varieties were used to study the tillering characteristics and regulations of multi-tiller maize under different plant densities and sowing dates. The results showed that tillers were co-elongated with leaves of main stem, the number of primary tiller (n) and leaf age of main stem (N) had the relationship of n = N-3, the secondary tillering had the same relationship as the primary one. Tillering ability showed significant differences among different maize varieties, Mexican’s tillering ability was the strongest, the maximum tiller number was about 25-40, and Keduo 4 was about 2-4 and then Wuyue 97-1 was about 1-2, however, Zhengdan 958 had no tiller in general. The tillering ability of maize could be affected by sowing date and plant density. Higher temperature and sunlight and lower plant density were favorable to tiller’s development. With the postponement of sowing date, the interval from seeding to tillering became shorter, the growth of tiller’s leaves became quicker, and the maximum tiller number was increased. When sowed on 25 April and 25 June at 45 000 plant ha-1
population, the maximum tiller number of the Keduo 4 was 3.50 and 4.00 while the ultimately tiller number was 2.33 and 2.00, respectively, so the eliminating rate of tiller was 33.4% and 50.0% respectively. The similar changes were observed in 30 000 and 60 000 plant ha-1
populations. With the increment of plant density, tiller’s occurrence was postponed, and the leaf ages decreased on same day after emergence of seedling, tiller number of main stem with the same leaf age and the maximum and ultimately numbers reduced, the tillers’ eliminating rate increased. When sowed on 25 April, taken the 30 000, 45 000, and 60 000 plant ha-1
populations, the maximum tiller number was 3.80, 3.50, and 3.22, and ultimately tiller number was 3.00, 2.33 and 1.67, so the eliminating rate was 21.05%, 33.43%, and 48.14%, respectively. The changes were similar when sowed at 25 June.