Wheat response to interactive effects of boron and salinity

In semiarid regions with irrigated agriculture, excess boron (B) often occu rs in association with moderate to high salinity. However, little informati on is available on plant uptake of B under saline conditions. This greenhou se study was conducted to determine the interactive effects of salinity and varying concentrations of boron on growth, yield and ion relations of whea t (Triticum aestivum L., cv. 'Yecora Rojo'). Plants were grown in sand cult ures that were irrigated four times daily with modified Hoagland's nutrient solution. Sixteen treatments were initiated 4 d after planting in a comple tely randomized factorial experiment with 4 salinity levels (electrical con ductivities of the irrigation waters = 1.5, 4, 8, and 12 dS m(-1)) and 4 B concentrations (1, 5, 10, and 15 mg L-1). Salinizing salts were NaCl and Ca Cl2 (2:1 molar basis). Symptoms of B toxicity were closely correlated with B concentration in the leaves and injury became severe when leaf-B exceeded 400 mg kg(-1). At each concentration of external B, shoot-B was least unde r nonsaline conditions and increased significantly as salinity increased. S hoot-calcium (Ca) concentration increased with increasing salinity, but was unaffected by applied B. Shoot-magnesium (Mg), and potassium (-K) decrease d significantly in response to increases in salinity and substrate B. Salin ity and B as well as their combined effects significantly reduced wheat bio mass production, yield components, and final grain yield.