黄土高原旱地冬小麦籽粒锌含量差异与主要土壤理化性状的关系

【目的】中国黄土高原旱地小麦籽粒锌含量普遍偏低,但存在较大的变异现象。揭示小麦籽粒锌含量变异的原因,从而调控作物锌营养,提高小麦籽粒锌含量。【方法】在2014—2015和2015—2016年,对地处黄土高原的山西、陕西、甘肃旱地冬小麦主产区的379个农户麦田土壤(0—100 cm土层)和小麦植株进行取样分析,研究旱地冬小麦籽粒锌含量差异及其与主要土壤理化性状的关系。【结果】该区域小麦籽粒锌含量介于12.2—50.7mg·kg~(-1)。相关分析表明,0—100 cm各土层水分含量和有效铁、多数土层的pH和有效磷、表土层的有效锰和有效铜均与小麦籽粒锌含量呈显著负相关;表层土壤(0—20 cm)硝态氮、速效钾、有效锌与籽粒锌含量呈极显著正相关;各土层土壤有机质和全氮含量、多数土层的铵态氮含量均与籽粒锌含量无显著相关关系。当籽粒锌含量达到高锌组水平(平均39.2 mg·kg~(-1))时,收获期0—100 cm土层水分含量为8.2%,比低锌组低23%;0—20 cm土层pH为8.3,比低锌组低1.4%;硝态氮、速效钾和有效锌含量分别为23、150和0.54 mg·kg~(-1),比低锌组高246%、27%和35%;有效磷、有效铁、有效锰、有效铜含量分别为12.1、3.2、10.6和1.0 mg·kg~(-1),比低锌组低21%、37%、6%和33%。【结论】黄土高原旱地田块间小麦籽粒锌含量存在较大的变异。土壤水分、pH、硝态氮、有效磷、速效钾和有效态铁锰铜锌含量是引起籽粒锌含量差异的原因,其中以水分和有效铁影响最大。优化农田水分和养分管理措施,提高土壤水分、氮、钾、锌供应能力,在不影响作物产量的情况下适当调控土壤磷、铁、锰、铜供应能力,有利于提高黄土高原地区小麦籽粒锌含量。

Variation of Winter Wheat Grain Zinc Concentration and Its Relation to Major Soil Characteristics in Drylands of the Loess Plateau

【Objective】 In dryland of the Loess Plateau, winter wheat grain zinc (Zn) concentration is usually very low in most areas, but it still varied a lot among different locations or fields. Clarification of the causes of grain Zn variation is essential for improving wheat Zn nutrition and grain Zn biofortification. 【Method】 During 2014-2015 and 2015-2016, both soil and wheat grain samples were collected from 379 randomly selected rain-fed fields of Shanxi, Shaanxi, and Gansu provinces, where wheat is widely planted. Pearson correlation was used to investigate the relationships between wheat grain Zn concentration and the selected soil characteristics. 【Result】 The wheat grain Zn concentration ranged from 12.2 mg·kg^-1 to 50.7 mg·kg^-1 among different fields. The Pearson correlation analyses showed that, grain Zn concentration was significantly and negatively correlated with soil moisture, available Fe in all 0-100 cm layers, soil pH, available P in most soil layers, and available Mn and Cu in top soil layers. While wheat grain Zn concentration was significantly and positively correlated with soil nitrate, available K, and available Zn in 0-20 cm layer. Moreover, grain Zn was found no correlation with soil organic matter, total N in 0-100 cm layers, and ammonium in most soil layers. At maturity, 0-100 cm soil moisture in the fields of high Zn groups (mean = 39.2 mg·kg^-1) was 8.2%, and 23% lower than that in the fields of low Zn groups; 0-20 cm soil pH in the fields of high Zn groups was 8.3, and 1.4% lower than that of low Zn groups; and soil available P, available Fe, available Mn, and available Cu of high Zn groups were 12.1, 3.2, 10.6, and 1.0 mg·kg^-1, and 21%, 37%, 6%, and 33% lower than that in low Zn groups, respectively. However, soil nitrate, available K, and available Zn of high Zn groups were 23, 150, and 0.54 mg·kg^-1, which were 246%, 27%, and 35% higher than that of low Zn groups, respectively. 【Conclusion】 Large wheat grain zinc variation was found among different areas and fields of the Loess Plateau, and it was mainly affected by soil characteristics including moisture, pH, nitrate, available P, available K, and available Fe, Mn, Cu and Zn, in which moisture and available Fe were more important. Optimizing agronomic water and nutrient management to increase soil water, N, K, and Zn supply capacity, and to some extent to decrease soil available P, and available Fe Mn and Cu without yield loss, should be potential measures for biofortification of wheat grain Zn on the Loess Plateau.