ABSTRACT
Topdressing different fertilizers causes differences in root traits, canopy photosynthesis and accumulation of photosynthetic products of wheat

Xiangqian Zhang1, 2, Zhu Zhao1, Yunqiu Shang1, Wei Li1, Yonggang Ding1, Shizhou Du1, Yuqiang Qiao1, and Huan Chen1*
 
Topdressing is crucial in wheat production, but it remains unclear whether topdressing different fertilizers with the same amount at jointing stage has a significant impact on wheat (Triticum aestivum L.), therefore, field experiments with four fertilizer treatments: Ordinary compound fertilizer (F1), wheat-specific compound fertilizer (F2), urea (F3) and no topdressing (CK) were conducted. Compared to F1 and F3, F2 significantly increased root length, root surface area, root volume, root diameter, root tips and root forks. Topdressing urea increased single leaf area of canopy when compared to F1. Compared to CK, F2 and F3 significantly enhanced chlorophyll content, while topdressing urea increased chlorophyll content when compared to F1. The effect of topdressing fertilizer on photosynthetic rate, stomatal conductance, and transpiration rate was consistently F2 > F3 > F1 > CK. The canopy photosynthetically active radiation in F2 was the highest, and in F3 was higher than in F1 (increased by 4.33% ~6.72%). Compared to topdressing urea, F1 and F2 improved grain filling rate, while topdressing was more beneficial for improving DM accumulation rate of stem and leaf; compared to topdressing F1, F2 improved accumulation rate of photosynthetic products. Topdressing compound fertilizer (F1 and F2 ) improved yield and harvest index when compared to topdressing urea, compared to F1, F2 increased yield and harvest index by 8.13% and 2.77% in 2025. This study demonstrates that topdressing the same weight of wheat-specific compound fertilizer improved root traits, canopy photosynthesis, yield and harvest index when compared to topdressing ordinary compound fertilizer and urea.
Key words: Canopy photosynthesis, harvest index, photosynthetic rate, root traits, topdressing, Triticum aestivum.
1Crops Research Institute, Anhui Academy of Agricultural Sciences, Hefei 230031, Anhui, China.
2Northwest A&F University (NWAFU), State Key Laboratory for Crop Stress Resistance and High-Efficiency Production, Yangling 712100, Shaanxi, China.
*Corresponding author (chenhuanyeah@163.com)