Synergistic Effects of Seaweed Extract Concentrations and Nitrogen Fertilization Levels on Growth and Yield of Wheat (Triticum aestivum L.) under Semi-Arid Conditions

Abstract

Optimizing nitrogen (N) fertilization is critical for wheat productivity, but challenges regarding nutrient use efficiency persist. Biostimulants, such as seaweed extract (SWE), offer a promising strategy to enhance crop performance. This study investigated the synergistic effects of SWE applied as a seed treatment (coating and priming) and varying N levels (0, 60, 120, and 180 kg N/ha) on the growth, yield, and physiological efficiency of wheat under semi-arid conditions. A split-plot field experiment was conducted where main plots were seed treatments and sub-plots were N levels. Results revealed a significant synergistic interaction (P < 0.05) between SWE application and N fertilization, enhancing final grain yield by up to 36% in the priming treatment compared to the control. This yield increase was primarily attributed to a significant improvement in key yield components, including the number of spikes per m², grains per spike, and thousand-kernel weight. We conclude that integrating SWE seed priming with optimized N fertilization (120–180 kg N/ha) is a potent strategy to enhance wheat productivity. This synergy appears to be driven by an improvement in the plant's Nitrogen Use Efficiency (NUE) and a favorable modulation of yield component trade-offs.