Peng Wang

As a drought-resistant and water-saving rice (Oryza sativa L.), the Shanlan upland rice germplasm can provide solutions to the food security problems caused by frequent water shortages. In most nitrogen (N) fertilizer management strategies targeting maximum rice yields, lodging (both root and stem) is often ignored. Hence, this study aimed to determine an optimal N fertilizer management strategy that balanced the trade-off between yield and lodging in Shanlan upland rice. Our research employed the “safety factor” (SF) technique to explore the root-lodging resistance (represented by SFr) and stem-lodging resistance (represented by SFs) of Shanlan upland rice using three N fertilizer methods, including conventional N fertilization (CNF), split–postponed N fertilization (SPNF), and controlled-release N fertilizer (CRNF), and three N application rates (80, 120, and 160 kg N ha⁻¹) for two consecutive years. Compared with CNF, the SFr improved by 14.9% for CRNF and 9.1% for SPNF. Likewise, the SFs increased by 22.7% for CRNF and 15.3% for SPNF. Moreover, Shanlan upland rice was found to be more prone to the risk of root lodging than stem lodging. At the same time, the grain yield and net benefit improved by 14.6% and 18.1% for CRNF, respectively, compared with CNF. Hence, employing the CRNF technique was more effective at reducing the lodging risk of Shanlan upland rice. Moreover, increasing the N application rate beyond 120 kg N ha⁻¹ did not significantly increase the grain yield for CRNF but the lodging resistance and net benefit were reduced. In conclusion, with an N application rate of 120 kg N ha⁻¹ for CRNF, Shanlan upland rice could achieve a relatively stable and high net income and can be recommended to growers for adoption.

Understanding the agronomic interventions that ensure higher crop yields and minimize their chances of failure is critical for meeting global nutritional demands. Rice is a staple food crop that is prone to lodging risk, particularly when higher yields are desired. The potential role of a combined application of Zinc (Zn) and Silicon (Si) in determining the grain yield and lodging resistance has been rarely investigated under field conditions. Thus, field trials were carried out to evaluate the grain yield and lodging resistance of rice at two different locations i.e., Qionghai and Wuzhishan, under three levels of Zn (0, 40, and 80 kg ha⁻¹) and Si (0, 120, and 240 kg ha⁻¹). The results showed that Zn application at the rates of 40 and 80 kg ha⁻¹ increased rice yield by 9% and 5% at Qionghai, and by 5% and 6% at Wuzhishan, respectively. The improved grain yield due to Zn application could be attributed to the increased panicles m⁻², splikelets m⁻², and aboveground biomass. Meanwhile, Zn failed to show any remarkable impact on stem and root lodging susceptibility. Conversely, no significant influence of applying Si on grain yield was observed, while its application at the rates of 120 and 240 kg Si ha⁻¹ enhanced the stem and root lodging resistance (denoted by their respective safety factors, for stem (SF_s) and for root (SF_r) by 32% and 22% at Qionghai, and by 11% and 34% at Wuzhishan, respectively, compared to zero Si application. The improved lodging resistance in terms of SF_s and SF_r could be ascribed to the increased stem bending strength and anchorage strength, while self-weight moment of whole plant decreased. In summary, a beneficial role of Si in lodging resistance and Zn in yield enhancement were evidenced in the present study across the two sites. It can be concluded that by combining 40 kg Zn ha⁻¹ with 120 kg Si ha⁻¹, both grain yield and lodging resistance could be simultaneously improved in rice crops.