Abstract: In order to select the appropriate returning amount and manner of wheat straw in lime concretion black soil, split-plot experiment was conducted with maize Zhengdan958 as experimental material, and seedling quality and photosynthetic parameters were measured. The treatments were as follows: no-tillage with 2/3 straw retention (Treatment 1), rotary tillage with 2/3 straw retention (Treatment 2), deep tillage with 2/3 straw retention (Treatment 3), no-tillage with whole quantity straw retention (Treatment 4), rotary tillage with whole quantity straw retention (Treatment 5) and deep tillage with whole quantity straw retention (Treatment 6). It was shown that the seedling number, planting depth and uniformity, the seedling height and uniformity of Treatment 3 were the highest, of which the photosynthetic parameters such as leaf area index (LAI) at middle and late growth stage and the area of three ear-leaves and chlorophyll content in leaves were significantly (P<0.01) higher than other treatments. Statistical analysis indicated that the seedling quality and photosynthetic parameters of 2/3 straw retention were higher than those of whole quantity straw retention. Under the same straw retention amount, the seedling quality and photosynthetic parameters of deep tillage were higher than those of rotary tillage and no-tillage. In general, deep tillage with 2/3 straw retention showed the best returning efficiency.

Key words: wheat straw, lime concretion black soil field, maize, seedling quality, photosynthetic parameters