Vegetable Crops: Improvement of Tolerance to Adverse Chemical Soil Conditions by GraftingImproving Crop Resistance to Abiotic Stress

Owing to limited availability of arable land and the high market demand for vegetables around the world, Solanaceae and Cucurbitaceae crops are frequently cultivated under unfavorable soil conditions. These include salinity, alkalinity, heavy metals, and excessive amount of trace elements. Plants exposed to adverse chemical soil conditions exhibit various physiological and biochemical disorders leading to stunted growth and severe yield loss. One way to avoid or reduce losses in production caused by adverse soil chemical conditions in vegetables would be to graft them onto rootstocks capable of reducing the effect of external stresses on the shoot. Grafting is an integrative reciprocal process and, therefore, both scion and rootstock can influence tolerance of grafted plants to adverse soil chemical conditions. Grafted plants grown under adverse soil chemical conditions often exhibited greater growth and yield, higher photosynthesis, better nutritional status, and lower accumulation of Naþ and/or Cl, heavy metals, and excessive amount of trace elements in shoots than ungrafted or self-grafted plants. This chapter gives an overview of the recent literature on the response of grafted plants to adverse soil chemical conditions and the mechanisms of tolerance to adverse soil chemical conditions in grafted plants related to the morphological root characteristics and the physiological and biochemical processes. The chapter will conclude by identifying several prospects for future research aiming to improve the role of grafting in vegetable crops grown under abiotic stress conditions.