(2005) suggested that the Cucurbita rootstock excludes some B and that this, in turn, decreases the B concentration in the grafted plants. B can be absorbed by the root cell symplast or loaded into the xylem by means of two main transport mechanisms: passive diffusion through the lipid bilayer, and passage through proteinaceous channels in the cell membrane (Dannel et al., 2002 Dordas et al., 2000). Grafted and non-grafted melon plants were irrigated with fresh water (EC = 1.8 dS/m), saline water (EC = 4.6 dS/m) or secondary effluent enriched with B at up to 10 mg/L (Edelstein et al., 2005, 2007). To determine the mechanisms responsible for the lower microelement concentrations in the fruits of the grafted plants, detailed experiments were conducted in the greenhouse. In general, the concentrations of B, Zn, Sr, Mn, Cu, Ti, Cr, Ni, and Cd were significantly lower in the fruits of grafted vs. The concentrations of various microelements in the fruits of the grafted and non-grafted melon plants are presented in Fig. The field plots were irrigated with secondary effluent for 4 years, and melon (non-grafted plant) and (grafted plant) were grown in these plots. The effects of plant grafting on microelement concentrations in the fruit of melon plants under field conditions were studied in field plots with clay soil. (2005) suggested that grafted plants (Fig. This is particularly true for, which are often regarded as a safe and nutritious food source. Absorption of these elements by the plants could affect their growth and yield, and increase the possibility of contaminants entering the food supply chain.Ĭonsumers are becoming increasingly concerned about because of the possible adverse effects on environmental quality and human health. Relatively high concentrations of Na+, Cl- and microelements in the soil solution could be toxic to plants and to humans. Long-term use of these types of water for irrigation could increase the accumulation and concentrations of microelements and saline elements (Na, Ca, Mg, and Cl) in the soil (Ben-Hur, 2004 Feigin et al., 1991). Similarly in effluents, the EC and pH values, and the concentrations of microelements such as heavy metals and B, and of nutrients and dissolved organic matter are, in general, significantly higher than in fresh water. The electrical conductivity (EC) of saline water is much higher than that of fresh water, and it may exceed 5 dS/m when the dominant ions are Na and Cl. Moreover, the pressure to avoid disposal of nutrient-rich effluents into water bodies has contributed to the rapid expansion of effluent reuse for irrigation (Halliwell et al., 2001). To satisfy the demand for food and to combat desertification in this region, marginal water sources, such as treated domestic sewage (effluent) and saline water, are being increasingly used for irrigation (Ben-Hur, 2004). Grafting for the use of root systems as biological filters to prevent contaminants’ penetration into vegetable plantsĪ major part of the Mediterranean region is characterized by water scarcity, with long dry summers and short wet winters.
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