不同沙土配比基质对岗松幼苗根系形态及营养吸收的影响

Effects of Substrates with Different Sand-soil Ratios on Root Morphology and Nutrient Absorption of Baeckea frutescens Young Seedlings

为了探讨岗松(Baeckea frutescens)根系在养分受限时的适应对策,以1年生岗松幼苗为试验材料,设置5个不同养分梯度的沙土混合基质,研究岗松幼苗的根系形态、功能、不同径级根系变化规律以及养分吸收特征。结果表明,养分受限严重时岗松幼苗整体生长受到严重抑制,但根冠比显著上升,幼苗选择将生长资源向地下部分转移,增加根系功能来适应逆境;养分受限程度较轻时,幼苗的根长和比根长变长,根表面积变大,细根比例增加,扩大根系在土壤中的范围提高吸收能力;养分充足的条件下,幼苗粗根比例上升,根直径增加,比根长下降,生长资源向地上部分转移,以提高植物抗逆性和降低根系生长率;根系形态的变化与磷元素的吸收、运输和积累关系密切,基质养分的增加也主要促进了幼苗对磷元素的吸收。

Adaptive strategy of roots of Baeckea frutescens young seedlings when nutrient limitation was explored.Taking B.frutescens annual seedlings as materials,root morphology,function,regulation of different root diameters and nutrient absorption were analyzed with five different levels of nutrient supply.Results showed that growth of the whole plant was inhibited when nutrients were severely limited,but root-shoot ratio increased.Seedlings tended to transfer growth resources to roots and increased root function to adapt to adversity.Root length,root surface area,specific root length and proportion of fine roots increased when nutrients were slightly limited.Seedlings tended to expand root range in soil to improve absorption capacity.Proportion of thick roots and root diameter increased,but specific root length decreased when nutrients were sufficient.Resources were transferred to aboveground to improve stress resistance and reduce root growth rate.Change of root morphology was closely related to phosphorus absorption,transportation and accumulation.Increase of substrate nutrients promoted phosphorus absorption of seedlings.