A Study on the possibilities of increase of nitrogen use efficiency in wreat under the Cukurova condition

Nitrogen Use Efficiency (NUE) of wheat (Triticum aestivum L.) can be improved by split application of nitrogen (N) and plant growth regulators (PGR). The effect of split N-application and PGR was investigated in a field study conducted during 1998/99 growing season at the experimental area of Çukurova Agricultural Research Institute/ Adana. A total nitrogen supply of 210 N kg ha-1 was splitted in different doses (NA:80, 80, 50; NB:30, 90, 90; Nc:30, 110, 70; ND:30, 70, 110 kg N ha-1) at seeding, tillering and stem elongation, respectively. As PGR, Chlormequat- Chlorid-Ethephon (CCE) with two doses (R0: no CCE, Rj: 3500 cc ha-1 R2: 5500 cc ha-1) was applied at the beginning of stem elongation. With the exception of grain protein content, no remarkable differences were found between N-treatments for investigated traits. However significant PGR effect was observed for most of the investigated traits, except grain protein content. PGR increased grain yield and therefore NUE by 17% and 20%, respectively. The increase in grain yield by PGR is due to increased ear grain yield, which is associated with increased grain number per ear, which was probably resulted in distribution of dry. matter in favor of the developing ear during the elongation of the lower parts of the stem. Key words: Wheat, split N-application, plant growth regulator, nitrogen use efficiency.