【作者】 杨习文；

【导师】 田霄鸿；

【作者基本信息】 西北农林科技大学 ， 植物营养学， 2011， 博士

【摘要】 在我国,小麦是北方居民尤其是广袤农村地区人口的主食,是提供热量和矿物质的主要来源。一方面,由于我国小麦主产区大多属石灰性土壤地区,土壤有效锌（DTPA-Zn）含量要么<0.5 mg·kg^-1的缺锌临界值,要么处于0.5～1.0 mg·kg^-1的潜在缺锌范围,而以后者为主。在这类土壤上生长的小麦籽粒锌含量尚不能满足人体对锌的数量需求;另一方面,小麦籽粒中还存在一些降低人体对锌利用率的抗营养因子,其中植酸作为籽粒中磷素主要贮存形式最为引人关注,其含量过高会显著降低锌的所谓生物有效性,亦即人体对锌的吸收利用率。因此,提高石灰性土壤地区小麦籽粒锌含量和锌生物有效性业已成为同等重要的科学和生产实践问题。尽管有不同方法和途径,但是利用外源施用锌肥的农艺措施来提高小麦籽粒锌含量和生物有效性,在我国小麦主产区的研究还十分薄弱。众所周知,由于磷锌之间存在很强的颉抗作用,磷显著影响锌的吸收。因此,在当前一般小麦田施磷量较高的情况下,如何维持籽粒中高的锌含量和低的植酸含量就成了解决解决人体缺锌问题的关键。本研究以潜在缺锌石灰性土壤为重点,以探讨小麦磷-锌营养关系和外源施锌方法对小麦籽粒锌含量及生物有效性的影响为拟解决的关键问题,通过苗期或全生育期的培养和田间试验,进行了磷锌配合供应对小麦锌及其它微量元素含量的影响,磷锌配合土施、锌肥在小麦不同生育期喷施对小麦籽粒锌含量及其生物有效性的影响等方面的研究。通过以上工作,得到了以下主要结果:1.采用螯合-缓冲营养液对小麦进行了苗期培养试验,在3个P水平(0、0.6、3.0 mmol·L^-1)和3个Zn水平(0、3、30μmol·L^-1)的完全组合下对小麦苗期的磷锌关系进行了研究。结果表明,在小麦苗期,磷锌的缺乏与过量均抑制小麦生长,磷缺乏比供磷过量的抑制程度更大,而供锌过量比锌缺乏的影响更为强烈,磷缺乏和供锌过量主要影响小麦幼苗分蘖和地上部干物质积累。供磷过量时,小麦根部存在着明显的P-Zn拮抗,抑制了根部的锌吸收,但供磷却提高了锌在小麦植株体内向地上部转运;锌缺乏时,小麦叶片会积累大量的磷,而供锌则会抑制磷在小麦植株体内向地上部的转运。在小麦苗期,磷、锌均处于正常水平时其交互作用有利于锌的吸收和向地上部转运,但抑制了磷向叶部的转运。2.螯合-缓冲营养液小麦苗期培养试验结果还表明,在小麦幼苗中锌与铜的吸收存在明显的拮抗作用,但供锌则促进了锌和铜的转运,而锰转运则受到了抑制;过量供锌时,大量锌被转运到冠部,同时明显抑制了铁锰铜的吸收总量;磷的供应显著地抑制了铁的吸收,但磷的供应提高了锌、铜、锰的转运率;磷、锌在对锌与铁、铜、锰间吸收竞争的影响中,锌本身的影响要比磷的影响更为明显,供锌明显促进了小麦幼苗对锌的吸收;在小麦幼苗冠部,锌与铁的竞争中,供磷利于锌的吸收,缺磷则利于铁的吸收;锌与铜及锌与锰间的竞争中,缺磷时利于锌的吸收,供磷则利于铜和锰的吸收。3.采用螯合-缓冲营养液进行了小麦全生育期培养试验,试验中P设4个水平:0.1、0.6、3.0、6.0 mmol·L^-1,Zn设2个水平:0和3.0μmol·L^-1;完全设计,探讨了供P供Zn对小麦P-Zn关系以及小麦籽粒中锌与植酸含量的影响。结果表明,供锌后,小麦籽粒锌含量和吸收量分别是不供锌的2.74和3.64倍,植酸含量及植酸与锌的摩尔比分别降低了9.64%和68.19%,供锌还增加了小麦籽粒干重,提高了小麦籽粒磷含量,促进了磷向籽粒中转运,同时也提高籽粒中锌的转运率;小麦根部存在明显P-Zn拮抗。小麦籽粒中植酸含量随磷供应浓度的增加而增加;过量供磷抑制了小麦对锌的吸收,阻碍了锌向小麦籽粒中转运;且小麦籽粒中磷的转运率随着磷供应量的增加而降低。4.在田间采用再裂区设计进行了小麦磷锌肥配施试验,其中主因子为小麦基因型,依次为郑麦9023、西杂1号、小偃22、中育6号;副因子为磷肥,设5个水平,分别为:0、50、100、150、200 kg P₂O₅·hm^-2;副副因子为锌肥,设2个水平,即0、7 kg Zn·hm^-2。结果表明,在潜在缺锌土壤上,土施锌肥对小麦产量无明显影响,施用磷肥可显著增加其产量;供试的小麦基因型对锌肥的反应存在着基因型差异;施磷量在0～150 kg P₂O₅·hm^-2时,籽粒中磷锌含量均随施磷量的增加而增加,但在施磷量为200 kg P₂O₅·hm^-2时施磷则降低了籽粒中锌含量;磷肥施用显著地增加了小麦籽粒的植酸含量及植酸/锌摩尔比,锌肥施用对小麦籽粒的植酸含量无明显影响,但在施用磷肥的条件下施用锌肥则降低了小麦籽粒植酸/锌摩尔比。5.在潜在缺锌土壤上,采用再裂区设计对小麦进行了连续两年的田间锌肥喷施试验,主因子为喷锌时期,分别为:拔节期（4月1日～4月15日）,扬花期（4月15日～4月29日）,灌浆前期（4月29日～5月13日）和灌浆后期（5月13日～5月27日）。副因子为氮肥,设3个水平:0,120 kg·hm^-2,240 kg·hm^-2;副副因子为锌肥,设2个水平:喷施蒸馏水,喷施锌溶液。结果表明,喷锌后,第一年和第二年小麦籽粒中锌含量分别增加51.65%和73.53%,植酸含量分别降低11.06%和16.84%,植酸与锌的摩尔比分别下降了42.45%和52.45%;在不同时期喷锌处理中,喷锌后两年小麦籽粒锌含量顺序为:灌浆前期>灌浆后期>扬花期>拔节期,且两年小麦籽粒锌含量及其增幅均在灌浆前期最大,锌含量分别为59.71和54.63 mg·kg-1,增幅分别67.35%和107.48%;植酸/锌摩尔比减幅均在灌浆前期喷锌时最大,分别降低47.24%和59.12%。喷锌后小麦籽粒锌含量增幅在不施氮较施氮更加明显。喷锌降低了小麦籽粒磷含量,但喷锌对小麦籽粒磷含量的影响要远远小于其对籽粒锌含量的影响;氮素是影响小麦籽粒蛋白质含量的主要因素,随着施氮量的增加小麦籽粒蛋白质含量明显增加。6.连续两年喷锌试验结果还表明,在潜在缺锌土壤上,喷施锌肥后,小麦籽粒的铁平均含量在第一年和第二年分别提高12.4%和12.9%;但灌浆期喷锌会降低小麦籽粒的铜含量,而喷锌对籽粒锰含量无明显影响;喷锌后小麦籽粒锌铁铜锰吸收总量第一年和第二年分别增加17.8%和19.9%;喷锌后小麦籽粒植酸含量的下降也提高了其铁锰铜生物有效性。施用氮肥还增加了籽粒锌铁铜锰的吸收总量;施用氮肥也同时降低小麦籽粒植酸含量。综上所述,本研究可以得出以下主要结论:（1）小麦中,P-Zn拮抗作用主要发生在小麦根部,但在其他器官内也会发生;且不仅在二者配比不合理时发生,即使在配比合理时也会发生。（2）在潜在缺锌的石灰性土壤上,土施锌肥对提高小麦籽粒锌营养品质效果不明显,喷施锌肥是较好的选择。适量施磷时可以增加小麦籽粒锌含量,过量施磷时,籽粒中也会发生磷锌拮抗。（3）灌浆前期是提高小麦籽粒锌含量和生物有效性的最佳喷锌时期,喷施锌肥既大幅增加了小麦籽粒锌含量,也明显降低了其植酸含量,因此显著提高了小麦籽粒锌营养品质,从而可以有效改善从饮食中摄取锌营养较少且以小麦为主要食物来源的缺锌人群的健康状况。更多还原

【Abstract】 Wheat is as a staple food for the north residents especially the rural areas of the population in China. Daily calories and minerals uptake is mainly derived from wheat. However, wheat was mainly grown in calcareous soil in which the amount of DTPA-Zn was among 0.5-1.0 mg·kg^-1. Low available Zn in soil attributed to the low grain Zn concentration. Some anti-nutrients also existed in wheat grain, especially phytic acid which is the mainly storage form of P in grain. High phytic acid content could significantly reduced Zn bioavailability and then the absorption of Zn in human body was relatively reduced. Therefore, improving grain Zn concentration and bioavailability in calcareous soil has become equally important.There are litter researches about Zn fertilization on wheat grain Zn concentration and bioavailability in China. It is generally accepted that there is a significantly interaction between Zn and P. P had a significantly negative effect on Zn absorption. A question should be raised that how to improve grain Zn concentration and reduce phytic acid on the condition that P fertilization was also at a high level in wheat field. In order to study the interaction between P and Zn and effect of Zn fertilization on grain Zn concentration and bioavailability in calcareous soil, a hydroponic and a field experiment was carried out. These researches included effect of P combined with Zn fertilization on grain Zn concentration and other micronutrients and effect of P combined with Zn supplied to soil and foliar spray of Zn in different wheat growth stages on grain Zn concentration and bioavailability. The main results from our studies were as follows:1. A nutrient solution experiment was conducted to investigate the interaction of Zn and P nutrition of wheat plants at the seedling stage in chelater-buffered solution. Zn rates were supplied at three levels of 0, 3 and 30μmol·L^-1, P was also designed in three rates, namely, 0, 0.6, 3.0 mmol·L^-1. The results showed that the growth of the wheat seedlings were decreased under the deficient or excessive supply of P and Zn, the effect of deficient P supply was more remarkable than that of the excessive P supply, and the effect of excessive Zn supply was stronger than that of the deficient Zn supply; the effects of deficient P supply and excessive Zn supply were mainly reflected in the tillers and the biomass of shoot. The obvious content of the roots were decreased, but the translocation rate of Zn was increased when P was supplied. A large mount of P were accumulated in the leaves of the wheat under the condition of Zn deficiency, and the translocation rate of P was decreased by the supply of Zn.2. In addition, in wheat seedling plant, there was obvious antagonism between Zn and Cu at wheat seedling stage, but the translocations from root to shoot of Zn and Cu were increased under the supply of Zn, while that of Mn was decreased; A large mount of Zn was transported to the shoot under excess Zn supply, and the total translocation of （Fe+Cu+Mn） was decreased drastically at the same time. The uptake of Fe was inhibited by the P supply, but the translocation ratio of Zn, Cu and Mn increased under the P supply; the effect of Zn itself was more remarkable than P on the uptake between Zn and Fe, Cu, Mn, the uptake of Zn was increased obviously under the Zn supply. To the shoot of wheat seedling, the uptake of Zn was easier than Fe under P supply, but the uptake of Fe overmatched that of Zn without P supply; For Zn and Cu, the uptake of Zn excelled that of Cu with no P supply, but the uptake of Cu outbalanced Zn after P supply, the same as the uptake between Zn and Mn.3. To investigate the effects of supplying Zn and P on the harvest wheat plant, an experiment in chelater-buffered solution was conducted, P rates were supplied at three levels of 0.1, 0.6, 3.0 and 6.0 mmol·L^-1, Zn was designed in two rates of 0 and 3.0 mmol·L^-1. The results indicated that when supplying with Zn, the Zn concentration and content of wheat grain were 2.74 and 3.64 times to those of no Zn supplying, respectively, the concentration of phytic acid and the molar ratio of phytic acid to Zn of wheat grain was decreased by 9.64% and 68.19% under Zn supply compare to no Zn supplying, respectively; In addition, the dry weight of wheat grain was increased under Zn supplying, so did the concentration of P, and the translocation of P and Zn to wheat grain were also increased by Zn supplying; There was obvious P-Zn antagonism in roots of wheat; The uptake of Zn to wheat was depressed when excess P supplying, and the translocation of Zn to wheat grain was inhibited too; moreover, the translocation of P decreased with the elevation of P supply.4. A field experiment with zinc and phosphorus fertilization using split-split design was conducted. The main factor was wheat genotype, namely Zhengmai9023, Xiza1, Xiaoyan22 and Zhongyu6. The sub-factor was P fertilizer, P rates were supplied at three levels of 0, 50, 100, 150 and 200 kg P₂O₅·ha^-1, sub-sub-factor was zinc fertilizer, Zn was designed in two rates of 0 and 7.0 kg Zn·ha^-1. The results indicated that in potentially zinc deficiency soil, there was no obvious influence of zinc fertilization on the yield of wheat, but phosphorus fertilization performed well. The effects of zinc fertilization on different wheat genotypes were various. The synergism between phosphorus and zinc happened at the rate of 0¹50 kg·ha^-1（P₂O₅）, but there was an antagonism between phosphorus and zinc when the phosphorus fertilization reached more than 200 kg·ha^-1（P₂O₅）. The effect of phosphorus was stronger than that of zinc in the interaction of them. The phytic acid concentration and the phytic acid to zinc molar ratio increased remarkably with phosphorus fertilization. There was no evident effect of zinc fertilization on the concentration of wheat grain, but zinc supply decreased the phytic acid to zinc molar ratio on the condition of phosphorus fertilization.5. In order to investigate the effect of foliar application of zinc on zinc nutritional quality of wheat grain on potentially zinc-deficient calcareous soil. Field experiments using split-split design of foliar application of zinc were carried out in 2007-2008 and 2008-2009 cropping seasons. The main factor was zinc spraying stage, namely, jointing stage, flowering stage, early grain filling stage and late grain filling stage. The sub-factor was nitrogen fertilization, N rates were supplied at three levels of 0, 120 and 240 kg N·ha^-1. Sub-sub-factor was zinc rate; two Zn rates of spaying with Zn and without Zn （distilled water）. The results showed that the Zn concentrations of wheat grain of the first and the second cropping season were increased by 51.65% and 73.53% after foliar application of zinc, respectively; the concentrations of phytic acid were decreased by 11.06% and 16.84%, respectively; and the molar ratios of phytic acid : zinc were decreased by 11.06% and 16.84%, respectively. The zinc concentrations of two cropping seasons after foliar application of zinc were in the order of early-filling stage > late-filling stage > flowing stage > jointing stage; The zinc concentrations and their increasing rates of wheat grain of two cropping seasons were both highest when foliar application of zinc at earlier filling stage among the four different growth stages, the zinc concentrations of wheat grain of the first and the second cropping season were 59.71 and 54.63 mg·kg^-1, respectively, and the increasing rates were 67.35% and 107.48%, respectively; so did the decreasing rates of the molar ratios of phytic acid: zinc; and they decreased by 47.24% and 59.12%, respectively. The increasing rates of zinc concentrations of wheat grain of two cropping seasons were more significant with no nitrogen fertilization than that with nitrogen fertilization. The concentration of P of wheat grain was decreased by zinc foliar application, but the effect of zinc spraying on the concentration of P was much smaller than that of the concentration of zinc. Nitrogen was the main factor to the concentration of protein of wheat grain, and the protein concentration increasing visible along with the increasing nitrogen fertilization.6. In the field experiment of zinc spraying, during the first and second year, Fe concentrations were increased by 12.4% and 12.9% on average, but foliar Zn application at seed filling stage decreased the Cu concentration wheat grain, and there was no significant effect of Zn spraying on the grain Mn concentration, the total content of（Zn+Fe+Mn+Cu）of wheat grain were increased by 17.8% and 19.9%, the phytic concentration decreased by 11.06% and 16.92%, respectively; so the availability of micronutrients were improved. N fertilization decreased grain Mn concentration, but increased the total content of （Zn+Fe+Mn+Cu）, and it decreased the phytic acid concentration of wheat grain.To sum up, some conclusions can be made as follows: （1） the antagonism of Zn and P exists mainly in the roots, and it also will happen in other organs of wheat; This antagonism not only occurs when the levels of P and Zn are abnormal but also occurs even when P and Zn is well-balanced. （2） On potentially zinc deficient soil, zinc fertilization has no remarkable effect on the zinc nutritional quality of wheat grain; foliar zinc application is the better choice. (3 The optimum time of zinc spraying is the early-filling stage, the zinc concentration of wheat grain can be increased obviously by zinc spraying at this growth stage, and the phytic acid concentration also can be decreased by doing so. The zinc nutritional quality can be improved remarkably when foliar zinc application is conducted at early grain filling stage.更多还原