Biomechanical Response of the Root System in Tomato Seedlings under Wind Disturbance

Wind disturbance as a green method can effectively prevent the overgrowth of tomato seedlings,and its mechanism may be related to root system mechanics.This study characterized the biophysical mechanical properties of taproot and lateral roots of tomato seedlings at five seedling ages and seedling substrates with three different moisture content.The corresponding root system-substrate finite element(FE)model was then developed and validated.The study showed that seedling age significantly affected the biomechanical properties of the taproot and lateral roots of the seedlings and that moisture content significantly affected the biomechanical properties of the seedling substrate(p<0.05).The established FE model was sensitive to wind speed,substrate moisture content,strong seedling index,and seedling age and was robust.The multiple linear regression equations obtained could predict the maximum stress and strain of the root system of tomato seedlings in the wind field.The strong seedling index had the greatest impact on the biomechanical response of the seedling root system during wind disturbance,followed by wind speed.In contrast,seedling age had no significant effect on the biomechanical response of the root system during wind disturbance.In the simulation,no mechanical damage was observed on the tissue of the seedling root system,but there were some strain behaviors.Based on the plant stress resistance,wind disturbance may affect the growth and development of the root system in the later growth stage.In this study,finite element and statistical analysis methods were combined to provide an effective approach for indepth analysis of the biomechanical mechanisms of wind disturbances that inhibit tomato seedlings’growth from the root system’s perspective.

Development of single row automatic transplanting device for potted vegetable seedlings

In China,low degree of automation seriously affects the working efficiency and quality in vegetable transplanting.As one of the most important vegetables in China even in the world,tomato was taken as the research object in this study.An automatic single-row transplanting device was designed,based on the statistical analysis of the physical and mechanical properties of tomato seedlings of a typical variety.Based on the technology of mechatronics,the device integrated the functions of transporting seedling tray,automatic seedling extraction and mechanical planting.The kinematics orthogonality solution combined with the dynamic sequence solution method was used to optimize and analyze the kinematic parameters of the automatic seeding mechanism,and the“sickle”trajectory was obtained.According to the position and movement requirement for taking and dropping seedling,the mechanical conditions and the working parameters of key execution parts were obtained by using analytic drawing method to analyze the mechanical condition of seedling collecting mechanism.The transplanting experiment was conducted at room temperature of 25°C,and the age and moisture content of the seedlings were 40 d and 55%,respectively.The results showed that the highest success rate was 92.59%,and the lowest rate of leakage was 23.13%,when the transplanting frequency was 60 plants/min.The lowest success rate was 77.78%,and the highest rate of leakage was 38.75%,when transplanting frequency was 120 plants/min.When the transplanting frequency is between 60-90 plants/min,the device can meet the requirement of high speed transplanting for potted vegetable seedling.

Development of a metering mechanism with serial robotic arm for handling paper pot seedlings in a vegetable transplanter

This paper describes the development of an automated metering mechanism for vegetable transplanter.It consisted of a 3-DOF serial robotic arm and an automatic feeding conveyor.The robotic arm was developed to pick and drop tomato seedlings raised in biodegradable paper pots.The volume of each pot was 50 cm^(3)(3.5 cmdiameter and 5.2 cmheight)with a maximumtotalweight of 47 g including potmix and seedling.Amatrix type feeding conveyorwas developed to convey the pot seedlings to a predefined positionwhere the robotic armcould pick up these seedlings one by one.LDR(Light Dependent Resistor)-LED(Light Emitting Diode)sensing unit was used to perform the intermittent movement of the conveyor.The developed system was evaluated under both laboratory and field conditions.The robotic arm was able to pick and drop 20 seedlings per minute and its effective cycle time per handling one seedling was varying from 2.5 to 3.1 s.Power consumption of the conveyor of the developed system and the robotic arm was 18 W and 16 W,respectively.The conveying,metering and overall efficiency of the developed metering mechanism under laboratory condition were 96.83%,95.91%and 92.86%,respectively as compared to 94.7%,93.28%and 88.33%,under field condition.The developed robotic armbasedmeteringmechanismwas simple,light inweight and effectively handled the pot seedlings without damage and would thus help in mechanizing transplanting of vegetable seedlings.