低磷胁迫对红豆草根系构型的影响

Effects of low phosphorus stress on root architecture of sainfoin

为研究低磷胁迫对红豆草根系构型的影响,本试验采用营养液沙培法,对生长80 d的5份红豆草材料进行常规磷(1.00 mmol·L^(-1) KH_(2)PO_(4),NP)和低磷胁迫处理(0.01 mmol·L^(-1) KH_(2)PO_(4),LP),分别在处理后0、12 d和24 d采样分析根系平面几何构型和立体几何构型的差异。结果表明,低磷胁迫下,供试红豆草根长增大,磷敏感红豆草6在胁迫12 d和24 d时增幅最大,分别较胁迫0 d增加了25.60%、35.06%,而其根表面积、根体积、根平均直径和根尖数的增长明显受到抑制,且随胁迫天数增加,抑制效果显著。随胁迫天数的增加,供试材料的最长根系通道内部连接总数增加,根系外部连接总数减少,胁迫24 d时,耐低磷红豆草5的外部连接总数降幅最大,较胁迫0 d下降了26.49%;供试材料的拓扑指数均较小,接近0.5,根系构型接近叉状分支,随胁迫时间的延长,拓扑指数增大,根系构型有向鱼尾形过渡的趋势,胁迫24 d时,与NP相比,耐低磷红豆草5和10295的拓扑指数增幅最大,分别为12.85%和12.91%;各材料分形维数随着胁迫天数的增加而增大,分形丰度则降低,胁迫24 d时,耐低磷红豆草5的分形维数增幅最大,分形丰度降幅最小,分别较胁迫0 d增加5.71%和降低4.69%。表明耐低磷红豆草5通过改变根系构型适应逆境条件的能力更强。

To study the effects of low phosphorus stress on the root architecture of sainfoin,five sainfoin materials grown for 80 days were treated with constant normal phosphorus(1.00 mmol·L^(-1) KH_(2)PO_(4),NP)and low phosphorus stress(0.01 mmol·L^(-1) KH_(2)PO_(4),LP)by nutrient solution sand culture method.Samples were taken at 0,12 days and 24 days respectively,and the planar and three-dimensional geometric architecture of roots were studied.The results showed that under low phosphorus stress,the root length increased,and the phosphorus sensitive sainfoin 6 had the largest increase at 12 d and 24 d of stress,by 25.60%and 35.06%,respectively.However,the root surface area,root volume,root average diameter and root tip numbers were significantly inhibited,and with the increase of stress days,the inhibitory effect became more significant.The total number of internal connections of the longest root system channel of the tested material increased,while the total number of external connections of the root channel decreased.At 24 d of coercion,the low-phosphorus tolerant sainfoin 5 had the largest decrease,with a decrease of 26.49%.The topological index of the tested materials were all small,close to 0.5,and the root architecture was close to dichotomous branching,which increased with the extension of stress time,and had a transition to herringbone branching.At 24 d of stress,the topological index of low-phosphorus tolerant sainfoin 5 and 10295 increased the most,12.85%and 12.91%respectively.The fractal dimension of each material increased with the increase of stress days,while the fractal abundance decreased.At 24 days of stress,the increase of fractal dimension of low-phosphorus tolerant sainfoin 5 was the largest,and the decrease of fractal abundance was the smallest,which was 5.71%and 4.69%higher than that at 0 days of stress,respectively.Indicating that low-phosphorus tolerant sainfoin 5 had a stronger ability to adapt to the stress conditions by changing the root architecture.