Peng WANG, Shengqun JIAO, Hongjie TANG, Yanxue DANG, Qingfu DU, Jihui LI, Bushuai ZHONG, Bingguo SONG
Abstract ［Objectives］ This study was conducted to select vegetable soybean varieties （Glycine max （L.） Merr.） that are suitable for local cultivation and meet export requirements.
［Methods］ Through continuous years of comparative experiments on broccoli and vegetable soybean varieties， detailed biological characteristic and economic quality data of multiple varieties were obtained.
［Results］ Vegetable soybean variety Taiwan 75-3 had very prominent early-maturing trait， the highest quality （qualification rate）， and higher yield than the control check （CK）; and the early-maturing trait of vegetable soybean variety Kaohsiung 9 was also prominent， and its yield was higher than that of the CK. They could be promoted as the main vegetable soybean varieties for spring open field cultivation in this region. Among the tested broccoli varieties， Lake had a higher yield， and was relatively tolerant to cold. It had an early harvest period， and was planted as an early autumn variety in this region. Naihan Youxiu showed the highest yield， good quality， cold resistance， and strong adaptability， making it suitable for planting as a late autumn variety in this region.
［Conclusions］ This study provides technical guidance for the cultivation of local broccoli and vegetable soybean.
Key words Vegetable soybeans; Broccoli; Biological characteristic; Commercial character
Received：
January 5， 2023 Accepted：
March 6， 2023
Supported by Project of Shandong （Linyi） Modern Agriculture Research Institute of Zhejiang University for Serving Local Economic Development （ZDNY-2020-FWLY01004）.
Peng WANG （1982-）， female， P. R. China， senior agronomist， devoted to research about horticultural technology and standardization.
*Corresponding author.
With the continuous improvement of peoples living standards， the requirements for safety， nutrition， and functional characteristics of vegetables are becoming increasingly high， and the safe production and consumption of vegetables have become a top priority in food safety. Broccoli （Brassica oleracea L. var. italica Plenck） and vegetable soybean （Glycine max （L.） Merr.） are rich in nutrients and functional components， and favored by consumers both domestically and internationally［1］. Vegetable soybean belongs to Glycine in Leguminosae， and is a general term for soybean varieties that are usually harvested and consumed between R6 （full grain stage） and R7 （immature stage） when the pods are plump and the color of the pods is emerald green. Vegetable soybeans are rich in protein， various amino acids， VA， VB， VC， VE， and various minerals such as calcium， iron， and phosphorus. They are a nutritious and unique health food with a long market supply period， great market potential， and good economic benefits［2］. Especially， frozen vegetable soybeans have a huge potential to meet the annual demand of international and domestic consumer markets， and account for a large proportion of various vegetables. Vegetable soybeans are harvested during the tender stage of their development. After harvesting， vegetable soybeans are prone to yellowing and degreening， and their shelf life can only be maintained for 1-2 d， after which their sensory and edible quality rapidly decreases， which becomes an important factor restricting their quality improvement. In response to the bottleneck problem that currently restricts the development of the export vegetable industry， with vegetable soybean varieties led by Qingguo Company as the main object， under the goals of being suitable for quick freezing and high quality， a comparative experiment was carried out on broccoli and vegetable soybean varieties for several consecutive years to select vegetable soybean varieties that are suitable for planting in the local area and meet export requirements. This study provides technical guidance for planting of broccoli and vegetable soybean in local areas.
Materials and Methods
Test varieties
The test vegetable soybean varieties were Taiwan 75， Taiwan 75-3， Taiwan 75-5， Kaohsiung 3， Kaohsiung 9， and Taiwan 2802， with Taiwan 75 as the control check （CK）.
The test broccoli varieties were Youxiu （CK）， Yanxiu， Hanxiu， Lake， and Datuoluo， all of which were purchased from the market by the testing unit.
Field management
The experiment was conducted at the vegetable base of Qingguo Companys ecological plantation. The previous crop in the vegetable soybean experimental field was broccoli. After deep plowing and sun-drying in winter， the soil was light clay with good fertility and convenient drainage and irrigation. The plots were 133 m2 in area each， arranged randomly and repeated 3 times. The planting density should be in accordance with local customs. The plants were cultivated in the open field with plastic film covering. The management measures for all varieties throughout the entire growth period were consistent. A compound fertilizer was applied at a rate of 450-750 kg/hm2 as the base fertilizer before sowing during soil preparation， and nitrogen fertilizer was applied at a rate of 75-150 kg/hm2 during the seedling stage in combination with intercropping and weeding. During the flowering and pod setting period， topdressing or foliar fertilizers should be applied according to the growth of plants. In case of drought， irrigation should be carried out in a timely manner to reduce flower and pod loss， and promote pod preservation and plumping.
Five varieties of broccoli were sown at the same time， and the borders were 1 m wide. After evenly sowing， the borders were covered with fine soil， and covered with a sunshade net to prevent high temperature and rainstorm scouring and improve seedling survival rate. Field planting was carried out on August 18. A randomized block design was adopted. The plots were 9.7 m2 in area each， and repeated 3 times. Before planting， 60 000 kg/hm2 of decomposed organic fertilizer， 330 kg/hm2 of superphosphate， and 150 kg/hm2 of urea were applied. The planting was carried out according to a plant spacing of 45 cm and a row spacing of 45 cm， with 40 plants per plot. During planting， 750 g of borax was prepared into a solution， which was applied as the base fertilizer in holes per hectare. After planting， the fertilizer and water management method of promoting in the early stage， stabilizing in the middle stage and enhancing in the later stage was adopted. When the rows were sealed， 150 kg/hm2 of potassium fertilizer was added， and 225 kg/hm2 of urea was applied at the initial stage of flower head formation.
Investigation contents
In this study， the growth period performance of the tested vegetable soybean varieties， including the sowing date， seedling emergence date， initial flowering date， flowering date， pod setting date， initial fresh pod harvest date and growth period of each variety was investigated. The investigated plant traits included podding habits， plant shape， effective plant height， total pod number， effective pod number， effective pod percentage， and plant disease resistance. The commodity traits and yield of fresh pods and quality performance of the tested vegetable soybean varieties， including fresh pod color， pod type， fresh weight of 100 pods， fresh weight of 100 seeds， pod length， pod width， percentage of two- or three-grain pods， yield， and quality （qualification rate） （%）， were also investigated.
In this experiment， the initial harvest date of broccoli was when 10% of the flower heads could be harvested; the harvest date was when 50% of the flower heads could be harvested; and the final harvest date was when 90% of the flower heads could be harvested. The growth period was the number of days from the planting date to the initial harvest date. The qualification rate of flower heads was the percentage of flower heads that meet market sales standards in the total number of plants. The market sales standard is that the flower heads are not deformed， and the flower buds are well developed， not hollow， and not rotten.
Results and Analysis
Early maturity of vegetable soybean
From Table 1， it can be seen that the growth period （from sowing to fresh pod harvesting， the same below） of Taiwan 2808 was the shortest， at 85 d， which was 25 d earlier than Taiwan 75 as the CK. The growth period of Taiwan 75-5 and Kaohsiung 3 took the second place， which was 20 d earlier than the CK. Taiwan 75-3 and Kaohsiung 9 were 15 d earlier than the CK.
Plant traits of vegetable soybean
Table 2 shows that the six varieties tested had vigorous plant growth and determinate podding habit. Except for the plants of the CK with a semi-open shape， all other varieties had a convergent shape.
The effective plant heights of Taiwan 75-3， Taiwan 75-5， and Kaohsiung 9 were similar to the CK， while vegetable soybean varieties Kaohsiung 3 and Taiwan 2808 had effective plant heights 9 and 5 cm higher than the CK， respectively.
The average percentages of effective pods per plant of vegetable soybean varieties Taiwan 75-5 and Kaohsiung 3 were 1.7 and 1.1 percentage points lower than the CK， respectively. However， the average total pods per plant of both were higher than the CK by 6 and 4.6 pods， and the effective pods were higher than the CK by 4.1 and 3.2 pods. The average percentages of effective pods per plant of vegetable soybean varieties Kaohsiung 9 and Taiwan 2808 were over 90%， more than 13.8 percentage points higher than the CK.
For the average number of effective pods per plant， Kaohsiung 9 was similar to the CK， while Taiwan 2808 was 2.7 pods higher than the CK， and Taiwan 75-3 was lower than the CK.
The disease resistance of Taiwan 75-3 and Kaohsiung 9 showed the best performance in the field， while Taiwan 75-5 and Taiwan 2808 showed better performance in the field， and Taiwan 75 serving as the CK showed extremely poor performance in the field.
Commerciality of vegetable soybeans
From Table 3， it can be seen that the fresh pod color of vegetable soybean varieties Taiwan 75-5， Kaohsiung 3， Kaohsiung 9， and Taiwan 2808 was the same as the CK， the pods of which was green， while Taiwan 75-3 showed bluish yellow pods. Except for vegetable soybean variety Kaohsiung 9， which was of the straight gourd pod type， the rest were of the curved sickle type. The fresh 100-pod weight of vegetable soybean variety Taiwan 75-5 was 273.8 g， which was 42.2 g higher than the CK， and the fresh 100-pod weight of vegetable soybean variety Kaohsiung 3 was 260.1 g， which was 28.5 g higher than the CK. Other varieties were lower than the CK. Compared with the CK， vegetable soybean varieties Kaohsiung 3 and Taiwan 75-5 had larger grains， with fresh 100-grain weights 7.2 and 1.8 g higher， respectively. The percentages of two and three pods in both varieties were similar to the CK， and the highest percentage of two and three pods was found in Taiwan 75-3， accounting for 86.8%.
Yield and quality （qualification rate） of vegetable soybean
From Table 4， it can be seen that the yield of vegetable soybean variety Taiwan 75-3 was 27.6% higher than that of the CK， which was extremely significant. Kaohsiung 9 took the second place， with a significant increase of 13.4% compared with the CK. Kaohsiung 3 only increased yield by 1.8% compared with the CK. The yields of vegetable soybean varieties Taiwan 75-5 and Taiwan 2808 decreased by 7.4% and 9.5%， respectively， compared with the CK. The highest quality （qualification rate） was observed in Taiwan 75-3， reaching 65%， and the next was Kaohsiung 9， reaching 62%. Taiwan 75 serving as the CK was the lowest， only 40%.
Growth period of broccoli
From Table 5， it can be seen that the plants of Youxiu and Naihan Youxiu were the highest， followed by Mantuoluo， and Yanxiu plants were the shortest. Naihan Youxiu plants had the highest opening. The head diameters of the five varieties ranged from 13.5 to 19.5 cm. The weight of single head was highest in Naihan Youxiu， followed by Youxiu and Mantuoluo， and the lowest in Yanxiu. The number of lateral branches was the highest in Youxiu， followed by Yanxiu and Mantuoluo， and Naihan Youxiu and Lake had fewer lateral branches. The head color of all five varieties was mainly green， and Naihan Youxiu and Mantuoluo showed bright green heads， and the heads of Yanxiu were strong green. Except Yanxiu， the heads of which were slightly loose， all other varieties showed relatively compact heads. The flower grains were the largest in Youxiu， moderate in Naihan Youxiu and Lake， and the smallest in Yanxiu and Mantuoluo. Except for the slightly concave and convex surface of the flower heads of Yanxiu， all other varieties showed a smooth flower head surface. The shapes of flower head were mainly nearly round or round， and the process yield was the highest at 52% in Naihan Youxiu， followed by Lake with a qualified rate of flower heads at 50%， and the lowest in Yanxiu， the process yield of which was only 45%.
Economic traits of broccoli
From Table 6， it can be seen that Naihan Youxiu and Lake were resistant to diseases， and Mantuoluo was moderate in resistance， while Youxiu and Yanxiu had poor disease resistance. In terms of cold tolerance， the cold tolerance in Naihan Youxiu was strong， and Lake was relatively tolerant to cold， while Mantuoluo had moderate cold resistance， and Yanxiu was the worst.
All varieties were mainly harvested from the main flower heads， and the yield of side branches was not calculated. At the end of the harvest of main flower heads， statistical analysis was conducted on the yield of various plots. Through analysis of variance， it was found that the yield differences between varieties reached a highly significant level. Multiple comparisons （SSR method） were conducted on the plot yields of the five varieties， and the results are shown in Table 6.
From Table 6， it can be seen that the yield of Naihan Youxiu was the highest， reaching 24 669.0 kg/hm2， followed by the yield of Youxiu， reaching 24 612.0 kg/hm2， and the yield of Lake was the lowest， reaching 22 141.5 kg/hm2. The yield difference between Mantuoluo and Yanxiu was not significant， but the yield differences from other three varieties were extremely significant.
Broccoli yield and resistance
Results and Conclusions
Among the tested vegetable soybean varieties， vegetable soybean variety Taiwan 75-3 had very prominent early-maturing trait， the highest quality （qualification rate）， and higher yield than the CK; and the early-maturing trait of vegetable soybean variety Kaohsiung 9 was also prominent， and its yield was higher than that of the CK. They could be promoted as the main vegetable soybean varieties for spring open field cultivation in this region. Among the tested broccoli varieties， Lake had a higher yield， and was relatively tolerant to cold. It had an early harvest period， and was planted as an early autumn variety in this region. Naihan Youxiu showed the highest yield， good quality， cold resistance， and strong adaptability， making it suitable for planting as a late autumn variety in this region. At present， the cultivation mode of two crops of soybean and broccoli is adopted in production. After the harvest of soybean， it is during the high-temperature rainy season， and the emergence rate and survival rate of broccoli are low， resulting in a significant reduction or extinction of yield. Meanwhile， planting and harvesting require a large amount of labor， resulting in high production costs and low efficiency. Frozen soybeans and broccoli products are exported to high-end consumer markets in Europe， America， Japan， and China， and suffer from strict requirements for product quality and safety standards. Conventional cultivation methods are difficult to meet these requirements. Raw materials for processing that meet export quality can be produced by adopting comprehensive physical， biological， and agronomic prevention and control measures. The harvesting period of soybeans is closely related to their quality， which is difficult to be controlled during the production process， often resulting in poor quality. Further research is needed on the relationship between different maturation levels and quality.
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