臭氧浓度升高和叶面施锌对小麦籽粒产量、锌浓度及有效性的影响

研究臭氧浓度升高和叶面施锌对小麦产量和籽粒不同组分锌营养的影响,为气候变化背景下小麦的锌生物强化提供理论依据和技术参考。利用自然光气体熏蒸平台,以富锌小麦品种青紫1号为供试材料,臭氧处理设清洁空气和臭氧浓度升高(100nL·L-1,拔节至收获),锌处理设对照(喷清水)和叶面施锌(开花期及花后1周叶面喷施0.1%Zn2+),成熟期测定小麦产量及其构成因素、籽粒各组分的锌浓度、锌含量、植酸浓度以及植酸与锌的摩尔比。叶面施锌处理对小麦籽粒产量没有影响,但臭氧浓度升高使产量平均下降66%。臭氧胁迫导致的产量损失主要与粒重明显减轻(53%)有关,其次亦与每穗粒数减少(27%)有关,而穗数没有变化。麦粒各组分锌浓度、植酸浓度以及植酸与锌摩尔比均表现为麸皮次粉面粉。与清洁空气相比,臭氧浓度升高使籽粒各组分的锌浓度和植酸浓度均明显增加,分别增加15%～41%和8%～45%,各组分植酸与锌摩尔比无显著变化;臭氧浓度升高使小麦面粉锌累积量占籽粒总锌的百分比显著减少。与对照相比,叶面施锌使小麦各组分锌浓度平均增加22%～24%,使植酸与锌摩尔比平均减少15%～19%,但籽粒各组分植酸浓度以及锌在各组分的分配比例均无显著影响。臭氧与锌处理对所有测定参数均无交互作用,但这两个处理与籽粒组分之间多存在不同程度的互作效应。臭氧胁迫环境下青紫1号籽粒产量和锌累积量大幅下降,籽粒各组分锌浓度显著增加,但生物有效性没有变化;花后叶面施锌对小麦产量没有影响,但使籽粒不同组分锌的营养水平均明显增加,且增幅不受臭氧浓度升高的影响。

Impacts of elevated ozone concentration and foliar zinc application on yield, grain zinc content and bioavailability of wheat

We studied the effects of elevated ozone concentrations and foliar zinc (Zn) applications on grain yield, Zn content, and bioavailability of the wheat grain fractions. This was done to provide a scientific basis and technical reference for Zn biofortification of wheat under climate change scenarios. The wheat cultivar Qingzi 1 was grown in glasshouse-type fumigation chambers from late elongation stage until maturity. Two chambers had low ozone concentration and acted as controls (clean air, 10 nL·L^-1) and anothers two had elevated concentration of ozone and acted as stress treatments (ozone, 100 nL·L^-1). Foliar spray of ZnSO₄ solution (0.1% Zn²⁺) was applied at flowering and one week after flowering. The yield and its components, Zn concentration, Zn content, phytic acid concentration (PA) and the molar ratio of PA to Zn (PA/Zn) of grain fractions were determined at maturity. Zinc treatment had little effect on grain yield. Elevated ozone concentration reduced grain yield by 66%; these were attributed to a 27% reduction in grain per panicle and a 53% reduction in thousand-grain weight, with no change in panicle number per square meter. Zinc concentrations in three grain fractions:bran, shorts, and flour differed significantly, with the Zn concentration in flour being the lowest and that in bran being the highest. PA and the PA/Zn ratio showed the same tendency. Elevated ozone concentration increased Zn concentrations in grain fractions by 15%~41% and PA concentrations by 8%~45%, compared to clean air, which did not lead to any changes in the PA/Zn. Elevated ozone concentrations reduced the proportion of Zn accumulated in wheat flour to the total Zn content in grain. The foliar application of ZnSO₄ increased Zn concentrations in grain fractions by 22%~24% and decreased the PA/Zn by 15%~19%, compared with control (water spray), but had no effect on PA or Zn distribution in the grain fractions. There was no interaction between ozone and Zn treatments for all measured parameters, but interactions between ozone treatment and grain fraction or Zn treatment and grain fraction were found for several parameters. Ozone stress decreased grain yield and Zn accumulation while increasing Zn concentrations but had no effect on Zn bioavailability of all grain fractions. Although foliar Zn application at early grain growing stage did not change grain yield, it significantly increased Zn concentration and bioavailability of the different grain fractions. However, the increases were not influenced by ozone pollution.