Effect Of Bud Promoting Fertilizer And Main Crop Stubble Height On Growth Of Rice Ratooning Buds And Ratooning Yield Formation

Rice ratooning is one of new production patterns and its planting area is increasing in recent years in the Yangtz River Valley in China.However,the ratooning buds development and grain yield and its quality were affected by varieties and the cultivation methods.Among various affecting factors,the bud-promoting fertilizer and main crop stubble height are the critical affecting factors related to the ratoonig yield and grain quality.Hence,this study aims to test the effect of bud-promoting fertilizer and main crop stubble height on the growth of rice ratooning bud and ratooning yield formation.A field experiment was carried out in Chidong town,Qichun county,Hubei province in 2016.The experiment was laid out based on split-split design,The main plots were different harvest height,the main sseason stubble height of 40 cm and 20 cm;the split plots were 4 bud-promoting fertilizer treatments,45 and 90 kg N hm^-2 applied at the main crop season at 15 and 20 days after heading,which represented with treatments codes of T_15-45、T_15-90、T_25-45 and T_25-90,respectively;the split-split plot were varieties including four local adaptation varieties Liangyou-6326（LY6326）,Fengliangyouxiang-1（FLYX1）,Tianliangyou-616（TLY616）and Huanghuazhan（HHZ）.The split-split plot was 24 m²,with 4 replicates.The results showed that:1.Main season stubble height had significant effect on the ratooning yield.The yield of 40 cm main season stubble height treatment is higher than that of 20 cm main season stubble height treatment,four varieties showed the same tendency.The effect of bud-promoting fertilizer treatments on ratooning yield is slightly different between two main season stubble heights.When main season stubble height is 20 cm,the yield of bud-promoting fertilizer treatment that applying 90 kg N hm^-2 at 25 days after heading date is significantly higher than the yield of the treatment that applying 45 kg N hm^-2 and 90 kg N hm^-2 at 15 days after heading date in FLYX1 and HHZ,T_25-90 increases 5.28%-17.7%,14.9%-29.8% than T_15-90 and T_15-45 respectively.When main season stubble height is 40 cm,the yield of bud-promoting fertilizer treatment that applying 90 kg N hm^-2 at 25 days after heading date is significantly higher than the yield of the treatment that applying 45 kg N hm^-2 at 15 days after heading date in LY6326、FLYX1 and HHZ,The yield of T_25-90 is significantly higher than that of T_15-90 in HHZ,Three other varieties showed the same tendency,but not significant.T_25-90 increases 5.28%-17.7%,14.9%-29.8% than T_15-90 and T_15-45 respectively.2.The way bud-promoting fertilizer treatment that applying 90 kg N hm^-2 at 25 days after heading date increased rationing yield is increasing the sink size of ratooning season.T_25-90 had significantly higher spikelets per m² than three other bud-promoting fertilizer treatments.Spikelets per m² of T_25-90 increased 11.8% and 14.0% than T_15-90 and T_15-45 respectively,seed setting rate of T_25-90 decreased 1.4% and 4.5% respectively.Spikelets per panicle of T_25-90 increased 10.6% and 10.3% than T_15-90 and T_15-45 respectively,the panicle number of T_25-90 increased 1.0% and 4.2% than T_15-90 and T_15-45 respectively.3.The bud-promoting fertilizer had significant effect on the growth and development of ratooning bud after main season was harvested.The effect of T_25-90 is not significantly different to other three bud-promoting fertilizer treatments on the length,living rate and weight of ratooning bud,but it had significantly promoted the germination of rationing bud after the harvest of main season.when the main season stubble is 40 cm,the bud fertilizer treatment that applying 90 kg N hm^-2 at 25 days after heading date has signifiantly increased the rate of newly tillers generate、the LAI of ratooning middle tillering day、ratooning heading day,and it has larger biomass accumulation than other treatments.4.Main season stubble heights significantly affected the quality of Ratooning rice.The rate of milled rice of 40 cm main season stubble height was lower than that of 20 cm main season stubble height,and that was found consistent in the four varieties.The chalkiness rate of 40 cm main season stubble height was lower than that of 20 cm main season stubble height,and its difference reached significant level in HHZ;the ratio of length and width of 40 cm main season stubble height is higher than that of 20 cm main season stubble height,it had reached significant level in FLYX1,TLY616 and HHZ.Bud fertilizer has little effect on Ratooning Rice quality,except the milled rice of T_25-45 had significantly promoted in FLYX1 under 40 cm stubble height,and no significant difference was found among four bud-promoting fertilizer treatments in other three varieties.Our finding indicates that bud-promoting fertilizer treatment that applying 90 kg N hm^-2 at 25 days after heading date promotes the rapid germination of regeneration buds after the harvest of main season,forming a higher number of spikelets per m² and net dry matter accumulation in ratooning mature stage,promoting the enhancement of yield;the milling quality of 40 cm main season stubble height is better than that of 20 cm main season stubble height,but under the same main season stubble height treatment,bud-promting fertilizer treatments had little effect on ratooning rice quality.