For many years, mechanical harvesting of processing tomatoes was considered to be impossible in Japan, because of the intensive cultivation in small and narrow fields, and the wide variation in fruit maturation caused by rain and inconstant weather. Therefore, Japan is lagging far behind the West in the study of mechanical harvesting.
Recently, due to Japan's rapid industrial development, labor for harvesting tomato is becoming more difficult and expensive to procure. In addition, the international liberalization of trade requires lower harvesting costs.
In response this situation, a study was conducted from 1968 to 1978 at the Shinshu University; 1) to investigate time foctors in the traditional hand-picked harvest and to estimate the propriety of mechanical harvesting, 2) to measure the physical properties of fruits, and mechanical damages in their harvesting, 3) to investigate structures of vines and field conditions, 4) to design and test compact machines, and 5) to discuss the utility of these machines.
In this paper, 1) was described and its result, in summary are as follows.
(1) Average working time by the traditional hand picking methods was calculated with successive data from the Department of Agriculture; and today, working time has reached 142.4hrs/10a and occupies 52.2% of total working time for processing tomato culture.
(2) Simplification of the hand picking motion (therblig), does not increase picking efficiency significantly.
(3) In order to estimate the practicality both of the once-over harvest method and the combination of hand selection and once-over method, the yield by each method was compared to the yield by the traditional hand picking method, using varieties of Wasedaruma and Chico III. The ratios of yields by three mathods were estimated using both the field test data and histrical data. It was found that in proportion to the high yield of the effective but time-consuming traditional method, the once-over harvest produced a yield of about 60-70%, and the combination method produced a yield of about 75-85%.
It seems that adoption of the once-over principle to Japanese fields leaves some difficult problems behind us. But as the suitable varieties for mechanical harvesting are still developing, the fully mechanical or the semi-mechanical harvest method can soon be implemented in place of traditional hand picking method in various areas.

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It is considerd that processing tomato fruits cultured in high humidity conditions such as in Japan, are more susceptible to mechanical damage than fruits produced in other countries. However, new varieties able to withstand the mechanical forces imposed during mechanical harvesting are being developed.
Accordingly, this study was conducted using Wasedaruma and other dwarf cultivars for the design of processing tomato harvester.
The results ware summarized as follows.
(1) In paralleled plate compressing, the maximum allowable static load for crack of matured Wasedaruma fruits (round) was 4.13Kgw in axial position and it was 3.62kgw in transverse position. Similarly, the load of Chico III (pear shape) was 4.55kgw and 4.64kgw. In comparison wounded fruits were about one-third less resistant to cracking, in each variety.
(2) In order to determine the maximum allowable free fall height, matured Wasedaruma fruits were dropped down from the height of 31.6∼250.0cm on a flat iron face, both vertically and at a 45 degree incline. The frequency of cracking increased greatly as the height of drop increased and also, in vertical collision the cracking damage was more serious than that of 45 degree's collision. Percentage occurrence of cracking varied directly with fruit weight.
In the case of collision with right angle steel corners or various diameters of steel rod, the occurence of cracking was less than that of flat iron plate.
In all occasions, crack did not occur at less than 31.6cm (impact speed 2.5m/sec) in free fall height.
(3) Matured Wasedaruma fruits were dropped from a height of 81.6cm on to a flat iron surface until they cracked. With repeated drops up to 5, cracking increased to more than 80%. At about 10 drops cracking approached 100%.
(4) Magness-Taylor pressure tester plungers (11 and 8mm∅) and two other similarly shaped plungers in smaller sizes (4 and 5mm∅) were used to measure resistance to puncture for both mature and green Wasedaruma fruits. The relation ship between diameters of these plunger and puncture resistance was found to be linear in both mature and green fruits.
(5) The maximum allowable height of pointed objects resembling the plungers within a harvesting machine was estimated by the maximum depth of depression by the plunger in the fruit surface. The safe height was found to be approximately 50∼70% of the plunger diameter.
There are wide variations in the physical properties of fruits, due to veriety, cultural patterns, weather conditions and other factors. Therefore it seemed that the allowable limits of mechanical forces in harvesting ought to be assumed smaller in actual condition than those above-mentioned.

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