Maize yield in a strip-till system can be increased by increasing nitrogen accumulation, plant growth, and ear development around silking stage in Northeast China

Strip-till (ST), including straw mulching in the inter-row and localized fertilization in the intra-row, is a conservation tillage system for improving soil quality and crop growth. However, the yield advantage of maize under ST compared to conventional tillage (CT) remains unstable, and the strategies to increase maize yield under ST are unclear. This study aims to understand the physiological mechanism underlining maize yield formation under ST by comparing two maize cultivars, DKM753 and DK517, with contrasting yield performance in ST versus CT systems. Compared to CT, ST resulted in a 4.5% yield increase for DKM753 but a 5.6% decrease for DK517. These yield differences were primarily attributed to variations in grain number per ear (GN). During the rapid growth stage (V14-R3), i.e., two weeks before and after silking, DKM753 showed a 6.7% increase in maximum growth rate (Vmax) and a 6.3% increase in average growth rate (V) under ST, whereas DK517 exhibited decline of 8.5% in Vmax and 12.3% in V. Significant positive correlations are observed between Vmax and V with GN under ST (R2 = 0.79 and R2 = 0.90, respectively). Enhanced dry matter accumulation in DKM753 under ST was attributed to increased leaf expansion rates, contributing to a larger photosynthate source. The straw mulching and localized nitrogen fertilization increased root-zone nitrogen availability at silking in ST compared to CT. DKM753 had a greater root system which made better use of the soil N and lead to an increased leaf nitrogen accumulation by 14.9% under ST. It is concluded that maize yield under the strip-till system is determined by grain number per ear, which can be increased by increasing nitrogen accumulation, plant growth, and ear development around silking stage. A sound root system can efficiently utilize soil nitrogen resources under the strip-till system, increasing plant nitrogen accumulation and thereby promoting plant growth. (c) 2024 Crop Science Society of China and Institute of Crop Science, CAAS. Production and hosting by Elsevier B.V. on behalf of KeAi Communications Co., Ltd. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).