关键词: 地膜覆盖, 地膜覆盖, 烤烟根系, 产量, 产值, 品质

Abstract:

Abstract: (OBJECTIVE)The writer analyzed breeding advance of common maize hybrid grain yield and its relative traits after Chongqing City managed by Centre directly,and understanded the main development tendency for maize cross breeding; (METHOD)We applied the collected data about corn region test of Chongqing City in 1997~2009,and analyzed the genetc gain of common maize hybrid grain yield and its relative traits using “district test check method”; (RESULTS)The results showed that maize cross breeding of Chongqing City had achieved significant advance since it has been managed by Centre directly, hybrid grain yield of level ground and hills had averagely raised 2.83% per year, and hybrid grain yield of mountain region had averagely raised 2.01% per year, comparing with the grain yield level of check varieties at initial stage after Chongqing City managed by Centre directly,at which the grain yield level of check varieties was continuously increased. In the traits of relation with grain yield, it was high significant for the genetic improvement effect of rows per ear and weight of 100 grains to the varieties of level ground and hills,and it was high significant for the genetic improvement effect of ear length, rows per ear and grains per row to the varieties of mountain region; (CONCLUSION) In present and a particular period from now on, the tactics of common maize cross breeding should be mainly attacked grains per row and weight of 100 grains with stabilizing bear period and plant height, appropriated increasing ear length and rows per ear in Chongqing City. Key words: maize; check varieties; test varieties; grain yield; genetic improvement