Mediation and ANCOVA Models to Study the Influence of Solvent Retting Traits and Plant Physique on Bast Fiber Yield and Retting Time

ABSTRACT

The study aims in applying two statistical tools to analyze the retting behavior of plant stems for extracting bast fibers for industrial applications. At first, a mediation model is employed to investigate the first hypothesis of this work that involves studying the color response of the retted solvent as a function of retting time on the responsible variable, fiber yield (%). Statistically, there is a significant indirect effect of retting time on fiber yield (%) through retting trait (β = −0.0142, 95% C.I. [−0.0274, −0.0011]) – a statistical inference bolstered by the Sobel test result, confirming the mediation effect (p-value = 0.0329 < 0.05; z-score = −2.1334; bootstrapping of 5000 resamples). Next, the second hypothesis of the current work involves analyzing the impact of stem form-factors on their retting time using the statistical tool, ANCOVA. The partial- η² indicates that cultivar treatment accounts for 30% variance of the retting time while controlling for the effects of two covariates – diameter and length of the stems, in this case. By controlling the Type-I error, Bonferroni and similar post-hoc tests also confirm the statistical significance of cultivar categories pertaining to their mean retting time. Future work could focus on these underlying hypotheses and study the impact of microorganisms, environmental factors, and cultivar treatment variables on the retting time to optimize the overall fiber yield and production process.

摘要

本研究旨在应用两种统计工具分析用于提取工业用韧皮纤维的植物茎的脱胶行为. 首先,采用中介模型来研究这项工作的第一个假设,该假设涉及研究脱胶溶剂的颜色响应,作为脱胶时间对相关变量纤维产量(%)的函数. 统计上,脱胶时间通过脱胶性状(β=-0.0142,95%C.I.-0.0274,-0.0011)对纤维产量(%)有显著的间接影响,这是一个由Sobel检验结果支持的统计推断,证实了中介效应(p值=0.0329<0.05;z分数=-2.1334;自举5000个重取样). 接下来,当前工作的第二个假设涉及使用统计工具ANCOVA分析茎形因素对其脱胶时间的影响. 部分η2表明,在这种情况下,品种处理占脱胶时间的30%方差,同时控制两个协变量的影响——茎的直径和长度. 通过控制I型误差,Bonferroni和类似的事后检验也证实了与平均脱胶时间相关的品种类别的统计显著性. 未来的工作可以集中于这些基本假设,并研究微生物、环境因素和品种处理变量对脱胶时间的影响,以优化整体纤维产量和生产过程.

KEYWORDS:

• Mediation model
• ANCOVA
• bast fiber
• retting time
• retting color
• plant stem
• fiber yield

关键词:

• 调解模式
• 韧皮纤维
• 脱胶时间
• 脱胶颜色
• 植物茎
• 纤维产量

Highlights

• Demonstrating solvent retting dynamics to optimize fibre extraction of cellulosic fibres

• Studying the color response of the retted solvent as a function of retting time

• Investigating the effect of retting time on fibre yield through MEDIATION tool

• Quantifying the impact of stem form-factors on their retting time using ANCOVA tool

• Applying both categories of liberal (e.g., Fisher’s LSD) and conservative (e.g., Bonferroni’s, Tukey’s, and Scheffe’s) Post-hoc tests to examine significance with four different cultivars

Acknowledgments

The authors would like to thank Dr. Mashiur Rahman (Biosystems Engineering, University of Manitoba, Canada) for his valuable supervision on the natural fibre synthesis techniques. Also, the authors extend their gratitudeto the community of University of Manitoba, University of Alberta, MITACS Canada, and Media Lab, Massachusetts Institute of Technology (MIT), USA, for their continued support and constructive guidelines for the responsible conduct of scientific research studies.

Data availability materials

All data generated or analyzed during this study are included in this article.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Ethics approval and consent to participate

This research does not contain any studies on human participants or animals performed by the author.

Supplementary material

Supplemental data for this article can be accessed online at https://doi.org/10.1080/15440478.2022.2091707