Study On Growth Characteristics And Yield Formation Of Machine Transplanting Rice Under No-tillage Condition

The quantity and quality of labor for rice production declined markedly, mechanized planting willbecame more and more important in rice production system in China. Conventional tillage is the mostwidely used method for land preparation of paddy field, and transplanting is the traditional but stilldominant method for rice establishment. There are some disadvantages in conventional tillage systemcompare with no tillage, such as that cultivation layer is much deep for mechanized planting due toexcess tillage, the plant depth is too deep in field with conventional tillage, that is disadvantage togrowth recovery, tiller and yield formation. In this study, we compared mechanized transplanting quality,biomass production, yield components and economic benefits between no tillage and conventionaltillage. We study the effects of soil soak time, planting density and nitrogen rates on rice growth underno tillage condition. The results are as follows:1. It is clear that the effect of no tillage on transplanting quality, seedling growth and yield. The plantdepth is too deep in field with conventional tillage that is disadvantage to tiller and seedling growth.The seedling plant depth reduced40%under no tillage conditions compared with conventionaltillage conditions. The percentage of floating seedling and damage seedling was much higher underno tillage conditions than conventional tillage conditions. The tiller and panicles per plant increased,but root biomass and length decreased under no tillage conditions compared with conventionaltillage conditions, and no tillage caused root accumulation in surface soil layer (0-5cm). Thechlorophyll concentration of flag leaf was higher under no tillage conditions than conventionaltillage conditions after flowering. The yield under no tillage conditions was higher than underconventional tillage (0.6%-2.3%), but it is not significant. The increase percentage of yield wasdifferent in different year and varieties.2. The effects of soil soak duration on soil bulk density and mechanized transplanting quality wasclear. The soil bulk density decreased with soil soak duration increased, the soil bulk densitydecreased to0.8-0.9g/cm~3in0-25cm depth after15days soil soak duration, the transplanting depthwas in1.0-1.9cm, and the percentage of floating seedling, lodging seedling and damage seedingwas not significant difference compare with traditional mechanized transplanting. In view of theeffects of soil soak duration on soil bulk density, mechanized transplanting quality and yield, it isgood for mechanized transplanting that the field soil soak duration required more than10days. Ifsoil soak time was not enough, bulk density was high for mechanized transplanting in the surfacesoil layer, resulting in a large number of floating seedlings.3. The fitting density for mechanized transplanting under no-tillage condition was found. The rowspace was not changed, but the hill space can be changed in16-21cm, the rice yield improved whenthe hill space reduced and planting density increased. The higher planting density resulted inincreasing the max tiller number, panicle number, and leaf area index, reducing light transmittance,improving solar utilization, total biomass and nitrogen uptake.4. It is clear that the effect of nitrogen rate on rice growth and nitrogen use efficiency under no-tillage mechanized transplanting system. It is a single peak curve relation between nitrogen rate and yield.The panicle number increased with nitrogen rate, but the effective panicle percentage decreased.The high yield can obtain through enhancing nitrogen input under low planting density condition.The leaf length and chlorophyll content increase when nitrogen input increase, nitrogen agronomicefficiency and the nitrogen partial factor productivity decreased with the nitrogen rate increased, theoptimum planting density was21hills per m2, and the optimum nitrogen input was180kg/hm2.5. The economic benefit of no tillage mechanized transplanting system was determined, and establishthe method to support the no-tillage mechanized transplanting system.The average yield was1.25%higher under no tillage than conventional tillage condition. There were differences between thedifferent varieties, the average increase of income was276yuan/ha. Weeding costs increasedsharply under no-tillage mechanized transplanting system due to increase of herbicides and manualweeding costs. Economic benefit was much higher under no tillage system than conventional tillagesystem. Further research need to be conduct such as soil management, nutrient management andweed control to improve no-tillage mechanized transplanting system.