Long-term effects of straw incorporation on seedling emergence and seedling quality of winter wheat on the Huang-Huai-Hai Plain

Rapid emergence and high-quality seedlings are an important basis for achieving high yields and high-quality grains in wheat production. It is not clear how long-term straw incorporation affects the emergence and quality of wheat seedlings in lime concretion black soil. Based on a 12-year long-term fixed-site experimental field, a three-year field experiment with wheat-maize rotation was conducted on the Huang-Huai-Hai Plain of China in 2020-2023 to assess the effect of straw incorporation on seedling emergence and seedling quality of wheat. The treatments comprised no-tillage wheat straw mulching and conventional tillage with maize straw return (T1), conventional tillage with maize straw return only (T2), and without straw incorporation (CK). The results showed that seedling emergence time (SET) and seedling emergence peak day (SEPD) in the T1 and T2 treatments were delayed compared with those of the CK. The SET was delayed (by 0.3-2.0 d), and the seedling emergence speed (SES) decreased (by 5.88%-25.01%), whereas the differences in emergence rate were not significant. The T1 and T2 treatments led to increases in leaf area, number of tillers per plant, and number of secondary roots at the six-leaf stage compared with those of the CK. Principal component analysis revealed that the first principal component that affected wheat seedling growth was dominated by the leaf area index and the net assimilation rate, whereas the leaf weight ratio mainly contributed to the second principal component. Straw incorporation delayed the wheat SET and the SEPD, and reduced the SES in the seedling emergence stage, but increased the leaf area, number of tillers per plant, and number of secondary roots in the seedling establishment stage, thereby promoting the development of strong seedlings. This study provides theoretical support for the efficient utilization of straw resources and the improvement of the quality of wheat seedlings on the Huang-Huai-Hai Plain.