Impact of Layered Controlled Release Urea on Wheat Growth, Grain Yield and Dry Matter Accumulation in Northern Huanghuai Plain, China

Muhammad Akhtar^1*Wu Liuge¹Chen Jian¹Su Yuxiao²Zheng Yuntan²Lu Yulun²Zheng Shanchao²Deng Aixing¹Song Zhenwei¹Zheng Chengyan^1*Zhang Weijian^1*

• ¹Key Laboratory of Crop Physiology and Ecology, Institute of Crop Sciences (CAAS), Beijing, China
• ²Dongping County Agricultural Bureau, Dongping County, 271500, China, Dongping County, China

Nitrogen (N) fertilization plays a pivotal role in optimizing wheat growth and grain yield; however, suboptimal application strategies often result in inefficient nitrogen use, adversely affecting crop development and dry matter accumulation (DMA). Addressing the urgent need to enhance nitrogen use efficiency (NUE) in sustainable agricultural systems, this study evaluates the effects of layered applications of controlled-release urea (CRU) on wheat growth, grain yield, and DMA over a threeyear field trial conducted from 2021-2024. Five nitrogen treatments were compared: a control with zero N fertilizer (CK), one-time basal application of normal urea at a depth of 8-10 cm (NU 1layer), one-time basal application of controlled release urea (CRU) at a depth of 8-10 cm (CU 1layer), one-time basal application of normal urea at soil layers of 8-10 cm and 18-20 cm (NU 2layer), and one-time basal application of CRU at soil layers of 8-10 cm and 18-20 cm (CU 2-layer).The results over the three-year period indicated that the CU 2-layer treatment significantly enhanced CGR during critical growth phases, including jointing-anthesis (39.94% and 29.72%) and anthesis-maturity (10.78% and 16.05%), leading to increased wheat grain yields (9.29% and 14.73%) compared to CU 1-layer and NU 2-layer treatments, respectively. Furthermore, NUE and protein content were markedly higher in the CU 2-layer treatment. Analysis of yield components revealed that the increased grain yields associated with CU 2-layer application were primarily due to enhanced 500-grain weight and improved productive spike numbers per square meter, which resulted from a sustainable N supply. Additionally, findings from pre-anthesis and post-anthesis dry matter accumulation and translocation were essential for achieving high grain yields with CU 2-layer. The CU 2-layer treatment maintained higher SPAD values for the flag leaf and photosynthesis rates during the anthesis and early grain filling stages. Overall, the CU 2-layer application effectively optimized agronomic and physiological processes, contributing to improved wheat production and highlighting its potential for sustainable agricultural practices.