原文1：Transplanters for Use in Developing CountriesA ReviewDeveloping countries contribute 72% of the total vegetable production in the world. The transplanting operation is one of the most labor intensive in vegetable production. It is largely done by hand in India and most developing countries and incurs large investments in labor, time,and cost. This article presents the details of construction of vegetable transplanters in addition to recent advances in their development.Performance of transplanters under actual field conditions is discussed.Traditional Methods of Transplanting Vegetable SeedlingsFerminger (1953) reported that in India, for small-scale vegetable gardening, holes of 60 cm diameter and 30 cm deep are manually dug in the field at desired spacings. The soil is mixed with farmyard manure, bone meal,and wood ashes. The hole is then filled to a depth of 1520 cm and packed. A seedling is placed in the middle of the hole and topsoil is filled around the seedling, compacted, firmed, and soaked with water. A shelter is built to shade the seedling under dry weather conditions. This method does not require any field preparation. A shovel or spade is the only implement used.Classification of Vegetable Transplanters and SeedlingsTransplanters are designed based on seedling type to be used. The semiautomatic transplanters can be used for almost all types of seedlings (Table 1). The bare root seedlings are obtained by pulling seedlings directly from nursery beds. The soil block seedlings are obtained by sowing of seeds in moist soil cubes made by mixing soil, peat, compost,and sand (Press, 2001). The cell mold seedlings are grown in flexible plastic (Tsuga, 2000) or heavy-duty injection-molded trays(Horticultural Supplies Co., Mumbai, India) with cells to fill with the soil mix and sow the seed. Trays can contain 128, 200, or 288 cells, in which the arrangement of cells is 8 16, 10 20, and 12 24, respectively(Tsuga, 2000). The Horticultural Supplies Co. tray has five sections,each with 30 or 40 cells, supported by an outer tray, which can hold 150 or 200 seedlings. The shape of the cell is an inverted truncated pyramid. Another method for transplant production is the paper pot,generally made from recycled paper. Paper pots provide an individual area for each seed to germinate and the plant to develop (Indian Institute of Horticultural Research IIHR, 2006). A total of 128 or 200 pots can be placed on a tray in 8 8 or 10 10 arrangements (Tsuga,2000).Semiautomatic and fully automatic transplanters can be used for plantingcell mold and paper potproduced seedlings. The linked paper pot,or a chain of pots prepared by connecting a series of paper pots, is made by joining two-ply sheets of paper with water-resistant adhesive(Nambu and Tanimura, 1992). They do not require a tray for holding seedlings but require an arrangement to separate the chain of pots into individuals before feeding them to the planting unit. Linked paper pots are used only with fully automatic transplanters.The walking-type semiautomatic transplanters are either self-propelled or hand tractoroperated machines. They are rare because the operator has to concentrate on the operation of the machine and feeding the seedlings.Riding-type two-row or three-row semiautomatic transplanters are tractor mounted or tractor pulled machines, whereas those that are used with more rows are tractor pulled. The walking-type automatic transplanters are self-propelled machines for sowing a maximum of four rows. Ridingtype automatic transplanters are either self-propelled (up to four rows) or tractor pulled (up to eight rows). Further, Marr (1994) described types of transplanters called punch planters (automatic) and water-wheel planters (semiautomatic). The punch planters transplant through plastic mulches by puncturing the mulch and the soil and setting the seedling into the holes. The water-wheel planters are similar to the punch planters with the addition of a large tank filled with water or fertilizer solution. As the hole is formed for the transplant, a portion of the solution is injected into the transplant hole. Seedlings are hand-set into the watered hole by operators riding low near the ground (Model 1600 of Robert Marvel Plastic Mulch, Annville, Pa.). As the seedling is pushed in, mud from the bottom comes up along the sides and covers the top to complete the transplanting operation. Munilla and Shaw (1987) described a dibbling transplanter in which holes are made in the soil and seedlings are planted in the holes.Seedling Box or Tray HolderA seedling box is provided on semiautomatic transplanters to store bare root seedlings for feeding to the planting unit. It is rectangular in cross section and is open at the top. Long rectangular seedling boxes are used in transplanters (Model 2000, Mechanical Transplanter Co., Holland, Mich.)used for planting long seedlings, in which a conveyor belt is provided,which can be