▶ During the past years, the primary objective of horticulture has been to increase yield and productivity. However, high quality is even more important than total yield for attaining competitiveness ...in modern horticulture due to the beneficial role of vegetables in human diet. ▶ This report gives an overview of the recent literature on the effects of grafting on fruit vegetable (Solanaceae and Cucurbitaceae) quality including physical properties, flavor and health-related compounds of the product. The review will conclude by identifying several prospects for future researches aiming to improve the product quality of grafted vegetables.
In horticultural industry, the focus has traditionally been on yield. However, in recent years consumers interest in the quality of vegetable products has increased worldwide. Vegetable quality is a broad term and includes physical properties (1), flavor (2), and health-related compounds (3). Grafting vegetable plants onto resistant rootstocks is an effective tool that may enable the susceptible scion to control soil-borne diseases, environmental stresses and increase yield. However, in these cases, the characteristics of the three areas might be affected by grafting as a result of the translocation of metabolites associated with fruit quality to the scion through the xylem and/or modification of the physiological processes of the scion. Possible quality characteristics showing these effects could be fruit appearance (size, shape, color, and absence of defects and decay), firmness, texture, flavor (sugar, acids, and aroma volatiles) and health-related compounds (desired compounds such as minerals, vitamins, and carotenoids as well as undesired compounds such as heavy metals, pesticides and nitrates). There are many conflicting reports on changes in fruit quality due to grafting and whether grafting effects are advantageous or deleterious. The differences in reported results may be attributable in part to different production methods and environments, type of rootstock/scion combinations used, and harvest date. This report gives an overview of the recent literature on the effects of grafting on fruit vegetable (Solanaceae and Cucurbitaceae) quality including physical properties, flavor and health-related compounds of the product. The review will conclude by identifying several prospects for future researches aiming to improve the product quality of grafted vegetables.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
Only a few environmental factors have such a pronounced effect on plant growth and development as ultraviolet light (UV). Concerns have arisen due to increased UV-B radiation reaching the Earth's ...surface as a result of stratospheric ozone depletion. Ecologically relevant low to moderate UV-B doses (0.3-1 kJ m(-2) d(-1)) were applied to sprouts of the important vegetable crop Brassica oleracea var. italica (broccoli), and eco-physiological responses such as accumulation of non-volatile secondary metabolites were related to transcriptional responses with Agilent One-Color Gene Expression Microarray analysis using the 2×204 k format Brassica microarray. UV-B radiation effects have usually been linked to increases in phenolic compounds. As expected, the flavonoids kaempferol and quercetin accumulated in broccoli sprouts (the aerial part of the seedlings) 24 h after UV-B treatment. A new finding is the specific UV-B-mediated induction of glucosinolates (GS), especially of 4-methylsulfinylbutyl GS and 4-methoxy-indol-3-ylmethyl GS, while carotenoids and Chl levels remained unaffected. Accumulation of defensive GS metabolites was accompanied by increased expression of genes associated with salicylate and jasmonic acid signaling defense pathways and up-regulation of genes responsive to fungal and bacterial pathogens. Concomitantly, plant pre-exposure to moderate UV-B doses had negative effects on the performance of the caterpillar Pieris brassicae (L.) and on the population growth of the aphid Myzus persicae (Sulzer). Moreover, insect-specific induction of GS in broccoli sprouts was affected by UV-B pre-treatment.
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IZUM, KILJ, NUK, PILJ, PNG, SAZU, UL, UM, UPUK
Thirteen different pak choi (Brassica rapa ssp. chinensis) cultivars were characterized regarding their glucosinolate profile analyzed by HPLC-DAD-MS. The identified glucosinolates were subjected to ...principal component analysis, and three distinct groups of pak choi sprouts were identified. Group differences were marked mainly by variations in the aliphatic glucosinolate profile such as differing levels of 3-butenyl glucosinolate and 2-hydroxy-3-butenyl glucosinolate as well as by their varying proportional ratios. In addition, the three groups of pak choi sprouts varied by the presence or absence of 2-hydroxy-4-pentenyl glucosinolate and in level and composition of butyl glucosinolates. This classification is reflected by relative mRNA expression level of 2-oxoacid-dependent dioxygenase. As in sprouts, the major glucosinolates in mature leaves were found to be the aliphatic glucosinolates. However, unlike in sprouts, an additional aliphatic glucosinolate, 5-methylsulfinylpentyl glucosinolate, was detected as characteristic ontogenetic variation in mature leaves in 12 of the 13 pak choi cultivars analyzed.
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IJS, KILJ, NUK, PNG, UL, UM, UPUK
► Low K+ supply (4 vs. 8mM in the nutrient solution) resulted in a reduction of root growth, yield, fruit appearance, and carotenoids. Firmness and concentration on single and total fruit sugars ...increased. ► Grafting onto commercial rootstocks improved root growth and morphology, yield, concentration of carotenoids and also titratable acids in fruits especially at low K+ supply. The portion of blossom end rot was reduced. ► The alleviation depended on the rootstock scion combination. ► Possible reasons for the advantage of grafting, such as change in dry matter partitioning in favour of the fruits, improved Ca2+ availability and transport, increased photosynthesis and associated relationship between sugar and synthesis of ascorbic acid and carotenoids, are discussed.
Grafting is nowadays regarded as a rapid tool aimed at increasing environmental stress tolerance of fruit vegetables. In cultivation systems oversupply of cations, saline or drought conditions and the type of the growing system can easily cause potassium (K+) deficiency and thus, lead to a damage of physiological processes. The hypothesis was raised that rootstocks alleviate stress symptoms of tomato at moderate deficient K+ supply (4mM) compared with regular (8mM) in the nutrient solution. Moreover, the long-term response of grafted plants (‘Classy’, ‘Piccolino’) was studied to quantify the effectiveness of rootstocks (‘Maxifort’ and ‘Brigeor’) in mitigating K+ stress particularly on tomato yield and fruit quality attributes, such as appearance, firmness, taste and health promoting compounds. K+ deficiency resulted in a reduction of root growth, yield, fruit appearance, and carotenoids. On the other hand, firmness and concentration on single and total fruit sugars increased. In most of the characteristics negatively affected by low K+ supply, grafting was able to alleviate these effects. Thus, rootstocks improved root growth and morphology, yield, concentration of carotenoids and also titratable acids in fruits especially at low K+ supply. The portion of blossom end rot was reduced. However, the alleviation depended on the rootstock scion combination. Possible reasons of the rootstock effects were discussed, such as change in dry matter partitioning in favour of the fruits, improved Ca2+ availability and transport, increased photosynthesis and associated relationship between sugar and synthesis of ascorbic acid and carotenoids.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
The effect of three different nitrogen (N) supply forms differing in their ammonium-to-nitrate (NH4:NO3) ratio (100% NH4, 50% NH4 + 50% NO3, 100% NO3) under three different levels of daily ...photosynthetic active radiation (PAR) (low, 5.0; medium, 6.8; high, 9.0 mol m−2 day−1) on a range of desirable health-promoting phytochemicals in Brassica rapa subsp. nipposinica var. chinoleifera and Brassica juncea was determined. The 100% NH4 supply under medium PAR levels led to the highest concentration of glucosinolates based on a low nitrogen/sulfur ratio as well as high levels of carotenoids in the leaves of both Brassica species. However, the 100% NH4 supply under low and medium PAR levels resulted in low concentrations of flavonoids based on high N concentration in the leaves. Thus, the data provided here have strong implications for crop management strategies aimed at optimizing both the concentration and composition of a range of phytochemicals.
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IJS, KILJ, NUK, PNG, UL, UM, UPUK
The aim of this study was to investigate the modifying influence of moderate ultraviolet‐B (UV‐B) radiation exposure on structurally different flavonol glycosides and hydroxycinnamic acid derivatives ...during pre‐harvest using kale, a leafy Brassica species with a wide spectrum of different non‐acylated and acylated flavonol glycosides. Juvenile kale plants were treated with short‐term (1 day), moderate UV‐B radiation 0.22–0.88 kJ m−2 day−1 biologically effective UV‐B (UV‐BBE). Twenty compounds were quantified, revealing a structure‐specific response of flavonol glycosides and hydroxycinnamic acid derivatives to UV‐B radiation. A dose‐ and structure‐dependent response of the investigated phenolic compounds to additional UV‐B radiation was found. The investigated quercetin glycosides decreased under UV‐B; for kaempferol glycosides, however, the amount of sugar moieties and the flavonol glycoside hydoxycinnamic acid residue influenced the response to UV‐B. Monoacylated kaempferol tetraglucosides decreased in the investigated UV‐B range, whereas the monoacylated kaempferol diglucosides increased strongly with doses of 0.88 kJ m−2 day−1 UV‐BBE. The UV‐B‐induced increase in monoacylated kaempferol triglucosides was dependent on the acylation pattern. Furthermore, the hydroxycinnamic acid glycosides disinapoyl‐gentiobiose and sinapoyl‐feruloyl‐gentiobiose were enhanced in a dose‐dependent manner under UV‐B. While UV‐B radiation treatments often focus on flavonol aglycones or total flavonols, our investigations were extended to structurally different non‐acylated and acylated glycosides of quercetin and kaempferol.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
We evaluated the effects of phosphate (Pi-deficiency: 0.1 mM; Pi-sufficiency: 0.5 mM), phosphite (low-Phi: 0.1 mM; medium-Phi: 0.5 mM; and high-Phi: 2.5 mM), and two mean daily photosynthetically ...active radiations (lower PAR: 22.2 mol ⋅ m
⋅ d
; higher PAR: 29.7 mol ⋅ m
⋅ d
), as well as their interactions, on flavonoid, nitrate and glucosinolate (GL) concentrations and growth characteristics in hydroponically grown
cv. Mibuna Early and
cv. Red Giant. As expected, higher PAR increased dry matter and contrariwise decreased number of leaves but only in
. Total flavonoid and individual flavonoid compounds increased with the higher PAR value in
. Pi-sufficiency resulted in a lower quercetin concentration in both species, the isorhamnetin and total flavonoid concentrations in
, and the cyanidin concentration in
, in comparison to Pi-deficiency. Similarly, Pi-sufficient plants exhibited lower GL concentration, especially alkyl-GLs in
and alkenyl-GLs and an aryl-GL in
. Pi did not affect the nitrate concentration in either species, and nor did Phi influence the flavonoid concentrations in either species. In
, medium Phi (0.5 mM) increased the 1-methoxyindol-3-ylmethyl GL concentration by 28.3%, as compared to that observed at low Phi. In
, high Phi level increased the but-3-enyl-GL concentration by 18.9%, in comparison to values recorded at medium Phi.
plants exposed to higher PAR increased total flavonoids concentration. In both
species, higher PAR stimulated the alkyl-, alkenyl-, and indole-GLs. The interaction of lower PAR and increasing Phi significantly decreased flavonoid concentration in
, whereas increasing Phi at higher PAR increased such concentration in this species. The same combination reduced the concentration of 2-phenylethyl- and indol-3-ylmethyl-GL in
. The highest indol-3-ylmethyl-GL concentration was observed when Pi was deficient combined with medium Phi in
. Thus, PAR, Pi and Phi may modulate flavonoid, GL and nitrate concentrations in
species, which may be a useful tool to improve the nutraceutical quality of these leafy vegetables if properly managed.
Non-mycorrhizal fungal root endophytes can be found in all natural and cultivated ecosystems, but little is known about their impact on plant performance. The impact of three mitosporic dark septate ...endophytes (DSE48, DSE49 and
Leptodontidium orchidicola
) on tomato plant characteristics was studied. Their effects on root and shoot growth, their influence on fruit yield and fruit quality parameters and their ability to diminish the impact of the pathogen
Verticillium dahliae
were investigated. While shoot biomass of young plants was enhanced between 10% and 20% by the endophytes DSE48 and
L. orchidicola
in one of two experiments and by DSE49 in both experiments, vegetative growth parameters of 24-week-old plants were not affected except a reproducible increase of root diameter by the isolate DSE49. Concerning fruit yield and quality,
L. orchidicola
could double the biomass of tomatoes and increased glucose content by 17%, but this was dependent on date of harvest and on root colonisation density. Additionally, the endophytes DSE49 and
L. orchidicola
decreased the negative effect of
V. dahliae
on tomato, but only at a low dosage of the pathogen. This indicates that the three dark septate endophytes can have a significant impact on tomato characters, but that the effects are only obvious at early stages of vegetative and generative development and currently too inconsistent to recommend the application of these DSEs in horticultural practice.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
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