# Modeling and Parameter Calibration of Morchella Seed Based on Discrete Element Method
## 1 Introduction  
Morchella (morel mushrooms) holds significant economic value, primarily due to its rich nutritional content, remarkable medicinal properties, and strong market demand. As a rare edible fungus, Morchella is widely used in high-end cuisine, health products, and pharmaceuticals. Its abundance of proteins, amino acids, vitamins, and minerals gives it a prominent position in the health food market. Moreover, advances in artificial cultivation techniques and the growing demand in international markets have created substantial economic benefits and promising commercial prospects for the Morchella industry. Known for its unique flavor and rich nutrients, Morchella is recognized globally as a rare edible fungus [1]. With the advent and continuous innovation of exogenous nutrient bag technology [2], the cultivation area of Morchella in China has rapidly expanded, making it one of the most popular cultivated fungi [3, 4]. China has now become the world's largest outdoor cultivation base for Morchella [5]. Currently, Morchella sowing is mainly performed manually, highlighting the importance of developing intelligent machinery specifically designed for Morchella sowing to meet the growing demand. Morchella seeds, as a type of low-temperature fermentation fungus, exhibit cohesive particle behavior due to moisture and particle stickiness, forming agglomerated structures, which are characteristic of bulk materials. Currently, there is limited research on the contact parameters of cohesive particulate materials. With advancements in computer technology,the discrete element method (DEM) has been widely applied in agricultural equipment research [6; 7]. DEM is a method for analyzing the contact interactions between particles and between particles and boundaries, as well as their different physical and mechanical properties [8]. Since DEM simulation was first applied to material parameter calibration, it has been introduced by many scholars into various particle calibration models, providing a valuable reference for the design and optimization of seeding machinery [9]. This approach effectively enhances production efficiency and reduces costs. In the production and processing of Morchella, accurately calibrating the DEM parameters of Morchella seeds is of great significance. Through DEM simulation, characteristics such as seed flowability and piling behavior can be optimized, which helps improve the efficiency of equipment design, streamline production processes, and reduce experimental costs and time. Parameter calibration not only enhances simulation accuracy but also provides data support for automated production and planting systems, promoting the scale and modernization of the Morchella industry. In countries such as the United States and France, many scholars have conducted calibration studies on DEM parameters for various agricultural materials. [PERSON] et al. [10] and his team used a rotating drum apparatus to calibrate the particle-to-particle and particle-to-material interactions of wheat seeds, successfully measuring static and rolling friction coefficients, which were effectively applied in DEM simulations of wheat. However, this method has limitations when applied to the calibration of Morchella seeds. The morphology, softness, and adhesiveness of Morchella spores are significantly different from those of wheat seeds, making it difficult for the rotating drum to accurately capture their interactions. Additionally, Morchella cultivation requires strict control over environmental factors such as temperature and humidity, which the rotating drum cannot accommodate. [PERSON] et al. [11] and his team developed a near-infrared reflectance spectroscopy (NIRS) calibration method to estimate fiber content in rapeseed, revealing significant genetic differences across genotypes. While this NIRS-based calibration method succeeded in measuring fiber content, it may not be suitable for Morchella seed calibration.