Influence of nitrogen fertilization on winter wheat physiological parameters and productivity

Abstract

The experiment was carried out in the Experimental Station of Aleksandras Stulginskis University at 2009–2010 on winter wheat (Triticum aestivum L.) varieties ‘Ada’ and ‘Tauras DS’. The rates of fertilizers during wheat vegetation were as follows: N90, N135 and N150. In sowing time both varieties were fertilized with complex fertilizers N30P80K120. In tillering stage winter wheat was fertilized with calcium ammonium nitrate N60. In stem elongation stage plants were fertilized through leaves with urea solution N30 and N40. In milky ripeness stage plants were fertilized through leaves with urea solution N15 and N30. The photosynthetic pigment and soluble sugar contents were measured at stem elongation stage (BBCH 34-36), flowering stage (BBCH 71-73) and milky ripeness stage (BBCH 71-73). The obtained results show that photosynthetic pigment and carbohydrate contents are suitable indicators of the activity of the winter wheat photosynthetic system. Properly selected nitrogen rate and additional fertilization time may suspend the senescence processes. Nitrogen remobilization and photosynthetic activity during growing season are strongly genotype dependent. An additional nitrogen fertilization delays degradation of photosynthetic pigments, prolongs the period of active photosynthesis and ensures a more effective assimilate transport into seed and thus determines yield. Nitrogen significantly influenced winter wheat productivity; however, the optimal fertilization rate depended on genotype.