| Zn(Zn) is an essential element for the growth of wheat, and constitutes the component and activator for many enzymes that participate in the metabolism of nitrogen(N) and synthesis of auxin in plants. However, due to the low application of organic and micronutrient fertilizers in recent years, soil available Zn concentration is low and plants are always deficient in Zn, especially on calcareous soils in northern China. When the soil available Zn supply is insufficient, Zn fertilization is often used to remedy the problem. In order to fully play Zn fertilizer efficiency on plant growth, a field experiment was carried out to study the effect of spraying Zn fertilizer and Zn + three kinds of fertilizer additives(Urea, EDTA, Tween) respectively at booting stage on dry matter, N and Zn uptake, photosynthetic characteristics and yield. Results obtained are summarized as follows:(1). Zn fertilizer additives could to a certain extent improve Zn absorption and uptake amount in wheat.The foliar application of Zn fertilizer alone and Zn + additives together increased the Zn content of wheat in different aboveground parts: by 6.3- 13.5% on average and by 2.9-28.3% at maturity compared to the control. Although the differences between Zn + three additives and Zn treatments were not significant in Zn contents, additives addition made Zn contents increased by 4.5% of the total Zn uptake amount compared with Zn treatment alone, and addition of 1% urea was found to be the highest in Zn content.(2). Additive effect of Zn fertilizer on wheat N uptake.The foliar application of Zn fertilizer raised wheat N content in aboveground parts at the late growth stages. The mass fraction of N in wheat leaf, stem, sheath and spike at heading stage was higher than the mature period. Compared with other two additives, addition of 1% urea increased the total N uptake by 14.7% compared with the control, and 8.4% compared with Zn addition without additives.(3). Addition of additives improved the photosynthetic rates while reduced intercellular carbon dioxide concentrations of wheat.Addition of additives showed significant impacts on wheat flag leaf photosynthetic rate. Application of Zn +EDTA had the largest effect on the wheat flag leaf photosynthetic rate, followed by Zn + Twain. Although the three additives had no significant effects on stomatal conductance, they significantly reduced the intercellular carbon dioxide concentration of blades. For example, the intercellular carbon dioxide concentration was reduced by 6.3% due to spraying 1% urea. In addition, the Zn + EDTA significantly improved wheat flag leaf chlorophyll content, and intensified wheat flag leaf photosynthesis.(4). Effect of additive of Zn fertilizer on wheat dry weight.Spraying Zn fertilizer improved all parts of wheat aboveground dry weight, with an increase of averaged 6.5%. Of the treatments, the effect of 1% urea was significant while the effect of Twain and EDTA was not significant. Spraying Zn fertilizer plus 1% urea was beneficial for leaf and panicle weight increase at booting stage, and for stems increase at mature.(5). Foliar application of Zn fertilizer and Zn plus additives had a certain effect on yield increase.Spraying Zn fertilizer plus 1% urea increased wheat yield by 383 kg ha-1 compared to spraying Zn alone, and 650 kg ha-1 or rates 5.9-10.5% compared to no Zn addition. The Zn + EDTA increased wheat yield by 4.5%. Of the yield-building components, grain weight increase was the dominant factor that was influenced by Zn addition. |
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