施氮量对高粱籽粒灌浆及淀粉累积的影响

Effect of nitrogen application level on grain starch accumulation at grain filling stage in sorghum spikelets

本试验于2019-2020年以汾酒粱1号为材料,在0、75、150、225、300和450 kg N hm^(-2)6个施氮水平下,于花后每隔7 d采集不同穗位籽粒分析其灌浆特性及淀粉形成过程,探究不同氮素用量对高粱籽粒灌浆及单粒淀粉累积的影响。结果表明,与不施氮相比施氮75 kg hm^(-2)显著提高了穗粒数和产量,但随施氮量的增加产量没有显著变化;氮素对优势粒(始花日开始2 d内开花的籽粒)和劣势粒(始花日开始5~6 d间开花的籽粒)的单粒重及单粒体积、灌浆特性和单粒淀粉累积的影响趋势基本一致,施氮条件下单粒重、单粒体积和灌浆速率随施氮量增加而增加,但不施氮处理的单粒重和单粒体积仍高于各施氮处理,且缺氮显著延长了灌浆活跃期。籽粒淀粉累积速率与参与籽粒淀粉合成的关键酶ADP-葡萄糖焦磷酸化酶(AGPase)和可溶性淀粉合酶(SSS)活性显著相关;过量施氮(450 kg N hm^(-2))灌浆前期籽粒中AGPase和SSS的活性最高,促进了灌浆前期籽粒淀粉累积;施氮75 kg hm^(-2)灌浆前期籽粒中AGPase和SSS的活性和淀粉累积速率次之;虽然缺氮降低了灌浆前期籽粒中AGPase和SSS的活性,但在灌浆后期维持较高活性而延长了灌浆活跃期,因而后期具有较高的单粒淀粉累积速率,提升了单粒淀粉累积量和单粒重。

To investigate the effect of N application level on grain-filling and starch accumulation in individual sorghum grains,sorghum variety Fenjiuliang 1 was used as the experimental material in 2019 and 2020.Six N rates of 0,75,150,225,300,and 450 kg N hm^(–2) were applied before sowing to experimental plots in Shanxi,China.To analyze sorghum grain-filling and starch accumulation by the Richards’growth equation,the superior and inferior spikelets were sampled at seven days intervals at each sampling from anthesis to maturity.The rational N application level(75 kg N hm^(–2))showed the maximum grain number per panicle resulting in the maximum yield per hectare.For both superior and inferior spikelets,N had similar effects on grain weight,grain morphology structure,the characteristics of grain-filling,and grain starch accumulation.The grain weight,grain volume,and grain-filling rate increased with the increase of N application rate,whereas the maximum grain weight and grain volume was obtained with the zero N treatment.The grain starch accumulation rate was highly correlated with the activity of ADP-glucose pyrophosphorylase(AGPase)and soluble starch synthase(SSS).Compared to the zero N treatment,N application enhanced grain starch accumulation rate at early grain-filling stage and grain-filling rate,which may be due to the increased AGPase and SSS activity at the early grain-filling stage.Compared with rational N(75 kg N hm^(–2)),excessive N(450 kg N hm^(–2))promoted grain starch accumulation by enhancing the activity of AGPase and SSS at the early grain filling stage,whereas zero N application enhanced sorghum grain weight and grain starch accumulation by extending the grain-filling duration and enhancing the activity of key enzymes in grain involved in sucrose-to-starch conversion at the late grain-filling stage.