Commercial Fruit Quality Research Articles

Localized foliar application of iodine on tomato: An effective approach for targeted agronomic biofortification

Iodine is an essential mineral for the human body and inadequate intake causes iodine deficiency disorders (IDDs) worldwide. Agronomic biofortification is a promising complementary approach to other strategies to avoid IDDs. It consists of the enrichment of fruit and vegetables with nutritional elements through preharvest techniques. Tomato is an important, nutritious, and widely consumed crop. Despite a poor iodine accumulation in the fruit, tomato is an iodine accumulator. Our research focused on iodine enrichment of two table tomato types (cherry and mini-plum) in a commercial mediterranean greenhouse. Potassium iodate (KIO3) was applied four times through foliar spray at three concentrations (0, 1, 5 mM) at two localized sites of application (at plant apex and at the three leaves above the target truss, “target leaves”) until the mature green stage of a target truss (untreated and the same for each treatment). The application of 1 mM KIO3 solution at the target leaves was the most suitable approach for adequate fruit enrichment. The accumulation of 110 μg∙100 g−1 of fresh weight (FW) in cherry and 130 μg∙100 g−1 FW for mini-plum tomato largely satisfy the iodine recommended dietary allowance for adults, pregnant and lactating women. Plant health, yield and commercial quality of fruit (color, size, dry matter content, total soluble solids, titratable acidity, pH) were not affected, while some carotenoids and total phenolics were slightly incremented, indicating a possible positive influence on the nutritional quality. In conclusion, foliar application of iodine for the preharvest enrichment of tomato was a successful approach to biofortification in a commercial greenhouse. That suggests further research is needed to investigate and improve the iodine biofortification techniques in different crops and systems.

Advance Research on the Pre-Harvest Sprouting Trait in Vegetable Crop Seeds.

Pre-harvest sprouting (PHS), the germination of seeds on the plant prior to harvest, poses significant challenges to agriculture. It not only reduces seed and grain yield, but also impairs the commodity quality of the fruit, ultimately affecting the success of the subsequent crop cycle. A deeper understanding of PHS is essential for guiding future breeding strategies, mitigating its impact on seed production rates and the commercial quality of fruits. PHS is a complex phenomenon influenced by genetic, physiological, and environmental factors. Many of these factors exert their influence on PHS through the intricate regulation of plant hormones responsible for seed germination. While numerous genes related to PHS have been identified in food crops, the study of PHS in vegetable crops is still in its early stages. This review delves into the regulatory elements, functional genes, and recent research developments related to PHS in vegetable crops. Meanwhile, this paper presents a novel understanding of PHS, aiming to serve as a reference for the study of this trait in vegetable crops.

Evaluation of the biochemical composition and commercial qualities of introduced apple varieties in the conditions of Dagestan

The weight of a complex of unfavorable factors negatively affects the quality and sustainability of the resulting fruit products. One of the ways to increase the resistance of perennial plantations is the cultivation and introduction of apple varieties into the assortment that are complexly resistant to dominant diseases and stress factors. The main important property of varieties is the commercial quality and biochemical composition of fruits, which determine the main directions and taste qualities. Observations by IMI revealed patterns in the passage of the main phenological phases of the development of apple varieties, characterizing the greatest intervarietal variability, determined the dates characterizing the beginning and end of flowering, depending on the ripening period. The earliest flowering (13.04) and a long 16 days was noted in the summer variety of the Feya apple tree, and later in the late ripening Renet Simirenko (27.04) with a flowering time of eight days. Apple-tree varieties with high resistance to scab and powdery mildew were selected according to the ripening time: summer — Fortuna, autumn — Carmen and Talisman, winter — Talida, Nika. Identification of varietal characteristics of commercial qualities of fruits by attractiveness (fruit weight, taste, appearance) and varieties with a high content of dry matter (Fortuna, Nika), vitamin C — flying varieties Feya, Fortuna (17.0–14.5 mg / 100 g) were selected.

Ефективність застосування мікродобрив в інтенсивному саду яблуні ТОВ «Харківська фруктова компанія»

The use of biostimulating microfertilizers during foliar feeding makes it possible to reduce the introduction of mineral fertilizers into the soil. This method of fertilization is safe for the environment because the nutrients are applied in controlled amounts. The purpose of our research was to evaluate the effect of foliar fertilization of apple trees on productivity, commercial quality of fruits and economic efficiency. As a result of the research, a positive effect of the use of biostimulants in intensive apple plantations of Gala, Pinova, Fuji, Red Jonaprinz varieties was established. In the course of research, biological preparations of the company "Timak Agro Ukraine" of the brands Maxifruit, Fertileader Elite, Fertileader Axis were used. Application of these drugs was carried out according to the scheme: when the average size of the fruits was 30 mm, foliar treatment with biostimulants at the rate of 3 l/ha was carried out, followed by repetition after 10 days. To assess the effect of the biological preparation, apples were sorted into fractions according to the diameter of the fruit - less than 60 mm, 60-69 mm, 70-75 mm, more than 75 mm. They also calculated the yield and evaluated the marketable quality of the harvested fruits. It has been proven that foliar treatment of trees with biological preparations helps to increase the size of fruits, which in turn reduces the number of non-standard products (fruits with a diameter of less than 60 mm) and significantly increases the share of fruits larger than 70 mm. Due to their anti-stress properties, biological preparations had the maximum effect on the fruits of the Pinova variety, which is not sufficiently resistant to high temperatures and low air humidity, increasing the share of fruits larger than 70 mm by 21.4 % compared to the control and the small-fruited Gala variety, for which this increase was equal to 12.9 %. It was established that as a result of increasing yield, improving the size, and therefore the marketability of fruits, the average sale price increased, which in turn increased the economic efficiency of fruit cultivation. Key words: apple tree, variety, foliar fertilization, product quality, yield, economic efficiency.

Adaptive potential of apple varieties in the foothill zone of Dagestan

The article presents the results of studying the adaptability of apple varieties on the M9 clone rootstock in the agroecological conditions of the southeastern foothill subprovince of Dagestan. The purpose of the research is to identify the adaptive potential of apple varieties for the establishment of intensive type orchards in the zone of commercial horticulture. It is especially important to choose the optimal variant of scion-rootstock combinations of apple trees, which should be distinguished by annual productivity, high commercial quality of fruits and environmental sustainability. The southeastern foothill sub-province has great prospects for the development of commercial horticulture. The most common of the unfavorable environmental factors that negatively affect the vital activity of fruit crops are recurrent cold in spring and early frosts in autumn, when fruit plants are still windy. According to the results of the research, biometric parameters of growth and yield of trees in a young orchard were determined, depending on the type of plantings design. It is noted that at the age of three years, the condition of trees on a 5-point scale is good. The height of trees, depending on the rootstock, compared with the variety Renet Simirenko (control), reached an average of 2.3 to 2.9 m. On dwarf rootstocks of M-9, the diameter of the stem of the Majesti variety was 4.2 cm, the diameter of the Simirenko variety was 3.5 cm. The growth of annual shoots clearly reflects the growth activity of trees with different scion/rootstock combinations. It has been established that dwarf rootstocks provide a weakening effect and allow growing stunted trees with a compact crown, a strong stem and are convenient for care, harvesting. The largest number of fruit formations was observed in the introduced Majesti variety with a planting scheme of 3.0×1.5 on a dwarf rootstock M9(67sh), compared with the control variety of the Renet Simirenko (46pcs).The yield from one tree was 7.1 kg., in the control variety Renet Simirenko — (5.3 kg). When calculated per hectare, the Majesty variety produced 15.7 tons, Renet Simirenko — 11.7 tons.

Productivity of apple variety Majesti in the foothill zone of Dagestan

The article presents the results of studying the productivity of the parameters of the introduced apple variety Majesti on the clonal rootstock M9 in the agro-ecological conditions of the southeastern foothill sub-province of Dagestan. The purpose of the research is to identify the biological potential of the variety, the adaptive potential for the construction of intensive-type orchards in the industrial horticulture zone. It is especially important to choose the optimal variety-rootstock combinations of apple trees, which should be distinguished by early maturity, annual productivity, high commercial quality of fruits and environmental sustainability. The southeastern foothill sub-province has great prospects for the development of industrial horticulture. Of the unfavorable environmental factors that negatively affect the vital activity of fruit crops, the most often noted are return colds in spring and early frosts in autumn, when fruit plants are still growing. In accordance with the research program of the Federal Agrarian Scientific Center of the Republic of Dagestan, it is envisaged to study the influence of different rootstocks (M9, SK-2, SK-7, MM106) on the productivity of the Majesti variety. Based on the research results, biometric indicators of the growth and productivity of trees in a young garden were determined, depending on the type of planting design. It was noted that at the age of three, the condition of trees on a 5-point scale is good. The height of the trees, depending on the rootstock, reached an average of 2.3 to 2.9 m. On dwarf rootstocks M9, the stem diameter of the Majesti variety was 4.2 cm, of the control variety Renet Simirenko — 3.5. The growth of annual shoots clearly reflects the growth activity of trees with different varieties of rootstock combinations. It has been established that the growth of dwarf rootstocks provides a weakening effect and allows growing lowgrowing trees with a compact crown, a strong stem, that are convenient for earning and harvesting. The largest number of fruit formations was noted in the introduced cultivar Majesti with a 3.0x1.5 planting pattern on a dwarf stock M9 (67 pieces) then in comparison on the control variety Renet Simirenko it was46 pieces. Productivity per tree was 7.1 kg, in the control variety Renet Simirenko — 5.3 kg. Calculated per hectare, productivity of the Majesti variety is 15.7 tons, Renet Simirenko — 11.7 tons.

Mechanical Performances of Isolated Cuticles Along Tomato Fruit Growth and Ripening.

The cuticle is the most external layer that protects fruits from the environment and constitutes the first shield against physical impacts. The preservation of its mechanical integrity is essential to avoid the access to epidermal cell walls and to prevent mass loss and damage that affect the commercial quality of fruits. The rheology of the cuticle is also very important to respond to the size modification along fruit growth and to regulate the diffusion of molecules from and toward the atmosphere. The mechanical performance of cuticles is regulated by the amount and assembly of its components (mainly cutin, polysaccharides, and waxes). In tomato fruit cuticles, phenolics, a minor cuticle component, have been found to have a strong influence on their mechanical behavior. To fully characterize the biomechanics of tomato fruit cuticle, transient creep, uniaxial tests, and multi strain dynamic mechanical analysis (DMA) measurements have been carried out. Two well-differentiated stages have been identified. At early stages of growth, characterized by a low phenolic content, the cuticle displays a soft elastic behavior. Upon increased phenolic accumulation during ripening, a progressive stiffening is observed. The increment of viscoelasticity in ripe fruit cuticles has also been associated with the presence of these compounds. The transition from the soft elastic to the more rigid viscoelastic regime can be explained by the cooperative association of phenolics with both the cutin and the polysaccharide fractions.

Different visitation frequencies of native and non-native bees to vines: how much vegetation is necessary to improve fruit production?

Pollination is provided by biodiversity and maintains global food production. We investigated the effects of vegetation cover on the abundance of floral visitor and vine (Vitis labrusca Raf.) production. We expected an increase in both floral visitor frequencies and vineyard yields with an increase in native vegetation cover in the landscape. We also investigated different scenarios of visitor abundance with and without honeybees (Apis mellifera L.). We surveyed floral visitors from ten vineyard plots with different native cover surrounding them and related both visitors and native vegetation to fruit set. Considering some of these vineyards, we compared physical and chemical traits of berries to understand how they vary according to native vegetation. Floral visitor abundance was positively related to native vegetation cover. However, considering only native bee abundance, we found a dual (hyperbolic) response. Apis mellifera (L.) Africanized was the most abundant species and had the highest number of interactions; however, when removed from the network analysis, the relationship between vineyards and native bees became more specialized. The fruit size and mass of berries differed among vineyards, as did some chemical traits related to commercial quality of fruits, such as soluble solids, pH and flavonoids. Vineyards surrounded by intermediate areas of native vegetation present a balance between resource availability from vineyards and native vegetation. Apis and non-Apis (such as flies and small bees) floral visitors, known to have different effects on vine pollination, could hypothetically provide variation in vine production and quality. Considering a near 20% native vegetation increment, there was an enhancement, on average, of ten-fold more berries per bunch, the changing physical and chemical fruit traits by vegetation increment could also increase the aggregate value of vines and the value of pollination services in the economy.

Scrapped but not neglected: Insights into the composition, molecular modulation and antioxidant capacity of phenols in peel of eggplant (Solanum melongena L.) fruits at different developmental stages

Eggplant fruits are normally harvested and marketed when they reach the commercial maturity, that precedes the physiological ripening when dramatic changes in taste, composition and peel color take place. The biochemical changes in fruit peel across the developmental stages, characterized also by a sizeable decrement of anthocyanins, were studied in four eggplant genotypes differing for fruit pigmentation. HPLC-DAD, HPLC-ESI-MS and NMR analyses identified naringenin chalcone and naringenin 7-O-glucoside as the main phenolic compounds in extracts from the physiological ripe stage, along with compounds tentatively identified as glycosylated naringenin chalcone, naringenin and kaempferol. On average, the levels of anthocyanins, responsible for the peel pigmentation, dropped by 75% during development, while, surprisingly, the level of total phenols showed a slight decrease of 16%, with a final concentration of more than 1000 mg/100g dw. RT-qPCR expression profiling of nine genes coding for enzymes putatively acting at different steps of the involved pathways showed modulation mostly consistent with the observed changes in phenolic composition, with a remarkable decrease in the activity of flavonol reductase and an increase in flavonol synthase during berry development. Antioxidant activity monitored by peroxyl scavenging was similar at all developmental stages while Fremy's analysis evidenced a slight decrement at full physiological ripening. These results are valuable to address the improvement of eggplant commercial fruit quality and the valorization of unmarketable physiological ripe fruits, especially for the newly accumulation of the health-promoting compounds chalcones and flavanones.

Some indicators of the quality and cold storage of the fruit of new scab immune columnar apple cultivars

The qualitative indicators of the fruits of new scab-immune columnar apple cultivars selected by VNIISPK (‘Vostorg’, ‘Zvezda’, ‘Poezia’, ‘Priokskoe’ and ‘Sozvezdie’) were analyzed at the beginning and end of storage in the +2°C mode with parallel monitoring of weather conditions for 4 years of the research. The influence of meteorological conditions of the growing season on some components of the commercial quality of fruits and their storage life was noted. The most favorable conditions were formed in the years with optimal moisture of the growing season (hydrothermal coefficient (HTC) at the level of 1.0). The longest storage life was observed in ‘Zvezda Efira’–135 days, the shortest storage life was in ‘Poetry’–102 days. The yield of commercial fruits at the end of storage varied between 76.2% (‘Vostorg’) and 92.1% (‘Sozvezdie’). In 2018, anthracnose of fruits was recorded for the first time in ‘Vostorg’, ‘Poezia’ and ‘Priokskoye’. The genotypic resistance of fruits was observed to bitter pit (excluding ‘Zvezda Efira’), low-temperature breakdown of the pulp, in ‘Zvezda Efira’ and ‘Poezia’–to scald. The susceptibility to senescent breakdown of fruits was observed in all of the cultivars. ‘Sozvezdie’ was resistant to physiological disorders. There was a decrease in the content of sugars and organic acids and an increase in the value of the sugar-acid index in fruits at the end of storage.

Features of the economical yield formation of apple plants under non-root nutrition in the Southern Russia organic plantings

In this work are determined the prospects of application new complex fertilizer chelate “Naliv” for apple plants non-root nutrition in connection with optimization of economic yield formation in the Southern Russia organic plantations. The field experiment was carried out in the organic apple tree plantations of the educational farm "Kuban" of the KubSAU, planted in 2002. The experimental field soil is leached chernozem. Trees foliar dressing was carried out with organic fertilizer 40-45 days before harvest. Control variant was trees treatment with water. The accumulation of glucose and fructose, associated with a significant (1.4 times) increase in their average weight, activate in ripening fruits under fertilizer application as a late-summer foliar dressing. Equally, the economic yield increases by 14% compared to control value. The fertilizer application accelerates the generative apple bud dormancy beginning and, accordingly, dormancy ending. An increase in the abscisic acid content in generative buds in late autumn, initiated by the fertilizer action, plays a certain role in achieving this effect. Equally, the plants resistance to low temperatures of the spring increases. Thus, favorable conditions are created to improve the commercial quality of fruits and optimize fruiting in adjacent years under fertilizers application in organic apple plantations.

Source material for quince varieties selection with high commercial and consumer qualities of fruits in the Krymsk EBS, VIR Branch gene pool

The article presents the evaluation results of varieties, samples, and breeding elites of quince from the gene pool of VIR named after N.I. Vavilov preserved at the Krymsk EBS, VIR Branch. The article presents generalized material based on the study of technical parameters, biochemical composition of quince fruits and products of technological processing (canned food: juice, compote, jam). Differences between varieties by fruit weight and in terms of biochemical indicators content were established: soluble dry substances, sugars, sum of organic acids, ascorbic acid. In the conditions of southern Russia, quince fruits contain relatively higher levels of soluble dry substances (1.2-1.8 times) and ascorbic acid (1.5-2.0 times) compared to apples. According to the research results, selectionally valuable sources of high commercial fruit quality were distinguished, including attractiveness of appearance, taste and density of pulp, organoleptic, biochemical parameters of fresh fruits and evaluation of conversion products: Vernaya, Zvezdnaya, Granitnaya, elite 21-4-51. Varieties - sources of high content of soluble dry substances (23.30-24.58%), organic acids (1.45-1.76%), sugars (13.30-14.90%), ascorbic acid (37.01-42.24 mg/100 g) were identified. For amateur gardening, quince species forms Kaunchi 8, Kaunchi 9, Jardem are proposed as they are juicy, soft, with good biochemical indicators.

MONITORING THE CONDITION OF VEGETABLES, FRUITS AND PLANTS USING INFRARED THERMOGRAPHYMONITORING THE CONDITION OF VEGETABLES, FRUITS AND PLANTS USING INFRARED THERMOGRAPHY

Determining the quality of fruit and vegetable products and their storage is a topical problem, as evidenced by a significant number of works from near and far abroad. These works present the worldwide experience of using various optical methods for instrumental non-destructive assessment of the maturity and commercial quality of fruit and vegetables. Despite so many scientific works on this topic, the thermographic methods require further research to find out the prospects of using modern thermal imaging systems in the agricultural sector. The paper studies the possibility of using remote-sensing infrared thermography to monitor the state of vegetables, fruit, and plants during their growth and storage. To determine the quality of fruit and vegetable products by random sampling, apples, pears, and pumpkins, with no external (visible) damage, were tested for the presence of microbial infections in them during rotting. In a laboratory environment, the plants were studied after watering to determine the process of hydration through the trunk and leaves and thus assess their condition. The research used a matrix infrared thermograph developed by V.Lashkaryov Institute of Semiconductor Physics of the National Academy of Sciences of Ukraine. The studies have shown that infrared thermography detects internal damage to fruit and vegetables and allows assessing the watering of plants and their condition. As a result of this work, it has been shown that infrared thermography, as a diagnostic method, can be recommended for timely detection of the internal development of microbial infections that lead to spoilage of vegetables and fruit during long-term storage, as well as for monitoring the state of plants during their hydration. It has been shown that infrared thermography can be used to control the quality of fruit and vegetable products before putting them in long-term storage and during it. The method allows timely detection of damage, and is helpful in studying plants in the laboratory and in the field.

Prospects for selection-genetic studies of fruit crops

Aim and task: to increase the efficiency of selection with a significant increase in the parameters of varieties in terms of adaptability, productivity and commercial quality of fruits by including in the breeding process genetic methods for assessing the gene pool and the impact on it. Methods. Assessment of the genefund was carried out according to the “Program and Methods for Variety Studies of Fruit, Nut and Berry Crops” (Michurinsk, 1993; Orel, 1995). Breeding studies were carried out according to the “Program and methodology for selection of fruit, nut and berry crops (Michurinsk, 1980; Orel, 1999). Statistical data processing was performed according to B.P. (1985) using the software package "Excel 7", "Statistica 10". An analysis of the scientific literature on genomic selection. Results. A phenotypic assessment of the gene pool of fruit crops obtained as a result of distant hybridization and experimental mutagenesis was carried out. The equations of multiple regression are constructed, correlation interconnections between productivity and biological, biotic and abiotic factors are revealed. The criteria of the model of the “ideal” cultivar are determined and a comparative assessment of the best cultivars with it is carried out. Genotypic assessment of the gene pool was performed using methods of hybridological analysis, differential staining and PCR analysis of chromosomes. Promising areas of genomic selection of fruit crops are considered. Main conclusions. As a result of joint work between breeders and geneticists on the basis of genomic selection of fruit crops, carried out in two interrelated directions using: genetic methods for evaluating breeding material and genetic methods for influencing the genotype of the original cultivars, the selection efficiency will be increased and new cultivars will be obtained that are complex biologically valuable traits will significantly exceed the best standard cultivars.

Agronomic Behavior of Six Saladette Tomato Hybrids Grown under Shade Mesh

Aims: The objective was to evaluate six indeterminate saladette tomato hybrids in Southeast, Coahuila, Mexico. Under shade house covered with anti-aphid mesh, to determine their performance, commercial quality and adaptability.
 Study Design: The experimental design used in each test was completely randomized model with six treatments and three repetitions each. The treatments were hybrids Lubino were Lubino F1, Zopilote F1, Sahariana F1, Raptor F1, Quetzal F1 and RTF-713172 F1.
 Place and Duration of Study: The site was Parras Valley Tomatoes in Parras, Coahuila, México. During april to November 2017.
 Methodology: The distance between the lines were 1.80 m, between the plantpots 36 cm and two plants per plantpots, with approximately 30,000 plants per hectare calculated. The genotypes used were Lubino F1, Zopilote F1, Sahariana F1, Raptor F1, Quetzal F1 and RTF-713172 F1. The following agronomic characteristics were evaluates: yield, total number of fruits, average fruit weight, number of fruits per bunch, length between clusters, length of internodes, main stem thickness and commercial quality of fruit.
 Results: The results indicate that the highest yielding hybrid was Zopilote with 4.3 kg plant-1, followed by Saharan, the average weight of the product obtained best in Saharan and Quetzal with 122.33 and 118.33 g respectively, the most compact variety was Zopilote due to the shorter distance between bunches, contrary to what was demonstrated by Lubino.
 Conclusion: The best variety for the Southeast of Coahuila is Zopilote F1, due to its higher yield and for being a compact plant.

An optimal harvest maturity model for ‘Minneiska’ apple fruit based on the delta-absorbance meter

ABSTRACT A hand-held, chlorophyll content meter [the delta absorbance (DA) meter] was used to develop an optimal harvest maturity model for ‘Minneiska’ apples (Malus domestica Borkh). Fruit from four commercial orchards in the Annapolis Valley, Nova Scotia, Canada, were sampled weekly (25 fruit per location) over eight consecutive harvests during the 2011–2013 growing seasons. At each harvest, 60 fruit were measured for their DA value (IAD ), mass, firmness, titratable acidity (TA), soluble solids content (SSC), red skin colouration, starch-to-sugar conversion and internal core ethylene concentration. Following 3–3.5 months of refrigerated air storage at 3.5°C, samples were removed and assessed for fruit bruising, skin greasiness, rot and physiological disorders. Peel chlorophyll content was strongly and positively correlated with epidermal IAD measurements. IAD values declined significantly during fruit ripening and were negatively related to harvest week. The optimal harvest period was identified by aligning ‘at harvest’ IAD , fruit quality and ‘post-storage’ disorder data with the corresponding harvest week. IAD averages associated with harvests having high commercial fruit quality demarcated the optimal harvest boundaries. As the IAD values declined during fruit maturity, the upper boundary value of 0.26 was defined as ‘when to begin harvest’, while the lower boundary value of 0.12 was deemed ‘when to end harvest’ for longer-term storage.

Acidity Drop and Coloration in Clementine: Implications for Fruit Quality and Harvesting Practices.

The commercial quality of fruit is the result of a combination of internal (acidity, sugars, juice, etc.) and external characteristics (shape, size, color, visual defects, etc.). On citrus, the internal maturity of fruit is often reached prior and independently to their external maturity, inducing the use of degreening practices to artificially color fruit. However, for some sectors where degreening is not authorized, such as organic farming or up-market, it is important to understand the co-occurrence between fruit coloration and internal ripening, and its impact on fruit quality and harvesting management. Our study was based on a monitoring of the color and acidity of Protected Geographical Indication “Clémentine de Corse” orchards of producers in 2013 and 2014. Our results show that: (i) the dynamics of acidity drop during maturation are similar from one plot to another but staggered in time; (ii) fruit coloring occurs at different times during acidity drop; (iii) the synchronization between the coloring process and acidity drop determines both the quality of harvested fruit and the period during which orchards are harvestable, which we called the “harvestability window.” This study sheds new light on the quality of citrus harvested without fruit degreening and leads to propose actions to anticipate internal maturity evolution according to the coloring and spreading of the harvest period. The fruit acidity model obtained in this study will be extended to a practical application tool to predict fruit acidity and quality for a better-controlled harvest management.

Carotenoid biosynthesis and quality characteristics of new hybrids between tangor (Citrus reticulata x C. sinensis) cv. 'Murcott' and sweet orange (C. sinensis) cv. 'Pêra'.

Phenotypic characteristics, as well as the relation between carotenoid accumulation and gene expression during ripening were determined in fruits of five new hybrids between tangor cv. 'Murcott' and sweet orange cv. 'Pêra'. The genotypes were classified into the orange-like group, showing mainly epoxycarotenoids, oval fruit shape and yellowish color, or in the mandarin-like group, showing mainly β-cryptoxanthin, flattened shape and deep-orange coloration; although some hybrids presented intermediate characteristics. The diversity in carotenoid composition of hybrids and genitors were mostly explained by patterns of gene expression. High carotenoid (250-426 μg/g dry weight [dw]) and β-cryptoxanthin (81-125 μg/g dw) contents, observed in the mandarin-like group, were generally associated with high expression of upstream genes (GGPPS1, PSY, PDS). On the other hand, low expression/repression of these genes and high expression of downstream genes (BCHX and ZEP) were associated with low carotenoid (~158 μg/g dw) and β-cryptoxanthin (5-22 μg/g dw) contents and epoxycarotenoid accumulation, as occurred in the orange-like group. Breeding experiments resulted in hybrids with outstanding higher carotenoid contents than both genitors (up to 426 μg/g dw versus 158-250 μg/g dw in genitors), which was attributed to transgressive segregation. Differences among genotypes have great impact on commercial fruit quality and potential health benefits, such as the provitamin A content.

Ammonia thiosulfate in Japanese plum tree thinning

Abstract In order to test the use of ammonia thiosulfate (ATS) in the chemical thinning of the Japanese plum tree, a field experiment was conducted throughout the 2015/2016 and 2016/2017 crop growing seasons at Ponta Grossa, PR, Brazil. The experimental design adopted herein was a randomized block design (RBD). During the 2015/2016 season, the trial was comprised of two accesses and six treatments, such as T1 (control); T2 (ATS 4%); T3 (ATS 5%); T4 (ATS 6%); T5 (ATS 7%) and T6 (manual thinning) with four replications. During the 2016/2017 season, solely one plum tree access was taken into account along with six treatments, such as T1 (control); T2 (ATS 6%); T3 (ATS 7%); T4 (ATS 8%); T5 (ATS 9%) and T6 (manual thinning) and four replications. The evaluations were performed seven days before the application of ATS and 30 days before harvest to establish the percentage of fruit drop. The following response variables were assessed: diameter (D), fresh mass (MF), firmness (N), soluble solids (SS), titratable acidity (AT), ratio, pH and plant production (PP). Experimental data were compared by means of the Tukey test at 5% probability. The concentration of 8 % ATS was efficient in the chemical thinning of the Japanese plum fruits, having a diameter and productivity similar to the manual thinning, evidencing that such a product was amenable to enhance commercial fruit quality.

BREEDING FOR HOST RESISTANCE TO FIRE BLIGHT

Breeding for fire blight resistance in apple and pear has a long tradition. It was primarily related to the importance of the disease in the area where breeding programs are located. The main sources of resistance are wild species with low quality fruits. To introgress these sources of resistance, several breeding generations are required to develop resistant varieties with commercial fruit quality. Different methods are currently applied to speed up the generation cycle. However, also commercial cultivars and modern breeding material show considerable differences in susceptibility. Genotypes carrying a high level of resistance can be used as parents in breeding. Phenotypic scoring of resistance is mainly done by shoot inoculation tests on grafted plants in greenhouses. These tests can be complemented by outdoor flower inoculation tests to achieve a more comprehensive resistance evaluation. Progress in the development of molecular markers closely linked to fire blight resistance loci allow breeders for more efficient selection.