| Vegetable soybean (Glycine max (L.) Merr.) is a specialty soybean harvested as vegetable when the seeds are immature (R6 stage) and have expanded to fill 80 to 90 percent of the pod weight. Like field-dried soybeans, the seeds of vegetable-type soybean (edamame) varieties are rich in protein and highly nutritious. Worldwide, it is a minor crop, but it is quite popular in East Asia. Edamame is consumed mainly as snack, but also as a vegetable, an addition to soup, or processed into sweets.The date, timing, and method of harvesting vegetable soybean are of critical importance, and vary among varieties. To determine the adequate time to harvest green soybean cultivars, an experiment was carried out in the experimental farm of Zhejiang University. The randomized complete block with cultivar as the main plot and periodical sample as the subplot was used as experimental design.Growth measurement through the dry and fresh weights of pods (seed and pod wall), pods moisture, the amount of chlorophyll in seed and pod wall, soluble sugars and starch content in seed, pod growth rate, pods dimensions (length, width, and thickness), and seed hardness were the main analyses performed to reach the goal of this investigation.By the mean of growth measurement, it was found that for Hua Chun 18 and 9701 cultivars the date of harvesting starts at 31 and 29 DAF respectively when the dry weight of seed and pod wall intersect to 35 and 33 DAF. The suitable time to harvest Tai 75 was from 44 to 47 DAF and 47 to 49 DAF for AJMD. In the basis of pod filling rate and moisture content, is was suitable to harvest from 31 to 35 DAF for Hua Chun 18, 33 to 37 DAF for 9701, 53 to 58 DAF for Tai 75, and at 49 to 42 DAF for AJMD, while pod water content was about 65 %, 60 %, 61 %, and 62 % of fresh weight, respectively. By considering the starch content in seed, Hua Chun 18 could be harvested from 38 to 43 DAF, 9701 from 37 to 45 DAF, Tai 75 from 53 to 58 DAF, and AJMD from 49 to 58 DAF. hi Hua Chun 18, the soluble sugars were higher by 31 to 35 DAF, which was considered as the suitable period for harvesting. The adequate days to harvest 9701 cultivar was between 33 to 37 DAF. For Tai 75, the amount of soluble sugars peaked by 40 to 44 DAF, while hi AJMD, the rate of soluble sugars increased between 41 and 45 DAF, before declining progressively.With regard to chlorophyll content, Hua Chun 18 should be harvested by 29 to 34 DAF. It has showed that 9701 seeds and pods walls chlorophyll content increased from 31 to 35 DAF. For Tai 75, the suitable time to pick up green pods should be between 43 to 46 DAF. In the case of AJMD, the harvest should be performed by 39 to 45 DAF. It was found that one of characteristics of normal soybean maturation was that the pods walls lost chlorophyll, although the developing seed was still green.By following the indications recorded from the thickness of pods, Hua Chun 18 should be harvested at 45 DAF (81 % of total pods per stem were 6 to 7.9 mm), 9701 should be harvested at 40 DAF (90 % of pods thickness were up to 6.0 mm). The adequate period of harvesting Tai 75 and AJMD should be 58 and 52 DAF, respectively.This present investigation should propose to harvest while seeds are soft and show hardness between 9 and 10 kgpn"2, while pods are full enough. Hua Chuan 18 could be harvested by 35 to 36 DAF, 9701 between 43 and 45 DAF, Tai 75 between 58 and 62 DAF, and AJMD between 49 and 55 DAP.Results obtained from the degree of association between pods sizes and pods weights were not indicating concrete correlation between those parameters. Pods sizes did not depend significantly upon to pods weight. It was also found that quality components of green-type soybean were often subject to changes when days went on. They were fluctuating according to DAF. Therefore, it was revealed interesting to find out a day when correlations between each of those components were positively or negatively high in order to fix suitable time for harvesting. It was concluded that time of harvest should have to be deter...
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