Özet:

The objective of this research were to determine the effects of foliar fertilization (20% N: 20% P2O5: 20% K2O) at different growth stages on yield and nutrient contents of spring wheat (Triticum aestivum L.) and to reveal proper application time and frequency in Kostanai-Kazakhstan conditions. The field experiment was conducted according to randomized plot design with four replications with a seeding rate of 500 seed per m2 on the plots having a size of 5.0 m length and 4.0 m width. Foliar applications of the fertilizer at 1%rate were done at tillering (T), stem elongation (S), heading (H) stages of wheat and the combinations of these stages (T+S, T+H, S+H and T+S+H). Wheat yield values varied between the lowest 1.32 t/ha in the control and the highest 2.14 t/ha in the foliar fertilization done at tillering and steam elongation stages (T+S). According to control treatment, increases in grain yields by the foliar fertilization done at the different growth stages were determined as follows; T+S (61.7%) > T+H (47.4%) > T+S+H (41.8%) > S+H (41.6%) > T (38.5%) > S (19.1%) > H (16.6%). There was no significant difference among the macronutrient contents in grain obtained by the foliar fertilization at the different growth stages. N, P and K contents in the grain were close the values cited in the literatures. Ca and Mg contents deficiency in grain were determined due to the acidic soil pH condition of Kostanai-Kazakhstan. Nitrogen, P, K and Ca uptakes by grain, except Mg, generally increased with the all application of foliar fertilization. When the foliar fertilization was done at T+S stages, the highest macro nutrient uptakes by grain in wheat were generally obtained. This research indicated that the first foliar fertilization should be applied at the tillering stage and the best foliar fertilization management for high grain yield and nutrient uptake should be done two times at the combination of tillering and stem elongation stages. 

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