Introduction
⌅The seedling transplanting operation involved in vegetable cultivation is time-consuming, tedious, labour intensive and expensive (Khadatkar et al., 2018Khadatkar A, Mathur SM, Gaikwad BB, 2018. Automation in transplanting - A smart way of vegetable cultivation. Curr Sci115(10): 1884-1892.). In India, the labour requirement for manually transplanting vegetables varies from 240 to 320 man-h·ha-1 (Kumar & Raheman, 2008Kumar GVP, Raheman H. 2008. Vegetable transplanters for use in developing countries: A review. Int J Veg Sci14(3): 232–255. 10.1080/19315260802164921; Manes et al., 2010Manes GS, Dixit AK, Sharda A, Singh S, Singh K, 2010. Development and evaluation of tractor operated vegetable transplanter. Agric Mech Asia Afr Lat Am41(3): 89–92.; Kumar & Raheman, 2011Kumar GVP, Raheman H, 2011. Development of walk-behind type hand tractor powered vegetable transplanter for paper pot seedlings. Biosyst Eng110(2): 189–197. 10.1016/j.biosystemseng.2011.08.001). In peak seasons, manual labour can hardly meet the transplanting requirements of vegetable seedlings. Aside from the time commitment, manual transplanting entails much drudgery and human suffering (Sharma & Khar, 2022Sharma A, Khar S, 2022. Current developments in vegetable transplanters in developing countries: a comprehensive review. Int J Veg Sci28(5): 417-440. 10.1080/19315260.2022.2046672). The labourer has to stoop forward while placing the seedlings on the bed to avoid shattering the plug media and damaging its root, and stooping posture results in higher energy consumption and biomechanical stresses in the back compared to other working positions. At the same time, the labourer has to hold the plug tray in one hand, which results in static stresses in the hand. The labourer in actual transplanting must squat to move to the next planting position. The continuous use of bare fingers for making grooves in the soil causes inflammatory abrasion on fingertips and nails, leading to infection. The manual transplanting operation, performed in stooping and squatting postures, is a strenuous activity and is not feasible (Sharma & Khar, 2022Sharma A, Khar S, 2022. Current developments in vegetable transplanters in developing countries: a comprehensive review. Int J Veg Sci28(5): 417-440. 10.1080/19315260.2022.2046672). During squatting with movement activity and bending posture, oxygen consumption is 31-35 and 70-80 per cent of VO2 max (Grandjean, 1988Grandjean, É, 1988. Fitting the task to the man: a textbook of occupational ergonomics. 4th ed, Taylor and Francis, London, New York.). As a result, there is more weariness and reduced working capacity. Manual transplanting has become uneconomical because of rising labour costs in the last decade. The above-discussed manual transplanting limitation can be overcome using mechanical transplanters.
Planting, feeding, metering, soil covering, and a propulsion unit are a few of the functional components that mechanical transplanters typically include. One significant component is the seedling feeding unit, which supplies the planting unit with seedlings to facilitate the transplantation process. Thus, the effective operation of the transplanter is contingent upon the seedling feeding apparatus operating correctly. Numerous studies have been conducted in the past on developing seedling-feeding units. Nambu et al. (1997Nambu T, Miyamoto K, Matsuda K, 1997. Development of automatic sugar beet transplanter using chain pots. Jpn Agric Res Q31(4):249-55.) invented an automated sugar beet transplanting feeder. A continuous paper pot series and a mechanism to swiftly separate seedlings were created. Planting devices employed drop chutes. These new devices were fitted with a tractor-mounted 2-row and tractor-trailed 6-row transplanters. Field performance study revealed a 6.9 degree standard variation in planting angle for the two-row transplanter at 2.5 to 2.9 km·h-1 speed. Five years of studies at 24 farmers’ sites covered 42.1 acres. In Europe, a six-row transplanter was designed for wider areas. The six-row transplanter has a field capacity of 0.54 ha·h-1 and achieves the same planting accuracy as the two-row transplanter. Margolin et al. (1986Margolin A, Alper Y, Eshed A, 1986. Development of a semi-automatic transplanter. Acta Hortic187: 158-158. 10.17660/ActaHortic.1986.187.24) developed a semi-automatic transplanter using a horizontal feeding conveyor distributed into cross-wise panels where seedlings were manually fed in lots. Single plants were transported into split cone-cups by the conveyor, which positioned them in their natural evolving position in the ground. The field test revealed batch loading boosted the feeding rate to 90 plants·min-1. In a mechanical feeding unit with a feeding belt with cells on its surface, EL-Sheikha et al. (2014EL-Sheikha MA, EL-Morsy HE, Badr SE, EL-Balkimy WMZ, 2014. Development of a mechanical feeding unit suitable for onion seedlings. J Soil Sci Agric Eng5(11):1489-1508. 10.21608/JSSAE.2014.49779) examined how the linear speed of the feeding belt, the conveyor belt-feeding belt speed ratio, seedling bulb diameters, and cell width of the feeding belt affected onion seedling properties. Seedling feeding rate was optimal at 153 seedlings·min-1, with 5.69% inclined, 3% damaged, 0.11-0.12 m spacing, and 0.0994 kW power usage. Using onion seedlings (diameter > 0.005 <0.010 m) and a mechanical feeding device (0.347 m·s-1, 1.33 relative linear speed, 0.03 m feeding belt cell width), data was collected. Zhao et al. (2020Zhao X, Ye J, Chu M, Dai L, Chen J, 2020. Automatic scallion seedling feeding mechanism with an asymmetrical high‑order transmission gear train. Chin J Mech Eng33(1): 10. 10.1186/s10033-020-0432-9.) proposed a high-order non-circular gear train for automated scallion-seedling feeding. The intended gear train included an asymmetric transmission ratio that allowed the execution part to travel long and spin at a broad angle. The execution component might feed a scallion in the right posture because to its lengthy displacement and large rotation angle. The novel seedling-feeding mechanism parameter-design model was created using precise position points and trajectory-shape control points. Moreover, an aided-design program was constructed to acquire the scallion-seedling feeding mechanism parameter-solution domain. The transmission ratio was determined by optimizing the seedling-feeding mechanism parameters using software and kinematic simulation. A 93.4% statistical success rate was achieved by examining 1,000 seedlings at 100 per minute.
Shao et al. (2021Shao YY, Han X, Xuan GT, Liu Y, Gao C, Wang GP, et al. 2021. Development of a multi-adaptive feeding device for automated plug seedling transplanter. Int J Agric Biol Eng14(2): 91–96. 10.25165/j.ijabe.20211402.6003) developed a multi-adaptive plug seedling feeding system that can adjust to several plug trays for diverse seedlings for autonomous field transplanting. Control systems might automate seedling-feeding devices. Tomato, pepper, and cucumber plug seedlings were examined. In the prototype’s performance test, cucumber seedlings in a 50-cell tray had the best performance with an 88% success rate at 6 groups min-1. In 105-cell trays, tomato seedlings had the lowest success rate of 73.33% at 12 groups per minute. Due to its versatility, this investigation’s automated feeding technique may be used for several plug seedlings. Kumar & Raheman (2012Kumar GVP, Raheman H. 2012. Automatic feeding mechanism of a vegetable transplanter. Int J Agric Biol Eng5(2):1-8. DOI: 10.3965/j.ijabe.20120502.003) performed the laboratory evaluation of an automatic feeding mechanism of a vegetable transplanter and indicated that the feeding rate of 33 to 50 pot seedlings per minute can be achieved with a single set of conveyors. With 98 to 99% of all pot seedlings properly separated and fed for planting when the forward speed of the vegetable transplanter was 0.9 km·h-1, the feeding mechanism also worked effectively under actual field conditions. A feeding mechanism is the most critical component of the mechanical type of vegetable transplanter (Kumar & Raheman 2012Kumar GVP, Raheman H. 2012. Automatic feeding mechanism of a vegetable transplanter. Int J Agric Biol Eng5(2):1-8. DOI: 10.3965/j.ijabe.20120502.003).
In the union territory Jammu and Kashmir, India, small landholdings, undulating topography, terraced irregularly shaped fields, and farmers’ low investment capacity make mechanization challenging with the current farm equipment available in the market. Creating a mechanically fed vegetable transplanter that is inexpensive, portable, efficient, and low-cost is paramount. Consequently, efforts are underway to develop a tractor-mounted vegetable transplanter that utilizes mechanical feeding mechanisms. The present investigation focuses on the design and development processes of semi-automatic mechanical feeding mechanisms. Considering these constraints and requirements, the current investigation was initiated to design and develop feeding mechanisms for vegetable seedlings.
Materials and methods
⌅Utilizing the information gleaned from the available reviews, an analysis was conducted on the characteristics (Sharma et al., 2022Sharma A, Khar S, Sharma S, Singh JP, 2022. Investigation of physical traits of brinjal seedlings apropos to the design of a transplanter. Environ Ecol40 (2A): 476-481.; 2023Sharma A, Khar S, Chaudhary D, Thakur P, 2023. Study of biometric attributes of plug type tomato seedlings pertinent to transplanter design. Indian J Ecol50(2): 503-507. 10.55362/IJE/2023/3926) of vegetable crop seedlings (including spacing between rows and plants, stem diameter, and spread diameter) and experiment strategy, design aspects, development, assessment, and conclusions. The development of a tractor-mounted, two-row, semi-automatic type vegetable transplanter was conceptualized and designed utilizing computer-aided design software, a bill of materials, and a two-dimensional schematic by the findings.
Transplanter description and working
⌅The developed tractor-mounted vegetable transplanter was made up of two seedling holding trays, an operator seat, a speed reduction gearbox, cranks and connecting rods, two feeding mechanisms, a chain sprocket transmission system, a single lugged drive wheel with a diameter of 521 mm, body frame plates, and compaction wheels. The transplanter was constructed with the plug seedling spacing of 450 mm between plants and 600 mm between rows in mind. The seedling was manually placed into the mechanical feeding mechanisms when the machine moved ahead. The transplanting unit rose upward, releasing the seedling from the feeding unit. The operators began placing seedlings into the hollow pipes, the empty pit, and the planter within the casings of the horizontal magazine-style feeding mechanism and the revolving multi-chamber disc. After taking the seedling from the feeding unit, the transplanting unit moves downward, punches or digs a hole in the ground to the appropriate depth, and then opens the mouth of the digging unit of the transplanting unit by pushing the opening lever through the position of the vertical plates. The transplanter handled every seedling transplant in the same manner every time. The soil around the transplanted seedling was compressed by the press wheel on the rear of the machine. The drive for the whole system, including the feeding and transplanting mechanism, came from the chain and sprocket system, powered by the drive wheel, which rotates with the tractor’s forward motion. The transplanter’s stationary view is shown in Fig. 1.
Feeding mechanism purpose
⌅The feeding mechanism is the key component of every transplanter, and its job is to distribute seedlings evenly at the right time and place. Successful performance of the transplanter depends on the proper selection and design of the feeding mechanism. In the current study, two feeding mechanisms were designed and constructed. These mechanisms, a multi-chamber disc and dragging magazine with revolving and horizontal motion regarding the machine’s forward motion, performed the function of feeding vegetable seedlings to the transplanting unit to carry out the seedling transplanting operation.
Concept of feeding mechanisms
⌅This section discusses the methodologies, materials and methods used to design and develop the revolving multi-chamber disc feeding mechanism (FMRMD) and horizontal dragging magazine feeding mechanism (FMHDM). Computer-aided design (CAD) software (Solid Works) was used to conceptualise FMRMD and FMHDM based on the attributes of plug seedlings of tomato and eggplant crops. Following the 3D modelling process, an FMRMD and FMHDM mounted on a mechanical vegetable transplanter was designed and built using two-dimensional drafting and a bill of materials. The procedure adopted, and the material used to conduct this study has been presented under the following sub-heads;
Revolving multi-chamber disc feeding mechanism
⌅In the present study, the FMRMD (with the numerical arrangement in clock-like chambers on its periphery) was selected due to its easy manoeuvrability and simplicity in construction. Two circular 14-gauge mild steel (M.S.) plates of 762 mm (diameter) were used to fabricate a FMRMD The plates were joined to each other by welding an M.S. sheet, keeping a 76 mm distance between them, making it a multi-chamber disc. The 12 chambers of diameter 70 mm and length 76 mm were made on the multi-chamber disc to resemble the 12 numerical numbers printed on the wall clock. The 12 M.S. circular plates of 100 diameters were attached to one side every 12 chambers made on the multi-chamber disc via a nut and bolt system. A spring was attached between each circular plate and the opposite side of the pit to open and close the plates. The conceptual and fabricated view of the FMRMD is shown in Fig. 2.
Determination of the number of chambers on the revolving disc
⌅The primary function of the circular holes/chamber/grooves on the feeding unit is to hold the seedling upright during transplanting. The number of holes/grooves/chambers in the feeding unit was calculated using the following formula (Ningthoujam et al., 2016Ningthoujam B, Singh V, Nilatkar DK, 2016. Design and development of wooden plate metering device for onion bulb planter. Int J Appl Sci Eng4(2): 111-123. 10.5958/2322-0465.2016.00013.7; Soyoye, 2020Soyoye BO, 2020. Design and evaluation of a motorized multi-grain crop planter. Agric Eng Int: CIGR J22(1):54-66.).
where, Ng: No. of grooves/chambers on the revolving disc;
D : Diameter of the drive wheel, m;
I : speed ratio = ratio of the drive wheel shaft to metering shaft = (No. of teeth on metering shaft (Tm)/No. of teeth on drive wheel shaft (Td) = Tm/Td
Z : plant to plant spacing = 0.45 m
On substituting D: 0.521 m, I: 4, and Z: 0.45 m in the above equation, the number of grooves/chambers (Ng) obtained was 14.54, but for the requirement of maintaining uniformity in row spacing and to match the planting device timing, the number of grooves/chambers on rotating disc was taken as 12.
Chamber length and diameter of revolving multi-chamber disc feeding mechanism
⌅The diameter of the FMRMD chamber was selected based on the spread diameter of the vegetable seedlings. The canopy size of the plug seedling determines the necessary pipe through which a healthy plug seedling apposite for transplanting can travel vertically without being trapped. To evade seedling feed tube blockage, the diameter of the seedling feed chambers of the revolving multi-chamber disc should be higher than the essential canopy diameter of the seedling. The height of the FMRMD feeding mechanism was selected based on the length of the seedlings of the selected vegetable crops. The selected diameter and length of the chamber in the present study were 70 and 76 mm, respectively. It was also found during the study that a commercially available hand-held vegetable transplanter, which has a tube-like structure, has a diameter and length of 50 and 900 mm, and the seedlings of tomato and eggplant quickly passed through this tube without getting stuck. Therefore, a chamber of size 70 mm was found appropriate for the present study.
Design of rotational of the revolving multi-chamber disc
⌅The frequency of the rotation (rpm) of the revolving multi-chamber disc of the machine at a known speed of the machine and selected plant-to-plant distance between seedlings is given (Narang et al., 2011Narang MK, Dhaliwal IS, Manes GS, 2011. Development and evaluation of a two-row revolving magazine type vegetable transplanter. J Agric Eng48(3):1-7.) by the following relation:
where, n: rotation of the multi-chamber disc (rpm); Vm: machine speed (m·s-1)
Z: number of chambers on the disc; Ag: seedlings plant-to-plant distance (m)
On substituting the Vm: 0.28 m s-1, Z : 14.54, Ag : 0.45 m in the above equation, give n = 2.56 rpm. The expression mentioned above shows that the frequency of the rotation of the revolving multi-chamber disc increases with increasing the speed of the machine. Two metal sheets of 760 mm diameter were taken and welded together, keeping a 76 mm distance between them. Based on the seedling spread, twelve holes/pits of 70 mm diameter were made on the circular periphery of the disc with a depth of 76 mm at an angle of 30o (π/6) between each pair of chambers. The developed revolving multi-chamber disc was attached to the reduction gearbox output shaft from the center of the disc. The reduction gearbox was installed on the metal sheet and fixed on the machine frame. The drive to the reduction gearbox was provided from the ground/driver wheel through the chain sprocket system. The drive given to the reduction gearbox makes the multi-chamber disc (attached to the gearbox’s output shaft) rotate.
Horizontal dragging magazines feeding mechanism
⌅In the present study, the FMHDM was selected due to its simplicity in construction and easy availability of materials required. A quick return motion mechanism, essentially an offset slider-crank mechanism in which the slider has different average velocities in forward and return strokes, was employed to produce the quick horizontal dragging of the magazine. One of the strokes (forward/reverse) takes less time than the other because of the offset. As a result, even though the crank turns evenly, the slider completes one stroke faster than the other. It converts circular motion into reciprocating motion and reciprocating motion into circular motion. An offset slider-crank mechanism was employed (Fig. 3) to achieve the goals of the FMHDM mentioned above because the stroke line of the slider does not cross through the axis of the rotation of the crank.
The multi-chamber disc body was used as a base for the FMHDM. A solid temper rod of length 864 mm and 10 mm diameter was joined to the circular plate attached to the drive shaft with the help of a link and arm. On the temper rod, six hollow pipes (three for each row) were attached with the help of clamps which can be easily loosened and tightened with the help of the revolving screw. The M.S. hollow pipes of size 60 mm and 50 mm diameter and length of 102 mm were used. The dimensional and fabricated view of the FMHDM is shown in Fig. 4.
Displacement analysis of an offset slider crank (OSC) mechanism
⌅For the displacement analysis of an OSC mechanism, the quick return ratio and the stroke length must be determined. The quick return ratio (QRR) is the ratio of time taken for a forward stroke to time taken for a return stroke. This is the same as the angle swept by the crank in the respective strokes. The kinematic diagram of the OSC mechanism having ‘r’, ‘l’ and ‘e’ as crank length (O2A), connecting rod (AB) and offset, respectively, is shown in Fig. 5a.
The condition l > r+e must be satisfied for the crank to revolve entirely, where ‘r’ is the crank length, ‘l’ is the length of the link connecting the crank and the slider, and ‘e’ is the offset of the slider. The kinematic model view of the OSC mechanism is shown in Fig. 5b. Assuming the crank (O2A) is rotating in a circular motion with uniform angular velocity (ω) in a counter clockwise direction. Considering the fixed point O2, the distance of O2 from the BR (extreme right position) becomes l+r (also the radius of arc C) with a crank position at AR, whereas the distance of O2 from (extreme left position) becomes l-r (also the radius of arc D) with crank position AL. When the crank rotates from AR to AL, the slider moves from point BR to point BL, which is the forward stroke, and the corresponding angle travel by the crank is θ f. On the other hand, in a return stroke, the slider moves from BL to BR with the corresponding movement of the crank from AL to AR with an angle travel of θr. The equation used to determine the QRR is as follows:
QRR = time taken by forward stroke/time taken by return stroke
The equation for finding QRR can be written as below:
QRR = (θf/ω)/(θr/ω) = θf/θr
By considering <O2BLBR as <θ, from the geometry of kinematic diagram, it is estimated that, θf = 180 + θ, θr = 180 – θ.
Therefore, equation for determination of QRR can be written as
QRR = (180 + θ)/ (180 – θ)
By considering <O2BRBR1 as <α and <O2BLBL1 as <β from the geometry of kinematic diagram, it is estimated that, θ = β – α
Again, from the geometry of kinematic diagram, α and β can be determined as below:
sinα = (e/(l+r)), α = sin-1((e/(l+r)), and sinβ = (e/(l-r)), β = sin-1((e/(l-r))
Therefore, θ = sin-1((e/(l-r)) – sin-1((e/(l+r))
Finally, the equation for determination of becomes as follow:
QRR = (180 + sin-1((e/(l-r)) – sin-1((e/(l+r)))/(180 – sin-1((e/(l-r)) – sin-1((e/(l+r)))
Now, from the kinematic diagram stroke can be written as below:
stroke = BLBR = O2BR’ - O2BL’ = (l+r)cosα – (l-r)cosβ
where, O2BR’ = (l+r)cosα, O2BL’ = (l-r)cosβ
Therefore, stroke (S) = (l+r)cosα – (l-r)cosβ
Substituting the values of l: 152 mm, r: 64 mm, e: 50 mm
α = 13.38, β = 34.62, θ = 21.24, QRR = 1.27, S = 137.72 mm
As a result, for each row, three hollow pipes were positioned to drag the seedling to the guided hole in the stroke length of the slider (temper rod). With the help of rotating clamps, two 60 mm hollow pipes were fixed on the right side of the temper rod at a distance of 15 mm (keeping the outermost pipe centre coinciding with the right side guided hole) and a third 50 mm hollow pipe was fixed at a distance of 5 mm from the next fixed hollow pipe, considering the machine’s forwarding direction. On the other hand, two 60 mm pipes were set at a distance of 15 mm on the left side of the temper rod, with the innermost pipe centre aligned with the left side guided hole, and a 50 mm hollow pipe was fixed on the rod’s outermost side at a distance of 5 mm from the next fixed hollow pipe.
Working of the horizontal dragging magazines feeding mechanism
⌅In the FMHDM, with the help of a chain sprocket and reduction gearbox system, the rotary motion of the drive wheel is converted to the horizontal motion of the temper rod on which three hollow pipes (for each row) are attached, making it a horizontally moving magazine type feeding system. The rod on which hollow pipes are attached performed the reciprocating motion, which dragged the seedling to the opening point from where the seedlings were dropped to the transplanting unit. In this mechanism, the seedlings are manually placed in the hollow pipes, which move horizontally relative to the forward motion of the transplanter. The hollow pipes dragged the seedling to the drop point. The functional view of the FMHDM is shown in Fig. 6. At rest, hollow pipes 1, 2, 4 and 5 were filled manually with the seedling. As the horizontal motion starts (to the left), hollow pipes 2 and 5 drag the seedling over guided/drop whole, and pipes 3 and 6 are filled manually with the seedling. On further horizontal motion to the left, hollow pipes 1 and 4 drag the seedling to the guided/drop whole, and pipes 2 and 5 are filled manually with the seedlings. In the same way the seedling drops to the planter, the mechanism occurs when horizontal motion starts to the right.
Drive train for mechanisms
⌅The power from the driving wheel to the main shaft was transferred employing a chain and sprocket with 39 (T1) and 13 (T2) teeth on each sprocket. Another sprocket with 29 (T3) teeth was attached to another end of the main shaft, which drove the intermediate shaft with the same 29 (T4) number of teeth sprocket on one end. Then, the power was transmitted from the intermediate shaft to the input shaft of the reduction gearbox with the help of the identical 16 (T5, T6) number of teeth sprocket on both shafts in the case of FMRMD and the case of FMHDM, the power is transmitted by 39 (T5) teeth sprocket of the intermediate shaft to 13 (T6) teeth sprocket on the input shaft of the gearbox. The power was then transmitted to the feeding system after a reduction in the ratio of 12:1 with the help of a gear reduction box. The speed ratios of 4:1 and 1.33:1 were maintained to deliver seedlings appropriately with the proper spacing for the revolving disc and magazine feeding mechanism. The complete power path of the drive train system from the ground wheel is shown in Fig. 7. The drive train calculation is given under:
Speed ratio in FMRMD:
Speed ratio in FMHDM:
where, N1 and N4: rpm of drive wheel and driven gear
Feeding mechanisms planting frequency
⌅Planting frequency of revolving multi-chamber disc feeding mechanism
⌅In the FMRMD, the seedling chambers were grooved through the disc. The gearbox drives the seedling chamber of the feeding device to rotate. The bottom covers are provided to each seedling chamber, which opened at left (L) guided hole and right (R) guided hole (also called seedling injection port), which were spaced at row spacing. The bottom cover, having a vertical flat, was hinged with the seedling chamber and was provided with a spring attached to the disc through the inner side of the seedling chamber. A bracket was on the left and right guided hole or seedling injection port. When a particular chamber reached the seedling injection port, the bracket bottom was covered vertically flat, which caused the bottom cover to open and the seedling to discharge from the chamber. After the bottom cover of the seedling chamber was opened, the plug seedling was thrown in a horizontal motion, and the initial speed was equal to the seedling chamber speed. If the feeding device rotates too fast, the plug seedlings do not entirely fall from the seedling chamber, and the bottom cover is closed. This will cause the plug seedlings to be clamped. Equations 1, 2 and 3 were used to calculate the relationship between the displacement (D2) of the seedling chamber and seedling falling time (t), the relationship between the speed of the seedling feeding device (V) and transplanting frequency (q), and maximum separation frequency (qm).
Substituting the values related to the FMRMD mechanism from Table 1 into equation 1, 2 and 3, we obtained, D2: 0.024 m, q (single row planting frequency) : 29·12 plant·min-1, qm : 33.94 plant·min-1.
| Parameter | Description | Observations | |
|---|---|---|---|
| FMRMD[1] | FMHDM[2] | ||
| V | speed (m·s-1) of seedling chamber/dragging magazine | 0.10 | 0.033 |
| t |
• time (s) required for the seedling to fall and completely detach from the chamber; • time (s) required for the seedling to completely fall from the injection port |
0.24 | 0.24 |
| D1 | installation distance (m) of the seedling chamber/ dragging magazine | 0.103 | 0.033 |
| H | height (m) of the plug seedling | 0.208 | 0.208 |
| g | gravity acceleration (m·s-2) | 9.8 | 9.8 |
| D2 | distance of the seedling chambers/cups from opening to closing (m). | 0.024 | 0.0079 |
Planting frequency of horizontal dragging magazine feeding mechanism
⌅The dragging magazine was fitted on the tempered rod in the FMHDM. The gearbox drives the seedling dragging magazine of the feeding device horizontally towards the left and right guided holes (also called the seedling injection port), which were spaced at row spacing. If the feeding device rotates too fast, the plug seedlings do not entirely fall at the injection port. This will cause the plug seedlings to be clamped or lay down. The equations 1, 2 and 3 were used similarly as in the case of FMRMD for the calculation of D2, q and qm. Substituting the values related to the FMHDM from Table 1 into equations 1, 2 and 3, we obtained D2: 0.0079 m, q (single row planting frequency) : 30 plant∙min-1, qm : 34.87 plant·min-1.
Testing procedure
⌅The developed transplanter were mounted on the transplanter and tested in the field to investigate the effects of plug shape types, seedling ages and feeding mechanisms on Missing Index (MI) percentages for tomato (Solanum lycopersicum L.) and eggplant (Solanum melongena L.). The MI indicates the number of times a seedling misses the desired spacing. It was considered a miss if the distance between two plants was more significant than 1.5 times the theoretical spacing (Bakhtiari & Loghavi, 2009Bakhtiari MR, Loghavi M, 2009. Development and evaluation of an innovative garlic clove precision planter. J Agric Sci Technol11: 125-136. http://dorl.net/dor/20.1001.1.16807073.2009.11.2.1.2). The distance between two successive plants planted in the field along the six-meter length of the machine-transplanted field was measured for each trial. The machine was set for the row-to-row spacing of 600 mm and plant-to-plant spacing of 450 mm (± 50 mm) for the selected crop to be transplanted. The size and shape of the seedling tray cell influence plug-type seedlings’ development. The seedlings’ development is regulated by their control over the allocation of nutrients and water (Singh et al., 2005Singh B, Yadav HL, Kumar M, Sirohi NPS, 2005, Effect of plastic plug-tray cell size and shape on quality of soilless media grown tomato seedlings. Acta Hortic742: 57-60. 10.17660/ActaHortic.2007.742.7; Vijayreddy & Kumar, 2023Vijayreddy D, Kumar VV, 2023. Protray raising of vegetable nursery Seedlings. Agriallis5(2): 48-52.). Increased cell size will accommodate a greater volume of medium, providing a higher quantity of nutrients for the growth and maturation of the seedlings. Although some Indian academics have examined the influence of tray cell size and shape on the creation of vegetable transplanters (Narang et al., 2011Narang MK, Dhaliwal IS, Manes GS, 2011. Development and evaluation of a two-row revolving magazine type vegetable transplanter. J Agric Eng48(3):1-7.; Bhambota et al., 2018Bhambota S, Dixit > AK, Manes GS, Singh SK, 2018. Development and evaluation of vertical cup with split base type metering mechanism cum dibbler for semi-automatic transplanter using cell feed type nursery. Int J Curr Microbiol Appl Sci7(6): 3600-3611. 10.20546/ijcmas.2018.706.424), more investigation is required to understand this subject thoroughly. Transferring the seedlings after 32 days is recommended for the chosen crops. In order to investigate the effects of varying seedling age, two additional seedling ages were chosen: one week before the allowed seedling age and one week beyond it. These ages were picked in addition to the conventional seedling transplanting age.
For testing purposes, two plug-shape types (P1: square, P2: round), three seedling ages (S1: 25 days, S2: 32 days, S3: 40 days) and three seedling feeding methods (M1: FMRMD, M2: FMHDM, M3: FMDMF) were selected. The chambers and the hollow pipes of the FMRMD and FMHDM feeding system were filled with the seedling before transplanting, and the remaining seedling trays were placed on each of the seedling trays. On the other hand, in direct manual feeding (FMDMF), the transplanter was operated without a feeding mechanism, and the seedling was directly placed in the transplanter unit by uprooting the seedlings from the nursery trays and placing them in the well-prepared field. The tractor’s throttle lever was set to the correct position, and the first low gear was engaged to obtain the needed forward speed for the study to ensure proper planting operation and regular plant-to-plant spacing. Statistical analysis of the MI data for tomato and eggplant was done using a factorial randomized block design. The factorial analysis of variance was used to pair up each level and component, which made it simpler to comprehend how the levels and factors interact. The statistical program statistics package for the social sciences (SPSS 26) was used for variance analysis and mean comparisons at a 5% significance level.
Results and discussion
⌅Laboratory testing
⌅The working ability of the developed feeding mechanisms was initially tested in the laboratory. The drive wheel was rotated manually, and synchronization of the movement of the FMRMD and FMHDM was observed. A canister filled with soil was kept below the planting device, and seedling was placed in the feeding mechanism. The feeding mechanism was revolved/dragged by rotating the driving wheel, dropping the seedling at the drop point, which was captured by the planting device at its top position (closed) and then transplanted into a canister filled with soil when it reached its bottom position (open). Both the feeding mechanisms were tested in the same way, and the performance of the transplanter was found satisfactory.
Field testing
⌅The effect of the feeding methods (M1, M2, M3), plug types (P1, P2), and seedling ages (S1, S2, S3) on the MI percentage for tomato and eggplant are presented in Table 2 & 3 and are graphically illustrated in Fig. 8 and Fig. 9. The effect of the individual parameters on the MI is discussed below:
| Plug Type (P) | Feeding method (M) | Missing Index (%) | |||||
|---|---|---|---|---|---|---|---|
| Seedling Age (S) | P×M | ||||||
| S1 | S2 | S3 | |||||
| Square (P1) | M1 | 5.09 | 6.95 | 4.17 | 5.40 | ||
| M2 | 6.48 | 5.56 | 7.41 | 6.48 | |||
| M3 | 5.10 | 6.48 | 8.33 | 6.64 | |||
| P×S | 5.56 | 6.33 | 6.64 | - | |||
| Round (P2) | M1 | 4.63 | 2.78 | 3.71 | 3.71 | ||
| M2 | 8.79 | 8.33 | 7.41 | 8.18 | |||
| M3 | 7.41 | 5.09 | 4.17 | 5.56 | |||
| P×S | 6.94 | 5.40 | 5.10 | - | |||
| Variable | Variable Means (%) | ||||||
| P | P1 (6.17) | P2 (5.81) | - | ||||
| M | M1 (4.55) | M2 (7.33) | M3 (6.10) | ||||
| S | S1 (6.25) | S2 (5.86) | S3 (5.87) | ||||
| Source | P | M | S | P×M | P×S | M×S | P×M×S |
| p-value | 0.531b | 0.001a | 0.819b | 0.040a | 0.094b | 0.924b | 0.151b |
| Plug Type (P) | Feeding method (M) | Missing Index (%) | |||||
|---|---|---|---|---|---|---|---|
| Seedling Age (S) | P×M | ||||||
| S1 | S2 | S3 | |||||
| Square (P1) | M1 | 6.02 | 6.94 | 4.17 | 5.71 | ||
| M2 | 6.95 | 8.33 | 7.41 | 7.56 | |||
| M3 | 5.56 | 6.94 | 8.79 | 7.10 | |||
| P×S | 6.18 | 7.40 | 6.79 | - | |||
| Round (P2) | M1 | 6.02 | 2.78 | 3.24 | 4.01 | ||
| M2 | 9.72 | 6.48 | 8.79 | 8.33 | |||
| M3 | 8.79 | 6.02 | 4.17 | 6.33 | |||
| P×S | 8.18 | 5.09 | 5.40 | - | |||
| Variable | Variable Means (%) | ||||||
| P | P1 (6.79) | P2 (6.17) | - | ||||
| M | M1 (4.86) | M2 (7.87) | M3 (6.71) | ||||
| S | S1 (7.17) | S2 (6.17) | S3 (6.09) | ||||
| Source | P | M | S | P×M | P×S | M×S | P×M×S |
| p-value | 0.311b | 0.000a | 0.272b | 0.297b | 0.009a | 0.754b | 0.169b |
Effect of the feeding methods on the MI
⌅The percentages of the MI for the feeding methods M1, M2, and M3 for all the treatment combinations under research varied from 2.78 to 6.95, 5.56 to 8.79, and 4.17 to 8.33, respectively. The maximum MI percentage of 6.95 for M1 was attained at a treatment combination of P1S2, whereas the minimum MI percentage of 2.78 for M1 was attained at a treatment combination of P2S2. The maximum and minimum MI percentages of 8.79 and 5.56 for feeding mechanism M2 were attained at a treatment combination of P2S1 and P1S2, respectively. Similarly, the maximum and minimum MI percentages of 8.33 and 4.17 for feeding mechanism M3 were attained at a treatment combination of P1S3 and P2S3, respectively.
In the case of eggplant, the MI percentages for feeding mechanism type M1, M2 and M3 for all the treatment combinations ranged from 2.78 to 6.94, 6.48 to 9.72 and 4.17 to 8.79, respectively. The maximum MI percentage of 6.94 for M1was attained at a treatment combination of P1S2, whereas the minimum MI percentage of 2.78 for M1 was attained at a treatment combination of P2S2. The maximum MI percentage of 9.72 for M2 was attained at a treatment combination of P2S1, whereas the minimum MI percentage of 6.48 for feeding mechanism M2 was attained at a treatment combination of P2S2. Similarly, the maximum MI percentage of 8.79 for M3 was attained at a treatment combination of P1S3 and P2S1, whereas the minimum MI percentage of 4.17 for feeding mechanism M3 was attained at a treatment combination of P2S3.
Effect of the plug types on the MI
⌅The MI percentages for plug type P1 and P2 for all treatment combinations ranged from 4.17 to 8.33 and 2.78 to 8.79, respectively. The maximum MI percentage of 8.33 for P1 was attained at a treatment combination of M3S3, whereas the minimum MI percentage of 4.17 for P1 was attained at a treatment combination of M1S3. On the other hand, the maximum MI percentage of 8.79 for P2 was attained at a treatment combination of M2S1, whereas the minimum MI percentage of 2.78 for P2 was attained at a treatment combination of M1S2.
In the case of eggplant, the MI percentages for plug type P1 and P2 for all the treatment combinations under study ranged from 4.17 to 8.79 and 2.78 to 9.72, respectively. The maximum MI percentage of 8.79 for P1was attained at a treatment combination of M3S3, whereas the minimum MI percentage of 4.17 for P1 was attained at a treatment combination of M1S3. On the other hand, the maximum MI percentage of 9.72 for P2 was attained at a treatment combination of M2S1, whereas the minimum MI percentage of 2.78 for P2 was attained at a treatment combination of M1S2.
Effect of the seedling ages on the MI
⌅The MI percentages for seedling age S1, S2 and S3 for all the treatment combinations ranged from 4.63 to 8.79, 2.78 to 8.33 and 3.71 to 8.33, respectively. The maximum MI percentage of 8.79 for S1 was attained at the combination of P2M2, whereas the minimum MI percentage of 4.63 for S1 was attained at the treatment combination of P2M1. The maximum MI percentage of 8.33 was attained at P2M2, whereas the minimum MI percentage of 2.78 for S2 was attained at a treatment combination of P2M1. Similarly, the maximum MI percentage of 8.33 was attained at a treatment combination of P1M3, whereas the minimum MI percentage of 3.71 for S3 was attained at a treatment combination of P2M1.
In the case of eggplant, the MI percentages for seedling age S1, S2 and S3 for all treatment combinations under study ranged from 5.56 to 9.72, 2.78 to 8.33 and 3.24 to 8.79, respectively. The maximum MI percentage of 9.72 for S1 was attained at the treatment combination of P2M2, whereas the minimum MI percentage of 5.56 for S1 was attained at the treatment combination of P1M3. The maximum MI percentage of 8.33 was attained at P1M2, whereas the minimum MI percentage of 2.78 for S2 was attained at a treatment combination of P2M1. Similarly, the maximum MI percentage of 8.79 was attained at a treatment combination of P1M3 and P2M2, whereas the minimum MI percentage of 3.24 for S3 was attained at a treatment combination of P2M1.
Analysis of the MI for the tomato
⌅The factors’ mean and analysis of variance of the MI for tomatoes are depicted in Table 2. The mean percentages value of the MI for tomato crops varied from 4.55 to 7.33 among all the treatments, and the differences were statistically non-significant at a 5% significance level. The MI percentages was statistically at par for plug type and seedling age and varied between 5.81 to 6.17 and 5.86 to 6.25. The first-order interaction of plug type and feeding mechanism (P×M) and the main effect of the feeding mechanism was statistically significant (Fig. 10 & 11) on the MI at a 5% significance level. For feeding techniques, the MI percentages ranged from 4.55 to 7.33 and was highest for M2 and lowest for M1. The interaction among plug type, feeding methods, and seedling age was statistically non-significant on the MI at a 5% significance level.
Analysis of the MI for the eggplant
⌅The factors mean and analysis of variance of the MI for the eggplant are depicted in Table 3. The mean percentages value of the MI for the eggplant varied from 4.86 to 7.87 among all the treatment combinations, and the differences were statistically non-significant at a 5% significance level. The MI percentages was statistically at par for the plug type and seedling age and varied between 6.17 to 6.79 and 6.09 to 7.17. The first-order interaction of plug type and seedling age (P×S) was significant (Fig. 12) at a 5% significance level. The MI was the least with the P2 plug type and S2 seedling age. This could be because the P2 plug type and S2 seedling age have more base and adequate root growth, allowing the seedling to remain vertical when placed in the feeding mechanism. The main effect of the feeding method was statistically significant (Fig. 12) on the MI. In the feeding method, the MI percentages varied from 4.86 to 7.87 and was maximum for the M2 and minimum for the M1. The interaction among the plug type, feeding method, and seedling age was statistically non-significant on the MI at a 5% significance level.
According to numerous studies by other scientists, the percentage of missed plantings ranges from 3 to 15.7. In their study, Chaudhuri et al. (2001Chaudhuri D, Singh VV, Dubey AK, 2001. Refinement and adoption of mechanical vegetable transplanters for Indian conditions. Proc 35th annual convention of Indian Society of Agricultural Engineers (ISAE), College of Agricultural Engineering and Technology, Odisha University of Agriculture and Technology (OUAT), Bhubaneswar,Orissa, India.) documented a plant loss rate ranging from 3.70% to 6.67% during mechanical transplantation using a two-row vegetable transplanter for tomato and cauliflower crops. In investigating a tractor-operated single-row vegetable transplanter, Dixit & Garg (2002Garg IK, Dixit A, 2002. Design, development and evaluation of vegetable transplanter. Paper presented during 24th workshop of All India coordinated Research Scheme on Farm Implements and Machinery (ICAR) held at TNAU, Coimbatore, IndiaApril 18-21.) discovered that 15.7 percent of brinjal plants were absent. Han et al. (2021Han C, Hu X, Zhang J, You J, Li H, 2021. Design and testing of the mechanical picking function of a high-speed seedling auto-transplanter. Artif Intell Agric5: 64-71. 10.1016/j.aiia.2021.02.002) reported that when transplanting 60-day-old pepper seedlings with a high-speed seedling auto-transplanter, a 3% of missed planting occurred. A missing percentage of 5.33 was documented by Dhupal & Sahu (2020Dhupal G, Sahu S, 2020. Fabrication of manual operated two row tomato transplanter. J Pharmacogn Phytochem9(4): 290-293.) during the process of transplanting tomatoes using a manually operated two-row tomato transplanter.
Conclusions
⌅Two compact, simple, and handy semi-automatic feeding systems, namely revolving multi-chamber disc and horizontal dragging magazine (FMRMD and FMHDM), were designed and developed to increase the automation and dependability of mechanized vegetable seedling transplanting. They were developed to feed the plug-type vegetable seedlings to the transplanting unit. The feeding mechanism worked without causing any damage and tilting of pots. The theoretical planting frequency of the FMRMD and FMHDM was 33.94 and 34.87 plants·min-1. The first-order interaction of plug type and feeding mechanism in the tomato crop and plug type and seedling age in the eggplant crop were statistically significant on the MI, while the main effect of the feeding mechanism was also significant on the MI for both crops. The MI varied from 4.55 to 7.33% and 4.86 to 7.87% for all the feeding mechanisms under study for the tomato and eggplant, respectively. For both crops, the MI was maximum for the FMHDM and minimum for the FMRMD. The designed feeding systems may be used across numerous industrial settings.