The key to high-yielding peanut cultivation is the optimization of agricultural production practices. Regulating single-seed precise sowing (SSPS) density and paclobutrazol (P_bz) application concentration are effective practices that increase peanut yield by improving plant architecture, lodging resistance, and photosynthetic characteristics. Therefore, we conducted a two-factor field optimization experiment for the sowing density (D₁: 1.95 × 10⁵ plants ha⁻¹, D₂: 2.40 × 10⁵ plants ha⁻¹, D₃: 2.85 × 10⁵ plants ha⁻¹, and D₄: 3.30 × 10⁵ plants ha⁻¹) and P_bz application concentration (P₀: 0 mg L⁻¹ and P₁: 100 mg L⁻¹). The objective was to optimize agricultural production practices and provide a theoretical basis for high-yielding peanut cultivation by evaluating the effects of sowing density and P_bz application on plant architecture, lodging resistance, photosynthetic characteristics, and yield. The results showed that at the same P_bz application concentration, increasing sowing density increased lodging percentage and reduced leaf photosynthetic capacity. At the same sowing density, P_bz application reduced lodging percentage by decreasing plant height (PH), improving lignin biosynthesis-related enzyme activities, and enhancing stem puncture strength (SPS) and breaking strength (SBS). The paclobutrazol-induced alterations in plant architecture and lodging resistance improved light transmission at the middle and bottom leaf strata, resulting in the increase in relative chlorophyll content and net photosynthetic rate (P_n) of leaves. Furthermore, D₃P₁ treatment had the highest peanut yield among all treatments. In summary, the production strategy combining the sowing density of 2.85 × 10⁵ plants ha⁻¹ with the application of 100 mg L⁻¹ P_bz was found to be the optimal agricultural production practice for giving full play to production potential and achieving higher peanut yield.

Agronomically optimizing the timing and rates of nitrogen (N) fertilizer application can increase crop yield and decrease N loss to the environment. Wheat (Triticum aestivum L.)–peanut (Arachis hypogaea L.) relay intercropping systems are a mainstay of economic and food security in China. We performed a field experiment to investigate the effects of N fertilizer on N recovery efficiency, crop yield, and N loss rate in wheat–peanut relay intercropping systems in the Huang-Huai-Hai Plain, China during 2015–2017. The N was applied on the day before sowing, the jointing stage (G30) or the booting stage (G40) of winter wheat, and the anthesis stage (R1) of peanut in the following percentage splits: 50-50-0-0 (N1), 35-35-0-30 (N2), and 35-0-35-30 (N3), using 300 kg N ha⁻¹, with 0 kg N ha⁻¹ (N0) as control. ¹⁵N-labeled (20.14 atom %) urea was used to trace the fate of N in microplots. The yields of wheat and peanut increased by 12.4% and 15.4% under the N2 and N3 treatments, relative to those under the N1 treatment. The ¹⁵N recovery efficiencies (¹⁵NRE) were 64.9% and 58.1% for treatments N2 and N3, significantly greater than that for the N1 treatment (45.3%). The potential N loss rates for the treatments N2 and N3 were 23.7% and 7.0%, significantly lower than that for treatment N1 (30.1%). Withholding N supply until the booting stage (N3) did not reduce the wheat grain yield; however, it increased the N content derived from ¹⁵N-labeled urea in peanuts, promoted the distribution of ¹⁵N to pods, and ultimately increased pod yields in comparison with those obtained by topdressing N at jointing stage (N2). In comparison with N2, the N uptake and N recovery efficiency (NRE) of N3 was increased by 12.0% and 24.1%, respectively, while the apparent N loss decreased by 16.7%. In conclusion, applying N fertilizer with three splits and delaying topdressing fertilization until G40 of winter wheat increased total grain yields and NRE and reduced N loss. This practice could be an environment-friendly N management strategy for wheat–peanut relay intercropping systems in China.