施锌方法对小麦籽粒不同脱皮组分中锌与植酸及蛋白质分布的影响

Effect of Zn application methods on distribution of Zn,phytate and protein in wheat pearling fractions

【目的】探讨施Zn方式对小麦籽粒不同脱皮层次中Zn、植酸及蛋白质含量的影响,为通过农艺措施提高小麦全粒尤其是可食部分（胚乳）Zn含量及其生物有效性提供理论依据。【方法】以陕715（Zn高效基因型）和西农889（Zn低效基因型）为供试材料,设置不施锌肥（对照）、土施锌肥（15 kg/hm2）、喷施锌肥（质量浓度为3 g/L,总量为1.5 kg/hm2）、土施＋喷施锌肥4个处理,采用裂区设计进行田间试验,并利用JNMJ3型碾米机对小麦籽粒进行脱皮分层（从外向内依次为P1、P2、P3、P4、P5、P6,其中P1~P5主要为麸皮部分,P6主要为胚乳部分）,分析了小麦籽粒各层中Zn、植酸和蛋白质含量。【结果】在2个喷施Zn肥（土施＋喷施、喷施）处理下,P1-P5和P6层的Zn含量均显著增加,P1-P5中Zn平均分别增加53.4%,43.2%,P6层中分别增加61.1%,52.7%,而单纯土施Zn肥效果不明显。Zn、植酸在小麦籽粒P2层含量最高,蛋白质则在P3层含量最高,3种组分含量随着脱皮进程的增加从外层到内层呈现递减趋势;3种施Zn方式对P1-P5植酸含量影响不显著,但增加了P6层植酸含量;同时降低了籽粒各层蛋白质含量。土施＋喷施和喷施Zn肥处理均能显著降低P1~P5和P6层中植酸与Zn的物质的量（[植酸]/[Zn2＋]）,土施Zn肥处理则不能。【结论】Zn、植酸和蛋白质在小麦籽粒中分布不均匀,在籽粒外层含量均很高,尤其是糊粉层,胚乳中最少,且这种分布规律基本不受施Zn方式和小麦品种的影响。喷施Zn肥是提高潜在性缺Zn土壤上小麦全粒Zn尤其是胚乳部分Zn含量和生物有效性较为经济的方式,对缓减人体Zn缺乏有重要意义。

【Objective】 In order to alleviate Zn deficiency in human beings and provide therotical basis for its bioawailability,this study was conducted to assess the effect of Zn application methods on distribution of Zn,phytate and protein in wheat pearling fractions.【Method】 A field experiment of soil and foliar application methods of Zn fertilizer was conducted for 2 winter wheat cultivars（Shaan 715 and Xinong 889） in potentially Zn-deficient calcareous soil,with four main treatments,control（CK）,soil application of Zn（15 kg/hm2）,foliar application of Zn（quality concentration is 3 g/L,total quantity is 1.5 kg/hm2） and soil and foliar application of Zn.Six pearling fractions（P1,P2,P3,P4,P5,P6） of wheat grain were obtained using JMJ3 rice polishers,and P1-P5 were bran fractions of wheat grain,P6 mostly endosperm,and the concentration of Zn,phytate,protein of every wheat pearling fractions were determined.【Result】 Compared with the control treatment（no Zn application）,the methods of soil＋foliar application and foliar application of Zn increased Zn concentration in P1-P5 fractions by 53.4%,43.2%,respectively;and increased Zn concentration in P6 fraction by 61.1%,52.7%,respectively;However,soil application of Zn only did not increase.Generally,the P2 fraction（the outer 4%-8% layer of wheat grain） had the highest Zn and phytate concentrations,whereas the P3 fraction（the outer 8%-12% layer） ranked the highest for protein concentration.All the three components showed a diminishing trend as pearling progressed from the outer layers to the inner part of wheat grain.The effect of the three treatments of applying Zn on concentration of phytate in P1-P5 was not significant;however,the application of Zn increased phytate concentration in P6 and decreased the protein content in wheat pearling fractions.The phytic acid to Zn molar ratios significantly decreased under the soil＋foliar application and foliar application treatments,whereas,the effect of soil application of Zn on grain Zn bioavailability was not significant.【Conclusion】 The distribution of Zn,phytate,protein in wheat grain is uneven,the concentrations of three components are higher in the outer layer especially the aleurone tissue;the lowest concentration occurs in the starchy endosperm.Zn application methods and cultivars have not positive effect on the distribution patterns of the three components between the outer and inner parts of wheat grain.Compared with the three Zn application methods,the foliar application of Zn fertilizer to wheat is the economical and effective method to attain high Zn concentration and bioavailability in wheat grain especially for the endosperm,while alleviating Zn deficiency in human.