不同供镁水平对不同时期小麦幼苗生长速率的影响

以小麦(Triticum aestivum)为试材，采用砂基培养的方法，在镁浓度分别为对照组的0%、50%、100%、150%、200%和300%的营养基质上，培养剔除胚乳后的二叶期小麦幼苗7d、15d及30d，并分别测定该3个时间段小麦幼苗的株高、根长、地上部和地下部的生物量、叶绿素含量、根系活力以及相对生长速度（RGY）、相对生长速率（RGR）和根冠比等指标，研究不同供镁水平对不同时期小麦幼苗生长速率的影响。结果表明，缺镁（0%）严重影响了小麦全株的生长，供镁不足（50%）促进根系生长但抑制地上部分的生长，供镁轻度过量（150%、200%）对小麦生长发育影响较小，但过量供镁（300%）对小麦生长发育影响较大，且对根系的影响比对地上部的影响更显著。不同供镁水平处理小麦幼苗时，无论是7d、15d还是30d，RGR均随RGY的变化而变化，但二者在小麦幼苗的地上部均呈极显著正相关，而在根系二者的相关性不显著。另外，3个时期小麦幼苗的RGR和RGY，均以15d最高，7d次之、30d最低。

Influences of Different Magnesium Levels over the Growth Rate for Different Stages of Wheat Seedlings

With the Sand culture method, influences of different magnesium levels (0%、50%、100%、150%、200% and 300%) was explored to the wheat seedlings of different stages. Many targets such as plant height, root length, biomass, content of chlorophyll, activity of root, RGY, RGR and ratio of root to crown of the wheat were mensurated at the time of 7d, 15d and 30d of two leaves stage of wheat seedlings after their endosperms were removed at different magnesium levels.The results showed that different magnesium levels had unlike influences over the wheat seedlings. The growth of whole wheat was suffered seriously influence when magnesium was lacked（0%）; promoting root growth and restraining the other parts growth happened when magnesium was deficient（50%） and there was a little influence when magnesium was excessive（150%、200%）, but with magnesium content addition（300%）, the influence became visible, especially for the roots of wheat. In the different magnesium level treatments, RGR vary with RGY, particularly prominent for the ground parts of wheat, but not for the roots. It showed that the variation rate of biomass was influenced mainly by leaf length for ground parts of the wheat and for the root, influenced not only by the primary root length, but also by the secondary roots. In addition, in the terms of RGR and RGY of 3 stages of wheat seedlings, the result was 15d>7d>30d.