弱光条件下散射辐射比例增加对冬小麦籽粒灌浆进程的影响

Effect of Increasing Diffuse Radiation Fraction under Low Light Condition on the Grain-filling Process of Winter Wheat(Triticum aestivum L)

长江中下游地区太阳辐射呈现总辐射降低并伴随散射辐射比例升高的特点,到达地表的太阳辐射强度及其成分变化影响冬小麦的生长和发育。为阐明太阳总辐射减弱条件下散射辐射比例增加对冬小麦籽粒灌浆进程的影响,于冬小麦三叶期-成熟期在田间设置相同遮光率下散射辐射比例不同的2个处理,T1:遮光率14.10%,遮阴环境中散射辐射占总辐射比例31.09%;T2:遮光率14.42%,遮阴环境中散射辐射占总辐射比例39.98%,以不遮光为对照(CK)。小麦开花后每隔7d采样一次,至收获期共采样5次,测量其千粒重,并采用Logistic模型拟合籽粒灌浆过程,分析粒重增长动态和灌浆参数。结果表明:太阳辐射变化对籽粒灌浆时间无显著影响,主要通过影响小麦籽粒的灌浆速率从而影响千粒重。弱光下(T1处理)小麦籽粒灌浆过程中最大灌浆速率、平均灌浆速率以及渐增期、快增期和缓增期灌浆速率均减小,千粒重降低。弱光条件下散射辐射比例增加(T2处理),提高了籽粒最大灌浆速率、平均灌浆速率以及渐增期、快增期和缓增期灌浆速率,促进籽粒粒重增加。本研究的结果表明散射辐射比例增加能部分抵消太阳总辐射降低对籽粒粒重的负面影响。

The solar radiation reduction along with increasing diffuse radiation fraction has been observed across the middle and lower reaches of Yangtze river in recent half century. Wheat growth and production would be influenced by the changes of solar radiation reaching the surface and its composition. In order to investigate the effect of increasing diffuse radiation fraction under decreased solar radiation condition on the grain filling process of the winter wheat （Triticum aestivum L）, two treatments with different reduction ratio of diffuse radiation fraction and similar shading rate were set in the field experiment： T1, total solar radiation shading rate was 14.10% and diffuse radiation fraction was 31.09%; T2, total solar radiation shading rate was 14.42% anddiffuse radiation fraction was 39.98%, respectively; CK, no shading as control. The experiment was conducted from three leaves stage to mature stage of winter wheat. The 1000-grain weight was measured every 7 days from anthesis to mature period for 5 times totally. The Logistic model was used to simulate the grain filling process, the grain weight growing and the filling parameters. The results indicated that the grain filling time was not significantly affected by solar radiation reduction, but the 1000-grain weight was affected through decreasing grain filling rate. Under T1 treatment, the maximum filling rate, the average filling rate, the filling rate during the gradual increasing period , rapid increasing period and slow increasing period decreased, and the 1000-grain weight also decreased. Under the treatment of higher diffuse solar radiation fraction （T2 treatment）, the maximum grain filling rate, the average grain filling rate, the filling rate during gradual, rapid and slow growth periods were increased, and the grain weight was increased. This study indicated that the negative effect of solar radiation reduction on grain weight was offset by the effect of increased diffuse radiation fraction.