吐丝后不同阶段干旱胁迫对糯玉米子粒产量和淀粉品质的影响

以苏玉糯5号和渝糯7号为材料,试验对照和干旱处理下土壤相对含水量分别为75%和55%,干旱胁迫时间分别为子粒建成期和灌浆充实期,研究结实期不同阶段(子粒建成期和灌浆充实期)干旱胁迫对糯玉米子粒产量和淀粉品质的影响。结果表明,结实期干旱胁迫显著降低子粒产量,且降幅子粒建成期大于灌浆充实期。干旱胁迫下淀粉含量显著降低,总蛋白、球蛋白、谷蛋白含量显著增加,淀粉平均粒径增大、支链淀粉平均链长增加,相对结晶度升高,且影响子粒建成期大于灌浆充实期。糯玉米粉峰值黏度受灌浆充实期干旱胁迫影响较小,在子粒建成期干旱胁迫下显著降低。糯玉米粉热焓值在子粒建成期干旱胁迫下降低,灌浆充实期干旱胁迫下增加。苏玉糯5号回生值干旱胁迫下显著降低,且降幅灌浆充实期较大;渝糯7号回生值受子粒建成期干旱胁迫影响较小,灌浆充实期干旱胁迫下显著增加。

Effect of Drought Stress at Different Post-silking Stages on Grain Yield and Starch Quality of Waxy Maize

The effects of drought stress at different post-silking stages(grain formation stage and grain filling stage) on grain yield and starch quality of waxy maize were studied using Suyunuo 5 (SYN5) and Yunuo 7(YN7) as materials. The soil relative moisture contents were 75% and 55% under control and drought conditions, respectively. The grain yield was significantly reduced by drought at different stages, and the reduction was severe when water deficit occurred at grain formation stage. Drought stress significantly decrease the starch content, increase the contents of total protein, globulin and glutelin, enlarge the average starch granule size, rise the proportion of long amylopectin chains, and improve the relative crystallinity, and the effect of grain formation stage was greater than that of grain filling stage. Flour peak viscosity was unaffected by grain filling stage drought stress but significantly decreased when plants suffered water deficit at grain formation stage. The flour gelatinization enthalpy was decreased and increased when drought occurred at grain formation and filling stages, respectively. Drought stress decreased the retrogradation percentage of SYN5 and the decrease was larger when plants suffered drought at grain filling stage. The retrogradation percentage of YN7 was not affected by drought at grain formation stage but was increased by drought at grain filling stage, respectively.