State quo of cultivar registration and extension of first-cropping two-line hybrid rice in Yangtze River Area and its enlightenment to Zhejiang Province
To investigate the rules and present situation on the development of first-cropping two-line hybrid rice in Yangtze River Area,the data of cultivar registration and promotion area during 1998-2015 were collected and analyzed. The results showed that: 1) the first-cropping two-line hybrid rice was getting more and more important due to its increasing planting area in the Yangtze River Region. Up to the end of 2015,a total of 139 first-cropping two-line hybrid rice combinations had been registered. Among them...