我国主要麦区小麦籽粒锌含量对叶喷锌肥的响应

【目的】我国小麦籽粒锌含量普遍偏低,叶喷锌肥是提高小麦籽粒锌含量的重要措施,研究我国主要麦区小麦籽粒锌含量对叶喷锌肥的响应,对小麦科学施用锌肥、 调控小麦籽粒锌营养状况有重要意义。【方法】本研究在我国14个省(市)主要麦区布置了30个田间试验,在每个试验点设置不喷锌对照和叶面喷锌两个处理,以当地主栽小麦品种为供试作物,通过测定收获期小麦产量、 各器官锌含量,研究了叶喷锌肥提高小麦籽粒锌含量的效果、 区域差异及其与土壤主要理化性质、 小麦拔节前植株锌含量的关系。【结果】 30个试验点的结果显示,叶面喷锌对小麦籽粒产量、 生物量和收获指数均无明显影响,但籽粒锌含量显著提高,叶面喷锌的籽粒锌含量比对照平均提高5.2 mg/kg(17.5%), pH7.0的区域提高5.3 mg/kg(16.4%), pH 7.0的区域提高5.2 mg/kg(18.4%)。小麦地上部锌吸收与分配在两个区域间没有显著差异,叶面喷锌的小麦籽粒、 颖壳和茎叶平均锌吸收量分别为255.5、 26.0和117.5 g/hm2,比对照增加19.4%、 28.7% 和99.2%; 锌收获指数为64.1%,比对照降低12.2%。籽粒锌利用率和籽粒锌强化指数也不受区域的影响,平均值锌利用率为3.0%,锌强化指数为3.8 mg/kg。无论叶面喷锌与否,籽粒锌含量和土壤有效锌均呈显著正相关,土壤有效锌含量每升高1.0 mg/kg,籽粒锌含量平均提高约4.0 mg/kg; 籽粒锌含量和土壤pH呈显著负相关,土壤pH每升高1个单位,籽粒锌含量平均降低3.8 mg/kg; 籽粒锌含量与土壤有机质没有显著相关性。小麦籽粒锌含量与拔节前植株锌含量极显著正相关,拔节前植株锌含量每升高1.0 mg/kg,籽粒锌含量平均提高0.4 mg/kg。【结论】 除叶面喷施锌肥外,调节土壤酸碱性,提高土壤有效锌含量,促进小麦生长前期植株对锌的吸收对改善我国小麦锌营养均具有重要意义。

Response of wheat grain Zn concentration to foliar sprayed Zn in main wheat production regions of China

【Objectives】 Wheat grain zinc (Zn) concentration is generally low in China, and foliar application of Zn fertilizers is an important approach of increasing the grain Zn concentration. Therefore, researches and knowledge on response of wheat grain Zn concentration to foliar Zn application are of great importance for reasonable application of Zn and improving wheat grain Zn nutrition in China.【Methods】 Thirty field trials were conducted to study effects of the foliar Zn application on the wheat grain Zn concentrations, their differences between acid and alkaline soil regions, and the relation of grain Zn concentrations to main soil properties and the wheat shoot Zn concentration before the jointing stage in 14 provinces in major wheat production areas of China.【Results】 Results from the thirty field trials show that the foliar Zn application has no effect on grain yields, biomass amounts and harvest indies of wheat, but significantly increases the grain Zn concentrations by an average of 5.2 mg/kg (17.5%), with a 5.3 mg/kg (16.4%) increase in acid soil regions and a 5.2 mg/kg(18.4%) increase in alkaline soil regions. There are no significant differences between Zn uptakes and distribution of wheat in the acid and alkaline soil regions. Compared with the control, the foliar Zn application increases Zn uptakes of wheat grains, glumes, and stems by 19.4%, 28.7% and 99.2%, and up to 255.5, 26.0 and 117.5 g/hm2 respectively. The Zn harvest index of wheat under the foliar Zn application is 64.1%, 12.2% lower than the control. The grain Zn recovery rates and grain Zn biofortification indices are nearly the same in the acid and alkaline regions, with averages of 3.0% and 3.8 mg/kg respectively. A significant positive correlation (P0.05) is found between soil DTPA-Zn and the grain Zn concentration, with the grain Zn concentration increased by 4.0 mg/kg for each 1.0 mg/kg increase of DTPA-Zn, while a significant negative correlation (P0.001) is found between top 0-20 cm soil pH and the grain Zn concentration, with the grain Zn concentration decreased by 3.8 mg/kg for one unit topsoil pH rise. The grain Zn concentration is also significantly (P0.001) correlated with the shoot Zn concentration before the jointing stage, with each 1.0 mg/kg increase of the shoot Zn concentration resulting in 0.4 mg/kg grain Zn concentration increase. There is no significant correlation between topsoil organic matter contents and grain Zn concentrations. 【Conclusions】 Apart from the foliar Zn application, regulation of soil pH, increase of soil available Zn and promotion of wheat Zn uptake at the early growth stages are also important for increasing wheat grain Zn level in China.