Maize emergence speed and its relationships with water and heat conditions in Northeast China and meteorological assessment of the maize emergence period

In 2010-2011,a two-factor experiment of water stress and sowing date for spring maize ( Zea mays) was conducted to reveal the effects of soil moisture and air temperature on the spring maize emergence speed in Northeast China,and to establish the corresponding models for assessing and predicting the maize emergence period. The maize emergence speed had close relationships with the soil moisture and air temperature. The maize emerged faster under the conditions of more sufficient soil moisture and higher air temperature,while delayed under dry weather and low temperature. Under the conditions of the average soil moisture (S) in 0-20 cm layer be- ing 21% -25% ,soil available water capacity ( H) being 50 -70 mm,and average air tempera- ture ( T) being 18-20 ℃ ,the maize emerged about 10 d after sowing; at the S was 18%-21% , H was 30-50 mm,and T was 16. 5-18 ℃ ,the emergence was prolonged to about 18 d; while at the S was 18% ,H was 30 mm,and T was temperature 16. 5 ℃ ,the emergence was prolonged to 25 d,and even,no seedling appeared. The relationships between the interval days from seeding to emergence ( D) and the S,H,and T were D = 78. 017-1. 746S-1. 642T or D = 60. 776-0. 288H-1. 937T. These indicators and models could be applied in the assessment and prediction of the maize emergence period,and in the guidance of drought-resisting activities and weather services.