[Synergistic improvement strategy of spring maize yield and water use efficiency under shallow buried drip irrigation...

To elucidate the mechanisms by which shallow buried drip irrigation enhances water saving and yield in semi-arid areas, and to develop an irrigation regime that synergistically improves spring maize yield and water use efficiency (WUE), we conducted a two-year completely randomized block experiment in the semi-arid area of western Liaoning from 2023 to 2024. There were three irrigation frequencies (F₁-F₃, irrigation every 7, 14, and 21 days, respectively) and four irrigation quotas (I₁-I₄, corresponding to 60%, 80%, 100%, and 120% of crop evapotranspiration (ET_c), respectively). We investigated the effects of these two factors on maize root-breeding sap flow, dry matter accumulation, net photosynthetic rate (P_n), yield, and WUE. The results showed that under the same irrigation quota, compared with F₁ and F₃, the F₂ treatment significantly increased the root-breeding sap flow and dry matter accumulation during the seedling stage by 16.3%-24.4% and 18.7%-27.4%, respectively, leading to a 4.3%-8.0% increase in WUE, and exhibited a higher P_n at 8:00 and 16:00 during the tasseling stage. Under the same irrigation frequency, compared with I₁, I₃, and I₄, the I₂ treatment increased root-breeding sap flow and dry matter accumulation across all growth stages (except during the jointing stage) by 11.6%-43.3% and 6.5%-21.5%, respectively, resulting in a 4.0%-18.0% increase in yield; it also showed a higher P_n at 8:00, 14:00, and 16:00. Considering the interactive effects of those two factors, the F₂I₂ treatment significantly promoted root-breeding sap flow and dry matter accumulation during the milky stage. Path analysis showed that root sap flow and dry matter accumulation during the milky stage, and P_n at 8:00 and 16:00 during the tasseling stage, were the key factors driving the synergistic improvement in maize yield and WUE. In summary, an irrigation frequency of once every 14 days combined with an irrigation quota of 80% ET_c is the optimal irrigation strategy for spring maize under shallow buried drip irrigation in semi-arid areas.