| In recent twenty years, one important infant science, application of RE in agriculture is developed in China. Addition of RE with appropriate dose can raise crop production and improve crop quality, which has been confirmed by many experiments. However, its mechanism has not been fully understood.The splitting and elongating of cell is a basis of plant growth. Plant endogenous hormones play a vital role in the ongoing process that the cell split and elongate. Plant growth regulators can control plant growth in good ways, which have been directly applied to plant. Rare earth elements can also adjust the growth process of plant.This experiment adopts rice as treated crop and studies rare earth elements La ,Ce on hormones counterbalance and nutrition elements N, P, K absorption in rice seedlings, and relationship between endogenous hormones levels and nutrition elements, by the way of water incubation ,combined with analysis of indoors. Our aim is to search for the relationship between rare earth and hormones counterbalance, then to provide academic reference data for the mechanism of the effects of rare earth elements on crops and the safety evaluation of rare earth used in agriculture.This experiment concentration treated with La, Ce is 0mg/L, 1mg/L, 2.5mg/L, 5mg/L, 10mg/L, 25mg/L, 50mg/L, and 100mg/L respectively. In addition, set CK group-not sprayed with exogenous hormones, sprayed with exogenous GA group and sprayed with MET group. Four endogenous hormones IAA, GA, ZT and ABA are determined with high performance liquid chromatography. Nutrition elements N, P, K, are determined with classical methods.By analyzing theorically, that rare earth can speed plant growth must have some relationship with growth hormones in plant, which can speed growth. The study results have also been confirmed from this experiment. Endogenous hormones levels in leaves and roots of rice seedlings are influenced differently by rare earth and the effects on the latter are more distinct than the former. Three endogenous hormones IAA, ZT, ABA change differently under effect of different dosages rare earth.The study results have proved:1. Endogenous IAA levels in leaves and roots of rice seedlings have been restrained by La.2. Endogenous GA levels in leaves and roots of rice seedlings have been raised by low dosages La, Ce and maximize stimulus dosages are all 10 mg/1. Otherwise, they have all been restrained by high dosages.3. Endogenous ZT levels in leaves and roots of rice seedlings have been raised by La and maximize stimulus dosage are 25 mg/1, 10 mg/1 respectively.4. Ce have raised endogenous IAA levels in leaves and maximize stimulus dosage is 2.5 mg/1, but only at 5mg/l can rise that in roots, other dosages have restrained addition of that.5. Ce have been raised endogenous ZT levels in roots, and maximize stimulus dosage is 10 mg/l, but have restrained their addition in leaves.In addition, spraying exogenous hormones can also regulate plant growth. When spraying exogenous GA, endogenous IAA, GA levels in roots and leaves, and endogenous ZT levels in roots of seedlings have all been raised. When spraying MET, endogenous IAA, ZT levels in roots and leaves and endogenous GA levels in leaves of seedlings have all been restrained.When treated with rare earth elements, endogenous hormones levels in roots and leaves of seedling in sprayed exogenous hormones group have been changed.La, Ce in low dosages have both raised endogenous IAA, ZT levels in leaves of seedlings in sprayed with exogenous GA group. La has also raised endogenous GA levels in leaves of seedling in that group, but Ce only in 10 mg/L can raise addition of that. La has restrained endogenous IAA levels in roots of seedlings in that group, but has raised endogenous GA, ZT levels in that group. Ce has raised endogenous ZT levels in roots in that group, but only 2.5 mg/1 can raise endogenous IAA levels, and in 4-14 mg/1 can raise endogenous GA levels.La, Ce in low dosages have both been raised endogenous IAA, GA level... |
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