Experiment in the Timely Sowing of Maize in Southeastern Gansu and the Analysis of its Suitable Sowing Period

[Objective] The effect of sowing date on the utilization of climate resource and maize yield,and the variation of warming climate affecting the suitable maize sowing were studied. [Method] The suitable sowing date of maize in Southeastern Gansu was determined through the experiment in its timely sowing. [Results] Total number of day and the accumulated temperature of whole growth period was with little difference even though there was a quite difference in the interval of days from the sowing to emergence,from the period of seven leaves to jointing stage,from the milky stage to mature stage and the accumulated temperature of ≥ 10 ℃ between the early seeding and later sowing of maize. The interval time of the partial period of maize growth and development in early seeding was increased and the interval time from the maize was shortened. There was a linear change in accumulation of the biomass of whole maize growth period with the variation of the accumulated temperature of ≥ 10 ℃. The difference in the maize biomass before its jointing stage in various sowing dates was less and the increment of the maize biomass after its jointing stage in average sowing date was higher than these of the other sowing dates. The average sowing date was more appropriate sowing time,in which the biomass accumulation of maize seed in mature stage was also higher than tease of other sowing dates. [Conclusion] The reference for the full use of climatic resources was provided through the experiment.