Evaluation Of Different Types Of Rice Cultivars For Direct-seeded Ratoon Rice System

Ratoon rice is the production of a second rice crop from the stubble left behind after the main crop has been harvested.The ratoon crop develops by regenerating rice tillers from nodal buds of the stubble.Transplanting is the dominant establishment method in ratoon rice system in China.Taking the advantages of saving water and labor and increasing system productivity,direct seeding rice?DSR?has been an optimal option for rice production.And incroporating DSR into ratoon rice system,direct-seeded ratoon rice?DSRR?could be a promising strategy for sustainable development of rice production in central China.Nevertheless,the lack of suitable variety limited the further development of DSRR.It has been suggested that the desired characteristics of rice varieties that fits DSRR include appropriate growth duration,high lodging resistance,high regeneration rate and ratoon season yield.Therefore,the objectives of present study were 1)to determine the types and characteristics of rice varieties that are suitable for DSR-RR in central China;2)to evaluate the relationship between regeneration rate and grain leaf ratio or dry weight per stem after harvesting of the first crop.The results showed that 1)the average annual growth durations of middle season rice varieties were 198 days,which were simliar with that of late season rice varieties,while the annual growth durations of early season rice varieties were 34 days shorter than that of middle season rice varieties.Shorter annual growth durations in early season rice varieties,resulting wastes of temperature and solar resources.2)the lodging index of tall stem varieties was significantly higher than that of middle and short stem varieties.3)the ratoon season yield and annual yield of hybrid rice varieties(5.35 t ha^-11 and 13.07 t ha^-1,respectively)were significantly higher than that of inbred varieties(3.58 t ha^-1 and 11.18 t ha^-1,respectively).4)the regeneration rate of ratoon rice was negatively correlated with grain-leaf ratio while positively correlated with dry weight per stem after harvesting of the crop?R=0.62,P<0.05?,both grain-leaf ratio and dry weight per stem after harvesting of the first crop could be to predict the regeneration rate for rice cultivars?R=0.60,P<0.05?.5)in consideration of the annual growth duration,lodging resistance,ratoon season and annual yield,the cultivars Tianyouhuazhan and Huiliangyou 898 were suitable for planting in DSRR system in central China.