Foxtail millet is a characteristic miscellaneous grain crop with many benefits in current agricultural production and is crucial in the adjustment of the planting structure and the sustainable development of dry farming. However, the harmful effects of weeds have become a critical challenge, restricting the modern production of foxtail millet. The effect of penoxsulam on the chlorophyll metabolism pathway of foxtail millet and its physiological mechanism was studied. Spraying penoxsulam on foxtail millet leaves significantly reduced the content of chlorophyll synthesis precursors (5-aminolevulinic acid (ALA), Porphobilinogen (PBG), Protoporphyrin IX (ProtoIX), Mg-protoporphyrin IX (Mg-ProtoIX), and Protochlorophyllide (Pchlide)). Moreover, the activities of key synthetic enzymes (magnesium chelatase (MgCh) decreased compared to control, while the activities of degrading enzymes (pheophorbide a oxygenase (PAO) and pheophytinase activities (PPH) increased significantly. The study revealed the mechanism of penoxsulam inducing crop phytotoxicity by interfering with the dynamic balance of chlorophyll metabolism, which provided a theoretical basis for the scientific application of herbicides and the study of foxtail millet drug resistance.

Film mulching drip irrigation (FMDI) has shown strong yield-promoting effects in arid regions, but its regulatory effects on sorghum, under the unstable soil hydrothermal conditions of the agro-pastoral ecotone zone, remain poorly understood. Sorghum production in this region is frequently constrained by uneven precipitation, high evaporative demand, and limited thermal resources. This study aimed to clarify the role of film mulching drip irrigation in improving the soil hydrothermal environment and photosynthetic performance of sorghum, thereby enhancing yield in the agro-pastoral ecotone of northern China. Compared with bare land without film mulching or drip irrigation (CK), FMDI increased soil temperature by 0.33–2.25 °C and soil moisture by 13.87–18.10% at 0–20 cm depth, alleviating early growth constraints. The leaf chlorophyll b content and carotenoid content of sorghum increased by 55.61% and 55.27%, respectively, while the net photosynthetic rate (Pn) increased by 32.35% and photosystem II (PSII) photochemical efficiency also improved. Random forest (RF) and partial least squares structural equation modeling (PLS–SEM) analyses indicated that chlorophyll, gas exchange, and soil moisture were key drivers of yield formation. Ultimately, FMDI increased yield by 67.08%, indicating that FMDI is an effective irrigation–mulching strategy for improving sustainable sorghum production in the agro-pastoral ecotone zone.

Foxtail millet (Setaria italica L.) is an important crop in northern China’s arid and semi-arid regions. Frequent spring droughts and limited irrigation facilities often cause poor seed germination due to insufficient soil moisture, threatening food security. The irrigation-sowing technique, which creates a localized moist microenvironment around seeds, effectively addresses this issue. However, this technique has been poorly studied, and its effects on foxtail millet seed germination remain unclear. To address this, field experiments were conducted using a two-factor split-plot design, with three drought levels and five irrigation gradients. The results showed that irrigation-sowing increased soil moisture, promoted root–shoot growth coordination, and improved germination characteristics. Transcriptome analysis of seeds under moderate drought compared the optimal irrigation treatment (13.5 m³·hm⁻²) with the non-irrigated control (0 m³·hm⁻²), identifying 2169 differentially expressed genes. Seeds receiving irrigation exhibited higher transcript abundance in pathways related to carbohydrate metabolism, energy production, secondary metabolism, and hormone signaling. Physiological measurements further showed increased α/β-amylase activity, while starch, sucrose, and cellulose content decreased. Glycolytic enzyme activity was enhanced, and ATP content increased by 125%. Additionally, phenylpropanoid metabolism was promoted, and proanthocyanidin accumulation increased by 11.5%. Hormone analysis showed that the contents of IAA and GA increased as germination progressed by 29.09% and 54.70%, respectively, while ABA content decreased. Overall, irrigation-sowing serves as an upstream moisture signal that reshapes metabolic and hormonal states associated with improved germination performance.