Stock scion relationship: A review from the ornamental plant perspective

Grafting is a widely used horticultural technique that enhance plant performance, especially in ornamental species with poor rooting ability. It involves joining a desirable scion with a compatible and vigorous rootstock, as seen in crops such as rose, bougainvillea, jasmine, hibiscus and cactus. This method is primarily adopted to combine desirable traits such as growth vigour, disease resistance, adaptability stress tolerance and aesthetic appeal. Grafting scions from mature, flowering plants onto juvenile rootstocks retains their maturity, allowing earlier flowering. Inter-specific grafting merges traits for ornamental breeding and hybrids. Although practiced for centuries, the precise physiological and molecular interactions between the rootstock and scion remained unclear until recent advances in plant science. Modern research, particularly through next-generation sequencing, has confirmed that genetic and molecular exchanges occur across the graft union. These interactions significantly influence the scion’s physiology, including nutrient uptake, growth patterns, stress resistance and flowering behaviour. As graft incompatibility can result from hormonal imbalance, phenolic accumulation, or poor vascular connection between scion and rootstock. It highlights recent findings on morphological, physio-chemical and molecular mechanisms involved in rootstock-scion communication. Understanding these complex interactions enables the development of superior grafted ornamentals with enhanced aesthetic qualities, resilience and extended blooming periods. This integrated perspective is crucial for improving the efficiency and creativity in ornamental plant production and providing a foundation for future research into grafting-induced trait enhancement.