# Integrating Root Morphology Based on Whole-Pullout Test of Model Roots: A Case Study
## 5 Conclusions  
This study conducted vertical pullout orthogonal experiments on model roots with different morphologies and aimed to determine the sensitivity and significance of various root morphological factors on the vertical pullout resistance of plant roots. This study also aimed to provide a reference for vegetation selection in vegetative slope protection. Based on the results, the following key conclusions were drawn:  
1. The results of the range analysis indicate that the factors influencing the vertical pullout resistance of a plant root system can be ordered in terms of sensitivity, from highest to lowest, as follows: number of lateral roots, taproot length, unit weight of soil around the root, and branching angle of the lateral root. A variance analysis further confirmed that the number of lateral roots and taproot length were the primary factors affecting the magnitude of the root system's vertical pullout resistance. 2. An analysis of the trend for the vertical pullout resistance of a root system with changes in various factors showed that an increase in the number of lateral roots from two to three leads to a 64% increase in the average vertical pullout resistance. An increase in the taproot length from 50 cm to 60 cm results in a 46% increase in average vertical pullout resistance. Additionally, for every 10 additional compaction hits, the average vertical pullout resistance increases by 25%. The average vertical pullout resistance is positively correlated with the number of lateral roots, taproot length, and the unit weight of soil around the root, reaching its maximum at the highest levels for these factors. Therefore, further enhancing these factors' levels can lead to greater vertical pullout resistance and better combinations of these factors. 3. Incorporating the sensitivity index (\(I_{S}\)) into the calculations further confirmed the order of sensitivity for the four factors--lateral root number, main root length, soil weight around the root periphery, and lateral root branching angle--on the vertical pullout resistance of plant root systems. The obtained results were consistent with Conclusion (1). 4. Through the results of the vertical pullout orthogonal experiments on model roots and a comprehensive \(\mu_{X}\) theoretical analysis method, it was concluded that the branching angle of the lateral roots had no significant effect on the vertical pullout resistance of the root system. In vegetative slope protection projects, preference should be given to plants with well-developed lateral roots, longer taproot lengths, and stronger root systems for slope reinforcement. Figure 6: Root system force analysis. This study aimed to explore the impact of plant root morphological characteristics on vertical pullout resistance, considering only the unit weight of soil around the root and assuming other soil conditions around the root to be constant. It is important to note that the soil conditions around roots, such as soil type, particle size, and moisture content, significantly affect the root's pullout resistance. Employing real plant root systems with numerous lateral roots and long taproots for indoor and field in situ experiments and using methods such as machine learning, multiple regression analysis, and response surface analysis to establish predictive models represent one approach for further studying on the effects of plant root systems on vertical pullout resistance. The results of such studies will have great scientific significance and engineering value. Conceptualization, K.Z. and J.Z. ; methodology, K.Z. ; validation, J.Z. and L.Z. ; formal analysis, K.Z. and X.L. ; investigation, K.Z. and K.W. ; resources, J.Z. and L.Z. ; data curation, J.Z. ; writing--original draft preparation, K.Z. ; writing--review and editing, K.Z. and L.Z. ; visualization, K.Z. ; supervision, J.Z. ; project administration, J.Z. ; funding acquisition, J.Z. All authors have read and agreed to the published version of the manuscript.