施氮时期对小麦籽粒HMW-GS积累及GMP粒度分布的影响

Effect of Nitrogen Fertilization Timing on HMW-GS Accumulation and GMP Size Distribution in Wheat Grains

在225kghm?2施氮水平下,设置起身肥(SE,GS30)、拔节肥(JT,GS32)和孕穗肥(BT,GS41)3个追施氮肥处理(底追比1:1),研究了追肥时期对强筋小麦济南17和弱筋小麦鲁麦21籽粒HMW-GS积累和GMP粒度分布的影响。结果表明,两品种籽粒HMW-GS于花后14d均已形成,济南17籽粒HMW-GS和GMP含量均高于鲁麦21,说明强筋小麦具有较强的谷蛋白积累能力。济南17成熟期籽粒HMW-GS和GMP含量以SE处理最高,施氮时期后移其含量呈下降趋势。JT处理显著提高鲁麦21灌浆中后期HMW-GS的积累速度,延长HMW-GS的快速积累期。济南17SE处理和鲁麦21JT处理的籽粒x型亚基(1、4或5、7)在灌浆中后期的积累速率显著提高。追肥时期对y型亚基的积累速率无显著影响。追氮时期后移均提高两品种籽粒GMP小颗粒的(粒径<12μm)体积和表面积百分比,降低大颗粒(粒径>100μm)体积和表面积百分比。济南17粒径>12μm的GMP颗粒数目百分比因追氮时期后移而增加,鲁麦21粒径>12μm的GMP颗粒数目百分比则降低。含4+12亚基的强筋小麦济南17比含5+10亚基的弱筋小麦鲁麦21偏向于更高的大颗粒体积比例,说明亚基间的聚合和GMP颗粒的分布不仅与亚基类型有关,而且与单位面粉中亚基的含量密切相关。

Wheat processing quality has close relationships with high molecular weight glutenin subunits（HMW-GS） and glu-tenin macropolyer（GMP） in grains.Nitrogen fertilization scheme could affect the accumulation of HMW-GS and the size distri-bution of GMP.In this study,we used a strong gluten winter wheat cultivar,Jinan 17,and a weak gluten winter wheat cultivar,Lumai 21,to investigate the effects of nitrogen topdressing stage on the accumulation of HMW-GS and the size distribution of GMP in grains.The nitrogen fertilizer rate during the whole growth period was 225 kg ha？1,of which a half was applied as base fertilizer and the other half was topdressed at pseudo stem erection（SE,GS 30）,jointing（JT,GS 32）,or booting（BT,GS 41） stage.The spike samples were collected from 7 d after anthesis（DAA） to maturity with a 7-day interval.The HMW-GS in grains formed before 14 DAA,and Jinan 17 had higher contents of HMW-GS and GMP than Lumai 21,which indicated that more glu-tenin is accumulated in the strong gluten cultivar than in the weak gluten cultivar.At maturity,the contents of HMW-GS and GMP in Jinan 17 showed decreasing trends with the delay of topdressing practice,and the highest values were observed in the SE treatment.In Lumai 21,compared to the SE and BT treatments,the JT treatment significantly accelerated the HMW-GS accumu-lation at middle-late stage of grain filling,and the rapid accumulation period was prolonged.At middle-late stage of grain filling,the accumulation rates of x-type subunits（1,4,5,and 7） were increased significantly in the SE treatment of Jinan 17 and the JT treatment of Lumai 21,whereas the y-type subunits were seldom affected by nitrogen application timing.For both cultivars,delay of nitrogen topdressing enhanced the percentages of volume and surface of GMP particle with diameter less than 12 μm,but re-duced those of GMP particle with diameter larger than 100 μm.The percentage of GMP particle number with diameter larger than 12 μm was increased in Jinan 17 with the delay of nitrogen topdressing but decreased in Lumai 21.The percentage of large GMP particle volume was higher in Jinan 17（containing subunit pair 4＋12） than in Lumai 21（containing subunit pair 5＋10）.This result suggested that polymerization of subunits and GMP particles are related to not only the subunit type but also the subunit content per unit of flour.