不同土壤肥力条件下麦秆还田与氮肥运筹对杂交稻氮素利用、产量及米质的影响

以杂交稻F优498为材料,研究了高、低土壤肥力下麦秆覆盖与氮肥运筹对杂交稻主要生育期氮素吸收利用特征、产量及米质的影响,并探讨了不同土壤肥力下麦秆覆盖和氮肥运筹对结实期剑叶SPAD值与稻米品质的形成的影响。结果表明,不同土壤肥力下,麦秆覆盖均有效促进杂交稻各生育时期氮素积累,提高了氮素利用效率以及稻谷产量,增加了稻米蛋白质含量、稻米胶稠度,显著降低了稻米垩白度以及垩白粒率,且高土壤肥力下麦秆覆盖优于低土壤肥力下麦秆覆盖处理。同时,不同土壤肥力下麦秆覆盖处理,均以m基肥∶m蘖肥∶m穗肥为3∶3∶4的氮肥运筹模式最优,均能有效调节水稻灌浆结实期叶片SPAD值,提高水稻氮素吸收利用效率及稻谷产量;但稻米品质方面,高土壤肥力以m基肥∶m蘖肥∶m穗肥为5∶3∶2时最佳;而低土壤肥力可适当提高氮肥后移比例,以m基肥∶m蘖肥∶m穗肥=3∶3∶4最佳。相关分析表明,水稻灌浆期剑叶SPAD值与稻米出糙率、整精米率以及蛋白质含量显著或极显著正相关(r=0.47*~0.90**);与垩百度、垩白粒率负相关,但相关未达显著水平;而高土壤肥力下稻米品质各项指标分别与齐穗后19~27d剑叶SPAD值,低土壤肥力下麦秆覆盖与齐穗后13~19d剑叶SPAD值相关系数最大。

Effects of Wheat Straw Mulching and Nitrogen Management on Grain yield,Rice Quality and Nitrogen Utilization in Hybrid Rice Under Different Soil Fertility Conditions

The effects of wheat straw mulching and nitrogen management on hybrid rice (F you 498) nitrogen (N) uptakes and utilization and grain yield and quality under high and low soil fertility  conditions were  evaluated. The experiment was conducted in paddy field at various soil fertility levels in the Rice Research Institute of Sichuan Agricultural University in 2013. A split plot design was used at different soil fereility levels with wheat straw mulching as the main plot and no wheat straw mulching as control, and N fertilizer management as sub plots combined with N application  level of  135 kg/hm2. The result indicated that the rice SPAD value of flag leaf at grain filling stage, nitrogen uptake and utilization efficiency were improved, as well as the grain yield and rice quality. Under high soil fertility, the rice N uptake and grain yield were higher than that under low soil fertility level,while the grain percentage of chalky kernel and chalkiness degree followed an opposite trend.  The  grain yield and the rice flag leaf SPAD during  grain filling stage both increased under wheat straw mulching with the N application ratio of 3∶3∶4  for basal fertilizer, topdressing at tillering stage and at panicle initiation stage,  as well as N uptakes and utilization efficiency and the grain quality. Furthermore, under low soil fertility level, the  percentage of chalky kernel and chalkiness degree also decreased. The correlation between grain quality and SPAD of flag leaf during filling stage showed that under wheat straw mulching the rice flag leaf SPAD generally had significant or extremely significant positive correlation with the percentages of brown rice and head rice, and had  negative correlation with the  percentage of chalky kernel and chalkiness degree，and the correlation coefficients between flag leaf SPAD and grain quality maximized in the middle filling stage.