Fruits with a high content of biologically active compounds are essential in preventing many diseases. Therefore, the interest in searching for and testing new plant sources for bioactive constituents remains strong. Although many publications on individual species exist, their results are difficult to compare directly due to varying methods and conditions of analysis. Only a few studies have investigated many different species in a single analysis. Therefore, we examined and compared 21 different genotypes, using various measurement methods for total phenolic content (TPC) (Folin–Ciocalteu, FBBB), total antioxidant capacity (ABTS, FRAP, DPPH), and the HPLC technique for the total ascorbate concentration in freshly harvested fruits. One-way ANOVA, Principal Component Analysis, and Pearson Correlation were used to analyse and compare the results. The tested samples showed significant differences in TPC, ascorbate content, and antioxidant capacity. The correlation between the content of bioactive compounds and antioxidant capacity depended on the analytical methods, with results obtained using the FRAP test being the most strongly correlated. Due to higher levels of polyphenols, ascorbate, and antioxidant potential, the most promising species for further evaluation appear to be Chaenomeles × californica, Actinidia kolomikta, Mespilus germanica, and ×Sorboaronia fallax.

The N uptake can affect kiwiberry yield and quality; however, the relationship between an increasing N dose and micronutrient accumulation in leaves and fruit is still to be elucidated. Interrelationships between essential nutrients are one of the most important issues in terms of effectiveness in plant mineral nutrition. A pattern in leaf nutrient accumulation throughout the growing period is required to indicate a suitable sampling time for the purpose of nutrient diagnostics and controlled plant feeding. The experiment was conducted on two commercially available cultivars of kiwiberry, ‘Weiki’ and ‘Geneva’, during the 2015–2016 growing seasons with an increasing soil N fertility (30–50–80 mg N kg−1 soil DW) to test the relationship between soil N level and leaf/fruit micronutrient concentration. The leaf Zn, Cu, Fe, and Mn concentrations significantly increased with a higher N supply in ‘Geneva’, while in ‘Weiki’ only Mn increased. Leaf B, Fe, and Mn gradually increased throughout the growing season, while Cu decreased. Between mid-July and the beginning of August, the lowest fluctuations in the micronutrient contents were recorded. The effect of the growing season on leaf micronutrient accumulation was highly significant; except for Fe, significantly higher micronutrient levels were revealed in 2016. Compared to the leaves, the growing season effect was smaller in the case of fruit micronutrient concentrations. Irrespective of cultivar, the increase in N fertilization resulted in a higher fruit Mn concentration and was insignificant in the case of other micronutrients. The results indicate that the N dose may affect the accumulation of micronutrients within a certain range depending on the tissue type and the genotype.

The quality of fruit as a source of bioactive ingredients is related to the genetic characteristics of plants, but it can also be modified by growing conditions. Therefore, long-term research can be extremely valuable in evaluating various crop plants, especially novel ones. The aim of the research was to test four popular European kiwiberry (Actinidia arguta) cultivars (‘Geneva’, ‘Bingo’, ‘Weiki’, ‘Anna’) in terms of selected morphological features, yield, and chemical composition as well as their variability over 3 years. It can be concluded that the studied genotypes were very diverse in terms of the biochemical compounds’ concentration in individual seasons. The cultivars ‘Anna’ and ‘Weiki’ were the most similar ones with respect to each other in terms of morphology and chemical composition. The cultivars ‘Bingo’ and ‘Geneva’ were definitely different. ‘Bingo’ was characterized by the largest and most uniform fruits in each season and had the highest concentration of vitamin C but the lowest carotenoid concentration. In turn, ‘Geneva’ produced the smallest fruit in each season with the highest concentration of polyphenols and a high concentration of carotenoids and displayed the highest antioxidant capacity regardless of the determination method. The research was performed with the application of computer-supported statistical analysis.

More than ten thousand apple cultivars with high variability in the quality traits and year-round availability place apples at the forefront of consumed fruits. Yet consumers and producers alike are still looking for new apple cultivars with specific quality attributes such as plant resistance to biotic and abiotic stresses as well as a high health-promoting potential. The model plants were three cultivars: a new ‘Chopin’ and an old ‘Granny Smith’, scab resistant cultivars with green peel, and a red-skinned cultivar ‘Gala Schniga’. Apple peel and flesh were analyzed separately during two growing seasons: 2016 and 2017. The total ascorbate and phenolics as well as individual phenolic compounds, such as (+)-catechin, (−)-epicatechin, chlorogenic acid, phloridzin, and rutin concentrations, proved to be highly tissue-type and cultivar dependent. The apple of the ‘Chopin’ and ‘Granny Smith’ cultivars expressed much lower skin-to-flesh antioxidant potential differences as compared to ‘Gala Schniga’. The lowest differences between tissue types were observed in the case of chlorogenic acid and flavan-3-ols, followed by total phenolics and ascorbate concentrations. Except for phloridzin, ‘Gala Schniga’ exhibited the highest differences in global and individual phenolic compound concentrations as well as total antioxidant capacity between the apple peel and flesh. ‘Chopin’ was definitely distinguished by the highest concentration of ascorbate in both the peel and the flesh and expressed a higher concentration of flavanols, especially compared to ‘Granny Smith’. In contrast to ‘Gala Schniga’, ‘Chopin’ was richer in chlorogenic acid, (+)-catechin, and (−)-epicatechin in the flesh. The total antioxidant capacity of the green-peel apple cultivars was similar to that of the red-peel one. A narrower range of differences between the concentration of antioxidants in apple peel and flesh could mean better health-promoting properties and might be related to a greater resistance to environmental stress factors.

The genetic and/or the agronomic approaches are two main ways to enhance concentrations of biologically active compounds in fruits and vegetables. In this study, the apple antioxidant status was evaluated from the second to the fourth year after planting in relation to an increasing N-dose applied—with or without plant microbial inoculation in the field conditions. Cultivar ‘Šampion Arno’ was selected to test these relationships. In the growing season, N treatment and inoculation effects were monitored for the apple peel total phenolics and selected individual phenolic compounds ((+)-catechin, (−)-epicatechin, chlorogenic and caffeic acids, rutin and phloridzin) and total ascorbate concentration. Additionally, as an environmental stress marker measurement of glutathione reductase, ascorbate peroxidase and catalase activity were conducted. The year effect was most pronounced, while the N or applied inoculum effects were much weaker. Great differences in antioxidative enzyme activity and phenolic concentrations between years were revealed. Nitrogen fertilization reduced the fruit’s global phenolic accumulation compared to the control, but the N-effect varied depending on individual phenolic compounds, N dose and N application method. None of the tested factors influenced the ascorbate concentration. There was a certain tendency to increase antioxidant properties in the control group (without mineral N fertilization) but with the application of bio-fertilizer, which may seem promising for future research in this scope.

The aim of this study was to assess the enzymatic and non-enzymatic antioxidant status of kiwiberry (Actinidia arguta) leaf under different N regimes tested three times in field conditions during the 2015 growing season in two cultivars (‘Weiki’ and ‘Geneva’). Leaf total antioxidant capacity using ABTS, DPPH and FRAP tests was evaluated in the years 2015 to 2017, which experienced different weather conditions. Both cultivars exhibited a significant fall in leaf L-ascorbic acid (L-AA) and reduced glutathione (GSH) as well as global content of these compounds during the growing season, while total phenolic contents slightly (‘Weiki’) or significantly (‘Geneva’) increased. There was a large fluctuation in antioxidative enzyme activity during the season. The correlation between individual antioxidants and trolox equivalent antioxidant capacity (TEAC) depended on the plant development phase. The study revealed two peaks of an increase in TEAC at the start and end of the growing season. Leaf L-AA, global phenolics, APX, CAT and TEAC depended on the N level, but thiol compounds were not affected. Over the three years, TEAC decreased as soil N fertility increased, and the strength of the N effect was year dependent. The relationship between leaf N content and ABTS and FRAP tests was highly negative. The antioxidant properties of kiwiberry leaves were found to be closely related to the plant development phase and affected by soil N fertility.

This study investigated the antioxidant status of roots, leaves, and fruit upon microbial inoculation (AMF+PGPR, arbuscular mycorrhizal fungi, and plant growth-promoting rhizobacteria, respectively) of young organically farmed apple trees over two growing seasons. Three cultivars—‘Topaz’, ‘Chopin’, and ‘Odra’—were selected to test the relationship between inoculation and enzymatic and non-enzymatic antioxidant components. The antioxidant metabolism was highly dependent on tissue type and growing season. The greatest effect on antioxidant status following application of the inoculum was found in roots, then leaves, but it was almost negligible in fruit. Roots were influenced most by application of the inoculum in the first growing season, while leaves were influenced most in the second season. Considerable differences between the inoculated and control plants were found for root glutathione reductase (GR) and catalase (CAT) activity, as well as glutathione and ascorbate contents; root phenolics were not influenced by inoculation. In the case of leaves, effect of microbial inoculation on GR activity was revealed in the first growing season, while for global phenolics in the second season, and only the concentration of glutathione was significantly higher in the leaves of inoculated trees in both growing seasons. Leaf ascorbate content and CAT activity were not influenced by the microbial inoculation. The control and inoculated trees expressed a similar total antioxidant capacity, irrespective of the tissue type tested. Furthermore, the response of the cultivars to inoculation varied and also changed in consecutive growing seasons. Based on this study, it is likely that the effect of microbial inoculum as a tool for enhancing health-promoting properties in the fruit of perennial plants is weaker than that described for vegetables where different plant organs are edible.

BACKGROUND Actinidia arguta known as the 'kiwiberry' or 'mini kiwi' is relatively new among the cultivated berry species. Recent studies indicate the kiwiberry fruit could be an important source of many health-promoting compounds. A knowledge-based fertilisation concept was evolved to define optimal strategies for feeding Actinidia with nitrogen (N) because a deficit and excess of N both have a negative impact on plants and the surrounding environment. RESULTS Kiwiberry yield and fruit internal quality significantly depended on soil N level, cultivar and growing season. A higher soil N led to an increase in carotenoid content and a decrease in phenolic content, whereas ascorbic acid and glutathione contents were not affected by soil N fertility. Under the highest N dose, enzymatic antioxidants were activated. Trolox equivalent antioxidant capacity clearly decreased with an increasing N level. CONCLUSIONS Competent and skilful fertilisation management should focus on balancing a high fruit yield and maintaining their high quality. Based on yield level and fruit antioxidant potential, the N guide values for A. arguta vary between 30 and 50 mg N per kg(-1) of soil. The recommended N dose may depend on overall soil quality traits and cultivar N demand, as well as on weather conditions. (c) 2020 Society of Chemical Industry

Actinidia arguta (Siebold et Zucc.) Planch. ex Miq. is functionally a cryptic dioecious plant and successful pollination is crucial for achieving high quality fruit. The extent and bases of morphological variability in female genotypes have been well studied, but here we focus on the males. Mature plants of seven male A. arguta genotypes were studied in 2016 and 2017 during which a suite of phenological and morphological features was measured on ten randomly chosen one-year-old canes on each plant. This analysis was complemented by two other, specialized measures potentially related to pollination efficiency, namely pollen quality, and quantity. The time of bud break was similar each year across all genotypes and the pollen quality was uniformly very high (viability - 95.0-99.9% and germination - 89.0-97.3%). However, the ten genotypes exhibited high variability in both the number of flowers per inflorescence and pollen quantity, indicating marked differences in their flowering potential and efficiency as pollinizers. The male kiwiberry indicators developed in this study - flowering potential and pollen efficiency, appear to be effective tools for the comparative evaluation of male A. arguta genotypes.

ABSTRACT Nutrient use efficiency and overall plant fertilization strategies are key issues in food production in increasingly adverse environmental conditions. The plant Actinidia arguta (Siebold et Zucc.) Planch. ex Miq. is a species that has increased cultivation in recent years. The aim of this study was to assess seasonal leaf macronutrient changes and the relationship between soil nitrogen (N) fertility and N, as well as the concentration of other leaf essential macronutrients. The experiment was conducted during the growing seasons of 2015–2016 and tested two cultivars: “Weiki” and “Geneva”. Soil N level had a significant impact on the concentration of all leaf macronutrients, except sulfur, in both cultivars. Leaf macronutrient concentration was significantly lower in 2015, which was characterized by a higher average temperature and lower precipitation than the long term averages. A clear downward trend for leaf N and potassium concentrations was observed during the vegetation period. In contrast, leaf calcium and magnesium concentrations increased gradually throughout the season, while phosphorus and sulfur concentration changes were more cultivar dependent. In the soil and climatic conditions in which study was conducted (Central Europe), a time from mid-July to mid-August seems to be the suitable for leaf sampling for diagnostic purposes. Fruit macronutrient composition was predominantly cultivar and year dependent.

Kiwiberry ( Actinidia arguta ) is dioecious species which is now commercially grown in several countries worldwide. A study was conducted to determine the influence of five pollen sources derived from A. arguta (three cultivars), A. arguta var. purpurea ‘Rot’ and A. chinensis var. deliciosa ‘Tomuri’ on fruit and seed characteristics for three female A. arguta cultivars. Average fruit weight and biochemical features—fruit total phenolic concentration (TPC), ascorbate (ASC), pigments, total antioxidant activity and seed proteins profile were evaluated. TPC was determined using the Folin–Ciocalteu reagent assay. ASC, individual phenolic compounds and pigments composition were analysed using HPLC technique. Seed protein composition was analysed based on SDS-PAGE. Fruit phenolic and dry matter contents were influenced to a large degree by pollen sources while ASC content did not. The type of male and female parents used in the study were found to have a considerable effect on these parameters. The biggest differences in fruit phytocompound contents were found between female parents. The ‘Geneva’ cultivar showed the highest concentration of the most bioactive compounds tested. Four phenolic acids and five flavonoids were present in the highest concentrations in tested kiwiberry fruit. Actinidia chinensis var. deliciosa ‘Tomuri’ pollen clearly modified the seed protein spectrum with a 17 and 23 kDa protein. The obtained results indicate that to achieve desired fruit biochemical characteristics, the pollen source (male vines) should be selected individually for particular female cultivars, especially in the case of polyphenol content. Our findings suggest that not only A. arguta but also A. arguta var. purpurea and A. chinensis var. deliciosa ‘Tomuri’ males may be suitable as pollinizers for kiwiberry fruit production.

The kiwiberry (Actinidia arguta (Siebold et Zucc.) Planch ex Miq) has become a widely studied species in recent years due to its high resistance to low temperature and high content of health-promoting phytochemicals. The aim of this study was to verify the effect of pre-storage application of oxalic acid, salicylic acid and acetylsalicylic acid, calcium chloride (CaCl2) and 1-methlycyclopropene (1-MCP) on quality changes of the kiwiberry cultivar 'Weiki' during cold storage. During six weeks of storage fruit firmness, titratable acidity and the total ascorbate content decreased from an average of 61 N, 1.5%, 857 mg kg(-1) to 2.5 N, 1%, 380 mg kg(-1), respectively. Contrary, the soluble solids and the total phenolics content increased from an average of 0.30%, 73.5 mg kg(-1) to 0.51%, 172 mg kg(-1), respectively. Application of 1-MCP clearly improved fruit firmness and inhibited the ascorbate loss. Compared to the control, the fruit firmness and total ascorbate content was higher by 50% and 13%, respectively. The acetylsalicylic acid treated fruit exhibited significant drop of phenolics as compared to the control. There was no significant difference in fruit total antioxidant activity determined immediately after harvest and at the end of storage (16.7 vs 17 mmol kg(-1), respectively). Fruit treated by salicylic acid, CaCl2 and 1-MCP was characterized by a significantly higher titratable acidity compared to the control group. This study showed that the highest ability to maintain fruit quality during cold storage was exhibited by 1-MCP treated kiwiberry.

The kiwiberry (Actinidia arguta) has become increasingly popular not only due to its taste, but also due to its benefits for health. The kiwiberry contains a range of bioactive compounds, with antioxidant activity predominantly associated with phenolic compounds and ascorbate. The aim of this study was to determine the phenolic compounds and the total ascorbate concentration of the peel and flesh, as well as the total antioxidant ability in six kiwiberry cultivars relative to the commercially cultivated kiwifruit ‘Hayward’ (Actinidia deliciosa). Kiwiberry peel was up to 12.6 and 3.0 times richer in phenolics and ascorbate respectively than its flesh. Kiwifruit peel was only 4.7 times richer in phenolics and contained less ascorbate than its flesh. In contrast to kiwifruit, kiwiberry peel can be considered a meaningful source of potentially healthy bioactive compounds, with its contribution to the health benefits offered by the whole fruit depending on its flesh-to-peel ratio.

The main objectives of this study were: (i) to determine the differences between guide values concerning soil N-level for yielding and the content of health-promoting compounds; (ii) to evaluate the positive/negative relationships between the enzymatic and non-enzymatic antioxidants and the increasing N-fertility; (iii) finally, to assess the degree to which genotype and soil type may modify the N-dependent response. Two kale genotypes, Redbor F-1 and Winterbor F-1 characterized by red and green colour of leaves, and two types of soil, mud and lessive soil, were selected to test these interrelationships.The best yield and internal quality of kale plants was obtained at the N range between 100 and 200 mg N dm(-3). Of these two, the lower N-level should rather be recommended for the red-leafy kale and in the case of the mud soil. Compared to control, there was no clear negative impact of increasing N-level (in the range 100-300 mg N dm(-3)) on non-enzymatic antioxidants determined in both kale genotypes in this study. N-fertility considerably affected glutathione reductase in both cultivars, whereas ascorbate peroxidase and catalase activity remained relatively stable. In general, kale plants grown on the lessive soil expressed significantly higher antioxidative enzyme activity as well as ascorbate, thiols and dry matter content as compared to mud soil. Green-leafy kale was characterized by a considerably higher yield and total ascorbate and glutathione contents, whereas red-leafy Redbor F-1 expressed significantly higher concentration of global phenolics and total antioxidant ability (FRAP-assay). There were no substantial differences between cultivars in N-dependent response of the examined bioactives. (C) 2014 Elsevier B.V. All rights reserved.

Seasonal and cultivar variations of the phenolic, thiol, and ascorbate compound contents as well as the antioxidative enzyme activity in six cultivars of highbush blueberry were investigated. Berries of the ‘Earlyblue’, ‘Patriot’, ‘Bluecrop’, ‘Duke’, ‘Darrow’ and ‘Lateblue’ cultivars were sampled in 2005 and 2006. Chlorogenic acid, (-)-epicatechins, and ascorbate contents and CAT activity were found to be at the lowest degree affected by growing season conditions. ‘Seasonal effect’ had, however, a huge impact on the GR activity, as well as L-cysteine and glutathione content, suggesting that the glutathione system was highly influenced through growing factors in blueberry fruit. Berries of ‘Earlyblue’ were the richest source of antioxidants, at the same time revealing their quite stable quantity over the examined years. The second highest in bioactive stability was ‘Duke’, classified as medium with respect to antioxidant content.

The content of calcium and potassium and lipoxygenase (LOX) activity as well as the expression of LOX encoding gene in the fruit of apple cultivars that are both susceptible and resistant to bitter pit were evaluated. Fruits were collected and analyzed after harvest in the 2004 growing season and again after four months of common cold storage. The main reason was the explanation of relationship between those LOX activity and K:Ca ratio on bitter pit occurrence during storage. The biggest differences between the tested cultivars were noted in LOX activity and Ca content, followed by K:Ca ratio and the lowest potassium content. The cultivars that were resistant and susceptible but without symptoms of bitter pit exhibited higher calcium content compared to cultivars with signs of bitter pit, and with a drop in LOX activity after storage. A negative correlation was found between LOX activity and Ca content and a positive correlation was found between K:Ca ratio and LOX activity.

The quali-quantitative distribution of phenolic compounds varies considerably between apple flesh and peel, but the concentration of phenolics is substantially higher in the peel than flesh. Because the peel comprises only a small percentage of the entire fruit weight, its significance as a donor of phenolics is disputable. We assessed the contribution of the peel to the total phenolic yield of 19 apple cultivars. Calculations were based on the weight of the whole fruit and the peel (which is frequently discarded) and the concentration of individual phenolic compounds. On average, 8, 24, 32, 50 and 66% of chlorogenic acid, (+)-catechin, (−)-epicatechin, phloridzin, and rutin, respectively, were present in the peel, which constitutes about 6–8% of the whole apple weight. With the exception of chlorogenic acid, 50% or more, on average, of the above phenolics were present in the peel of ‘Granny Smith’, ‘Idared’, ‘Red Rome’, ‘Jonamac’ and ‘Gloster’ apples; the highest percentage was found in ‘Starking Delicious’ apple peel (82%). The lowest peel contribution to total phenolic content per whole apple ranged between 26 and 29% and was observed in ‘Pilot’, ‘McIntosh’ and ‘Prima’ apples. Presented results may be useful for further investigations of the relationship between phenolics and agronomical parameters or future selection of apple genotypes having improved nutritional quality when consumed as fresh or as processed apple products.

This study was to discover if there is any relationship between antioxidant status after harvest and bioactives fate during apple storage. The clearer link in this issue concerned enzymatic part of antioxidant apparatus, for which the particularly high year effect was noted. Except for anthocyanins, non-enzymatic bioactives end-status was not strictly related to their harvest size. However the content during the first months of storage might be closely connected with antioxidant status measured after harvest. A significantly higher concentration of majority assessed antioxidants was characterized by apple harvested and stored in 2005/2006 season, on the average. Simultaneously many, statistically proved, correlations over storage between the examined antioxidants at that time existed. Total antioxidant power (FRAP assay) significantly increased after the first storage period, probably as a result of fruit acclimatory response to storage conditions, and next decreased. In general, changes of FRAP value reflected fluctuations of individual compounds measured in this study.