR50) with proline treatment was tested. The total berry yield, photosynthesis and leaf water potential (LWP) significantly decreased as irrigation application rates declined. The IR125 treatment with proline (PIR125) produced the highest overall berry production. The use of proline significantly increased berry production by 23%. Exogenous proline generated 3.5 kg/1 m3 greater yields than control in terms of irrigation water use efficiency (IWUE). Under the IR50 conditions, the treatment of proline yielded a 32% higher than the control. Moreover, proline significantly increased fruit soluble solids content (SSC) by 6.4%. The production system achieves the highest cost-benefit ratio (CBR) under PIR125 whereas the lowest cost-benefit ratio under IR50. When each scenario was considered at individually, it was evident that the more water used the more efficient high tunnel strawberry production. The fact that proline generated an increase in CBR in all four irrigation regimes proves this amino acid's economic effectiveness. As a result, PIR125 is recommended for the highest efficiency and CBR in Mediterranean environment. However, it has been discovered that using proline to alleviate this problem in areas where water is limited could be quite helpful.

Fertilizer type and irrigation frequency affect plant growth, yield, and gas exchange of containerized strawberry cultivars

Small-scale strawberry production in southeastern states requires cultivars adaptive to local climates and with season extension potentials. This study investigated plant growth, yield, gas exchange, and fruit quality of ten strawberry (<italic>Fragaria ×ananassa</italic> Duch.) cultivars affected by fertilizer type and irrigation frequency in a containerized production system in 2018. Bare root liners of seven June-bearing and three day-neutral cultivars were grown in 2-gallon containers , fertilized with a conventional fertilizer or an organic fertilizer at comparable rates, and irrigated once or twice daily with the same total irrigation volume<bold>.</bold> Strawberry cultivars varied in vegetative growth (including plant growth index (PGI), leaf SPAD, number of crowns, visual score, and root dry weight) and fruiting characteristics (including first harvest date, yield, number of fruit, berry size, fruit soluble solids content, and firmness). Day-neutral cultivars ‘Evie 2’ and ‘Seascape’ produced the highest total yields and late-season yield in June. The conventional fertilizer resulted in higher PGI, leaf SPAD, plant visual score, fruit yield in May, daily water use, and net photosynthetic rate than the organic fertilizer. Two irrigations per day increased substrate moisture compared with one irrigation per day, and increased shoot dry weight with the conventional fertilizer application. Irrigation frequency did not affect PGI, leaf SPAD, gas exchange, fruit yield, or quality in tested strawberry cultivars.

Positive effect of red/blue light supplementation on the photosynthetic capacity and fruit quality of 'Yanli' strawberry

In order to meet people’s demand for strawberry during winter and early spring, strawberry is usually cultivated in solar greenhouses with forcing cultivation in northern China. However, low light intensities and short-day are the major obstacles that restrict strawberry growth. Therefore, it is crucial to solve the problem of insufficient light in strawberry production. In this study, we established LED facilities to supplement the red/blue light (R/B = 2:1) before sunrise and after sunset in the solar greenhouse. We found that the plant height of the strawberry under supplemental R/B light was 13%-17% higher than that of the control, and the crown diameter of the plants was increased by 1.07-1.38 fold compared with the control for two consecutive years. The net photosynthesis of strawberry plants was 19% higher than that of the control. In addition, the strawberry primary fruits’ fresh weight during the stage of full ripeness and the total fruit weight/plant was 18%-24% and 27%-33% higher than that of control for two years, respectively. Fruit soluble solid content and firmness were increased by 1.05-1.21 fold and 1.06-1.18 fold compared with those of control during the two years, respectively. Moreover, we found some differentially expressed genes between red/blue light supplementation and control by RNA-seq data, including light-responsive genes (<italic>PRR95</italic>/<italic>LHY</italic>/<italic>CDF3</italic>/<italic>CO16</italic>/<italic>BHLH63</italic>/<italic>BBX21</italic>/<italic>PAR1</italic>/<italic>SIGE</italic>) and sucrose metabolism-related genes (<italic>SWEET9</italic>/<italic>BAM1</italic>). This study provided a foundation for revealing the mechanism of red/blue light supplementation on photosynthesis and fruit quality of strawberries and could help to improve the cultivation techniques for 'Yanli' strawberry.

Tomato fruit quality is more strongly affected by scion type and planting season than by rootstock type.

Previous studies of tomato rootstock effects on fruit quality have yielded mixed results, and few attempts have been made to systematically examine the association between rootstock characteristics and tomato fruit quality. In this study, grape tomato ('BHN 1022') and beefsteak tomato ('Skyway') were grafted onto four rootstocks ['Estamino' (vigorous and "generative"), 'DR0141TX' (vigorous and "vegetative"), 'RST-04-106-T' (uncharacterized), and 'SHIELD RZ F1 (61-802)' (mid-vigor, uncharacterized)] and compared to non-grafted scion controls for two growing seasons (Spring and Fall in Florida) in organically managed high tunnels. In both seasons and for both scions, the two vigorous rootstocks, regardless of their designation as "vegetative" ('DR0141TX') or "generative" ('Estamino'), exhibited negative impacts on dry matter content, soluble solids content (SSC), SSC/titratable acidity (TA), lycopene, and ascorbic acid contents. Similar effects on fruit dry matter content and SSC were also observed with the 'RST-04-106-T' rootstock, although little to no change was seen with grafting onto 'SHIELD RZ F1 (61-802)'. Further studies are needed to elucidate the impact of rootstock vigor on tomato volatile profiles and consumer sensory acceptability in order to better determine whether any of the documented effects are of practical importance. On the other hand, the evident effects of scion cultivar and planting season on fruit quality were observed in most of the measurements. The scion by rootstock interaction affected fruit length, firmness, pH, and total phenolic content, while the planting season by rootstock interaction impacted fruit firmness, pH, total antioxidant capacity, and ascorbic acid and lycopene contents. The multivariate separation pattern of planting season, scion, and rootstock treatments as revealed by the canonical discriminant analysis further indicated that the influence of scion cultivar and planting season on tomato fruit quality could be much more pronounced than the rootstock effects. The fruit color (C* and H°), length and width, SSC, pH, total antioxidant capacity, ascorbic acid, and lycopene contents were the main attributes distinguishing different scion-planting season groups.

Meteorological and tree-management factors related to soluble solids content of apple fruit and crop load management for producing high soluble solids content fruit in high-density planted ‘Fuji’

Sweetness is one of the most important drivers of consumer preference in apples (Malus x domestica Borkh.). Despite the market demand for apples with high sugar content, cultural and agronomic practices applied in the field for producing apples with high soluble solids content (SSC) has not been established. We tried to clarify what factors regulate the SSC of fruit by creating a regression model that predicts SSC with factors related to meteorology and crop load management as variables. The highest correlation with SSC was obtained from six-year meteorological data using a four-week average solar radiation value starting August 28. When the SSC was estimated by a regression model using the average solar radiation (SR), the number of fruits per cm2 trunk cross-sectional area (CL), and the number of fruits per tree (NF), the estimated and measured values were close to each other, indicating that year- and tree-dependent variation in the SSC of fruit can be explained mainly by the SR and the CL or NF, respectively. The four weeks starting August 28 coincided with the time when starch was most accumulated in fruit, and a high correlation was found between the starch content in this period and the SSC at harvest. It could be said that it is necessary to restrict the number of fruits per tree by the period—90 days after full bloom—to produce fruit with high SSC in ‘Fuji’. A target number of fruit per tree for maximizing the cumulative yield of fruit with an SSC of 14 oBrix or more was estimated to be less than that for maximizing the cumulative yield without biennial bearing.

An improved method for predicting soluble solids content in apples by heterogeneous transfer learning and near-infrared spectroscopy

Predicting fruit soluble solids content (SSC) is a hot topic in non-destructive detection. Biological variability of fruit decreases the accuracy of the prediction model. Therefore, modeling methods that can reduce the negative effect of biological variability are necessary. In this paper, an improved modeling method based on the partial least squares (PLS) regression was proposed, using convolutional autoencoder and heterogeneous transfer learning for feature extraction. The dataset used for calibration and prediction contains spectra and corresponding SSC values of apples collected from 2012 to 2018. In comparison with the traditional PLS method, the proposed method performed better for long-term SSC prediction of apples with biological variability. The correlation coefficients calculated on validation set were 0.934, 0.940, 0.915, 0.899, 0.901, respectively. The root mean square errors calculated on validation set were 0.736 °Brix, 0.694 °Brix, 0.674 °Brix, 0.571 °Brix, 0.620 °Brix, respectively. Besides, the proposed method could still achieve relatively satisfactory results when the quantity of calibration samples was less.

Effect of Rootstock on ‘Tasti-Lee’ Tomato Yield and Fruit Quality in a High Tunnel Production System

Grafting tomatoes with vigorous rootstocks can be used to increase yield in high tunnels without significant soilborne disease pressure. However, evidence suggests that grafting with high-yielding rootstocks could compromise the accumulation of primary and secondary metabolites. ‘Tasti Lee’ is a hybrid tomato that is bred to have a superior fresh-eating quality and higher lycopene content. The objective of this experiment was to investigate the yield and fruit quality impacts of grafting ‘Tasti Lee’ with rootstocks with ranging vigor and typical yield performance in high tunnels. Nongrafted ‘Tasti-Lee’ and ‘Tasti-Lee’ scion grafted onto ‘Maxifort’, ‘DRO141TX’, ‘Fortamino’, ‘Estamino’, and ‘RST-04-106-T’ rootstocks were trialed in a high tunnel in Kansas for three consecutive growing seasons (2018–20). The trials were arranged in a randomized complete block design with four replications. Total yield, marketable yield, average fruit size, and distribution of fruit size classes were assessed. Red ripe tomato fruit were harvested to determine the soluble solids content, titratable acidity, lycopene content, vitamin C content, antioxidant capacity, and fruit firmness. ‘Maxifort’, ‘DRO141TX’, ‘Estamino’, and ‘Fortamino’ significantly increased marketable yield (kg/plant) by 31.5% to 47.0% more than nongrafted plants. In contrast, ‘RST-04-106-T’ did not lend any significant yield benefit. Regardless of the rootstock, grafting increased the marketable average fruit weight by 20 g. Grafting did not have significant effects on any of the fruit quality attributes assessed. However, the soluble solids content of fruit from plants grafted to ‘RST-04-106-T’ was 10% higher (P &lt; 0.05) than that grafted to ‘Maxifort’, indicating that rootstock genotype can influence this quality trait. Our findings suggest that growers can graft the tomato ‘Tasti-Lee’ with select vigorous rootstocks to increase marketable yield without sacrificing fruit quality for high tunnel production.

Dynamic Prediction of Preharvest Strawberry Quality Traits as a Function of Environmental Factors

Fruit quality is of increasing importance for consumers but is a complex trait for growers, as it is affected by environment, genotype, and crop management interactions. Decision support tools, such as computer models that simulate crop growth and development can help optimize production but require further improvement to simulate quality aspects. The goal of this study was to apply the newly developed CROPGRO-Strawberry model in the Decision Support System for Agrotechnology Transfer (DSSAT) model framework and develop a module for the dynamic prediction of quality traits for strawberry. Experimental data from Florida with quality measurements from multiple harvests were correlated with indices based on preharvest weather conditions (temperature, radiation, rainfall) and simulated model parameters (evapotranspiration) during fruit development. Two quality relationships based on linear equations were identified and integrated into the model to simulate strawberry fruit soluble solids content (r2 = 0.89, d = 0.97) and titratable acidity (r2 = 0.55, d = 0.85) based on preharvest temperature. A strategic analysis with historical weather data for a subtropical growing region over a 10-year period showed the importance of seasonal climate variability for simulated strawberry yield and fruit quality across different harvest months. The improved CROPGRO-Strawberry model is the first process-based crop model to predict selected quality traits across multiple harvests throughout the season and can be extended to other crop models for which quality traits are important.

Mulching broad ridges with a woven polypropylene fabric increases the growth and yield of young pear trees ‘Yuluxiang’ in the North China Plain

Unlike traditional ridging, mulching broad ridges with a woven polypropylene fabric (WPF) can reduce soil evaporation during the drought season and avoid long saturation time in the root zone of pear trees during the rainy season. In this study, field experiments were conducted from 2017 to 2020 in a pear orchard in the North China Plain to investigate the effects of mulching broad ridges (0.3 m in height and 2 m in width) with WPF on soil temperature and moisture, nitrogen leaching, vegetative and reproductive growth of young pear trees (Pyrus bretschneideri Rehd. ‘Yuluxiang’). The experiments involved two treatments, namely, control (traditional no-ridge planting without mulching) and mulching broad ridges with WPF (RM treatment). The results showed that the RM treatment increased soil moisture and temperature and decreased nitrogen leaching, resulting in vigorous growth of the young pear trees. Moreover, the RM treatment increased the tree trunk cross-sectional area and height of the young pear trees by 37% and 8% in 2020, respectively. The nitrate nitrogen content at the soil layer depth of 0–30 cm was significantly higher in the RM than that in control. Furthermore, the RM treatment significantly increased the fruit yield due to larger tree size. In addition, compared with control, significantly higher fruit soluble solid content of RM treatment was detected in 2020. High precipitation (423 mm) occurred during fruit enlargement stage in 2020, RM treatment decreased the rainfall infiltration in the ridge and the soil moisture in root region, resulting in the improvement of fruit quality, compared with control. Therefore, mulching broad ridges with WPF can be implemented to increase soil moisture during drought season, soil temperature, and nitrate nitrogen content, thereby improving the growth and fruit yield of young pear trees. Additionally, it can reduce soil moisture in the root zone during the rainy season and improve the fruit quality of the trees. Finally, it can reduce nitrate nitrogen leaching, thereby reducing environmental pollution.

‘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.