| Rice is traditionally cultivated in flooded soil, which consums a great deal of water and is one of the most water-consumed crops in the world estimated by FAO in 1996. Along with the decrease of available fresh water resource in the world, water saving agriculture is becoming more popular worldwide. Thus, a number of studies have been conducted in rice cultivated in non-flooded condition, especially in water use efficiency (WUE) in the rice production system. Since China is the largest producer of rice grain and one of the thirteen countries being most short of water in the world, it is of great significance to study and spread the technique of rice culitivation in non-flooded soil. A ground cover rice production system in non-flooded soil is proposed among the different techniques. In order to illustrate water-saved mechanism of rice cultivated under non-flooded soil mulched with different materials, field experiments were conducted to compare irrigation, water-loss, soil water and temperature condition, rice development, final rice grain yield and water use efficiency among different treatments.The experiments were carried out in such two different systems as waterlogged and aerobic cultivation in 2001 and 2002. The experimental field was selected in the suburb of Yancheng city of Jiangsu Province, located at latitude 33 27'N, longitude 120 11'E. And tiny concrete-pool experiments were also carried out in green house in Nanjing Agricultural University in 2003. Both field experiments and tiny concrete-pool experiments have the same treatments, including three treatments in non-flooded soil with plastic film mulching (PF), straw mulching (SM), bare (B) and control (CK) in waterlogged soil. The results were as follows.The whole growing period of rice cultivated under non-flood condition was obviously delayed for about 4~10 days compared with that under waterlogged condition. This delaymostly happened in sowing-jointing period, the delay of which was about 6~10 days. The extending speed of rice leaves under non-flooded soil was slower than that underwaterlogged soil especially in joimting period. And the height of rice crop in non-flooded soil was also significantly shorter than in waterlogged rice, i.e. about 21.4~42.2cm shorter in former. However, the tillers of rice in aerobic soil were higher than waterlogged rice.The effect of ground cover with different materials on soil temperature and water condition was significant with the order of PF > SM > B. The soil temperature hi 5 cm and 10 cm in waterlogged soil was obviously lower than those in non-flooded soil. The soil temperature of PF was 1 掳C higher than that in SM in sowing-jointing and booting-Maturity periods, while the difference between them became less hi jointing-booting and booting-heading periods. However the soil temperature of SM was almost the same as that of B.Rice grain yield and straw yield in waterlogged soil were significantly higher than those in non-flooded soil. Almost the same yields of rice were obtained in aerobic soil mulched with plastic film and rice straw and they were higher than those in treatment without mulching. The components of rice grain yield in non-flooded condition were not as rational as waterlogged condition. Higher plant density was accompanied with more inefficient tillers, and it would lead to great reduction of the spike/tiller ratio, filled-grain numbers per panicle and thousand-grain weight. Among different ground cover treatments, the difference of panicle numbers and that of filled-grain numbers per panicle were not signicant, and the components of rice grain yield in treatments with plastic film or rice straw mulching were a little better than treatment without mulching while thousand-grain weight of PF was lower than that of the others.The irrigation water amount used in waterlogged treatment was significantly higher than that in non-flooded treatments. The total water use efficiency in waterlogged treatment was only 0.4-0.5 kg-m"3, while that of non-flooded treatments were three times higher. Ther...
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