The review, led by Khushal B. Muradi and colleagues at Kerala Agricultural University in India, arrives at a moment of mounting pressure on global vegetable production. In 2022, worldwide vegetable output surpassed 1.17 billion tons, with Asia contributing more than 70 percent of the total, led by China at 52.1 percent and India at 12.4 percent. Yet projections indicate that global deficits in fruit and vegetable availability will worsen by 2050 unless production systems become dramatically more efficient and resilient. Meanwhile, climate change has intensified the frequency and severity of abiotic stresses such as drought, heat, cold, salinity and flooding, while soil-borne pathogens including Fusarium species, Verticillium dahliae, bacterial wilt caused by Ralstonia solanacearum and root-knot nematodes of the genus Meloidogyne continue to inflict substantial losses by attacking the very tissues, roots and vascular systems, that anchor plant productivity.

Grafting addresses these threats through a deceptively simple intervention. A high-yielding scion, the aerial portion of a preferred cultivar, is united with a rootstock selected for its vigorous root architecture, its resistance to soil pathogens, or its capacity to regulate water and ion uptake. The resulting plant combines the fruit quality of the scion with the underground resilience of the rootstock. Because the technique requires no genetic modification and no chemical fumigants, it occupies a distinctive niche among sustainable intensification strategies. The review documents commercial adoption across more than thirty countries spanning Asia, Europe, North America, Africa and Central Asia, from greenhouse-intensive systems in Spain and the Netherlands to smallholder operations in Bangladesh, Tanzania and Nepal.

The technical repertoire of grafting has expanded considerably from its manual origins. Splice grafting, the dominant method for solanaceous crops such as tomato, pepper and eggplant, involves cutting scion and rootstock at oblique angles and aligning them for cambial contact. The review notes that wider cutting angles between 50 and 70 degrees can improve survival in tomato even when stem diameters vary, a finding with direct implications for robotic systems. Cleft grafting, in which the rootstock stem is split vertically to receive a wedge-shaped scion, offers superior mechanical strength and tolerates diameter mismatch, while tongue grafting creates interlocking cuts that produce exceptionally strong unions. A variant known as double-root grafting preserves the root systems of both partners, and in tomato trials under saline water irrigation it increased yield by 7.9 to 27.4 percent compared with self-rooted plants while improving water-use efficiency.

For cucurbits such as watermelon and cucumber, hole-insertion grafting, in which a tapered scion is punched into a hole in the rootstock hypocotyl, has proven particularly amenable to automation. Tube grafting, which uses a small supporting sleeve to hold the union in place, remains a nursery staple for slender-stemmed crops. Machine and robotic grafting systems are now approaching commercial maturity: a plug-tray grafting machine evaluated in watermelon achieved approximately 774 plants per hour, 1.65 to 2.55 times faster than manual grafting, with comparable survival rates. The authors caution, however, that mechanical errors in cutting and alignment still limit consistency and that further precision improvements are needed before automation can be deployed universally.

Whatever the method, success hinges on the biology of the graft union itself, and the review provides a detailed account of what happens at the cellular level in the days and weeks following fusion. Wound-induced division of parenchyma cells at the cut surfaces produces a callus bridge between the partners. A new vascular cambium then differentiates into secondary xylem and phloem, restoring the plumbing through which water, nutrients and signaling molecules flow. The timing is remarkably consistent across species. In tomato, callus proliferation begins three to five days after grafting and vascular bridges form by seven to fourteen days. In cucumber grafted onto bottle gourd, vascular bridging appears as early as day five. In watermelon, callus formation begins around day eleven with complete vascular bundles by day twenty-five. Temperature matters too: oriental melon grafted onto pumpkin forms callus markedly faster at 28 degrees Celsius than at 18 degrees.

Hormonal orchestration underlies every stage of this process. Auxin acts as the central regulator of vascular differentiation, while cytokinin and ethylene drive early cell proliferation and gibberellins contribute to vascular expansion. Abscisic acid and jasmonates modulate stress responses during establishment, and reactive oxygen species, particularly hydrogen peroxide, function as signals governing lignin deposition and vascular strand formation at the interface. Recent molecular work has added further layers of complexity: the enzyme beta-1,4-glucanase, encoded by a gene designated GH9B3, contributes to cell adhesion and vascular continuity in cucurbits, and sugar availability along with TOR-related energy signaling influences healing efficiency in cucumber-pumpkin combinations. The review emphasizes that mobile signals such as RNAs, proteins and epigenetic modifications, which have been documented in broader plant systems, still require direct validation in vegetable crops.

Equally critical is what growers do after the blade falls. The healing phase, typically lasting five to ten days, demands high relative humidity of 85 to 95 percent, moderate temperatures of 22 to 28 degrees Celsius and reduced light intensity to suppress transpiration while callus forms. Seedlings are then gradually hardened toward ambient conditions as vascular reconnection is completed. Nursery management, from sterilized growing media and mist irrigation to rigorous sanitation, determines whether these delicate unions survive, and the review warns that high seedling densities, repeated wounding and inadequate tool sterilization can facilitate transmission of serious pathogens including Clavibacter michiganensis and Pepino mosaic virus.

When compatibility, technique and nursery care align, the agronomic dividends can be substantial. Eggplant grafting has increased yields by up to 36.9 percent, and tomato yields under stress conditions have improved by approximately 35 to 47 percent, figures the review links directly to United Nations Sustainable Development Goal targets on food security. Rootstock-mediated resistance relies on both physical barriers and induced systemic defenses, activating salicylic acid and jasmonic acid signaling pathways. On the abiotic front, grafted cucumber shows reduced lipid peroxidation under drought and salinity, watermelon grafted onto pumpkin or fig leaf gourd gains cold tolerance through melatonin and jasmonate signaling, and cucumber grafting reduces cadmium accumulation by compartmentalizing the metal in cell walls. Novel dual-harvest combinations such as Pomato, tomato on potato, and Brimato, eggplant on tomato, hint at further creative applications.

The review is nonetheless candid about the technique’s limitations. Grafted seedlings cost substantially more than conventional transplants owing to premium rootstock seed, labor-intensive grafting and resource-hungry healing phases, making adoption economically difficult for smallholders who cannot recover costs within a single cycle. The commercial rootstock base is narrow, raising vulnerability to emerging pathogen races, and incompatibility, sometimes manifesting as immune-like hypersensitive responses between distant partners such as tomato and pepper, can remain hidden until plants fail in the field. Fruit quality outcomes are also mixed: while some combinations improve soluble solids and vitamin C, others reduce sugars, organic acids or lycopene content. The authors argue that future progress will depend on deeper understanding of epigenetic rootstock-scion communication, rootstock breeding for broader adaptation, affordable nursery technologies, and grafting robots equipped with machine vision and artificial intelligence. As a context-dependent but powerful strategy, they conclude, grafting is positioned to become a cornerstone of climate-resilient vegetable agriculture.