| [Object] Se is an essential trace element for human beings. It is an effective method to increase the intake of humans by improving the crops Se content. So the effect of different species Se application on its uptake and translocation of wheat were investigated with the sand culture experiment and field experiment. The content and distribution of different forms Se in wheat were evaluated in this study. The objective is to explore the absorption and transport mechanism of different species Se and to provide a basis for the Se-rich of spring wheat.[Method] The experiment included sand culture experiment and filed plot experiment. The sand culture experiment was used two species of Se as Se O32-and Se O42- under root and foliar application. The root application was applied at rates of 0, 0.5, 1 and 2 mg Se/pot. The foliar application was applied at rates of 0, 5,10 and 20 mg Se/L. And in the foliage treatments, 30 m L of Se solution was applied to each pot. The Se fertilizer was applied at heading stage.The field plot experiment was designed two Se species with Se O32- and Se O42-. And the application methods were performed by fertigation and foliar application. The three Se application rates under fertigation were set as 300, 600, 1200 g Se/hm2. The foliar application were set three Se application rates as5, 10, 20 mg Se/L. And in the foliar application treatments, 750 L/hm2 of Se solution was applied. No Se fertilizer was applied in the control treatment.[Result](1) Under different species Se by root application, the total Se content in the Se4+ treatments of wheat organs followed the order by roots> spikes> stems> leaves at mature stage, while it was in the order in the Se6+ treatments by spikes > leaves > stems> roots. The absorption Se4+ had mainly accumulated in the roots,and the most of Se6+ was transported to shoots. The total Se content of wheat organs both in the Se4+ and Se6+ treatments was in the order by spikes> leaves> stems> roots under foliar application. Most of Se was transpored to grain by foliar application. The Se content of wheat spikes in the Se6+ treatments was higher than in the Se4+ treatments at two methods. And the exogenous Se by foliar application in the spikes was higher than that by root application.(2) Under different species Se application, the content of Se4+ and Se6+ in the Se4+ treatments by root application was in the order as roots> spikes> leaves> stems, and the organic Se followed by roots>spikes> stems> leaves. While Se4+, Se6+ and organic Se content in wheat organs in the Se6+ treatments followed as the order by leaves> spikes> stems> roots, roots> leaves> spikes> stems and spikes> leaves>stems> roots, respectively. Under foliar application of exogenous Se, the Se4+ content in the Se4+ treatments followed as leaves> stems> spikes> roots, while it was leaves> spikes > stems > roots in the Se6+ treatments.Both the Se6+ and organic Se were in the order of spikes> leaves> stems > roots.(3) When applied Se4+ at roots the proportion of organic Se was the highest, followed by Se(VI) at roots and spikes and the Se(IV) was the less. What’s more, the proportion of organic Se and Se(VI) in roots were higher than those in spikes; When applied Se6+, it was Se(VI) that accounted for the most both roots and stems. The proportion of different species Se in leaves and spikes followed the order by organic Se>Se(VI)> Se(IV)。The organic Se, Se(VI) and Se(IV) of leaves and spikes in the Se6+ treatments were higher than those in the Se4+ treatments. Foliar application of Se the organic Se was the most in wheat and it mainly existed in spikes. And the Organic Se could achieve 50% on average. Spraying Se4+ wheat stems and leaves of Se(IV) was the highest. While the proportion of organic Se in stems and spikes was the highest in the Se6+ treatments. There was no significant difference between two species Se at the proportion of organic Se in spikes.(4) Both the two species Se applied by fertigation and foliar application could significantly increase the Se content of wheat grain in drip irrigation. And the Se content increased as the application amount.Except the application rate at 1200 g/hm2 by fertigation the grain Se content exceeded the selenium-rich cereal standards of China, the other rate under fertigantion treatments or foliar application treatments can satisfy the standards.(5) Conversion ratio of wheat grain in the Se4+ treatments were increased as the Se application amount.The Se6+ treatments increased and then decreased as the amount of Se application increased. Either the fertigation or foliar application, the highest conversion ratio was observed in the Se6+ treatments. The highest conversion rate in the fertigation was 60.6% at Se rate of 600 g/hm2, and the foliar application was62.7% at Se application rate as 15 g/hm2.(6) With the Se application amount increasece, the Se fertilizer use efficiency in the drip fertigation treatments reduced. By contast, Se fertilizer use efficiency in the foliar application increased and then decreased as the amount of Se increased. Se fertilizer use efficiency in the foliar application treatments was2.1 times higher than that in the drip fertigation application treatments. Both the drip fertigaiton and foliar application, the Se fertilizer use efficiency in the Se6+ treatments was higher than in the Se4+ treatments.[Conclusion] When supplied with Se4+ at roots, organic Se was the most in wheat organs. The absorption of the Se4+ had mainly been accumulated in roots. Where most of Se was organic Se, and the Se6+ was a little.When supplied with Se6+ at roots, Se6+ was transported from roots to shoots. In which Se6+ was reduced to Se4+and organic Se compounds in leaves. While foliar application of Se, the Se was directly converted in leaves, and the most of Se was accumulated in shoots. The absorption of Se in the Se6+treatments was better than in the Se4+ treatments at both methods, and the foliar application was better than root application of Se. The reference amount of Se by fertigation was 600 g/hm2 in filed, while it was 15 g/hm2 by folair application.And the absorption of Se6+was better than Se4+ at two methods. |
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