Effect of nitrogen sources, sulphur and boron levels on growth parameters of spring sunflower (Helianthus annuus L.).

摘要

A field experiment was conducted during spring seasons of 2005 and 2006 on a sandy loam soil at Karnal to study the effect of different nitrogen sources, sulphur and boron levels on the growth and physiological parameters of spring sunflower (Helianthus annuus L.). The effect of the two sources of nitrogen i. e. prilled urea (PU) and calcium ammonium nitrate (CAN) on various growth parameters of spring sunflower like leaf area index (LAI), crop growth rate (CGR), relative growth rate (RGR) and net assimilation ratio (NAR) remained statistically on par with each other. The application of sulphur and boron levels enhanced significantly all the growth parameters at their higher doses i. e. 50 kg sulphur/ha and 1.5 kg boron/ha, respectively although the response was higher at the initial doses of the each nutrient. Leaf area index increased substantially in between 50-75 days after sowing (DAS) and the highest values of leaf area index were recorded at 75 DAS, Application of various nutrients increased the dry matter accumulation of the crop plant and hence, other growth indices like CGR, RGR and NAR also increased significantly. The crop achieved the highest CGR in between 50-75 DAS, while the RGR and NAR values were recorded highest at the initial crop growth stages and declined thereafter.