Field Evaluation of a Transplanter and a Collector Under Development for Korean Spring Cabbage Production in Greenhouses

Abstract

Cabbage (Brassica rapa L. ssp. Pekinensis) is an important vegetable crop in the Republic of Korea, due to its essential role in kimchi production. However, labor shortages and an aging population necessitate mechanization to sustain productivity. This study aimed to evaluate the field performance of a cabbage transplanter under development with a commercial transplanter and a cabbage collector under greenhouse conditions. This study evaluated transplanting efficiency, planting performance, and yield of cabbage using seedlings at three distinct age groups (30, 35, and 43 days). A cabbage transplanter (Transplanter A) under development, a commercial model (Transplanter B), and manual transplanting were used for comparative analysis. At harvest, a tractor-mounted cabbage collector was used to collect and pack all the cabbages. Transplanter A demonstrated a forward speed of 1.27 km/h and an average planting rate of 2365 seedlings/h, significantly higher than manual transplanting (513 seedlings/h). The effective field capacity (EFC) ranged from 0.11 to 0.13 ha/h, compared to 0.019–0.028 ha/h for manual planting. While Transplanter A showed a higher missing transplant rate (18.17%) than Transplanter B (7.67%), it maintained consistently lower bad planting rates (2.5–4.5%) compared to Transplanter B (3.3–8.8%). In addition, it produced significantly higher cabbage weights (6070 g/plant) and better root metrics than manual transplanting. The cabbage collector achieved 100% efficiency with no crop damage or contamination. The transplanter under development proved effective for greenhouse use, offering faster operation, better planting accuracy, and higher yields, supporting broader mechanization in Korean agriculture.

1. Introduction

Spring cabbage (Brassica rapa L. ssp. Pekinensis) is a significant vegetable crop that holds substantial economic and nutritional value globally, including South Korea [1]. The country is one of the largest consumers of cabbage, particularly due to its cultural significance in the preparation of kimchi, a fermented dish that is a staple in the Korean diet [2]. As a staple ingredient in numerous traditional Korean dishes, including Kimchi, the demand for high-quality cabbage is consistently high [1,3]. The production of cabbage is not only essential for domestic consumption but also contributes to the export market, making it an economically important crop [4]. However, traditional methods of cabbage cultivation in South Korea, which largely rely on manual labor, pose significant challenges, particularly in regions facing labor shortages and increased production costs [5]. The agricultural workforce in Korea is aging, and there is a growing scarcity of younger workers willing to engage in physically demanding agricultural activities [6]. As a result, there is an urgent need to explore alternative methods of cultivation that can maintain or even enhance productivity while reducing the reliance on manual labor.

Spring cabbage is a high-value crop with increasing demand in Korea. The cultivation cycle for spring cabbage in greenhouses is relatively short, and farmers aim to optimize every aspect of the production process to align with market windows [7]. Greenhouse cultivation of spring cabbage presents a strategic advantage, particularly by mitigating risks associated with variable spring weather conditions [8,9]. In contrast to open-field farming, greenhouses offer the advantage of controlling environmental variables, enabling early planting and consistent quality [10]. Sudden temperature fluctuations, unexpected frosts, heavy rainfall, or early pest infestations can significantly impact open-field crops, leading to reduced yields and compromised product quality [8,11]. Despite these advantages, greenhouse-based spring cabbage production still faces several operational challenges. A primary constraint is the heavy reliance on manual labor, particularly in transplanting and harvesting processes. Traditional manual methods, although reliable, are labor-intensive, time-consuming, and increasingly unsustainable due to rising labor costs and the shrinking availability of agricultural workers [12,13]. Korea, similar to many developed nations, experiences a demographic shift characterized by an aging rural population and declining agricultural workforce [14]. These socioeconomic dynamics exacerbate the urgency for adopting mechanized alternatives capable of reducing labor dependency, enhancing efficiency, and lowering overall production costs.

Mechanization in agriculture, which refers to the application of machinery and technology in agricultural practices to enhance productivity and reduce manual labor, has emerged as a promising solution to address these challenges [15,16,17]. In cabbage cultivation, mechanization can be applied at various stages of production, including soil preparation, planting, maintenance, harvesting, and post-harvest processing [18]. The introduction of mechanized systems such as cabbage transplanters and cabbage collectors represents a significant advancement in this context. A cabbage transplanter is a machine designed to automate the transplanting process of cabbage seedlings into the field [19,20,21]. This technology ensures uniform planting depth, spacing, and seedling placement, which are critical factors for achieving optimal growth conditions and high yields [21]. The cabbage transplanter can significantly reduce labor costs and improve the efficiency of field operations.

The cabbage collector is another innovative machine that automates the harvesting process. Traditionally, cabbage harvesting is performed manually, requiring considerable time and effort. The cabbage collector facilitates the harvesting process by cutting the cabbage heads, removing them from the field, and collecting them for further processing or transportation [5,22]. This mechanization not only accelerates the harvesting process but also minimizes crop damage, ensuring better quality produce and reducing post-harvest losses [23]. Mechanization improves precision, leading to better crop management and higher yields, as seen with cabbage transplanters ensuring uniform access to nutrients, water, and sunlight [24]. Additionally, it saves time by speeding up production processes, which is crucial for large-scale farming. Advanced machinery also allows for monitoring and adjusting parameters like planting depth, spacing, and harvesting speed, optimizing crop performance in various conditions.

While mechanization offers numerous benefits, it also presents certain challenges that need to be addressed to ensure successful implementation. Unlike conventional transplanters designed for open fields, the greenhouse-specific machines need to be compact, lightweight, and capable of maneuvering within narrow planting rows without damaging the crop or greenhouse infrastructure [25,26]. Additionally, these machines must be user-friendly, cost-effective, and adaptable to different soil types and planting configurations commonly used in Korean greenhouse systems [5,13,27]. The development of greenhouse-compatible transplanters and collectors involves key technical challenges. These include precise seedling handling, adjustable planting depth and row spacing, accurate placement, and minimizing seedling damage [28,29,30]. Harvesting units need to collect mature cabbages without bruising, requiring gentle lifting mechanisms for improved accuracy and efficiency [31,32]. In addition, the high initial cost of purchasing and maintaining mechanized equipment is difficult for small-scale farmers, who constitute a significant portion of cabbage producers in Korea Republic [33]. Therefore, government support, targeted subsidies, and cooperative ownership models are vital for making mechanization more accessible to smallholder farms. Equally important is the provision of training and extension services to build farmers’ technical capacity to operate and maintain mechanized equipment, ensuring its effective and sustainable use.

Adaptation of mechanized systems to varying soil types, topographies, and climates is critical for their effective deployment [34,35]. At the same time, environmental impacts such as soil compaction must be addressed, as heavy machinery can degrade soil structure and reduce productivity [36]. To balance efficiency and sustainability, equipment should be tailored to site-specific conditions and integrated with conservation practices. In this context, the present study focuses on the design, testing, and evaluation of a new cabbage transplanter and collector under development specifically for greenhouse conditions.

The objective of this study was to evaluate the cabbage transplanter and collector currently under development by conducting thorough field evaluations specifically customized to the operational constraints and agronomic requirements of greenhouse spring cabbage production in Korea. This paper is structured to first highlight the significance of cabbage mechanization in Korea, followed by an outline of the experimental approach. The Section 2 escribes the comparative evaluation of an underdeveloped transplanter across three seedling ages (30, 35, and 43 days), focusing on planting performance, yield characteristics, and the efficiency of a tractor-mounted collector. The Section 3 present the outcomes of these field trials, while the Section 4 analyzes the findings, addressing key limitations and suggesting directions for future improvement. The Section 5 summarizes the major contributions and the implications for advancing mechanization in Korean cabbage production.

2. Materials and Methods

2.1. Study Site and Field Preparation

This study was conducted inside the greenhouse farm located in Yeasan, Republic of Korea. This facility provided a controlled environment essential for evaluating the mechanization of cabbage cultivation using cabbage transplanters and collectors. The greenhouse infrastructure, as shown in Figure 1a,b, consisted of multiple plastic-covered tunnels designed to protect crops from external weather conditions while maintaining optimal growing conditions such as temperature, humidity, and light exposure. During the transplanting to harvesting period (February 2024 to April 2024), the average daytime temperature inside both greenhouses ranged from 5 to 18 °C, with relative humidity levels of 55–75%. At night, a black curtain was used to reduce heat loss, as shown in Figure 1a,b. The greenhouses were designed with a clear interior structure, as seen in Figure 1c, ensuring proper ventilation and uniform soil preparation. Field preparation involved ensuring uniform soil texture and level, as demonstrated in Figure 1d. The soil texture at the site was classified as sandy loam, composed of 79.8% sand, 15.7% silt, and 7.6% clay. In addition, the average soil water content, electrical conductivity (EC), and bulk density were found as 23.45 ± 1.12%, 1.33 ± 0.16 dS/m, and 1.29 ± 0.031 g/cm³, respectively, from both greenhouses. Since the greenhouses were in the same location and the greenhouse soil homogeneity was almost similar, and transplanting and harvesting were performed on the same day, as well as other intercultural operations were the same in both greenhouses, it was considered the microenvironments were consistent. The soil was prepared with careful attention to leveling and aeration to create an ideal surface for transplanting, with the soil depth and distance between rows precisely measured to accommodate the mechanized transplanters.

The layout of the experimental plots is shown in the schematic representation in Figure 2. The greenhouse complex was divided into two distinct sections: Greenhouse A, equipped with the transplanter under development (Transplanter A), and Greenhouse B, utilizing a commercially available transplanter (Transplanter B). During harvesting, both greenhouses employed the same cabbage collector currently under development. Each greenhouse measured approximately 80 m in length, 6 m in width, and 2.5 m in height, providing sufficient spatial conditions for testing mechanized cabbage planting under various conditions.

The study utilized cabbage seedlings grown at different stages to evaluate the impact of mechanization in cabbage farming. Seedlings were sown on three different dates under controlled greenhouse conditions in a 128 holes seedling tray, resulting in varying growth stages before transplantation as shown in Figure 3a–c. To better understand the influence of seedling age on the efficiency and outcome of mechanized transplantation, three specific age groups were selected: 30-day-old seedlings (Seedling A), 35-day-old seedlings (Seedling B), and 43-day-old seedlings (Seedling C) as shown in Figure 3d–f. These are shown with clear visual representation of their respective growth conditions.

Within each greenhouse, the experimental field was divided into four plots, with each plot measuring 16 m in length and 6 m in width. These plots were allocated for transplanting cabbage seedlings of different ages: Seedling A in Plot 1, Seedling B in Plot 2 and 4, and Seedling C in Plot 3. Plots 1, 2, and 3 were transplanted and harvested using a transplanter and a collector under development, respectively, whereas Plot 4 was used for manual application with Seedling B. The separation of these plots allowed for a detailed comparison of seedling age and the impact on growth performance when subjected to mechanized transplantation along with manual transplantation. The systematic design of the greenhouses and field plots ensured that each treatment received equal attention regarding planting, irrigation, and fertilization, enabling a controlled comparison of cabbage mechanization techniques.

2.2. Cabbage Transplanter Used in This Study

In this study, two automatic cabbage transplanters were employed to comparatively assess their transplanting performance under controlled greenhouse conditions. The first transplanter, designated as Transplanter A (Model: PVZ1-45TDH, HSM Co., Ltd., Cheonan, Republic of Korea), is shown in Figure 4a. This machine is currently at the under-development stage and specifically designed to enhance automation, precision, and reliability in transplanting operations across diverse greenhouse and field environments.

Transplanter A is an advanced automatic irrigation-type seedling planter featuring a four-wheeled body and a modular seedling handling system. As shown in Figure 4a,b, the machine integrates a seedling tray, a picking unit, and a dibbling hopper unit. The picking unit carefully extracts individual seedlings from the tray using a mechanical arm, ensuring gentle handling and reducing the risk of damage. These seedlings are then transferred to the dibbling hopper unit, which uses a gear-driven cross-blade mechanism to deposit the seedlings precisely into the soil. The system is capable of planting into both bare and vinyl-covered ridges. A key innovation is the integrated planting irrigation system, which moistens the planting site before seedling deposition to facilitate smooth establishment. The schematic in Figure 4b clearly illustrates the sequential process—starting from tray-fed seedling pickup, downward transfer to the hopper, and final deposition into the ridge—ensuring a continuous, synchronized planting operation. With adjustable settings for row spacing and depth, the system is well-suited for precision agriculture and high-density transplanting applications in greenhouse environments.

The second transplanter evaluated in this study was the commercially available transplanter designated as Transplanter B (Model: SKP-100W, Kubota Corporation, Osaka, Japan), as shown in Figure 4c. Recognized for its high precision and reliability, Transplanter B incorporates a seedling tray, linkage-based picking mechanism, and gear-driven dibbling hopper for automated seedling insertion and depth control, and uniform spacing—critical factors for optimal crop establishment and growth. Designed to minimize soil disturbance and mechanical stress during transplanting, this model significantly enhances seedling survival and promotes robust early growth.

Moreover, Transplanter B features rapid adjustment capabilities for varying bed configurations, soil conditions, and planting patterns, making it adaptable for both open-field and greenhouse applications. Its proven operational flexibility and performance establish it as a reliable benchmark for evaluating mechanized transplanting efficiency in vegetable production systems.

Both transplanters aim to reduce labor costs and enhance planting efficiency, making them highly suitable for large-scale cabbage production. Their automation capabilities facilitate precise control of planting parameters, resulting in uniform crop stands and improved yields.

Table 1. Technical specifications of the cabbage transplanters used in field performance evaluation under greenhouse conditions in this study.

Parameter	Specifications
	Transplanter A	Transplanter B
Model	PVZ1-45TDH	SKP-100(W)-KR
Manufacturer	HSM	Kubota
Dimension (L × W × H)	2200 × 1010 × 1160	2160 × 890 × 1365
Weight (kg)	251	238
Engine type	Gasoline	Gasoline
Rated engine power (kW)	3.0	3.1
Output power (kW)	2.2	2.19
Rated engine speed (rpm)	1800	1600
Operating speed (m/s)	1.31 (forward)	1.5 (forward)
	0.45 (backward)	0.52 (backward)
Working width (mm)	650	650
Plant Spacing (mm)	300–600	300–600
Number of rows	1	1
Tray type (holes)	128, 200	128, 200
Working efficiency (hr/1000 m2)	1.1–1.6	1.1–1.6

summarizes the technical specifications of the two cabbage transplanters A and B used in this study.

2.3. Cabbage Collector Used in This Study

The cabbage collector used in this study is currently under development (Model: HD-CC4000, Hyundae Agricultural Machinery Co., Iksan, Republic of Korea), as shown in Figure 5a. This collector was specifically designed to address the practical needs of farmers, emerging from a robust process of innovative research and development. The cabbage collector is a tractor-mounted harvesting system powered via the power take-off (PTO) of the tractor that offers significant versatility and convenience. The design allows it to be easily driven on both farm roads and regular roads, making it highly adaptable to various transportation needs.

A standout feature of the cabbage collector is a foldable structure, which enables the collector to be compactly mounted and transported on a truck as shown in Figure 5b. This foldable design not only facilitates easy storage and transport but also allows for quick setup and deployment in the greenhouse and field, enhancing operational efficiency. The key advantages of the cabbage collector are the adoption of a top-tier hydraulic operation system. Figure 5c illustrates the technical schematic of the main components and dimensions of the collector system. This system is engineered to provide smooth, responsive control, which simplifies the operation of the collector significantly. The ease of operation is particularly beneficial for elderly farmers and female workers (Figure 5d), who may find traditional, more physically demanding machinery challenging to use. The hydraulic controls ensure that the collector can be operated with minimal physical exertion, making it accessible to a broader range of users and providing an ideal working environment across diverse farming operations. The technical specifications of the cabbage collector under development used during the mechanized collecting process in this study are mentioned in

Table 2. The technical specifications of the cabbage collector under development that are used for mechanized collecting under greenhouse conditions.

Parameter		Specifications
Model		HD-CC4000
Work range (mm)		4000
Mounted type		Tractor attachment 3-point linkage
Weight (kg)		850~900
Full size (L × Width × H) (mm)	When moving	2900 × 1500 × 2800
	When working	7500 × 1500 × 2100
	Folding method	Folding
Collection method		Conveyor belt transfer ceremony
Loading method		Toneback (automatic quick-pulling)
Driving		Hydraulic drive type
Drive power type		Tractor hydraulic
Attachment tractor (hp)		75 hp or higher
Workload (min/1000 m2)		20

.

2.4. Evaluation of Cabbage Transplanter and Harvester in Field Conditions

The performance of cabbage transplanters was rigorously evaluated under actual field conditions to assess their viability and efficiency. The evaluation focused on several key performance parameters, including field capacity, field efficiency, labor requirements, planting quality, and plant mortality. These factors are essential to determine the practical application of the transplanters in mechanized cabbage farming and to compare them with traditional manual methods. During the harvesting stage, various yield-related parameters of cabbage were measured using standardized manual methods and precision instruments, as illustrated in Figure 6. These measurements were essential for evaluating the agronomic performance of the transplanted cabbages and for comparing the effects of different transplanting methods.

2.4.1. Planting Angle and Planting Depth

The planting angle, defined as the angle of inclination between the plant stem and the vertical plane, plays a crucial role in plant development and yield. The plant with a planting angle between 0° and 30° are more likely to grow upright, ensuring better exposure to sunlight and more effective nutrient absorption [37,38]. The planting angle was measured for 15 seedlings per plot using a protractor or similar tool to ensure accuracy. Plants with angles greater than 30° were considered deficient, as they are less likely to stand upright, which could lead to poor growth or even plant damage during future cultivation steps.

Planting depth refers to the portion of the seedling buried in the soil. It was measured for 15 seedlings in each plot using a ruler or depth gauge. An optimal planting depth ensures that the seedlings are neither too deep nor too shallow, as both conditions can affect root establishment and plant stability. Shallow planting could expose the roots to air, leading to desiccation, while overly deep planting could delay germination and growth. For this study, the depth was carefully controlled and recorded, as uniform planting depth is one of the key advantages of mechanized transplanters compared to manual planting.

2.4.2. Missing and Lying Down Plants as Bad Planting Rate

One of the most common issues during transplanting is plant misplacement or omission. In this study, the number of missing plants per row was recorded, and the percentage of missing seedlings was calculated for each plot. Missing plants represent gaps in the field that can lead to an insignificant yield due to uneven plant distribution and competition for resources [39]. This parameter is essential for assessing the accuracy of the transplanter in placing seedlings consistently.

Lying down plants were also noted, defined as plants whose angle of inclination was less than 30° from the horizontal plane [37]. These plants are at a higher risk of not establishing properly, as they may fail to develop a strong root system or may be more vulnerable to damage from mechanical operations or environmental stressors. The percentage of lying down plants was calculated for each plot, providing an indicator of the ability of the transplanter to ensure proper seedling placement. Figure 7 illustrates an example of the quality of transplanting achieved under different planting conditions. In Figure 7a, the seedling is properly placed with a planting angle of approximately 90°, representing an ideal transplanting outcome. Figure 7b shows three distinct planting scenarios observed in the field: a correctly transplanted seedling (left), a missed transplant where the seedling was not inserted into the soil (middle), and a lying down seedling (right). Figure 7c provides another example of a lying down seedling, highlighting a common planting error that can occur due to improper positioning or equipment calibration.

2.4.3. Field Capacity and Field Efficiency

Theoretical and actual field capacity, along with field efficiency, were calculated to evaluate the productivity of the cabbage transplanters. Field capacity refers to the area covered by the transplanter in a given amount of time. The theoretical field capacity is calculated based on the width of the machine and its operational speed. Effective field capacity, on the other hand, takes into account all delays and inefficiencies during operation, such as turning at the end of rows, machine adjustments, and other interruptions. Theoretical and effective field capacity were calculated as Equations (1) and (2) as follows [40]:

$$\mathrm{F}{\mathrm{C}}_{\mathrm{T}}={\displaystyle \frac{\mathrm{W}\times \mathrm{S}}{10}}$$

(1)

$$\mathrm{F}{\mathrm{C}}_{\mathrm{E}}={\displaystyle \frac{\mathrm{W}\times \mathrm{S}\times \mathrm{F}\mathrm{E}}{10}}$$

(2)

where FC_T and FC_E are the theoretical and effective field capacity (ha/h), W is the width between-row spacing (m), and S is the average forward speed (km/h). FE is the field efficiency (%) under real condition.

Field efficiency is the ratio of effective field capacity to theoretical field capacity, expressed as a percentage as Equation (3) as follows [40]:

$$\mathrm{F}\mathrm{E}={\displaystyle \frac{{\mathrm{F}\mathrm{C}}_{\mathrm{T}}}{{\mathrm{F}\mathrm{C}}_{\mathrm{E}}}}$$

(3)

It provides insight into the real-world performance of the transplanter, including its ease of operation and adaptability to field conditions. A higher field efficiency indicates that the machine operates close to its theoretical potential, while a lower efficiency may point to issues such as frequent stoppages, mechanical breakdowns, or operator inefficiencies.

2.5. Comparative Field Performance and Statistical Analysis

The performance of the cabbage transplanters (Transplanter A), which is currently under development, was compared with both the traditional manual transplanting method and a commercially available transplanter (Transplanter B). The performance of the cabbage collector was also evaluated. This comparison aimed to evaluate the technical efficiency, operational feasibility, and practical acceptability of the mechanized systems among vegetable growers. The assessment focused on key performance indicators, including field capacity, field efficiency, missed planting rate, and labor requirements. The overall flow diagram of this study is shown in Figure 8. These metrics are particularly critical for small- and medium-scale farms, where mechanization must balance cost-effectiveness with reliability to ensure broader adoption.

Field trial data were subjected to descriptive statistical analysis to quantify performance differences among the three transplanting methods. A randomized complete block design (RCBD), with three treatments: T1 = A cabbage transplanter under development (Transplanter A); T2 = A commercially available model (Transplanter B), and T3 = Conventional Manual transplanting (MP), was performed. The experiment was laid out in an RCBD with 15 replications. Descriptive statistics such as means and standard deviations were calculated, and one-way analysis of variance (ANOVA) was conducted to detect statistically significant differences across treatments at a 5% significance level (α = 0.05). When significant differences were detected, post hoc comparisons were performed using Tukey’s HSD all pairwise comparison test to identify the percentage of the coefficient of variation (CV%) and level of significance (LS) of differences among different parameters of the treatments.

The statistical analyses were conducted using Statistix 10 (Analytical Software, Tallahassee, FL, USA), a statistical package tailored for agricultural research. The evaluated parameters included effective field capacity, theoretical field capacity, field efficiency, planting angle, and both missed and accurate planting rates. The use of these comprehensive metrics enabled a thorough evaluation of the field performance of the transplanters, highlighting operational strengths and potential areas for further refinement. Ultimately, the statistical findings provided a solid foundation for assessing the agronomic and economic viability of mechanized cabbage transplanting systems.

3. Results

3.1. Cabbage Seedling Parameters

Table 3. Cabbage seedlings’ morphological characteristics were measured during the experiment.

Seedling Type	Transplanter	Plant Height (cm)	Leaf Length (cm)	Leaf Width (cm)	Number of Leaves (avg.)
A (30 days)	Transplanter A	4.75 ± 0.61	3.6 ± 0.0.63	1.89 ± 0.25	8.2 ± 0.84
	Transplanter B	4.86 ± 0.53	3.76 ± 0.36	2 ± 0.28	8 ± 0.77
B (35 days)	Transplanter A	5.46 ± 0.71	5.16 ± 0.61	2.13 ± 0.39	9.1 ± 0.7
	Transplanter B	5.26 ± 0.50	5.23 ± 0.45	2.34 ± 0.29	8.9 ± 1.01
	Manual	5.22 ± 0.63	4.98 ± 0.61	2.26 ± 0.7	8.8 ± 0.46
C (43 days)	Transplanter A	7.73 ± 1.41	5.69 ± 0.95	2.65 ± 0.48	9.4 ± 1.01
	Transplanter B	8.1 ± 0.86	5.8 ± 0.39	2.67 ± 0.25	9.3 ± 0.1.57

presents the cabbage seedling morphological parameters of cabbage seedlings recorded prior to transplanting, offering a detailed comparison of seedling growth characteristics for both transplanter A and B used during the experiment. The measured parameters include plant height, leaf length, leaf width, and the average number of leaves per seedling. For transplanter A, seedlings were evaluated at 30, 35, and 43 days old, showing progressive increases in plant height and leaf dimensions as the seedlings matured. The highest leaf length (5.69 ± 0.95 cm) and width (2.65 ± 0.48 cm) were recorded at 43-day-old seedlings. Similarly, the Transplanter B followed this trend, with the maximum plant height (8.1 ± 0.86 cm) and leaf length (5.80 ± 0.39 cm) observed at 43-day-old seedlings. Seedlings at 35 days showed more consistent growth in terms of height, leaf length, and width for both transplanters. All seedlings exhibited steady growth in the number of leaves with increasing age, with a maximum average of 9.4 leaves at 43 days. These results highlighted the importance of using healthy seedlings with similar growth parameters to accurately evaluate the transplanting efficiency of both Transplanter A and B. By ensuring that the seedlings were uniform in terms of plant height, leaf length, leaf width, and leaf count, the study was able to focus on assessing the actual performance of the transplanters. This approach minimized the potential variability introduced by differences in seedling quality and allowed for a more reliable comparison of transplanting accuracy, depth consistency, and overall operational efficiency for both machines. Consequently, the results provide a clearer understanding of the ability of each transplanter to maintain optimal planting conditions, leading to better crop establishment and growth.

3.2. Cabbage Transplanter Performance

Several performance metrics, including working speed, theoretical field capacity (TFC), effective field capacity (EFC), and field efficiency (FE), average transplanting time, normal transplants, missing plants, and bad planting (where plants were inclined more than 30° from the vertical), were evaluated under standardized field conditions. The field conditions included a furrow-to-furrow distance of 68 cm, a furrow spacing of 30 cm, and a plant-to-plant distance of 40 cm. The comparison sheds light on the transplanting efficiency and effectiveness of the transplanter under development.

Table 4. Interaction effects of seedling age and transplanting method on cabbage transplanter field performance parameters.

Seedling Type	Treatment	Forward Speed (km/h)	Effective Width (m)	TFC (ha/h)	EFC (ha/h)	FE (%)
A (30 days)	T1	0.19B	0.60	0.01C	0.028C	52.79C
	T2	1.23A	0.60	0.074A	0.13A	57.87A
	T3	1.21A	0.60	0.072B	0.12B	59.57B
	Mean	0.87	0.60	0.052	0.087	56.74
	CV (%)	6.46	-	6.57	7.85	3.23
	SD	0.48	-	0.028	0.047	3.21
	p-value	0.00	0.00	0.00	0.00	0.00
	LS (0.05)	***	***	***	***	***
B (35 days)	T1	0.19B	0.60	0.011B	0.019B	59.58B
	T2	1.275A	0.60	0.076A	0.12A	64.50A
	T3	1.255A	0.60	0.075A	0.12A	63.38A
	Mean	0.91	0.60	0.054	0.086	62.49
	CV (%)	5.27	-	5.61	5.51	1.94
	SD	0.51	-	0.31	0.47	2.41
	p-value	0.00	0.00	0.00	0.00	0.00
	LS (0.05)	***	***	***	***	***
C (43 days)	T1	0.19B	0.60	0.011B	0.02B	54.97C
	T2	1.18A	0.60	0.071A	0.11A	61.88A
	T3	1.15A	0.60	0.068A	0.11A	60.24B
	Mean	0.84	0.60	0.050	0.083	59.03
	CV (%)	5.66	-	5.68	5.18	2.20
	SD	0.46	-	0.27	0.044	3.20
	p-value	0.00	0.00	0.00	0.00	0.00
	LS (0.05)	***	***	***	***	***

SD = Standard deviation; CV = coefficient of variation; LS = level of significance; T1 = manual transplanting; T2 = transplanting by Transplanter A; T3 = transplanting by Transplanter B; p < 0.05 was considered statistically significant. Levels of significance: p < 0.001 (***) means highly significant (0.1%), p < 0.01 (**) indicates very significant (1%), p < 0.05 (*) indicates significant (5%), and p ≥ 0.05 (ns), which means non-significant. A, B, C indicate means followed by a common letter indicating no statistically significant differences.

presents the interaction effects between seedling age (A, B, and C) and transplanting method (T1—Manual transplanting, T2—Transplanter A [underdeveloped], and T3—Transplanter B [commercial]) on key field performance indicators under greenhouse conditions, including theoretical field capacity (TFC), effective field capacity (EFC), and field efficiency (FE). For seedling type A (30 days), Transplanter A demonstrated the highest effective field capacity (0.13 ha/h) combined with a competitive field efficiency of 57.87%. In comparison, Transplanter B showed a slightly lower EFC (0.12 ha/h) but slightly superior field efficiency (59.57%). Manual transplanting recorded significantly lower performance metrics, with an EFC of only 0.028 ha/h and a reduced FE of 52.79%, indicating a substantial operational advantage for mechanized systems. For seedling type B (35 days), both transplanters delivered identical EFC values (0.12 ha/h), but Transplanter A slightly surpassed Transplanter B in FE (64.50% vs. 63.39%), both markedly outperforming manual transplantation, which had notably lower EFC (0.019 ha/h) and FE (59.59%). For seedling type C (43 days), Transplanter A achieved the better EFC (0.11 ha/h) and FE (61.89%), closely followed by Transplanter B (EFC 0.11 ha/h, FE 60.24%), both significantly exceeding the manual transplanting method’s EFC of 0.0210 ha/h and FE of 54.97%. Manual transplanting recorded significantly lower EFC and FE across all seedling ages, reflecting lower operational efficiency and greater field losses. These results confirm that mechanization substantially enhances transplanting efficiency by increasing effective working speed and reducing overlap and idle time under greenhouse conditions.

Table 5. Interaction effects of seedling age and transplanting method on the performance of underdeveloped, commercial, and manual cabbage transplanter under greenhouse conditions.

Seedling Type	Transplanter	Forward Speed (km/h)	Performance Indices
			Seedling Plating Rate (Seedling/h)	Normal Transplanting (%)	Missing Transplant Rate (%)	Bad Planting Transplant Rate (%) (>30°)
A (30 days)	A	1.23	2123.31	79.33	18.17	2.50
	B	1.21	1972.60	80.84	10.33	8.83
B (35 days)	A	1.27	2526.30	85.83	9.67	4.50
	B	1.25	2487.32	86.83	7.67	5.50
C (43 days)	A	1.18	2447.59	85.20	10.80	4.00
	B	1.15	2512.23	87.84	8.83	3.33
Avg.	A	1.22	2365.73	83.45	12.88	3.66
	B	1.20	2324.05	85.17	8.94	5.88
B	Manual	0.19	513.78	100	0	0

further presents the interaction effects between seedling age (A: 30 days, B: 35 days, C: 43 days) and transplanting method (Transplanter A: developed machine, Transplanter B: commercial machine, and Manual) on key transplanting performance indicators including forward speed, seedling planting rate, normal transplanting percentage, missing transplant rate, and bad planting transplant rate (>30° inclination). Both Transplanters A and B significantly surpassed manual transplanting in terms of forward speed (1.15 to 1.27 km/h versus 0.19 km/h). This higher operational speed directly resulted in enhanced seedling planting rates for Transplanter A (2123.31 to 2526.30 seedlings/h) and Transplanter B (1972.60 to 2512.23 seedlings/h), vastly superior to the manual method’s 513.78 seedlings/h. However, increased speeds posed challenges, such as higher missing transplant rates, particularly evident in Transplanter A, which ranged between 9.67% and 18.17%, compared to the relatively lower rates seen with Transplanter B (7.67% to 10.33%). Despite these issues, Transplanter A exhibited consistently lower bad planting rates (2.50% to 4.50%) compared to Transplanter B (3.33% to 8.83%), indicating a better ability to maintain accurate vertical alignment under operational stresses.

Overall, Transplanter A provided better efficiency and productivity across all seedling types, although careful speed management is crucial to minimizing planting errors and maximizing overall transplanting quality. From a technical standpoint, these findings highlight the inherent trade-offs in optimizing transplanter speed, emphasizing the necessity for fine-tuned operational control to maximize planting quality. Overall, Transplanter A generally provided superior efficiency, higher productivity, and better accuracy under typical operational conditions, positioning it as a preferable choice for large-scale cabbage transplanting operations.

3.3. Comparison with Manual Transplanting

The comparative analysis between manual transplanting and mechanized systems (Transplanter A and B) provides critical insights into operational speed, planting rate, and technical performance. Transplanter A demonstrated forward speeds ranging from 1.18 to 1.27 km/h, while Transplanter B operated at similar speeds between 121 and 1.25 km/h. In stark contrast, manual transplanting was conducted at a significantly lower speed of 0.19 km/h, representing an approximate 83–85% reduction in operational velocity compared to mechanized methods. This substantial speed enhancement with mechanized transplanters enables significantly higher area coverage per unit time, which is particularly advantageous for large-scale cabbage cultivation where timeliness is critical.

In terms of seedling planting rate, Transplanter A achieved 2123.31 to 2526.30 seedlings/h, whereas Transplanter B ranged from 1972.60 to 2512.23 seedlings/h, which was 1.5 to 7.2% higher than the commercial transplanter. Manual transplanting lagged far behind at 513.78 seedlings/h. This nearly five-fold increase in productivity with Transplanter A underscores the system’s superior throughput capacity. However, increased speed introduces technical trade-offs. Transplanter A experienced higher missing transplant rates (9.67–18.17%) compared to Transplanter B (7.67–10.33%). These missing rates reflect the mechanical feeding and placement consistency limitations that can occur at high operating speeds, especially when handling non-uniform seedling morphology or under inconsistent soil surface conditions. In terms of transplanting precision, manual planting achieved a 100% normal transplanting rate with zero incidence of missing or misaligned planting. This is attributable to the precision and adaptability of human operators who can respond in real-time to individual plant and soil conditions. By contrast, Transplanter A’s normal transplanting rate ranged from 79.33% to 85.83%, and bad planting (>30° inclination) remained relatively low (2.50–4.50%), indicating reasonable consistency but still reflecting mechanical limitations in handling and precise positioning.

Overall, while Transplanter A shows a slight disadvantage in planting precision compared to manual transplanting, it provides an overwhelming advantage in speed and operational efficiency. Although the precision gap (approx. 14–20%) may be relevant for delicate transplanting operations or in high-value crops, for large-scale cabbage farming, the time and labor savings gained through mechanization significantly outweigh the small reductions in planting accuracy. Transplanter A particularly stands out for its higher throughput, even though refinement in seedling feeding and placement mechanisms could further reduce its transplanting errors. Consequently, mechanized transplanting—especially with Transplanter A—represents a technically viable and highly productive alternative to manual labor in commercial cabbage production.

3.4. Cabbage Evaluation for Yield Productivity

Table 6. Interaction effects of seedling age and transplanting methods on cabbage growth and yield parameters at harvest.

Seedling Type	Treatment	Weight (g)	Height (cm)	Diameter (cm)	Leaf Length (cm)	Leaf Width (cm)	Number of Leaves (>10 cm)	Root Weight (g)	Root Length (cm)
A (30 days)	T1	5184.50A	40.90B	25.91A	41.20B	29.90A	65.40A	37.20A	19.80B
	T2	5763.00A	43.80A	27.25A	43.20AB	30.80A	69.10A	35.40A	16.80A
	T3	5385.00A	42.30AB	26.48A	43.80A	30.40A	67.10A	35.10A	16.60A
	Mean	5444.20	42.33	26.55	42.73	30.36	67.20	35.90	17.73
	CV (%)	16.27	4.59	5.51	6.41	8.69	9.37	23.20	13.67
	SD	857.68	2.35	1.70	2.84	2.64	6.13	7.07	2.69
	p-value	0.354	0.013	0.150	0.112	0.750	0.438	0.831	0.013
	LS (0.05)	ns	*	ns	ns	ns	ns	ns	*
B (35 days)	T1	5184.50B	40.90B	25.91B	41.20A	29.90AB	65.40A	37.20A	19.80B
	T2	6070.50A	43.40A	28.14A	42.60A	29.40B	69.40A	39.70A	18.20A
	T3	5451.10AB	41.80AB	26.80AB	42.50A	32.20A	67.20A	36.30A	17.70A
	Mean	5568.70	42.03	26.95	42.10	30.50	67.33	37.73	18.57
	CV (%)	12.92	5.55	6.50	5.57	9.28	6.46	18.30	12.11
	SD	853.14	2.44	1.76	2.20	2.94	4.35	8.05	2.51
	p-value	0.036	0.078	0.033	0.351	0.088	0.148	0.533	0.213
	LS (0.05)	*	ns	*	ns	ns	ns	ns	*
C (43 days)	T1	5184.50B	40.90B	25.91B	41.20A	29.90A	65.40A	37.20A	19.80B
	T2	5753.00A	42.00AB	27.59A	42.50A	30.30A	66.70A	36.50A	18.40A
	T3	5584.20AB	42.60A	26.71AB	42.30A	30.70A	66.10A	35.30A	18.80A
	Mean	5507.23	41.83	26.74	42.00	30.30	66.07	36.33	19.00
	CV (%)	13.27	3.28	5.47	4.68	7.99	7.26	19.03	12.52
	SD	744.05	1.71	1.51	2.05	2.35	3.99	7.47	2.42
	p-value	0.003	0.037	0.058	0.305	0.764	0.833	0.826	0.538
	LS (0.05)	**	*	ns	ns	ns	ns	ns	*

SD = standard deviation; CV = coefficient of variation; LS = level of significance; T1 = manual transplanting; T2 = transplanting by Transplanter A; T3 = transplanting by Transplanter B; p < 0.05 was considered statistically significant. Levels of significance: p < 0.001 (***) means highly significant (0.1%), p < 0.01 (**) indicates very significant (1%), p < 0.05 (*) indicates significant (5%), and p ≥ 0.05 (ns), which means non-significant. A, B, C indicate means followed by a common letter indicating no statistically significant differences.

presents the interaction effects of seedling types A (30 days), B (35 days), and C (43 days) and transplanting methods of manual transplanting, Transplanter A, and Transplanter B on cabbage growth and yield parameters measured at harvest. The evaluation includes plant weight, height, diameter, leaf metrics, number of leaves, root weight, and root length.

For seedling type A, cabbages transplanted using Transplanter A achieved the highest average weight (5763.00 g), plant height (43.80 cm), and leaf length (43.20 cm), outperforming both manual and Transplanter B. Additionally, the head diameter and root weight were also higher than manual transplanting but slightly lower than Transplanter B. However, Transplanter B showed a significant reduction in root length and width, suggesting that although yield was competitive, planting precision or soil compaction effects may have influenced root development. Tukey’s HSD test results indicate that for seedling type A, Transplanter A had statistically significant improvements over manual transplanting in plant height and root length.

In seedling type B, Transplanter A showed the highest productivity with significantly higher weight (6070.50 g), diameter (28.14 cm), and leaf metrics. Compared to manual transplanting, Transplanter A produced a greater number of leaves and had superior root development (root weight 39.70 g, root length 18.20 cm). Transplanter B performed comparably in plant height and some foliar characteristics but showed slightly reduced total biomass and root metrics, suggesting minor inefficiencies in transplanting consistency or depth uniformity. Statistically, Transplanter B showed better in weight, diameter, and root weight was significant.

For the 43-day seedling type C, yield performance was more uniform between transplanting methods. Transplanter A provided competitive results with the highest root weight (36.50 g) and a strong overall plant profile (weight 5753.00 g; height 42.00 cm). Notably, root length remained superior to manual transplanting and close to Transplanter B, indicating consistent rooting depth. While the 43-day-old seedlings (type C) initially exhibited significantly greater height compared to the 30-day-old seedlings (type A), this difference was not reflected in the final plant height after the growing period. This outcome can be explained by the compensatory growth response commonly observed in younger transplants. Although Seedling A started with a shorter height, it likely experienced more vigorous vegetative growth post-transplanting due to lower transplanting shock, better root establishment, and faster adaptation to the soil environment. In contrast, seedling B often has more developed shoot systems, which can be more susceptible to transplanting stress and root disturbance, potentially limiting their post-transplant growth rate. However, due to the variability observed (CV of 13.27% for weight), statistical differences were less prominent across treatments, except for root length, where Transplanter A was significantly superior to manual transplanting.

Weight and diameter were significantly affected by the transplanting method at 35 and 43 days, indicating improved establishment and biomass accumulation with mechanized transplanting. Root length also differed significantly at 30 and 43 days, with transplanters promoting greater root development. In contrast, the number of leaves and root weight remained statistically unaffected, suggesting these traits were less influenced by the transplanting method. Transplanter A consistently outperformed manual transplanting and generally matched or exceeded Transplanter B in yield-related traits, particularly for early (30-day) and optimal (35-day) seedling ages. The enhanced plant height, head diameter, and root development metrics observed with Transplanter A suggest a more favorable micro-environment created during transplanting—likely due to improved seedling placement consistency and less mechanical root damage. These findings reinforce the suitability of Transplanter A for improving cabbage productivity under mechanized operations, particularly when transplanting is conducted at physiologically appropriate seedling stages. Seedling age interacts with transplanting method, particularly in growth outcomes (e.g., weight and diameter), indicating the need to optimize both age and equipment for yield gains.

3.5. Cabbage Collector Performance

Table 7. Performance parameters of the cabbage collector during field operation under greenhouse conditions.

Driving Speed (m/s)	Total Time (min)	Collection (%)	Damage (%)	Foreign Object Mixing Rate (%)	Bag Replacement Time (s)	Bag Replacement Cycle	Work Efficiency (%)
0.14	7.37	100	0	0	45	3	100

presents the performance parameters of a cabbage collector during the experiment. The cabbage collector operated at a driving speed of 0.14 m/s, completing the collection task in a total time of 7.37 min. The collector achieved a 100% collection efficiency, meaning that all cabbages were successfully collected without leaving any behind. Importantly, no damage to the cabbages was reported, as indicated by the 0% damage rate, ensuring that the quality of the harvested produce remained intact. Additionally, the collector avoided contamination, with a 0% foreign object mixing rate, which demonstrates its effectiveness in separating cabbages from unwanted materials.

The cabbage collector required a bag replacement time of 45 s and went through a bag replacement cycle of 3 times during the operation. This suggests that the collector was designed to handle a large volume of cabbages before needing a new bag, contributing to its operational efficiency. Finally, the overall work efficiency was measured at 100%, indicating that the cabbage collector performed optimally without any significant downtime or inefficiencies throughout the experiment. These results suggest that the cabbage collector is highly effective in collecting cabbages quickly and with minimal operational interruptions, making it a reliable tool for mechanized cabbage harvesting. Figure 9 shows the operational performance of the cabbage collector under development during greenhouse field operations.

4. Discussion

The findings of this study provide a comprehensive evaluation of cabbage seedling characteristics, transplanter performance, and the overall efficiency of mechanized transplanting compared to manual methods. The results indicate that the growth parameters of seedlings play a crucial role in determining transplanting success. Both transplanter A and B exhibited optimal performance with 35 and 43-day-old seedlings, respectively, which demonstrated a balance between plant height, leaf length, leaf width, and leaf count. These seedlings resulted in the highest normal transplant rates while minimizing missing plants and bad planting. The results underscore the importance of selecting uniform and healthy seedlings to enhance transplanting accuracy and efficiency.

When comparing transplanter performance, transplanter A excelled in achieving higher normal transplant rates, particularly with older seedlings (35 days), but at the cost of longer transplant times. The primary issues observed during the operation of transplanter A, along with potential directions for improvement. Several key problems were identified during the transplanting process, impacting the efficiency of the transplanter and seedling quality, as shown in Figure 10. One of the significant issues encountered was that seedlings were being covered with soil after transplanting (Figure 10b) [41]. This problem likely stems from improper adjustment of the dibbler depth, which leads to excessive soil being placed over the seedlings, hindering their ability to emerge and grow effectively [12,42]. To address this issue, the dibbler depth needs to be accurately set and adjusted to ensure seedlings are correctly placed into the soil without being buried.

Field efficiency is a critical measure of mechanization performance, as it reflects not only the operational speed and area covered but also the quality and precision of planting. In this study, the higher field efficiency achieved by the developed transplanter was directly linked to more consistent planting depth and spacing, which promoted uniform early establishment, root development, and ultimately higher yields. By optimizing field efficiency, the mechanization process improves both operational productivity and crop performance, highlighting its value in modern cabbage production. High missing rate for seedling picking (Figure 10c) meant many seedlings were not being picked up effectively by the transplanting mechanism. This issue may be related to a mechanical failure in the picking mechanism, as it was observed that seedlings were attached too firmly to the tray [20,43]. This strong attachment could prevent the seedlings from being successfully picked up, resulting in gaps during transplanting. A potential solution is to adjust the picking mechanism to ensure proper detachment of seedlings from the tray without damaging them or missing the seedlings entirely [44,45]. Additionally, seedlings frequently fell from the picking device before being placed into the dibbler (Figure 10a), causing further transplanting inefficiencies. This issue could be due to improper tray rotation or incorrect picking that causes seedlings to loosen and fall before they reach the soil [46]. Adjusting the tray rotation or improving the precision of the picking mechanism could help resolve this problem by ensuring that seedlings remain securely in place until they are transplanted.

To improve the performance of Transplanter A, it is crucial to focus on enhancing the accuracy of the dibbler, optimizing the picking mechanism to reduce seedling attachment issues, and ensuring proper tray rotation. By addressing these key areas, the transplanter can achieve better transplanting efficiency, reduce seedling loss, and improve overall crop establishment. Additionally, seedlings often fell from the picking device before reaching the dibbler, which is the part of the transplanter responsible for planting the seedlings into the soil. This was likely due to improper picking or tray rotation, which caused the seedlings to loosen and fall prematurely [20,47]. The improvement suggested for this problem includes refining the picking mechanism and tray rotation to prevent seedlings from dislodging before they are correctly placed in the soil. Overall, these issues highlight the importance of fine-tuning Transplanter A to ensure optimal transplanting performance. The proposed improvements focus on addressing speed, alignment, and the handling of seedlings to minimize planting errors and enhance the efficiency of the machine [16,45]. By making these adjustments, Transplanter B can better ensure accurate, consistent transplanting and reduce seedling loss during the planting process.

The comparison with manual transplanting highlights the significant speed advantage of mechanized transplanting. Transplanter A was 83–85% faster than manual methods, allowing for greater field coverage in a shorter time. However, manual transplanting maintained a higher efficiency rate (100%) compared to transplanter A (86%) and transplanter B (89%). This finding reflects the precision of human judgment in planting, which machines have yet to fully replicate. Despite this, the slight reduction in transplanting efficiency is offset by the substantial gain in speed, making mechanized transplanting a more viable option for large-scale operations [34]. Mechanized transplanting improved cabbage growth, with transplanters A and B yielding better weight, leaf size, and root development than manual methods. Among seedling ages, 35-day-old seedlings performed best in weight, height, and robustness, while 43-day-old seedlings showed weaker roots and reduced weight. Optimal seedling age is crucial for mechanized farming success [45,48].

Table 8. Comparison of the transplanting performance of different types of transplanter for cabbage and other crops with the current study.

Transplanter Type	Crop Type	Transplanting (%)	Missing (%)	Field Efficiency (%)	Reference
Manually operated	Pepper	75.0	5.0	86.59	[37]
Semi-automatic dibbler type	Brinjal /Eggplant	100	0	61.18	[23]
Semi-automatic furrow opener type		100	0	61.18
Automatic transplanter (commercial)	Cabbage	86.0	0.8	-	[13]
	Broccoli	91.4	1	-
Automatic transplanter (prototype)	Cabbage	85.2	5.8	-
	Broccoli	91.0	6.4	-
Pedestrian-type	Cabbage	-	-	91.36–92.21	[17]
Automatic transplanter	Cabbage	93.31	3.77	-	[16]
Automatic transplanter	Cabbage	72.0	7.5	69.4	[29]
	Pepper	70.67	7.17
Automatic transplanter (commercial)	Cabbage	85.17	8.94	59.57	[This study]
Automatic transplanter (under developed)		83.45	12.88	57.87

compares the performance of various transplanting methods across different studies, focusing on transplanting rate, miss rate, and field efficiency for a range of crops, including cabbage, pepper, eggplant, and broccoli. The manually operated machine for pepper achieved a transplanting rate of 75% and miss rate of 5%, yielding a field efficiency of 86.59% [37]. Similarly, a semi-automatic dibbler for eggplant/brinjal achieved 100% transplanting efficiency with no miss rate, although its field efficiency was relatively low at 61.18% [23]. In the case of cabbage, a pedestrian-type automatic transplanter achieved a field efficiency of 91.36–92.21% [17], and another automatic transplanter for broccoli recorded a transplanting rate of 91.0% and a miss rate of 6.4% [13]. Compared with these studies, the automatic transplanter in this study demonstrated a transplanting rate of 83.45% with a miss rate of 12.88%, yielding a field efficiency of 57.87%. These results provided a promising potential of the developed transplanter while highlighting areas for further optimization, such as reducing the miss rate and increasing overall field efficiency.

The uniformity and health of seedlings are necessary for achieving optimal results in mechanized transplanting. As highlighted by different studies [16,29,37], mechanical transplanters require seedlings with consistent shape, height, and root plug firmness for smooth gripping and accurate placement. Variability in these traits can cause missed or misaligned transplants, increasing downtime and reducing overall field efficiency [29]. Moreover, uniform and healthy seedlings support precise planting depth and upright positioning, facilitating rapid root establishment and reducing transplant shock [13]. Ultimately, such consistency promotes more uniform crop growth and higher yields. These observations show the important role of seedling quality in maximizing the effectiveness and reliability of mechanized transplanting operations.

The cabbage collector used in this study demonstrated high operational efficiency, successfully collecting all cabbages without damage or contamination. Its ability to maintain 100% collection efficiency and work without significant downtime makes it a valuable tool in mechanized cabbage harvesting, further enhancing the viability of automated farming techniques. Key issues observed with the domestic cabbage collector during field operations as shown in Figure 11. Figure 11 illustrates the labor-intensive nature of the current cabbage collection process, showing workers actively involved in cutting, collecting, and replacing cabbage bags. The main challenge was the need for extra labor during the cutting and collection process. Cabbage harvesting often involves multiple manual steps, including cutting, handling, and positioning on the conveyor system for collection [5,23]. This increased the time and labor intensity of the operation, reducing the overall efficiency of the process. To address this, it is recommended to consider installing an automatic cut-off system within the collector [23]. This mechanism would reduce manual cutting, speeding up the process and reducing the need for extra labor.

Another issue identified was the additional labor and time needed to place the collected cabbage into bags. The manual bag replacement process slows down the collection and adds to the overall workload [6,14]. To mitigate this, an automatic bag replacement system or an automatic unloading system could be implemented. This would automate the replacement of collection bags, ensuring continuous operation without frequent stoppages. By minimizing the manual handling of cabbages, such improvements would significantly reduce labor requirements and increase collection efficiency [23].

A further challenge observed was the rolling of cabbages on the conveyor belt, which could lead to damage or misalignment of cabbages as they move through the collection system [22,23]. This issue may stem from improper belt speeds or sizes, or from insufficient marking of cabbage placement on the belt. It is suggested that adjustments be made to the belt size and speed to ensure proper handling of the cabbages during transport [40,45]. Additionally, marking the placement of cabbages on the conveyor belt could improve accuracy in positioning, reducing the risk of cabbages rolling or becoming displaced during collection.

While this study provides valuable insights into the effectiveness of different transplanters and mechanized cabbage farming, certain technical limitations should be acknowledged in future design improvements. The transplanter demonstrated inconsistent seedling feeding and occasional mechanical interruptions, affecting planting uniformity and efficiency. Limited maneuverability, especially near the edges and corners of the greenhouse, was attributed to structural constraints and low clearance, restricting the operational range. Additionally, the system lacked adaptability to different tray types and soil conditions, requiring manual adjustment and calibration for varied planting setups. Addressing these issues will be critical to enhancing the reliability, versatility, and automation of the equipment, ensuring its suitability across a wider range of greenhouse environments and planting conditions. In addition, the study was conducted under controlled greenhouse field conditions, which may not fully represent the variability encountered in real-world greenhouse farming environments, such as differing soil textures, weather conditions, and operator skills. Additionally, the assessment focused primarily on short-term transplanting and harvesting efficiency without long-term analysis of plant health and yield stability.

Future research should investigate the long-term effects of mechanized transplanting on crop yield and soil health under various environmental conditions. Further studies could also explore the integration of advanced precision agriculture technologies, such as automated seedling assessment and robotic planting systems, to enhance transplanting accuracy. Additionally, an economic analysis comparing the cost-effectiveness of mechanized versus manual transplanting would provide valuable insights for farmers considering mechanization. By addressing these areas, future research can contribute to further optimizing mechanized transplanting for sustainable and efficient cabbage production.

5. Conclusions

The mechanization of cabbage cultivation holds significant promise for addressing labor shortages, enhancing productivity, and ensuring the sustainability of cabbage farming in Korea. This study evaluated the performance of a mechanized cabbage transplanter and a cabbage collector under development under greenhouse conditions, providing valuable insights into their agronomic and operational efficiency. The results clearly demonstrated that mechanization significantly enhances transplanting speed, accuracy, and crop yield, addressing critical challenges in Korean cabbage farming.

Transplanter A achieved a maximum forward speed of 1.27 km/h and planted up to 2526 seedlings/h, outperforming manual methods, which recorded only 513 seedlings/h. The effective field capacity (EFC) for Transplanter A ranged from 0.11 to 0.13 ha/h, compared to 0.019–0.028 ha/h for manual transplanting. Field efficiency reached as high as 64.5%, significantly surpassing manual methods (52.79–59.58%). While Transplanter A exhibited a slightly higher missing transplant rate (up to 18.17%) than Transplanter B (as low as 7.67%), it consistently delivered lower bad planting rates (>30° inclination)—as low as 2.5%, compared to up to 8.8% with Transplanter B. Yield assessment showed statistically significant differences (p < 0.05) favoring Transplanter A, especially with 35-day-old seedlings. This treatment resulted in the highest average cabbage weight (6070 g), increased head diameter (28.14 cm), and superior root metrics (root weight: 39.7 g; root length: 18.2 cm). These values were better than both manual and commercial transplanting methods, underscoring the agronomic benefits of precise and consistent transplanting depth and spacing provided by the transplanter under development. The cabbage collector also performed optimally, achieving 100% collection efficiency, 0% damage rate, and no foreign object contamination. Its foldable design and hydraulic system further enhance usability, particularly for elderly and female operators.

The results support the adoption of mechanized transplanting, particularly with Transplanter A for commercial cabbage production. Despite minor trade-offs in transplanting accuracy compared to manual methods, mechanized systems significantly improved overall efficiency and yield productivity. The study also emphasizes the importance of matching seedling age with transplanter capabilities to optimize field performance. Future research should focus on enhancing transplanting accuracy through precision guidance systems, evaluating long-term agronomic and economic impacts, and integrating mechanized solutions into smart farming frameworks for sustainable crop management.