Highly active biostimulant Paecilomyces variotii extracts reduced controlled-release urea application while maintaining rice yield

BACKGROUND The high cost of controlled-release urea (CRU) has prompted this study to explore whether the amount of CRU can be reduced by adding biostimulants while maintaining or increasing rice yield. A 2 year field experiment was conducted with CRU at three levels (60%, 80%, and 100% of the recommended nitrogen (N) fertilizer) and a novel biostimulant Paecilomyces variotii extract (ZNC), to investigate their synergistic effects on yield, nitrogen use efficiency (NUE), and net profitability of rice. RESULTS Controlled-release urea achieved a significantly higher gain yield and NUE than conventional urea with the same N level, which could be attributed to its N supply. Even if the N level of CRU was reduced by 40%, both rice yield and net profit were still significantly higher than for the full amount of urea. Paecilomyces variotii extract sprayed on the surface of CRU at a dose of only 87.5 mL ha(-1) exhibited ultra-high effectiveness by increasing the panicles, the N accumulation, and the rice yield. Controlled-release urea enriched by ZNC achieved significantly higher gain yield than CRU alone, increasing the yield by 9.2% and 8.7%, respectively, in 2 years under the full recommended N rate. The combination of 80% CRU and ZNC showed no significant difference in rice yield from treatment with 100% CRU, indicating that the rate of CRU could be reduced by ZNC. The application of ZNC further increased NUE, N partial factor productivity, and net profit. CONCLUSION The CRU and ZNC combination provided a feasible approach for reducing N input while maintaining rice yield and agricultural sustainability. (c) 2021 Society of Chemical Industry.

Automated summary

This study found that the combination of controlled-release urea and biostimulant ZNC can reduce nitrogen input while maintaining or increasing rice yield and net profit. The synergistic effects of CRU and ZNC were most effective in significantly increasing rice yield and nitrogen use efficiency.