A Study On The Establishment Technique Of Direct Seeding Rice Under The Zero Tillage Condition

In order to explorer the influence of coated or pelleted seeds and seeding rate on rice establishment, growth and development and grain yield, the experiments with hybrid rice were conducted by using direct seeding under the zero tillage condition Changsha and Shimen county in 2002-2003. The main results were summarized as follows:The water absorption and germination of pelleted or coated seeds was not influenced by the seed thickening. And the opening of the seed-pelleting agents did not result in the loss of the active substance.Both pelleted seeds and coated seeds could ordinarily germinate under the submerged soils. The germination rate was up to 83.3% respectively. But the uncoated seeds (CK) could not germinate under the submerged soils. And the germination rate was as low as 19.2%. A possible reason for this was that the seed pelleting agent could supply the necessary oxygen for seed germination.The seedlings of coated seeds or pelleted seeds showed the characteristics of thick root diameter, density root hair, great root dry matter and strong root activity and large root uptake surface area. The free proline content was 61.1%-90.0% higher than that of CK and the chlorophyll content was also higher than that of CK.Compared with CK, the establishment rate and adult seedling rate of both pelleted seeds and coated seeds increased by 9.4% -14.8% and 6.2%-8.8% respectively. Meanwhile, the seedlings displayed shorter plant height, more green leaves, thicker basal stem diameter, more white roots, greater plant dry matter, and the stronger tillering ability. The seedlings of coated seeds also show the stronger resistance to the plant hoper, thrip and bakanae disease of rice.The tillers and effective tillers per plant were related to the seeding rate. In general, the large the seeding rate, the less the tillers and effective tillers per plant. Tillering ability per plant showed the tendency of less tillers with the increase in seeding rate.Seeding rate obviously affected the grain yield. The yield of Llangyoupeiju significantly decreased with the increase in seeding rate. But there was no difference of grain yield between the treatments of 1.5kg/mu and 2.0kg/mu. 1.5kg/mu could be taken as the suitable seeding rate.