Evolvement of rice cropping system and planting zonation in Zhejiang province

Rice cropping system has greatly changed during recent decades in Zhejiang province.Double rice cropping system decreased from 86% in 1993 to 34% in 2004 and single rice cropping system increased from 14% to 66% in the same period.With the change in rice cropping system,percentage of area covered with inbred variety decreased from 75% in 1995 to 50% in 2004 and with hybrid to more than 50% in 2004.With the popularization of panicle size variety and hybrid,cultivation techniques of seedling raising in dry land and system of rice intensification(SRI) were popularized to promote the advantage of tiller and large panicle.At the same time,labor-saving techniques,such as direct seeded rice and seedling broadcasting were popularized.According to the recent rice cropping system and type of variety in various regions,and refering to the original rice planting zones,rice planting area was classified into 6 rice planting zone listed below: Ⅰ.Zone of Japonica rice in single cropping system in Hangjiahu plain.Ⅱ.Zone of Indica and Japonica rice in single and double cropping system in Ningshao plain.Ⅲ.Zone of Indica rice in single and double cropping system in Wentai coast plain.Ⅳ.Zone of Indica rice in single and double cropping system in Jingqu basin.Ⅴ.Zone of Indica rice in single cropping system in hill area in the southwest of Zhejiang.Ⅵ.Zone of Indica and Japonica rice in single cropping system in hill area of the northwest of Zhejiang.Geographic region,character of ground and climate, rice cropping system,type of rice variety,percentage of rice planting area and main rice cultivation techniques in each zone were stated.