锌与有机农药及无机磷配合喷施对小麦籽粒锌强化的影响机制

Low Zn concentration of wheat grain and its low utilization effeciency in human being is a major public health problem in China. Currently, spraying Zn combined with pesticides and inorganic phosphorus has become a new global challenge and topic for achieving Zn biofortification of wheat grain as well as its mechanisms compared with spraying Zn alone. Here, we hypothesized that the Zn-pesticide compounds derived from spraying Zn combined with pesticides influence on Zn biofortification of wheat grain, and P-Zn antagonism was alleviated by the addition of pesticide in the spraying solution, resulting in reducing the concentration of phytic acid in wheat grain and consequently hancing the Zn utilization effeciency in human. Based on the mentioned hypothesis, the field and incubation experiments will be conducted and some new technologies such as 68Zn isotopic tracer and LA-ICP-MS will be also used as research methods. Accordingly, this project is objective to reveal the mechanism for Zn biofortification of winter wheat through investigating the effect of spraying Zn combined with pesticides on Zn uptake, transportation, and distribution, understand the reason for alleviating the P-Zn antagonism by spraying Zn combined with pesticides and inorganic phosphorus, and clearify the effect of the combined spraying practice on Zn utilization effeciency in human being. Eventually, these results will provide the guidance for achieving Zn biofortification of wheat grain as well as pest control.

我国小麦籽粒Zn含量及人体利用率较低对庞大人群健康构成严重威胁。与单独喷Zn相比，把喷Zn与农药及无机磷进行配合实施已成为小麦籽粒锌生物强化的最新尝试，故揭示该过程科学机制具有重要意义。本项目从“形成Zn-农药复合物与否可能会影响Zn-农药配合喷施的锌强化效果，减少Zn2+与磷酸根直接接触可能会克服Zn-P-农药三者配合的P-Zn拮抗，配合喷施可通过降低植酸含量提高锌利用率和品质”三条科学假设出发，拟采用田间及培养试验方法，并应用68Zn稳定性同位素示踪、LA-ICP-MS等技术，一是进行Zn与农药配合喷施对Zn在小麦体内吸收运转及分配的影响研究，揭示该过程影响籽粒锌强化效果的机制；二是阐明Zn-农药-P配合喷施中克服喷施各环节中P-Zn拮抗作用的机制；三是查明配合喷施对于小麦籽粒人体利用率及品质的影响。研究结果为喷Zn与病虫害防治一体化下实现小麦籽粒锌强化目标提供科学依据。

我国小麦籽粒Zn含量及人体利用率较低严重影响人体健康。与单独喷Zn相比，将Zn与农药及无机磷配合喷施是一种小麦籽粒锌生物强化的高效可行方法。据此本项目进行了田间、盆栽以及水培试验，揭示了：（1）Zn与农药配合喷施小麦体内Zn吸收运转和分配，及影响该过程籽粒锌强化效果的机制；（2）阐明Zn-农药-P配合喷施克服P-Zn拮抗作用的机制；（3）Zn与农药及无机磷配合喷施对小麦籽粒人体利用率及品质的影响。从而为病虫害防治一体化下喷Zn实现小麦籽粒锌强化目标提供科学依据。结果表明：（1）在开花期或灌浆期将Zn与农药配合喷施均能显著提高小麦地上部各器官Zn含量，与单独喷Zn相比无差异；在开花期和灌浆期分别将Zn与农药配合喷施和单独在一个时期喷施相比籽粒Zn含量进一步提高。与单独喷Zn相比，Zn+农药处理小麦地上部各器官Zn携出量、各营养器官中Zn含量及有效性均显著提高，花后Zn吸收量、向籽粒转移量、对成熟期总Zn贡献率进一步提高。（2）与喷施ZnSO4•7H2O相比，Gly-Zn的籽粒富锌效果较弱，但能够在一定程度上抑制P-Zn拮抗。Zn+农药或Zn+农药+P能够显著增加小麦籽粒、茎秆、叶片和颖壳中可溶性锌与非可溶性锌含量。Zn+农药+P与Zn+农药相比，小麦地上部各器官Zn含量显著降低，籽粒、茎秆和颖壳锌携出量显著降低，对叶片锌携出量无降低作用；在不喷Zn条件下，喷P对小麦地上部各器官Zn含量无影响。（3）喷Zn能够显著提高全粒、面粉、麸皮以及馒头中锌的生物有效性，且与农药配合喷施并未影响锌生物有效性的提高，而与无机磷配合喷施后则显著降低。将Zn与能够提高籽粒氮含量的烟酰类农药配合喷施，能够提高全粒和面粉中醇溶蛋白及谷蛋白含量，使锌的生物有效性进一步提高。因此，ZnSO4•7H2O籽粒富锌效果优于Gly-Zn，在潜在缺锌土壤上，将Zn与农药或Zn与农药及无机磷配合喷施均能显著提高小麦地上部各器官Zn含量，提高全粒、面粉及馒头锌的生物有效性，是一种克服人体缺锌问题且易于实际应用的有效方法。