2022 Volume 91 Issue 4 Pages 328-336
Three kinds of green manure crops (Crotalaria juncea, C. spectabilis, Sesbania rostrata) were cultivated from May to September were cultivated to evaluate biomass production and subsequent buckwheat growth in Okinawa. Biomass and uptake of several minerals were smallest in S. spectabilis and highest in C. juncea and S. rostrata, but Mg uptake was significantly higher in C. juncea than in S. rostrata. The growth and grain yield of the autumn buckwheat depended on the green manure biomass. In particular, they were similar following S. rostrata as application of inorganic fertilizer alone (control plot). The growth and grain yield of February sown buckwheat sown in February and grown with inorganic fertilizer in all plots after buckwheat sown in October was marginally better in the green manure plots than in the control plot. SPAD values in the leaf at the first flowering node at 54 days after sowing were significantly higher in the green manure plots than in the control plot. The SPAD value had a significant high positive correlation with the grain N content. I consider that N mineralization was slower in the green manure plots than in the control plot. I infer that the development of branches and grains was promoted in the green manure plots as a result of continued N supply until the late growth stage.
