Article Info Manuscript received: June, 2022 Revised manuscript accepted: February, 2023 Keywords : Engineering properties, machinery, plug- type seedling, transplanter, vegetable seedling https://pub.isae.in Journal of Agricultural Engineering (India) Vol. 60 (1): January-March, 2023 doi: 10.52151/jae2023601.1792 Engineering Properties of Some Plug-type Vegetable Seedlings for Development of Automatic Vegetable Transplanter Ajit Pralhad Magar 1, 2 *, Sachin Madhukar Nalawade 3 , Avdhoot Ashok Walunj 4 , Abhijit Khadatkar 1 , Sanjay Chandrakant Bhangare 4 , Madhukar Nilkanth Bhalekar 3 , Charudatta Anantrao Nimbalkar 3 , and Bhaskar Bharat Gaikwad 5 1 Scientist, ICAR-Central institute of Agricultural Engineering, Bhopal- 462 038; 2 Ph.D. Research Scholar, 3 Associate Professor, 4 Assistant Professor, Mahatma Phule Krishi Vidyapeeth, Rahuri – 413 722; 5 Senior Scientist, ICAR-National Institute of Abiotic Stress Management, Baramati-413115. *Corresponding author e-mail address: ajitpmagar1355@gmail.com ABSTRACT Transplanting of vegetable seedlings has been referred as a critical and time-consuming activity in vegetable production system. In India, manual transplanting operation of vegetable seedlings is done in most areas due to non-availability of appropriate transplanter, and is drudgery prone. To mechanize this operation, vegetable transplanter needs to be developed considering engineering properties of plug-type seedlings as tomato, brinjal, and cabbage grown in pro-tray. Basic engineering properties of 30-day old seedlings of tomato, brinjal, and cabbage relevant to design of vegetable transplanter were evaluated. The moisture content of whole seedling and root bulb of tomato, brinjal, and cabbage seedlings were 84.3 (± 3.6), 86.7 (± 4.5), and 84.57 (± 3.7)% w.b., respectively. The average respective heights of the seedling were 162.44 (± 19.80), 129.4 (± 16.96), and 114.13 (± 19.98) mm, whereas, canopy major dimensions were (length) 110 ± 15.62, 79.3 ± 16.08, 91.93 ± 14.44 mm, respectively. The coeffcient of frictions offered by mild steel were 0.81 (± 0.08), 0.81 (± 0.07), and 0.89 (± 0.04) for tomato, brinjal, and cabbage seedlings, respectively; and adhesion force between pro-tray and seedlings were 1.43 (± 0.40), 0.95 (± 0.22), and 0.41 (± 0.04) N, respectively. The average compression forces of the root bulbs were 6.05 ± 1.53, 5.8 ± 0.56, and 10.26 ± 0.16 N; and average needle penetration forces into root bulbs was 5.18 (± 0.86), 7.83 (± 0.56), and 19.47 (± 0.59) N for tomato, brinjal, and cabbage seedlings, respectively. The properties of vegetable seedling as physical (seedling height, stem thickness, weight, and canopy) and mechanical (coeffcient of friction, adhesion force, compression force of root bulb and stem, and pick-up needle penetration force in root bulb) are required for development of seedling pick-up mechanisms used in advanced vegetable transplanters. The machine system mainly involves equipment for plant handling, planting, transplanting, storing, aeration, etc. Khura et al. (2010) used the properties of onion bulb for development of an onion digger. These properties mainly include plant length of onion crop, average value of equatorial and polar diameter of onion bulb, average weight of onion bulb with leaves, and bulk density. One of the many reported applications of seedling properties is the development of vegetable transplanters. These transplanters may be semi- automatic or automatic (Choi et al., 2002; Kumar and Raheman, 2008; Pandirwar et al., 2018; Magar et al., 2021a). Metering devices in semi-automatic transplanters were designed using seedling properties. Narang et al. (2011) designed a revolving magazine metering mechanism on the basis of seedling spread diameter and height of brinjal seedlings. Magar et al. (2021b) optimized seedlings grown in cylindrical paper pots whose seedling properties such as seedling weight, seedling canopy, pot diameter, height of pot, 0256-6524/©2023 ISAE