Grafted hazelnut: a sustainable agricultural practice to face summer stressful conditions

The European hazelnut is sensitive to water stress given its low capacity of stomatal control and its shallow root system, which spreads mainly in the top 0.4-0.5 m of soil depth. Climatic summer stress is detrimental to hazelnut yield, especially in the second half of July and the first half of August, when maximum oil accumulation in the kernel occurs. In this study, grafted and own-rooted young hazelnut plants of three high-quality cultivars were cultivated in central Italy to investigate possible differences in growth and production in the first eight years after planting. The grafting of C. avellana on C. colurna rootstock affects both vegetative development and nut production. Grafted plants of 'Tonda Romana' were most productive, showing a very positive effect on yield of this cultivar. In general, the higher vegetative and productive growth of adult grafted plants in the eighth year after planting shows the close affinity between the two species. A positive influence on yield for a longer period of time is expected in grafted hazelnut plants.