结实期叶面施锌对小麦籽粒不同部位锌生物有效性的影响

The Effect of Foliar Zn Application at Grain Filling Stage on Zn Bioavailability in Grain Fractions of Modern Winter Wheat Cultivars

2011年在土培条件下,以扬麦16号、扬麦13号和扬辐麦2号为供试材料,于花后每隔一周分别喷施0.2%或0.4%ZnSO43次,以喷施等量清水为对照,成熟期收获小麦籽粒并进一步区分为麸皮、次粉和面粉,测定各组分植酸浓度以及植酸与锌的摩尔比,明确结实期叶面施锌对小麦籽粒锌有效性的影响。结果表明:对照小麦籽粒麸皮、次粉和面粉植酸平均浓度分别为19.4、5.3、1.8mg·g-1,最高和最低浓度相差约11倍。0.2%、0.4%ZnSO4处理对小麦麸皮、次粉和面粉中的植酸浓度均无显著影响,小麦面粉部位植酸与锌摩尔比明显小于麸皮和次粉部位。0.2%ZnSO4处理使供试品种麸皮、次粉和面粉部位的植酸与锌摩尔比平均分别下降37%、44%和43%;0.4%ZnSO4处理使对应部位植酸与锌摩尔比平均分别减少54%、58%和54%,均达极显著水平。尽管籽粒各组分植酸浓度以及植酸与锌摩尔比多存在品种间差异,但品种与锌处理间未发现互作效应。结合该研究前报可知,小麦花后叶面施锌不仅大幅增加现代小麦品种籽粒不同组分的锌浓度,而且使锌的有效性明显增强,是一种快捷的生物强化手段。

Phytic acid is a chelating agent which binds minerals and makes them unavailable for dietary absorption. Zinc is an essential micronutrient for humans but its bioavailability in many cereal grains is low because of a high molar ratio of phytic acid to zinc, which is considered as an important parameter for evaluating zinc bioavailability in the human body. Phytate/zinc molar ratios above 15 are considered to indicate low bioavailability. In order to improve grain Zn bioavailability of local modern wheat, an experiment using foliar fertilizer application was conducted in Yangzhou, China. Winter wheat cultivar Yangmai 16, Yangmai 13 and Yangfumai 2, grown in a cement tank filled with clay loam soil, were treated by foliar Zn application at 3 rates of 0（control）, 0.2% and 0.4% of Zn as ZnSO4 solution at grain filling stage. The first Zn treatment was applied at 1 week after flowering（WAF）, the second and third application were at 2 and 3 WAF, respectively. The plants in control plots received clean water. The results showed without foliar Zn application, phytic acid（PA） concentrations in bran, shorts and flour of wheat grains were 19.4 mg·g^-1, 5.3 mg·g^-1 and 1.8 mg·g^-1, respectively; Phytic acid concentration in bran was 11 times higher than in flour. Zinc application had no significant effect on PA concentration in different grain fractions. The Zn bioavailability indicator, the molar ratio of phytic acid to Zn（PA/Zn） showed that PA/Zn in flour was lower than that in shorts or bran. Compared with control treatment, 0.2% ZnSO4 foliar application at grain filling stage decreased PA/Zn in bran, shorts and flour by 37%, 44% and 43%, respectively; 0.4% ZnSO4 foliar application at grain filling stage decreased PA/Zn in bran, shorts and flour by 54%, 58% and 54%, respectively. Foliar Zn application after flower improved Zn bioavailability in different grain fractions through increasing Zn concentration in grains of modern wheat cultivars, which is a fast and effective biofortification approach to improve Zn nutrition in humans as well as animals.