Application Effects of Sweet Sorghum Bagasse On Growth, Yield and N Uptake in Komatsuna.

The effects of sweet sorghum bagasse (SSB) application on komatsuna growth, yield and N uptake were investigated and compared with those of surface-applied rice straw (RS), inorganic fertilizer (IF) or no fertilizer (NF) application. Komastuna (Brassica rape L. perviridis Group) is a typical and Japanese leafy vegetable that is often employed as an experimental crop. SSB were either incorporated into or surface-applied on upland soil. Wagner pots (0.02 m²) containing 1.6 kg dry soil were fertilized with inorganic fertilizer (N: P₂O₅: K₂O = 15: 15: 15 g m^-2) in each treatment except for NF, SSB (1t dry weight m^-2, TC 45.1%, TN 0.347%, C/N 133) in the SSB-applied treatments and RS (1t dry weight m^-2, TC 39.0%, TN 0.506%, C/N 77.0) in the RS-applied treatment. The SSB C/N ratio was higher than that of the RS. On April 18, 2010, after application of IF, SSB and RS, nine seed of komatsuna were seeded in each pot and thinned to three seedlings at 11 days after sowing. The cultivation was conducted in greenhouse with four replications. At 21 days after sowing (DAS), the plant height and number of leaves of komatsuna were significantly lower in NF treatment than those in the other treatments. There were no significant differences in the leaf chlorophyll content index among all treatments. Each komatsuna growth index (plant height, number of leaves, and leaf chlorophyll content) in the SSB applied treatments was not significantly different from that in the IF and RS applied treatment at 21 DAS. Therefore, the negative application effects of SSB, one of the organic matters with high C/N, on komatsuna growth at 21 DAS were not observed. Further studies are necessary to evaluate the effect of sweet sorghum bagasse application in soil on komatsuna yield and N uptake.