Effect of boron and farmyard manure application on growth, yields, and boron nutrition of sunflower

To examine the role of organic manure on boron (B) availability, a greenhou se experiment was conducted to study the effect of B and farmyard manure (F YM) levels on growth, yields, and B accumulation of sunflower (Helianthus a nnuus L.). Application of B or FYM individually increased the plant height, capitulum diameter, dry matter yields of seed and stalk and their B concen tration and accumulation. The interaction of B and FYM levels had a signifi cant influence only on B concentration of stalk and total B accumulation of sunflower. In the absence of B application, use of highest level of FYM (1 0 g kg(-1) soil) significantly increased B concentration of stalk and total B accumulation by the crop while with B application, use of FYM at lower r ates was effective. Application of B or FYM, especially at higher rates of the latter (5 and 10 g FYM kg(-1) soil) increased the content of hot-water soluble soil B in the soil after crop harvest. The interaction of B and FYM levels had no significant effect on the content of hot-water soluble soil B. Application of FYM increased apparent availability of native and added B from soil to sunflower crops.