[Effects of straw returning on maize yield and root system spatial distribution under water stress]

To investigate the effects of straw amendments on the yield and root spatial distribution of maize under water stress, an experiment with rainproof shelter was conducted in the field experimental station of Shenyang Agricultural University in 2016 and 2017. The drip irrigation facilities were used to perform water stress treatments. Straw burying (T₁) and straw incorporation (T₂) as two approaches of straw amendments were conducted combined with three depths of 15 cm (D₁), 30 cm (D₂), and 45 cm (D₃) for straw returning, ploughing tillage at above three depths without straw presence as control in this study. During seedling and silking stages of maize, drought and water logging stresses were introduced respectively to the plants. Our results showed that the yield of maize under S₁T₁D₂ treatment in 2016 was significantly increased by 5.7%-7.1%. Compared with all the rest treatments, the dry weights of lateral roots and deep roots under S₁T₁D₂ treatment were increased by 67.3%-149.9% and 17.9%-116.4%, respectively. The dry matter accumulation in shoot of maize observed from S₁T₁D₂ treatment was significantly lower than those under other treatments, with 2.1%-35.8% reduction. Our results indicated that S₁T₁D₂ could significantly promote the growth and spatial distribution of maize root, accounting to release water stress and keep yield stabilization or promotion. Therefore, 30 cm of straw burying could be used as a suitable approach of straw returning for maize production in northeastern China, where the climate is with a pattern of drought first and waterlogging in later stage.