Experimental Study On Rice Water-level Production Function

Practice shows the water-level of paddy field is an important restraining index for guiding irrigation and drainage. So, to studying on the relationships of the paddy field water-level and the rice yield is important to establish the irrigation and drainage strategy.The manipulative experiment of different water-level in different growth stages was experimentalized in Experimental Station for Water-Saving and Agro-Ecology in Hohai University Water-saving Park for studying on the relationships of the paddy field water-level and the rice yield. The results are showed as follows: study on the dynamic tendencies of number of tillering, plant height, panicle length, leaf area index (LAI), net photosynthesizes and yield by observing the indexes of growth and Ecophysiological and analyzing yield component factors. The methods of ordinary least square regression (OLSR) and the EXCEL regress programming solver (EPRS) were adopted to establish the production function of water level of rice (addition model and multiplication model) which can reflect the relation between the yield of rice and the water levelas well as the time. Then the functions were compared. Finally, the sensitivity of rice by the evaluation criteria for the rice yield was discussed: under the water level of more than 5cm, the jointing and booting are found to be affected most severly, preceeding the tillering. The milk stage and ear sprouting and blooming is found to be relatively slight; under the groundwater level more than 20cm, the jointing and booting are found to be affected most severly, preceeding the ear sprouting and blooming, then the milk stage and the tillering.