BORON REQUIREMENTS FOR SUNFLOWER AND WHEAT

Plant species differ in their external and internal boron (B) requirements. The present research was conducted to establish the external and internal B requirements of sunflower (Helianthus annuus) and wheat (Triticum aestivum) at early vegetative growth. At low external B concentrations (≤ 0.13 μM), the growth of sunflower was severely depressed but by contrast the vegetative growth of wheat plants was free of B deficiency "symptoms. Sunflower plants achieved maximum growth at ≥ 1.2 μM B in solutions while wheat plants did so at ≥ 0.6 μM B. The critical B concentrations (mg kg−1 dry matter) in the youngest open leaf blades of sunflower and wheat plants were 19.7 and 1.2 at 10 days after transplanting (DAT), respectively.