In this study, we evaluated the possibility of increasing Zn and Fe bioavailability in twenty-six popularly grown rice cultivars by external application of Zn through soil and/or foliar means. A field experiment was conducted in an Inceptisol applying Zn through soil and/or foliar means and the harvested whole grains were processed to brown rice and subsequently analysed for Zn, Fe, phytic acid and crude protein contents. Native Zn concentration in the brown rice of those tested cultivars varied from 22.9 to 79.7 with a mean of 40.3 mg kg−1. Zn concentration in brown rice increased to the tune of 17 and 95% upon Zn application through soil and soil + foliar, respectively, over the control across the tested cultivars. Zn application further caused a decrease in the phytic acid/Zn molar ratio to the magnitude of 64.0 and 23.0% upon soil + foliar and sole soil application, respectively. The decrease in phytate/Zn molar ratio was higher in high yielding varieties followed by local varieties, aromatics and hybrids and thus increased the bioavailability of Zn in brown rice. An antagonistic effect was also observed on the iron content in brown rice upon application of Zn. The decrease in iron concentration in brown rice was higher with soil + foliar application than with only soil application of Zn. Zn application through soil + foliar over basal application could be a useful strategy to produce Zn dense grains and to reduce the phytate/Zn and phytate/Fe molar ratios and thus enhancing their bioavailability. Application of Zn fertilizers can also enhance crude protein content in brown rice.

中文翻译：

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锌 (Zn) 施用方法影响糙米中锌和铁 (Fe) 的生物利用度

在这项研究中，我们评估了通过土壤和/或叶面方式外施锌来提高 26 个普遍种植的水稻品种中锌和铁生物利用度的可能性。通过土壤和/或叶面方式在 Inceptisol 中进行田间试验，将收获的全谷物加工成糙米，随后分析锌、铁、植酸和粗蛋白含量。这些测试品种的糙米中天然锌浓度从 22.9 到 79.7 不等，平均值为 40.3 mg kg-1。在通过土壤和土壤 + 叶面施用锌后，糙米中的锌浓度分别比测试品种的对照增加了 17% 和 95%。锌的施用进一步导致植酸/锌摩尔比下降至 64.0 和 23。土壤 + 叶面和单独土壤施用分别为 0%。植酸/锌摩尔比在高产品种中的下降幅度更大，其次是地方品种、芳香品种和杂交品种，从而提高了糙米中锌的生物利用度。在施用锌后，还观察到对糙米中铁含量的拮抗作用。土壤+叶面施用比仅土壤施用锌对糙米铁浓度的降低幅度更大。通过土壤+叶面喷施锌，而不是基施，可能是生产锌致密谷物和降低植酸/锌和植酸/铁摩尔比，从而提高其生物利用度的有用策略。施锌肥还可以提高糙米粗蛋白含量。植酸/锌摩尔比在高产品种中的下降幅度更大，其次是地方品种、芳香品种和杂交品种，从而提高了糙米中锌的生物利用度。在施用锌后，还观察到对糙米中铁含量的拮抗作用。土壤+叶面施用比仅土壤施用锌对糙米中铁浓度的降低幅度更大。通过土壤+叶面喷施锌，而不是基施，可能是生产锌致密谷物和降低植酸/锌和植酸/铁摩尔比，从而提高其生物利用度的有用策略。施锌肥还可以提高糙米粗蛋白含量。植酸/锌摩尔比在高产品种中的下降幅度更大，其次是地方品种、芳香品种和杂交品种，从而提高了糙米中锌的生物利用度。在施用锌后，还观察到对糙米中铁含量的拮抗作用。土壤+叶面施用比仅土壤施用锌对糙米中铁浓度的降低幅度更大。通过土壤+叶面喷施锌，而不是基施，可能是生产锌致密谷物和降低植酸/锌和植酸/铁摩尔比，从而提高其生物利用度的有用策略。施锌肥还可以提高糙米粗蛋白含量。在施用锌后，还观察到对糙米中铁含量的拮抗作用。土壤+叶面施用比仅土壤施用锌对糙米中铁浓度的降低幅度更大。通过土壤+叶面喷施锌，而不是基施，可能是生产锌致密谷物和降低植酸/锌和植酸/铁摩尔比，从而提高其生物利用度的有用策略。施锌肥还可以提高糙米粗蛋白含量。在施用锌后，还观察到对糙米中铁含量的拮抗作用。土壤+叶面施用比仅土壤施用锌对糙米中铁浓度的降低幅度更大。通过土壤+叶面喷施锌，而不是基施，可能是生产锌致密谷物和降低植酸/锌和植酸/铁摩尔比，从而提高其生物利用度的有用策略。施锌肥还可以提高糙米粗蛋白含量。通过土壤+叶面喷施锌，而不是基施，可能是生产锌致密谷物和降低植酸/锌和植酸/铁摩尔比，从而提高其生物利用度的有用策略。施锌肥还可以提高糙米粗蛋白含量。通过土壤+叶面喷施锌，而不是基施，可能是生产锌致密谷物和降低植酸/锌和植酸/铁摩尔比，从而提高其生物利用度的有用策略。施锌肥还可以提高糙米粗蛋白含量。