Wheat yield as influenced by urea applied with nitrification inhibitor and gibberellic acid
<p>Among the essential plant nutrients, nitrogen (N) is the most needed. Farmer apply N fertilizer, predominantly urea to meet crop N demand. However, a greater proportion of the applied urea-N is not being used by plants and lost to the atmosphere as ammonia or greenhouse gases. Therefore, it is necessary to enhance N use efficiency (NUE) of applied urea by minimizing such losses, which has environmental and economic implications. Nitrification inhibitor, such as nitrapyrin (NP), has the most potential to minimise N losses and enhance crop yield. Similarly, plant hormones, such as GA3, has the potential to reduce abiotic stress and improve plant growth and yield. &#160;&#160;<br>A field experiment was established on an arable site at University of Tehran, Karaj to determine the effect of urea applied with Nitrapyrin and GA3 on wheat yield in 2018-2019. Karaj has a Mediterranean climate with annual precipitation of 265 mm. A randomized complete block design in five replications was used in this study. Treatments were: T1 (control treatment - without urea), T2 (farmers practice - 138 kg N/ha), and T3 (best practice - 138 kg N/ha+NP+GA3). Urea was applied in three split applications (46 kg N/ha) at growth stage (GS 21) or tillering, (GS 32) or stem elongation, and (GS 40) or booting. GA3 in T3 treatment, was applied only at stem elongation stage.&#160;<br>The crop yield data showed that, urea applied with NP and GA3 had a significant (p &#8804; 0.01) effect on grain yield, biological yield, number of grains, 1000-grain weight and % Harvest Index (%HI) compared to other treatments. Urea applied with NP and GA3 increased grain yield (10.30 t ha-1) by 13.9% and 46.1% compared to farmer practices (9.04 t ha-1) and control treatment (7.05 t ha-1). These results suggest that co-application of urea with NP and GA3 has the potential to enhance wheat yield in semi-arid area of Iran.</p>