开花期干旱胁迫对鲜食糯玉米产量和品质的影响

为探明开花期(抽雄吐丝期)干旱胁迫对鲜食糯玉米(吐丝后23 d采收)产量和品质的影响,以苏玉糯5号和渝糯7号为试材,采用负水头供水控水盆栽装置控制土壤含水量,设置开花期正常供水(土壤相对含水量80%)和干旱胁迫(土壤相对含水量60%)2个处理,研究干旱胁迫对鲜食糯玉米产量(鲜果穗和鲜籽粒)、籽粒组分、糊化和热力学特性的影响。结果表明,开花期干旱胁迫减少籽粒数量、降低籽粒重量、缩小籽粒体积,导致鲜果穗和鲜籽粒产量损失。开花期干旱胁迫下鲜食期籽粒淀粉含量升高,但对于蛋白质含量渝糯7号降低,苏玉糯5号变化不显著。蛋白质组分中,对球蛋白含量影响不显著,清蛋白、谷蛋白和醇溶蛋白均显著降低。开花期干旱胁迫显著降低淀粉粒平均粒径。碘结合力2015年度显著下降,2014年度受干旱影响不显著。开花期干旱胁迫下籽粒峰值黏度、谷值黏度和终值黏度在苏玉糯5号中降低,在渝糯7号中升高。开花期干旱胁迫下两品种峰值温度降低,回生热焓值和回生值升高,而热焓值仅渝糯7号在2014年度升高。总之,开花期干旱降低糯玉米鲜果穗和鲜籽粒产量,增加籽粒淀粉含量,降低籽粒蛋白质含量、淀粉粒径和支链淀粉中长链比例,进而使籽粒回生增加,但糊化黏度两品种表现不同(渝糯7号升高,苏玉糯5号下降)。

Effects of Water Deficit at Flowering Stage on Yield and Quality of Fresh Waxy Maize

In order to clarify the influence of water deficit at flowering stage (tasseling silking stage) on yield and quality of fresh waxy maize (harvest at 23 d after silking), the fresh ear/grain yield and kernel components, pasting and thermal properties were measured using Suyunuo 5 and Yunuo 7. The soil moisture content was controlled by negative-pressure water supply and controlling pot device, and the relative soil moisture content for control and drought treatments was 80% and 60%, respectively. The drought at flowering stage decreased grain number, weight and volume, leading to the yield loss of fresh ear and grain. Under water deficit condition, grain starch content was increased, while protein content was increased in Yunuo 7 and unchanged in Suyunuo 5. For protein components, globulin contents was not affected by drought, while albumin, zein and glutenin contents were decreased when plants suffered water deficit at flowering stage. The starch granule size was reduced by drought for both varieties in both years, while starch iodine binding capacity for both varieties was decreased in 2015 and not affected in 2014 by drought. The peak, trough and final viscosities of grains were increased in Yunuo 7 and decreased in Suyunuo 5. Under drought condition, the grain peak gelatinization temperatures were decreased, retrogradation enthalpy and percentage were increased, while gelatinization enthalpy was only increased in Yunuo 7 in 2014. In conclusion, drought at flowering stage decreases fresh ear/grain yield, increases grain starch content, decreases protein content, starch granule size and the proportion of long chains in amylopectin, and increases the grain retrograde, while viscosities in response to water deficit are dependent on varieties (increases in Yunuo 7 and decreases in Suyunuo 5).