利用多视角图像法分析番茄幼苗根构型对氮水平的响应

【目的】 根系作为植物从环境中获取氮素的重要器官，如何无损并高效地获取其特征参数值是当今研究热点。随着高清成像技术的迅速发展，基于多视角图像法是研究植株根构型无损测量的新型方法。本研究对根系多视角成像系统和 GIARoot 软件平台相结合的多视角图像分析法精度进行了较系统的评估。并利用此套系统动态定量分析了不同氮素水平对番茄幼苗根构型的影响，为进一步研究植物根构型与矿质元素互作提供新的手段和依据。 【方法】 本研究以“中杂 109”番茄为材料进行水培试验，设置 4、12、20 mmol/L 3 个氮处理，分别以 N4、N12、N20 表示，定植于透明玻璃柱中 16 d。利用自行设计的根系多视角成像系统获取每天根系 360°图像序列，并基于 GIARoot 软件平台对图像序列进行根系特征参数的定量计算，在第 16 d 时将根系进行破坏性取样，将 GIARoot 基于无损测定分析的图像系列结果与 WinRHIZO Pro 的破坏性取样根系扫描图的计算结果进行对比评估。 【结果】 GIARoot 与 WinRHIZO Pro 根系特征参数评估结果总体上线性回归斜率在 0.96～0.99， R2 均为 0.99， RE 为 2.95%～12.69%，根总长、根总表面积、根总体积和根平均直径的 RMSE 分别为 44.73 cm、4.96 cm2、0.09 cm3、0.05 mm，各个根系特征参数差异均不显著 ( P > 0.05)。在 N4、N12、N20 3 个氮处理下，番茄幼苗定植 16 d 内各根系特征参数值均为 N12 处理最大，且 N20 的根总长、根总表面积、根垂直投影面积、根总体积分别比 N4 的高 14.2%、13.2%、35.8%、27.7%，而 N4 的横截面最大根个数、一级侧根个数分别比 N20 的高 28.2%、30.4%。不同氮水平间，第 4 d 根总长、根总表面积、根垂直投影面积出现显著性差异 ( P < 0.05)，N12 分别比 N20 显著高 113.9%、153.7%、113.8%。第 12 d 根总体积、横截面最大根个数出现显著性差异 ( P < 0.05)，N12 分别比 N20 显著高 57.0%、117.9%。而根平均直径 16 d 内无明显差异 ( P > 0.05)，均在 0.42～0.54 mm。 【结论】 利用将多视角成像系统和 GIARoot 软件平台结合的多视角图像法，进行无损测量获取根系特征参数值是可行的。通过对不同氮水平下番茄幼苗各根系特征参数分析表明，适当提高氮浓度可以促进番茄幼苗根系生长，20 mmol/L 的高氮对根系生长具有抑制作用，且相对于根总长、根总表面积、根垂直投影面积、根总体积，这种抑制对侧根数量尤为明显，氮素浓度对根平均直径影响最小。

Analysis of nitrogen effects on root system architecture of tomato seedlings using the multi-view images method

Objectives]Root is an important plant organ of obtaining nutrient from soil. Therefore, how to obtain root parameter values nondestructively and efficiently is a current research hotspot. With the rapid development of high-throughput imaging technology, nondestructive measurement based on multi-view images has become a new method to study root system architecture. In this study, precision of the root multi-view imaging system combined with GIARoot parameter analysis platform was accurately assessed. Then, effects of different N levels on root system architecture of tomato seedlings were analyzed dynamically and quantitatively. This multi-view imaging system can provide the basis for further study on the interaction of root system architecture and mineral elements.[Methods]Three N treatments were designed in the experiment, namely, N concentrations of 4, 12 and 20 mmol/L, indicating as N4, N12 and N20. Under the hydroponic condition,“Zhong Za 109” tomato seedlings were planted for 16 days in transparent glass column. The self-designed root multi-view imaging system was used to obtain daily image sequences around the growing root system. Then, root characteristic parameters along the plant growth were quantitative calculated with the GIARoot platform according to the photographed root system nondestructively. At the final measurement (16 d after the planting), destructive measurements were done on root system and analyzed with WinRHIZO Pro software, and the results were compared with GIARoot plantform.[Results]There were no significant differences on each root characteristic parameter between the GIARoot and WinRHIZO Pro (P> 0.05). The slopes of the linear regression between the parameters using the two methods were between 0.96 and 0.99, and values ofR2were all 0.99 and REs ranged from 2.95% to 12.69%. The RMSEs of network length, network surface area, network volume and average root diameter were 44.73 cm, 4.96 cm2, 0.09 cm3and 0.05 mm, respectively. Each root characteristic parameter of the N12 was the largest on the16th day among the treatments of N4, N12 and N20. The network length, network surface area, network area and network volume of the N20 were 14.2%, 13.2%, 35.8% and 27.7%, respectively, higher than those of the N4. However, the maximum number of roots and the number of primary lateral roots of the N4 were 28.2% and 30.4% higher than the N20, respectively. In addition, significant differences were found on the network length, network surface area and network area between the three N treatments on the 4th day (P< 0.05), and the values of them of the N12 were 113.9%, 153.7% and 113.8% higher than the N20, respectively. Meanwhile, significant differences were found on the network volume and the maximum number of roots between the three N treatments on the 12th day (P< 0.05), and the values of the N12 were 57.0% and 117.9% higher than the N20, respectively. However, there were no significant differences on the average root diameter on the 16th day (P> 0.05) and all of them were between 0.42 and 0.54 mm.[Conclusions]The multi-view images method combining the root multi-view imaging system with GIARoot platform, can nondestructively obtain the root characteristic parameters. The N effects on the root architecture characteristics showed that increasing N concentration within certain range could promote root growth of tomato seedlings. However, the N concentration of 20 mmol/L had an inhibition on tomato seedling root growth, particularly on the number of lateral roots, and N concentration had the least influence on the growth of root diameter.