Characteristics of dry matter production and nitrogen use efficiency of 37 spring maize hybrids with high-yielding potential in north of China

Selecting high nitrogen use efficiency (NUE) hybrid maize plays the most important role for high yield and high NUE in maize production. A pot experiment was conducted to evaluate the characteristics of dry matter (DM) production and NUE of spring maize hybrids released in the north of China currently. In this experiment, 37 maize hybrids with high-yielding potential were planted in pots and provided enough fertilizers and water in the growing season. The results indicate that 37 maize hybrids with high-yielding potential can be divided into 4 types according to the grain weight and nitrogen grain production efficiency (NGPE), the type Ⅰ is high yield and high efficiency, the type Ⅱ is high yield and moderate efficiency, the type Ⅲ is moderate yield and moderate efficiency, and the type Ⅳ is low yield and low efficiency. The type Ⅲ accounts for 56.8% of the 37 maize hybrids, while the type I is only 8.1% which is lower than that of the type Ⅱ (13.5%) and Ⅳ (21.6%). For these four-type maize hybrids, the DM accumulation and NUE are not significantly different before flowering, but are remarkably different after flowering. At the maturity stage, the DM and nitrogen distributions to grains of the type Ⅰare the highest, however, the DM and nitrogen distributions to roots and stalks of the type Ⅳ are the highest. Accordingly, the nitrogen transportation amount (NTA), nitrogen transportation efficiency (NTE) and nitrogen contribution rate (NCR) of the type Ⅰ are significantly higher than those of the other three types in this trial. Furthermore, the results of correlation and path analysis show that nitrogen dry matter production efficiency (NDMPE), grain weight and nitrogen content are significantly correlated to NGPE. Therefore, high grain weight and low nitrogen content of single plant are the basic characteristics of high-yielding and high-efficiency hybrids.