▶ Statistics of current global vegetable grafting. ▶ Advantages and disadvantages of using grafted vegetable transplants. ▶ Grafting methods and machines. ▶ Scion-rootstock interaction graft ...compatibility. ▶ Scion-rootstock interaction on quality and other measures.
Vegetable production with grafted seedlings was originated in Japan and Korea to avoid the serious crop loss caused by infection of soil-borne diseases aggravated by successive cropping. This practice is now rapidly spreading and expanding over the world. Vegetable grafting has been safely adapted for the production of organic as well as environmentally friendly produce and minimizes uptake of undesirable agrochemical residues. The number and size of commercial vegetable seedling producers has increased markedly reflecting the increase in farmers’ preferences for grafted seedlings of high-quality and better performance. In addition to the widely recognized advantages of disease tolerance and high crop yields, grafting technology is also highly effective in ameliorating crop losses caused by adverse environmental conditions such as low soil temperature and high soil salts, especially under protected cultivations where successive cropping or continuous farming is routinely practiced. Grafted seedlings are much favored in hydroponics farming systems where the chances of rapid spread of noxious diseases, once infected, is high. Active research has been focused to develop efficient rootstocks and handy grafting tools. In addition, researchers are eager to develop grafting machines or robots to reduce the higher price of grafted seedlings. The quality of grafted transplants is extremely important to maximize high-quality crop yield. Use of grafted vegetables has increased with the increased use of improved soil mix or substrate, farmer's preferences for better seedlings, efficient management of nursery systems, lower prices of grafted seedlings, and efficient nationwide delivery and/or transportation system. Improved grafting methods to cut down the labor cost for grafting and subsequent handling of plug-grown grafted transplants will contribute further to the increased use of grafted vegetables worldwide.
▶ Vegetables around the world (cucurbit and solanaceous plants) are grafted to alleviate unfavourable soil and environmental conditions. ▶ Unfavourable conditions stressed here are: (1) thermal ...stress (high and low temperature), (2) water stress (drought and flooding), and (3) stress by adverse soil chemical conditions (organic pollutants). ▶ Overview on use of grafting under practical horticultural conditions with abiotic stress. ▶ Discussion of agronomical, physiological, and biochemical mechanisms related to grafting used as tool to improve abiotic stress tolerance, as well as implications for rootstock breeding.
Due to limited availability of arable land and the high market demand for vegetables around the world, cucurbit (cucumber, melon, and watermelon) and solanaceous (eggplant, pepper and tomato) crops are frequently cultivated under unfavourable soil and environmental conditions. These include thermal stress, drought and flooding, and contamination by persistent organic pollutants. Plants exposed exhibit various physiological and pathological disorders leading to stunted growth and severe loss in fruit quality and yield. One way to avoid or reduce losses in production caused by adverse soil chemical and physical conditions and environmental stresses in vegetables would be to graft them onto rootstocks capable of reducing the effect of external stresses on the shoot. This review gives an actual overview how grafting can alleviate the adverse effects of environmental stresses on vegetable's crop performance at agronomical, physiological, and biochemical levels. Implications for the selection and breeding of stress-tolerant rootstocks are discussed.
▶ 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.
Grafting is an important integrated pest management strategy to manage soilborne pathogens and other pests of solanaceous and cucurbitaceous crops. Important diseases managed by grafting are caused ...by fungal pathogens such as
Verticillium,
Fusarium,
Pyrenochaeta and
Monosporascus; oomycete pathogens like
Phytophthora; bacterial pathogens, particularly
Ralstonia; root knot nematodes and several soil-borne virus pathogens. Rootstocks can include intraspecific selections that utilize specific major resistance genes and interspecific and intergeneric selections that exploit non-host resistance mechanisms or multigenic resistance. Rootstock selection has also been documented to impact foliar pests including pathogens, arthropods and viruses. Over-reliance on specific rootstocks in production systems has led to the emergence of new pathogens or shifts in the host specificity of the pathogen population, emphasizing the need for multi-tactic approaches to manage soilborne pathogens. One advantage and associated challenge of grafting is that rootstock selection for disease management is site specific depending on the presence, population structure and dynamics of the pathogen, as well as edaphic, environmental and anthropogenic factors. The use of grafting as an Integrated pest management tool to manage biotic stress will be most successful when carried out with increasing knowledge about the biology, diversity, and population dynamics of the pathogen or other pests and when complemented with sustainable farming system practices. This review highlights major uses of grafting to manage soilborne pathogens, provides some novel information on managing foliar or other soilborne pests (insects, mites, weeds) and offers discussion on future research and applications.
▶ Grafted plants for stress resistance, increase water and minerals uptake. ▶ A good graft union is fundamental for communication between scion and rootstock. ▶ The vascular union discontinuities at ...the graft union may lead to growth inhibition.
Due to the high market demand for off-season vegetables and the limited availability of arable land, vegetable seedlings are cultivated under changing environmental conditions which may induce stress. These conditions include cold, wet or dry environments, low or high radiation, etc. In addition, marginal water quality successive cropping can increase salinity and the incidence of pests and soil-borne diseases. Grafting is a horticultural technology, practiced for many years and in many parts of the world, in order to overcome many of these problems. The use of grafted plants in vegetable crop production is still rare compared to the use of grafting in tree crops. However, this technique is now being expanded greatly and the use of rootstocks can enhance plant yield through vigorous attainment of soil nutrients, avoidance of infection by soil pathogens and tolerance of low soil temperatures, salinity and wet-soil conditions.
This review focuses on the physiological and biochemical aspects of the rootstock–scion interaction for both Solanaceae and Cucurbitaceae species, considering the mechanisms involved in graft compatibility, nutrient and water uptake, assimilation and translocation of solutes and the influence of the rootstock on the main physiological processes of the scion.
▶ Transplants grafting is a mean for overcoming biotic and abiotic stress conditions. Formation of scion-rootstock interaction depends on adequate hormonal balance. ▶ Auxin, cytokinins, ABA and ...ethylene have important role in grafted plant development. ▶ Considerations of hormonal signaling may improve breeding of better rootstocks. ▶ Genetic engineering maybe applied for improvement of stress tolerance of rootstock.
The use of grafting technology in vegetable crops, represents a significant component of the vegetable industries throughout the world. Most, if not all rootstocks and successful grafting combinations are selected on the basis of empirical testing. Obviously, there is a need for better understanding of the endogenous factors which control rootstock scion communication and processes which lead to the beneficial effects of grafting. The huge progress in understanding signaling processes and the involvement of phyto-hormones in all aspects of plant development and crop productivity may be utilized for more profound probing into rootstock–scion communication in grafted plants. This review summarizes some of the research results in four aspects of hormonal signaling in rootstock–scion interactions: (1) formation of the rootstock–scion union; (2) rootstock–scion communication; (3) improvement of grafting interactions by hormonal manipulations; (4) hormonal influence on growth, flowering, and fruit quality.
▶ Salinity in soil or water is one of the major abiotic stresses that reduce plant growth and crop productivity worldwide. Most of the vegetable crops are glycophytes and, therefore, highly ...susceptible to soil salinity even at low electrical conductivity in the saturated soil extract. ▶ One environment-friendly technique for avoiding or reducing losses in production caused by salinity in high-yielding genotypes belonging to
Solanaceae and
Cucurbitaceae families would be to graft them onto rootstocks capable of ameliorating salt-induced damage to the shoot. ▶ The aim of this paper is to review the recent literature on the salinity response of grafted plants and the mechanisms of salt tolerance in grafted plants related to the morphological root characteristics and the physiological and biochemical processes. The review will conclude by identifying several prospects for future researches aiming to improve the role of grafting in vegetable crops grown under saline conditions.
Salinity is one of the major abiotic stresses that reduce plant growth and crop productivity in many vegetable production areas of the world. Grafting can represent an interesting tool to avoid or reduce yield losses caused by salinity stress in high-yielding genotypes belonging to
Solanaceae and
Cucurbitaceae families. Grafting is an integrative reciprocal process and, therefore, both scion and rootstock can influence salt tolerance of grafted plants. Grafted plants grown under saline conditions often exhibited better growth and yield, higher photosynthesis and leaf water content, greater root-to-shoot ratio, higher accumulation of compatible osmolytes, abscisic acid and polyamines in leaves, greater antioxidant capacity in leaves, and lower accumulation of Na
+ and/or Cl
− in shoots than ungrafted or self-grafted plants. This report gives an overview of the recent literature on the salinity response of grafted plants and the mechanisms of salt tolerance in grafted plants related to the morphological root characteristics and the physiological and biochemical processes. The review will conclude by identifying several prospects for future researches aiming to improve the role of grafting in vegetable crops grown under saline conditions.
▶ Some rootstocks of fruit vegetables modify the uptake of nutrients and heavy metals. ▶ Both morphological and physiological traits of rootstocks may modify uptake. ▶ Reduction of heavy metal uptake ...by rootstocks can protect both crops and consumers. ▶ Rootstocks raising nutrient uptake can improve yield and restrict nutrient leaching. ▶ Responses to heavy metal or nutrient stress depend on both scion and rootstock.
The response of grafted vegetables to stress conditions owing to the nutrient status, and the presence of heavy metals in the root environment may be different than that of self-rooted plants, depending mainly on the rootstock genotype. Several studies have indicated that some rootstocks are capable of restricting the uptake and/or the transport of heavy metals (e.g. Cd, Ni, Cr) and micronutrients (e.g. Cu, B and Mn) to the shoot, thereby mitigating the stress caused by excessive external concentrations of them. However, other mechanisms driven by the root system, such as detoxification of harmful elements or hormonal signals modifying gene expression in the scion, seem to be involved in the mitigation of stress caused by excessive external nutrient or heavy metal concentrations. On the other hand, the uptake and/or utilization efficiency of macronutrients (N, P, K, Ca and Mg) by plants may be enhanced by grafting onto some rootstocks. This is ascribed mainly to the root characteristics of these rootstocks, which are more vigorous than those of highly productive cultivated varieties. However, other mechanisms implicated in the efficiency of active nutrient absorption by the roots, as well as signals arising from the scion, which are mainly governed by sink demand, may also enhance nutrient uptake and utilization. The higher efficiency of some graft combinations of fruit vegetables to take up and utilize nutrients may mitigate yield losses owing to shortages of these nutrients in the root environment of plants and restrict nutrient losses due to leaching. Nevertheless, it is important to specifically test each grafting combination and not merely each rootstock for its ability to ameliorate nutrient or heavy metal stress because in many instances the responses depend on the rootstock/scion combination. This report gives an overview on the prospects and restrictions of grafting as a means to minimize the negative effects of heavy metals, excessive nutrient availability, nutrient deficiency, and alkalinity stress on vegetable crop performance taking into consideration agronomical, physiological and biochemical aspects.
The systemic model for floral induction, dubbed florigen, was conceived in photoperiod-sensitive plants but implies, in its ultimate form, a graft-transmissible signal that, although activated by ...different stimuli in different flowering systems, is common to all plants. We show that SFT (SINGLE-FLOWER TRUSS), the tomato ortholog of FLOWERING LOCUS T (FT), induces flowering in day-neutral tomato and tobacco plants and is encoded by SFT. sft tomato mutant plants are late-flowering, with altered architecture and flower morphology. SFT-dependent graft-transmissible signals complement all developmental defects in sft plants and substitute for long-day stimuli in Arabidopsis, short-day stimuli in Maryland Mammoth tobacco, and light-dose requirements in tomato uniflora mutant plants. The absence of donor SFT RNA from flowering receptor shoots and the localization of the protein in leaf nuclei implicate florigen-like messages in tomato as a downstream pathway triggered by cell-autonomous SFT RNA transcripts. Flowering in tomato is synonymous with termination of the shoot apical meristems, and systemic SFT messages attenuate the growth of apical meristems before and independent of floral production. Floral enhancement by systemic SFT signals is therefore one pleiotropic effect of FT orthologs.
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