Yield Determination in Major Small Grain Crops in Response to Nitrogen Fertilization

Small grain crops showed significant yield variation under different nitrogen fertilization treatments. Understanding factors influencing yield is crucial for optimizing productivity. This study assessed how nitrogen fertilization affects grain number, grain weight, and other yield components in triticale, wheat, six-rowed, and two-rowed barley across multiple locations and seasons. Key traits, including grain number per spike, spike number per unit area, and spike dry weight, were analyzed. Triticale cultivars achieved the highest average grain yield (GY) of 8709 kg ha-1, significantly outperforming wheat (7656 kg ha-1) and six-rowed barley (7676 kg ha-1), particularly under high nitrogen (100 kg N) fertilization, where triticale reached 9184 kg ha-1. Grain number per unit area (GN) was strongly positively correlated with GY across all crops, with the highest GN values observed in triticale (21,937) under 100 kg N fertilization. Fruiting efficiency (FE) and spike dry weight at anthesis (SDWa) showed crop-specific relationships with GN, with the strongest association between GN and SDWa observed in triticale, while FE exhibited the highest values in wheat (112.3) and the lowest in two-rowed barley (82). Triticale's superior yield was linked to greater grain number and spike dry weight, while wheat's high fruiting efficiency contributed to its performance. Despite its high spike number and spike dry weight, two-rowed barley had lower grain number per spike, limiting its yield. Nitrogen fertilization improved yield components across all crops, though trade-offs between grain weight and other traits were observed. These findings provide insights for breeders and agronomists in optimizing small grain production.