Evaluation of growth and yield of soybean accessions in the autumn winter season 2021 in gia lam

Evaluation of pest damage, pods shattered and lodging resistance of soybean varieties in the autumn-winter season 2021..... Pod and seed characteristics of soybean varieties in the autum

VIETNAM NATIONAL UNIVERSITY OF AGRICULTURE

SEASON 2021 IN GIA LAM

Instructor : PhD LE THI TUYET CHAM

Department : PLANT GENETICS AND BREEDING

Student : PHUNG THI HAI YEN

Student code : 611661

Class : K61KHCTT

HANOI – 2022

COMMITMENT

I hereby declare that this paper is my own work All of the results and data in this thesis are completely accurate and have never been submitted to any institution for evaluation In the references, all of the sources used in this paper were recognized

Hanoi, 22 nd February 2022

Student

Yen Phung Thi Hai Yen

Secondly, I would also like to express sincere thanks to the professors from the Faculty of Agronomy in general, and the lecturers from the Department

of Plant Genetics and Breeding in particular, who taught and established the best conditions for students during the learning process and research

Last but not least, I would want to express gratitude to my family and friends, who have always been by my side, giving me support and strength to complete this graduation thesis

I sincerely thank you

Hanoi, 22 nd February 2022

Student

Yen Phung Thi Hai Yen

CONTENT

COMMITMENT i

ACKNOWLEDGEMENT ii

CONTENT iii

LIST OF ABBREVIATION vi

LIST OF TABLES vii

LIST OF FIGURES ix

ABSTRACT x

CHAPTER 1 INTRODUCTION 1

1.1 Background 1

1.2 Objectives and requirements 2

1.2.1 Objectives 2

1.2.2 Requirements 3

CHAPTER 2 LITERATURE REVIEW 4

2.1 Origin, classification and distribution of soybeans 4

2.1.1 Origin of soybeans 4

2.1.2 Classification of soybeans 5

2.1.3 Distribution of soybeans 5

2.2 Ecological requirements of soybean plants 6

2.2.1 Light requirements 6

2.2.2 Temperature requirements 7

2.2.3 Water requirements 8

2.2.4 Soil requirements 9

2.2.5 Nutritional requirements 10

2.3 Botanical characteristics of the soybean plant 11

2.3.1 Root 11

2.3.2 Stem 13

2.3.4 Flower 15

2.3.5 Fruit 16

2.3.6 Seed 16

2.4 Soybean growth and development characteristics 17

2.4.1 Vegetative stage (V) 17

2.4.2 Reproductive stage (R) 18

2.5 Values of soybeans 20

2.5.1 Nutritional value 20

2.5.2 Economic value 22

2.6 Soybean production in the world and in Vietnam 25

2.6.1 Soybean production in the world 25

2.6.2 Soybean production in Vietnam 29

2.7 Soybean research and breeding in the world and in Vietnam 32

2.7.1 Soybean research and breeding in the world 32

2.7.2 Soybean research and breeding in Vietnam 35

CHAPTER 3 MATERIALS AND METHODS 39

3.1 Plant materials 39

3.2 Time and location of research 40

3.3 Research methods 40

3.4 Technical procedures applied in the experiment 40

3.4.1 Tillage, Furrow 40

3.4.2 Fertilizer 40

3.4.3 Take care 40

3.5 Trait measurements 41

3.5.1 Qualitative traits 41

3.5.2 Quantitative traits 43

3.6 Evaluation of pest damage, pods shattered and lodging resistance of soybean varieties in the autumn-winter season 2021 45

3.7 Data analysis 46

CHAPTER 4: RESULTS AND DISCUSSION 47

4.1 Phenological characteristics of soybean varieties in the autumn-winter season 2021 47

4.2 Morphological characteristics of soybean varieties in the in autumn-winter season 2021 50

4.3 Pod and seed characteristics of soybean varieties in the autumn-winter season 2021 53

4.4 Vegetative and morphological traits of soybean varieties in the autumn-winter season 2021 57

4.4.1 Plant height, number of leaves and number of nodes at the flowering and harvesting stage of soybean varieties in the autumn-winter season 2021 57

4.4.2 Other vegetative and morphological traits of soybean varieties in the autumn-winter season 2021 60

4.5 Evaluation of pest damage, pod shattering and lodging resistance of soybean varieties in the autumn-winter season 2021 64

4.6 Yield related traits of soybean varieties in the autumn-winter season 2021 68

4.7 Individual yield, actual yield and harvest index of soybean varieties in the autumn-winter season 2021 72

CHAPTER 5: CONCLUSIONS AND SUGGESTIONS 75

5.1 Conclusions 75

5.2 Suggestions 76

REFERENCES 77

SOME PICTURES ABOUT PROCESS CONDUCTED UNDERGRADUATE THESIS 84

LIST OF ABBREVIATION

AVRDC Asian Vegetable Research and Development Center

FAO Food and Agriculture Organization

GCO General Department of Customs

GSO General Statistics Office of Vietnam

USDA United States Department of Agriculture

LIST OF TABLES

Table 2.1 Nutritional value of soybean per 100g 20 Table 2.2 Status of soybean production in the world in the period 2011-2021 26 Table 2.3 Area, yield and production of soybeans of some countries in the

period 2016-2021 27 Table 2.4 Area, yield and production of soybean in Vietnam during 2010-2020 30 Table 3.1 Soybean varieties evaluated in the autumn-winter season 2021 39 Table 3.2 Qualitative morphological and seed traits observed in soybean 42 Table 3.3 Phenological traits observed in soybean 43 Table 3.4 Morphological and yield related traits observed soybean varieties in

the autumn-winter season 2021 44 Table 3.5 Evaluation of pest damage, pods shattered and lodging resistance of

soybean varieties in the autumn-winter season 2021 45 Table 4.1 Means for phenological phases of soybean varieties in the autumn-

winter season 2021 (days) 48 Table 4.2 Morphological characteristics of soybean varieties in the autumn-

winter season 2021 50 Table 4.3 Morphological characteristics of soybean varieties in the autumn-

winter season 2021 52 Table 4.4 Pod and seed characteristics of soybean varieties in the autumn-

winter season 2021 55 Table 4.5 Plant height, number of leaves and number of nodes at the flowering

and harvesting stages of soybean varieties in the autumn-winter season 2021 59 Table 4.6 Vegetative and morphological traits of soybean varieties in the

autumn-winter season 2021 61 Table 4.7 Pest damage, pod shatter and lodging resistance of soybean varieties

Table 4.8 Yield related traits of soybean varieties in the autumn-winter season

2021 69 Table 4.9 Individual yield, actual yield and harvest index of soybean varieties

in the autumn-winter season 2021 74

LIST OF FIGURES

Figure 2.1 Vegetative stage of soybean 17 Figure 2.2 Reproductive stages of soybean 18 Figure 4.1 Leaf and flower characteristics of soybean varieties in the autumn-

winter season 2021 53 Figure 4.2 Pod characteristics of some soybean varieties 56 Figure 4.3 Seed characteristics of some soybean varieties 56 Figure 4.4 Leaf folder and Pod borer of soybean varieties in the autumn-winter

season 2021 68

ABSTRACT

This study aimed to evaluate soybean varieties on morphological and agronomical traits to identify promising soybean varieties Plant materials included 29 soybean varieties evaluated in the autumn-winter season 2021 in Gia Lam, Hanoi The experiment was arranged in a randomized complete block design (RCBD) with 2 replications The area of the experimental plots is 1 m2, sown in 2 rows / furrow with the distance of 30 cm for rows and of 10 cm for plants As the result, there are six varieties: D140xDT12 (N), D140xDT12 (VS), DH4xAGS129 white, late, AGS134, 12192, and V selected for evaluation in other seasons such as spring, summer-autumn, and winter The soybean varieties had short, medium, and long growth durations, ranging from 79 days to 116 days All soybean varieties were distinguished by the dry pod color, which ranged from light to dark brown The soybean varieties differed in growth and development characteristics, such that some varieties had higher plant height, number of pods, number of leaves, and number of nodes At the harvesting stage, the plant height of soybean varieties ranged from 31.9 to 52.0 cm The 100-seed weight of soybean varieties varied from 8.2 to 26.1 g The DH4 white variety had the largest seed size and the highest 100-seed weight (26.1 g), followed by the 4986 variety (23.5 g) and the 4969 variety (22.3 g) The individual yield of soybean varieties ranged from 1.9 to 11.8 g/plant Actual yield of soybean varieties varied from 4.3 to 27.6 quintals/ha, D140xDT12 (N) variety had the highest actual yield with 27.6 quintals/ha, followed by D140xDT12 (VS) (23.8 quintals/ha), DH4xAGS129 white, late (20.4 quintals/ha), AGS134 (15.3 quintals/ha), 12192 (13.9 quintals/ha), and V varieties (13.8 quintals/ha) In conclusion, there are six potential varieties with high actual yield: D140xDT12 (N), D140xDT12 (VS), DH4xAGS129 white, late, AGS134, 12192, and V should be evaluated to exploit and diversify available genetic resources for many purposes of selection

CHAPTER 1 INTRODUCTION 1.1 Background

Soybean (Glycine max (L.) Merrill) is a legume that belongs to the

legume family Soybean is a valuable short-term industrial crop with great economic and nutritional value, ease of cultivation, adaptability, and the ability

to improve soil quality (Pham Bao Chung, 2015) It's ideal for crop rotation, intercropping, and overlapping with a variety of different plants Soybean products can be utilized for human consumption, animal feed, processing industry raw materials, and valued export commodities (Ngo The Dan et al., 1999) Soybean seeds contain both proteins and fats content As a result, soybeans are regarded as the world's most important source of protein and vegetable oil (Khan et al., 2020) There are currently around 80 countries growing and developing soybeans in the world, with the United States, Brazil, Argentina, and China having the largest soybean cultivated area and output

Soybean seeds contain amino acids, especially essential amino acids for the human body such as triptophan, leucine, isoleucyl, valine, lysine, and methionine Moreover, there are also contain minerals such as Ca, Fe, Mg, Na,

P, K,etc.vitamins B1, B2, D, K, E,etc The nutrient composition of soybean seeds (per 100 g) is as follows: 417 kcal (1,745 kJ), 12.5 g water, 35.3 g protein, 19.0 g lipids, 28.2 g carbohydrate, and 5 g minerals The protein content in soybean seeds is very high, about 4-5 times higher than that of rice, wheat and corn, but the starch content is quite low (Takuji et al., 2013) Soybeans are also processed into 600 different food types, including traditional foods like tofu, soy sauce, soy milk, etc and modern products such as candy, bread, cheese, etc

Soybean plants have been grown in Vietnam for a long time and in many parts of the country However, our country's soybean production has fallen in both area and yield in recent years, and it is no longer able to meet consumer

(Pham Bao Chung, 2015) The main reason leading to underdeveloped soybean production in our country is the lack of a set of high-yielding, stable and suitable varieties for each sub-region Currently, many regions still use local soybean varieties, so the yield is very low Soybean productivity in our country is currently only 1.5-2.0 tons/ha, while in the world it is 2.5-3.0 tons/ha (FAO, 2019) As a result, breeding research is becoming more interesting and concentrated, with one

of the most efficient areas being the selection and evaluation of lines and varieties from domestic resources

Soybeans are commonly grown in all seven ecological regions of Vietnam The Northern Midland and Mountainous Regions have the most soybean cultivation areas In the spring and summer-autumn seasons of 2014, the northern mountainous areas, particularly in Ha Giang, Cao Bang, Lao Cai, Dien Bien, and Son La, cultivated 50.000 to 60.000 hectares of soybeans

Many new varieties have been developed with high yield and quality Research and evaluation to look for promising lines and varieties with good growth and development, high yield, and wide adaptability are critical for increasing the diversity of soybean varieties in Vietnam, meeting production needs, and providing starting materials for the selection and breeding new soybean varieties with good yield and quality

Therefore, to contribute to solving that problem, we carried out the

subject: “Evaluation of growth and yield of soybean accessions in the

autumn-winter season 2021 in Gia Lam

1.2 Objectives and requirements

1.2.2 Requirements

- Evaluation of some morphological characteristics of soybean

germplasms varieties in the autumn-winter season 2021 in Gia Lam-Ha Noi

- Assessment of the growth of soybean accessions in the autumn-winter season in Gia Lam, Hanoi

- In the autumn-winter season of 2021, the tolerance and infection levels

of soybean lines and varieties will be evaluated in the field

- Determination of yield and yield components of soybean accessions

- Propose some promising soybean varieties to include in the next step of soybean breeding

CHAPTER 2 LITERATURE REVIEW

2.1 Origin, classification and distribution of soybeans

2.1.1 Origin of soybeans

Soybean is one of the crops that humans have known for a long time to use and produce, so the origin of the soybean plant was quickly established Historical facts, geographical evidence, and archeological evidence all confirm that soybeans originated in Asia, specifically China The soybean plant was domesticated in China over several pre-feudal dynasties, and was probably grown and researched during the Shang Dynasty (1700-1100 B.C) BC (Ngo The Dan et al, 1999) Then soybeans were grown in Japan and many other countries Between 200 BC and 300 AD, soybean farming technologies were transmitted

to Korea from northern China and Japan Soybeans are now an important source

of protein in the diets of many Asian countries, as well as a highly valued food and industrial commodity throughout the region Soybeans were first discovered

in Europe in the 18th century, and by the 19th century, they were thriving in the Americas

Soybeans have become a crop with outstanding commercial potential and are chosen for automated agriculture only when they are begun as seed crops and cultivated in appropriate water system zones in the United States (Hymowitz, 1988)

According to some research, soybeans were farmed in Vietnam during the Hung dynasty, even before mungbean and black beans (Ngo The Dan et al., 1999) Soybean is known as a potential crop with high nutritional values and it has made a significant contribution to the Vietnamese economy during the last few decades However, both soybean production areas and productivity are still significantly lower than in other nations across the world Today, Vietnam still has to import soybeans from the USA, China, and other countries

2.1.2 Classification of soybeans

Glycine genus is subdivided into 26 perennial wild indigenous Australian

species, which produce perennial harvests in Australia, the South Pacific Islands, the Philippines, Taiwan, and Southeast China The genome is of 2n, 4n and polyploidy (40, 80, 38, 78) (Chung and Singh, 2008; Orf, 2010) Except for

Glycine canescense, which is used for animal feed, hybridization between the

species in this subfamily is very unsuccessful Thus, the pre-embryo stage in vitro culture will be obtained to obtain some ripening fruit between the diploid

species of this subspecies and Glycine max Some crosses between G max and tetraploid species, G tomentella, can produce hybrid and F1 seeds, but the F1

plants are ineffective (Nguyen Van Hien, 2000)

According to the Hymowit and Newell system since 1984, there is also

the subsidiary Soja in addition to the genus Glycine The genus Glycine was separated into seven species of wild perennials, while the subgenus Soja was divided into two species: soybean cultivated Glycine max (L) Merr and the annual wild species G Soja Sieb and Zucc

is concentrated primarily in China The best soybean production regions in both the U.S and China are located between 35 - 45° latitude

2.2 Ecological requirements of soybean plants

2.2.1 Light requirements

According to Doan Thi Thanh Nhan et al (1996), light has an effect on the morphology of soybean plants, changing the flowering and ripening periods, as well as the height, leaf area, and many other attributes of soybeans, including seed yields

Light is decisive for photosynthesis, nitrogen fixation, and dry matter yield,

as well as many other properties dependent on photosynthesis The response of soybeans to light illustrates both sides: the length of light during the day and the intensity of light The role of light length is to determining the length of the day

Because soybean is a typical short-day crop, they have a significant response to day length The seedling period is especially susceptible to short daylight, decreases at the bud interval, and practically stops at flowering spines

All varieties that ripen late or ripen quickly after growing for 25-30 days will flower if the lighting time is less than 12 hours a day In long-day conditions (lighting time >18 hours/day) continuously, the plants grow and grow almost indefinitely, do not flower Flowering and seed formation require 6-12 hours of light every day

The rate of fruiting and fruit growth is also affected by the length of the day Short days increase the rate of beans and hasten the accumulation of dry matter in the fruit Soybeans lose fruit and few seeds after flowering if they are exposed to high air temperatures for a long time Light affects late-ripening varieties more than early-ripening maturing varieties The soybean seed group in Vietnam is currently highly prosperous

In Vietnam, soybean varieties are divided into 3 groups: the early ripening maturing group, the medium ripening maturing group and the medium late-ripening maturing group Early ripening maturing varieties with little reaction to

day length should be planted in all three seasons, while late ripened varieties have a distinct response, needing a reasonable crop arrangement (Doan Thi Thanh Nhan et al., 1996)

The influence through light intensity is shown in the following contents: soybean has a light saturation point at 23.680 lux (20% midday sunlight) The process of flower bud differentiation when the light intensity reaches over 1.706 lux The light intensity is too weak, the plants elongate, the plants tend to climb and the seed yield is poor The light intensity is lowered by 50% when compared

to normal, reducing the number of branches, the number of burned fruit, and the yield can be reduced by 50% The light intensity is high; the plants develop quickly and produce a large yield

Soybeans are found in latitudes ranging from 48° to 30° south As a result, the recommended planting area distribution varies by variety

For instance, the early ripening maturing group planted at a low latitude will flower early, resulting in a limited yield because the stems have not developed enough The late-ripening group is planted at 40° North latitude, has a long flowering period, is influenced by rain and wind before harvest, and seems

to have a low yield (Doan Thi Thanh Nhan et al., 1996)

2.2.2 Temperature requirements

Soybeans are temperate, but not a cold-tolerant crop The total amount of temperature changes from 1888°C to 2700°C depending on whether the varieties are early or late ripening Temperature influences soybean plant growth and development, as well as many other physiological activities

The best temperature for germination is about 18°C-26°C Seeds germinate rapidly above 30°C, although the germination is weak Low temperatures will cause the plant's growth to slow and make it more susceptible

to disease

The single-leaf period can tolerate temperatures below 0°C, whereas the double-leaf period grows at temperatures as low as 12°C However, the coefficient of leaf area increases with temperatures between 18°C and 30°C

Flowering and fruiting at temperatures below 18°C are not beneficial for the fruiting stage, and high temperatures above 40°C impact internode formation, internode growth, flower differentiation, and nutrient transfer to the seeds, all of which lead to poor grain quality

If the temperature is too low during the last stage of plant growth, the seeds will be difficult to ripen, ripen unevenly, and the quality of the seeds will suffer

In particular, temperature also significantly affects the nitrogen fixation of soybean plants When the temperature goes up above 33°C, the Rhizobium bacteria become restrained The optimal temperature range for nodule bacteria activity is 25°C to 27°C The transport of substances in plants is slower when the temperature is lower and stops at 2°C-3°C Soybean root nutrient uptake is influenced by soil temperature and minimum temperature is different for different cations

2.2.3 Water requirements

Although soybeans are an upland crop, water is one of the most significant demands and a major limiting factor in soybean productivity Water requirements for soybeans vary depending on climate conditions, farming techniques, and the soybean growth period During the entire growing process from sowing to harvesting, soybeans need between 350-400 mm and 600 mm of rain The water efficiency of soybeans is from 600 to 1000 g water/1 g dry matter (Doan Thi Thanh Nhan et al., 1996)

In the germination and seedling stages, water utilization is low due to the small canopy and most of the water is lost through evaporation on the ground Water absorption and respiration are required for seed germination The water

content in seeds must reach 50% to ensure this germination process When compared to wet soil, the germination rate of seeds in dry soil is significantly lower When the soybean is in the 3-5 trifoliate leaf stage, the water need of soybean plants gradually increases, then rapidly rises, and reaches a maximum

in the growth stage from flowering to full fruit When the fruit begins to ripen, the water requirement decreases again with leaf decay and the amount of water evaporation decreases Photosynthesis intensity, photosynthetic efficiency, total leaf area, and photosynthetic potential all influence plant growth All of these processes are affected by the absence of water

Satisfying water demand for soybeans during each stage of plant growth and yield are closely connected The effects of rainfall and humidity are most visible during the flowering and fruiting stages During this period, a shortage of water causes the plants to lose flowers and drop many fruits, reducing productivity significantly The decrease in yield is due to the low grain weight (large flat seeds), so adequate water supply is required during this time Nitrogen fixation is reduced in dehydration conditions, partially due to a decrease in photosynthetic products on the roots, and partly due to the direct influence of water potential on the nodule

However, soybeans are drought tolerant for a short time without impacting on yield During the flowering period, when drought occurs, flowers fall off a lot, but if adequate moisture is restored, the next flower burns will continue to flower and fruit When the fruit ripens, if it rains, some varieties can germinate right on the plant, resulting in a substantial loss in yield

2.2.4 Soil requirements

Soybean plants can be adapted to many different types of soil, but the best soil is loam, sandy soils that are well-drained, have adequate moisture retention, and are rich in organic matter (Ca, K) They are not suitable for sandy, rocky,

water has a significant impact on the growth and development of soybean plants

in terms of yield The suitable pH for soybean plants is from 5.2 to 6.5

According to Doan Thi Thanh Nhan et al (1996), soybeans can still be produced on basalt red soil, upland land, and hilly land Soybeans are difficult to grow in heavy loam soil, but when they sprout, they are quite adaptable In sand soil, soybean yield is not stable

2.2.5 Nutritional requirements

There are 16 essential elements for the growth and development of soybean plants Carbon (C), Hydrogen (H), and Oxygen (O) are the three primary elements in dry matter, and they are absorbed freely in the air as CO2, H2O, and O2 Other essential elements are N, P, K, Ca, Mg, S, Fe, Mn, Mo, Cu,

B, Zn, and Cl Furthermore, Cobalt (Co) is a necessary element for nitrogen fixation (N) and is also considered an essential element (Ngo The Dan et al., 1999)

Soybean is a plant that requires little nitrogen fertilizer because it is capable of fixing a great deal of nitrogen from the atmosphere However, soybeans still need to use soil nitrogen and fertilizers Many research shows that nitrogen fertilization before sowing has a detrimental effect on the N2 fixation process The rate of nitrogenous fertilizer during sowing has an inverse relationship with the number of nodules on the plant The number of nodules on the plant will be reduced if nitrogen fertilizers are supplied at 56 kg/ha, but they will not be affected if applied at 112 kg/ha during the flowering stage (Nathanson et al., 1984) Soybean plants react little to nitrogen fertilizer, but protein still increases yield, seed weight, seed protein and protein content The increase in yield and nitrogen ratio in seeds when applying more nitrogen proves that N2 fixation is not enough to supply plants If there is insufficient nitrogen during the flowering and fruit-forming period, the number of flowers and fruits

is reduced or flat, and the weight of seeds is decreased

Phosphorus plays an important role in the formation and development of nodules in soybeans Potassium (K) accumulates in leaves, and potassium fertilization increases growth peaks and seed production Potassium is required for nodule development According to Do Anh (1965), for soybeans, the optimal Ca: P: K ratio is 2: 1: 1.5 Phosphates that is difficult to dissolve, such as AlPO4 and FePO4, can be absorbed by soybeans Because soybeans have a high need for S, providing S will increase soybean yield Liming is essential on acidic soils The application of lime reduces the concentration of toxic substances such

as iron (Fe), aluminum (Al), and manganese (Mn), and provides calcium nutrition to the plant

Soybeans are in high demand with trace amounts of boron (B), copper (Cu) and zinc (Zn) The importance of trace elements is closely correlated with soil properties (Le Van Tri, 2002) Some trace element requirements are affected

by pH In Ca-rich soil, there is a Fe deficiency phenomenon This shortage can

be addressed by using foliar fertilization Mn is also essential for soybean plants, fertilized by row MnPO4 for higher efficiency than scattering Foliar application

is most beneficial when applied at the start of flowering or fruit development, or both However, if too much is applied, there will be a poisoning phenomenon, namely deformed leaves, yellow color and dead tissue

2.3 Botanical characteristics of the soybean plant

The root system is shallow, deep, and narrow, and the number of nodules varies according to variety, soil, climate, and planting technique

The root system's development can be separated into two stages:

Stage 1: The vigorous development of the first taproot and first secondary

root typically lasts 30-40 days following growth

Stage 2: The initial root layer grows slowly, the rootlets no longer sprout,

and some even dry out Small secondary roots extend and form around the root collar at this time till harvest This root layer is in charge of giving enough nutrients for the growth of stems, leaves, and fruit At this point, it is vital to cultivate the soil in order for this root layer to thrive

The presence of many nodules on the roots of soybean plants is an essential aspect to note Nodules in soybean roots are typically concentrated

in the soil layer 0-20 cm deep; from 20-30 cm deep, there are few or no nodules (Tran Van Dien, 2007) Nodules are the product of a symbiotic

relationship between some types of microorganisms Rhizobium Japonicum,

and soybean roots (Ngo The Dan et al., 1999)

The amount of nodules produced is highly dependent on soil conditions and soybean nutrients When growing soybeans on soybean soil, nodules form earlier and in greater numbers The soil is either overly acidic or alkaline, and it

is poorly formed Because the ideal pH for nodule formation is 6-7, it is critical

to select the proper soybean soil Nodule development is also influenced by nutritional factors In general, the nodule thrives when fully fertilized with NPK, and adding P2O5 promotes nodule development, while the effect of potassium is not clear (Tran Van Dien, 2001)

Microorganisms and nodules have a symbiotic relationship in which the more nutrients the soybean plant supplies for microorganisms to function, the more microorganisms develop and accumulate nitrogen for the plant's growth and development

2.3.2 Stem

Soybean stem is a herbaceous plant that is round in shape and covered in tiny hairs When the stem is young, it is green or purple in color, and the color of the stem is directly connected to the color of the flower later on The flower is white if the stem is green, and purple if the stem is purple

The average body has 14-15 internodes, with the lower internodes being shorter than the upper internodes since the upper internodes develop quickly in 35-40 days, therefore the internode is usually long The length of the internode varies depending on the variety and sowing season, and it normally ranges from

3 to 10 cm Soybean plants in the summer season generally have longer internodes than spring and winter crops The height of the body is determined by the length of the internode

The height of a soybean stem ranges from 0.3 to 1.0 m The whole stem of soybean has a short, thick undergrowth covering from base to tip Soybeans with thick, dark hair are often resistant to disease, drought, and cold By contrast, hairless soybean cultivars frequently exhibit low growth and resistance The presence of more or less hairy stems, which can be long or short, thick or sparse,

is a distinguishing feature between similar varieties

People are divided into four types based on their growth habits and stem characteristics of soybeans:

• Straight stem type: the trunk is hard, the stem diameter is huge, the stem

is not tall, the internode is short, the fruits are highly concentrated, and the flower variety is usually finite

• Horizoltal stem type: the main stem is branched with numerous little branches, soft branches, covered in a bunch on the ground, the stem is quite long, and small fruits are scattered

• Half-horizontal type: is an intermediate between two types of straight

• Climbing style: tiny, long stems, crawling on the ground or climbing on

a different substrate Soybean stems can branch directly from the axillary of a single or double leaf

Branches on the main stem are called branch 1, level 1 branch can be divided into level 2 branches The number of branches on a plant more or less varies according to variety, season, planting density, and cultivation conditions The average number of branches per plant is 2-5, there are some varieties in good growing conditions that may have more than 10 branches Soybean plants begin to branch about 20-25 days after they are planted The appropriate branch position is over 15 cm high, if it is too low, it is not suitable for mechanization The narrower the branching angle of the soybean, the better it is for increasing density

• Simple leaves: Whole leaves appear 2-3 days after the plant has grown and above the cotyledons Single leaves are symmetrical Plant growth is shown

by large, glossy green leaves

• Trifoliate leaf: each compound leaf has 3 leaflets, sometimes 4-5 leaflets The leaflets are alternate and usually green, but as they age, they turn yellow-brown

Most of the leaves are hairy Depending on the variety, the leaves take on

a variety of shapes, with small leaves yielding poor yields Drought tolerance is poorer in larger varieties, but yields are often higher

The number of compoud leaf more or less, the area of large or small leaves greatly influences the yield and depends on the planting season The leaves next to the flower cluster play an important role in supplying nutrition to

that flower cluster If the leaves in this position are yellow, the fruit in that position frequently falls off or flat

The number of large leaves is strongest during the flowering period.The plant is healthy and capable of great productivity when the leaf blade becomes big, wide, thin, flat, bright green

2.3.4 Flower

The small, flavorless soybean flower is a butterfly type The flower's color varies depending on the variety, but it is commonly purple, light purple, or white Most varieties have purple or light purple flowers White-flowered soybeans generally have a higher percentage of oil than purple-flowered soybeans Flowers appear in the leaf axils, branches, and head stems The flowers grow in clusters, with 1 to 10 flowers in each cluster, with an average of 3-5 flowers Soybean flowers bloom but the fruiting rate is low 20-30%

Soybean flowers are usually pollinated before flowers bloom and are pollinated The rate of delivery is very low, accounting for an average of 0.5-1% (Ngo The Dan et al., 1999)

self-Depending on the variety and the weather, the time to begin flowering may be sooner or later Early ripe varieties, after growing for less than 30 days, have flowering and new ripe varieties 40-45 days later have flowering The flowering time is long or short according to the variety and season Some varieties only last for 10 to 15 days The flowering period is normally from day

5 to 10 after the flowers begin to blossom, according to the results of the study Temperatures of 25-28°C, air humidity of 75-80%, and soil humidity of 70-80% are ideal conditions for flowering In fact, if the blooms are exposed to poor conditions, they will fall off in large numbers, resulting in significant fall loss The fruits are not ripe in concentration in varieties with a protracted flowering time

Depending on the variety, a bloom can have anywhere from 1800 to 6800 pollen seeds; large seeds have a large anther and many pollen grains Pollen grains are usually round, with different pollen grain numbers and sizes, large seeds often have more pollen grains than small varieties Pollen seeds germinate well at temperatures ranging from 18 to 23°C

2.3.5 Fruit

The number of fruits per flower cluster ranges from 2 to 20 and can reach

400 per tree One fruit contains 1 to 5 seeds, but most varieties usually contain 2-3 seeds Soy is straight or slightly curved, with a length of 2-7 cm or more The fruit ranges in color from white-yellow to dark yellow, brown, or black Fruit color is determined by carotene pigment, xanthophyll, hair color, and the presence of anthocyanin pigments When young, pods are hairy green (photosynthesis is possible due to chlorophyll) when ripe they have a brown color Soybean flowers bloom, but the fruiting rate is only 20-30% In the spring, a plant can have 120 flowers but only fruit about 30-40 fruits, and with only 2 to 3 fruits on a cluster of 5-8 flowers The burns at the base usually have little or no fruit From the 5th to the 6th burning, there is a high fructification rate and firm fruit

2.3.6 Seed

Soybean seeds appear in a variety of colors, including black, brown, yellow, and green, etc The yellow seeds have significant commercial value

The seeds come in a variety of shapes, such as kidney, oval, round, and so

on In seeds, the embryo accounts for 2%, the two scallop leaves for 90%, and the seed coat accounts for 8% of the overall weight of the seed

The sizes of large and small seeds differ depending on the variety The weight

of 1000 seeds ranges from 20 to 400 g, with an average weight of 100 to 200 g

Distinct varieties have different colors and shapes, which is a characteristic expression of the varieties

2.4 Soybean growth and development characteristics

It is divided into two phases: vegetative (V) and reproductive (R) In the first stage is the growth of vegetative (roots, stems, leaves); in the second stage, it is transformed to form a reproductive stage and reserves such as flowers, fruits, seeds,

2.4.1 Vegetative stage (V)

Figure 2.1 Vegetative stage of soybean

VE: Vegetative emergence - cotyledons have been pulled through the soil surface

VC: Vegetative cotyledon - unfolding of the unifoliolate leaves

V1: First trifoliolate - one set of unfolded trifoliolate leaves

V2: Second trifoliolate - two sets of unfolded trifoliolate leaves

V4: Fourth trifoliolate - four unfolded trifoliolate leaves

V (n): nth trifoliolate - V stages continue with the unfolding of trifoliolate leaves The final number of trifoliolate depends on the soybean variety and the environmental conditions

 The period from sowing to growing (VE-VC):

This period begins when the water-absorbent seed swells until the plant has two cotyledons External factors such as temperature, soil moisture, and grain quality influence this time The summer crop in this period is about 4-5 days in the right humidity conditions If the temperature is low, this time can be extended by up to 7-10 days The suitable temperature for this period is 260-300C

If the temperature is higher than 400, it affects seedlings, and if the temperature is lower than 80, it will cause the seed to grow longer The growing period must be sufficiently humid It requires moisture in this period of 75% - 80% This is the decisive period for tree density per unit area and seedling health

 The period from emergence to flowering (V1 - Vn)

This is the period of the vegetative stage In the first stage, the plant grows slowly and is influenced by temperature and humidity When it comes time to bud, the flower grows rapidly This is a key period for the body to grow, burn short, and root deeply This period is the best drought-tolerant plants; the growth time of this period depends on the genetic characteristics of the variety

2.4.2 Reproductive stage (R)

 There are 8 stages (R1-R8)

Figure 2.2 Reproductive stages of soybean

R1: Beginning flowering - plants have at least one flower on any node

R2: Full flowering - there is an open flower at one of the two uppermost nodes R3: Beginning pod - pods are 0.5cm at one of the four uppermost nodes

R4: Full pod - pods are 2 cm at one of the four uppermost nodes

R5: Beginning seed - seed is 0.3cm long in the pod at one of the four uppermost nodes on the main stem

R6: Full seed - pod containing a green seed that fills the pod capacity at one of the four uppermost nodes on the main stem

R7: Beginning maturity - one normal pod on the main stem has reached its mature pod color

R8: Full maturity - 95% of the pods have reached their full mature color

At flowering, soybeans continue to develop stems, leaves, and roots This period requires great nutrition Soybean flowers usually bloom in the morning, but if the weather is overcast or the temperature is low, the flowering time is delayed After pollination, the fruit forms fruit (5-7 days) When the fruit develops at its maximum, the seeds will develop The dry matter accumulation rate of the seed increases rapidly until the seed is firm Moisture in this period has a great influence on the growth rate of fruit and seeds The seeds reach their physiological maturity when the seeds are solid, the seed coat has the color of the variety, the pods turn ash yellow or gray-black, and the leaves are yellowed and shed

Especially during this period, soybeans are often damaged by insects and stink, and if heavy, their yield will be reduced Therefore, it is necessary to have control measures (using pesticides to eradicate the insects in appropriate doses when they first develop)

2.5 Values of soybeans

2.5.1 Nutritional value

- According to an analysis by the U.S Department of Agriculture (USDA)

Table 2.1 Nutritional value of soybean per 100g

- According to other sources of analysis:

In soybean seeds, there are chemical components: Protein (40%), lipids (12-25%), glucid (10-15%); There are mineral salts Ca, Fe, Mg, P, K, Na, S; vitamins A, B1, B2, D, E, F; enzymes, wax, resin, cellulose In soybeans, there are enough basic amino acids such as isoleucine, leucine, lysine, methionine, phenylalanine, triptophan, and valine In addition, soybeans are considered to be

a complete protein source because they contain significant amounts of essential amino acids for the body

non-Soy-based foods are considered a type of "boneless meat" because they include a large amount of plant protein that can be used to replace animal protein Even 100 grams of soybeans might have the same amount of protein as

800 grams of beef

Soybeans account for 60% of daily protein consumption in nations such

as Japan and China Soybeans have a significant higher protein content than other beans

2.5.2 Economic value

• Agricultural value

- Fodder for livestock:

Soybean is a good source of fodder for livestock (1 kg seed of soybean is equivalent to 1.38 units of animal feed) Because the whole soybean plant (stems, leaves, fruits, and seeds) is high in protein, by-products like fresh leaves and stems can be used as feed for animals or dried as a general feed Industrial by-products such as oilseed meal have quite high nutritional content: N: 6.2%, P2O5: 0.7%, K2O: 2.4%, so it is very good for animal feed (Ngo The Dan et al., 1999)

- Soil improvement:

Soybeans are an excellent crop for soil improvement It is estimated that per hectare, after planting, soybean leaves in the soil about 30-60 kg of N, if it grows well, which is equivalent to urea nitrogen and 5-8 tons of organic matter

(Pham Gia Thieu, 2000) If the soybean plant is arranged in a reasonable crop structure in the rotation system, it will have a positive effect on the subsequent crops, contributing to increased crop yield and lower N fertilization costs Soybean leaves and stems work effectively as fertilizer in place of organic fertilizer since the N content in the stems is 0.05% and 0.19% in the leaves (Nguyen Danh Dong, 1982)

Experienced farmers realize that after each crop, soybean yields higher yields, fewer pests and diseases, and saves 30% of fertilizer In the provinces of the Red River Delta, the rice yield here increased significantly compared to the formula of 2 rice crops with 1 winter corn crop, soil quality improved more clearly

• Industrial value

Soybeans are used as a raw material in a variety of industries, including the production of artificial rubber, paint, printing ink, soap, plastic, rayon, liquid fuel, and lubricating oil in the aviation industry, but mainly soybeans are used to press oil Currently, in the world, soybeans are the leading plant providing raw materials for oil pressing, soybean oil accounts for 50% of the total amount of vegetable oil Characteristics of soybean oil: slow drying, high iodine index: 120-127; Condensation at temperature: -15 to -18°C Hundreds of different industrial items are made from this oil, including candles, soap, and nylon

In the pharmaceutical industry, soybean meal is used to process antibiotic mold culture medium and to process some amino acids such as arginine and glutamic acid by hydrolysis of soybean acid

• Food value

Soybean seeds have significant nutritional value, with an average protein content of 35.5 to 40% Meanwhile, the protein content in rice is only 6.2-13%; corn: 9.8-13.2%; beef: 21%; chicken: 20%; fish: 17-20%; and eggs: 13-14.8%,

minerals important for life (Nguyen Thi Hien and Vu Thi Thu, 2004) Soybean seed is the only food whose value is evaluated for both protits and lipids simultaneously Among plant-based proteins, soybean protein has the highest quality The protein content of soybean seeds is higher than the protein content

of fish and meat and 2 times higher than that of other legumes

Soybean seeds contain higher fatty oil content than other legumes, so they are considered an important vegetable oil source Soybean lipids contain a high proportion of unsaturated fatty acids (about 60-70%) with a high assimilation coefficient and aroma, such as linoleic acid 52-65%, oleic 25-36%, and linolenic acid about 2-3% (Ngo The Dan et al., 1999) Using soybean oil instead of animal fat can prevent atherosclerosis

In soybean seeds, there are many vitamins, as well as vitamins B1 and B2, and vitamins like PP, A, E, K, D, C, etc In particular, in germinating soybean seeds, the content of vitamins increases, especially vitamin C Analysis of biochemical components shows that in germinating soybean seeds, in addition to high vitamin C content, there are other ingredients like vitamin PP, and many other minerals such as Ca, P, Fe, etc Because of such high nutritional content, soybeans have a high energy supply capacity of about 4700 cal/kg (Nguyen Danh Dong, 1982)

Currently, people have processed over 600 different products from soybean seeds, of which more than 300 types of food are processed by both traditional, manual, and modern methods in the form of fresh, dried, and fermented such as bean sprouts, tofu, soy sauce, to other premium products such as soybean coffee, confectionery, artificial meat, and many other products Soybeans, particularly black-seeded soybeans, are also a medicine to cure diseases They have beneficial effects on the heart, liver, kidneys, stomach, and intestines Soybeans are a good source of protein for people suffering from diabetes, rheumatism, neurological breakdown, or malnutrition Furthermore,

soybean works to make the human body long, energetic, increase memory and regenerate tissues, harden bones, and increase the body's resistance In medicine, soybean meal (which has lost its smell by steam) is mixed with cereal flour, cocoa is used as food for babies, people with diabetes, people with rheumatism, gout, overworked workers

Scientists also discovered that soybean herb has properties against cancer germs such as breast cancer, colon cancer, lung cancer, stomach cancer, and prostate cancer

2.6 Soybean production in the world and in Vietnam

2.6.1 Soybean production in the world

Soybeans are the world's fourth most significant oilseed crop, after wheat, rice, and maize It is cultivated in almost all countries around the world due to its adaptability, but soybeans are most concentrated in the Americas with more than 70%, which was followed by Asian countries (China and India) accounting for 23.15% (Hartman et al., 2016) The world's soybean genetic resources are currently stored mainly in 15 countries, including Taiwan, Australia, China, France, Nigeria, India, Indonesia, Japan, Korea, South Africa, Sweden, Thailand, the United States, and Russia, with 45.038 varieties (Tran Dinh Long, 2002)

Soybean production situation in the world in recent years is shown in table 2.2

Table 2.2 Status of soybean production in the world in the period 2011-2021

(million ha)

Yield (tons/ha)

Production quantity (million tons)

(Source: Faostat, 2020; https://apps.fas.usda.gov/psdonline/circulars/production.pdf)

Soybean production has increased dramatically throughout the world in recent years The area increased by 24 million hectares from 103.8 million hectares in 2011 to 127.8 million hectares in 2020 The yield increases substantially from 2.5 tons/ha (2011) and to 2.8 tons/ha (2020) Due to improved area and productivity, production quantity tends to increase over time from 2011

to 2020, with around 261.6 million hectares in 2011 and 363.2 million ha in

2020 The growth rate in area as well as productivity has confirmed that countries around the world are increasingly investing in developing and improving soybean production

Forecast in 2021, the total area of soybeans in the world was 132.4 million

ha, the yield was 2.9 tons/ha, and production was 384.4 million tons The largest areas of soybean production in the world are in the Americas, followed by Asia, Europe and Africa

America, Brazil, Argentina, India, and China are the leading countries in soybean production and their soybean production accounts for 90-95% of the

world production Among major producing countries, the Brazil is the top producer during the year 2016-2021, (40.40 million ha and 144.0 tons) in terms

of area and production in 2021, followed by USA (34.98 million ha and 121.0 tons), Argentina (17.20 million ha and 52.0 tons) and China (9.6million ha and 19.0 tons), respectively (Table 2.3) This is the result of the application of techniques, mechanization in agricultural production, high yield transgenic and pest resistance varieties In addition, in the development strategy, countries also increase the soybean acreage by replacing other crops such as sunflower (in Argentina), cotton (in the US), using grasslands (in Argentina and Brazil) or replacing native plants (in Brazil) (Masuda and Goldsmith, 2009)

Table 2.3 Area, yield and production of soybeans of some countries in the

The United States has developed and bred new soybean varieties as a result of selection procedures, mutagenicity, and hybridization In breeding programs, high-yielding varieties are employed as breeding sources In the United States, studies on soybean breeding using mutant approaches yielded a variety of results The United States has discovered soybean allergy-free cultivars after testing thousands of kinds over many years Today, the private sector is responsible for the majority of soybean variety development Public-sector breeders, on the other hand, continue to play an essential role Public-sector breeders prioritize germplasm enhancement, breeding methodology, and molecular technology advancement in addition to variety development The ability to breed new varieties that are adaptive to shifting environmental circumstances and management practices will be critical to modern agriculture'sproductivity in the future

China is a neighboring country to Vietnam and has similar farming practices Currently, China is the world's fourth-largest producer of soybeans In hybrid and imported varieties, China has implemented scientific developments Furthermore, China has a variety of programs aimed at improving soybean cultivars with pest and weed resistance that are suited to the sub-regional climate These typical varieties are CN001, CN002, and YAT12 China has also generated numerous novel types through mutation in recent years, such as Tiefeng 18, which is resistant to high alum, has good lodging resistance, high productivity, and good quality (Ngo The Dan, 1994)

In general, the world's soybean production has increased in recent years as

a result of its nutritional and economic worth The increase in soybean production and yield was attributed to a number of causes, the most important of which was variety According to forecasts, world soybean production will increase by 2.2 percent, reaching 371.3 million tons by 2030 However, the fact remains that when soybean production or demand increases, the cultivated land

seems to decrease That requires investment in research to improve seed yield (Masuda and Goldsmith, 2009)

2.6.2 Soybean production in Vietnam

Soybeans are an industrial and food crop in Vietnam that plays an essential role in the agricultural crop structure, particularly in the northern mountainous areas (Tran Van Dien, 2007) It adapts to many different agro-ecologicale zones, bringing many benefits to people and communities Therefore, the soybean growing area is expanded and concentrated in some

areas, such as:

 The Northern mountainous midlands

 The Red River Delta

 Southeast region of Vietnam

 Mekong River Delta

In Vietnam soybean production has decreased in recent years due to low yields and the continuing decline in growing area as farmers switch to more profitable crops, including other field crops, fruits, and vegetables Soybean production continues to fall well below the demand from the food, livestock, and aquaculture feed sectors Soybean production over the years has shown that the development of soybean production areas in the country tends to decrease rapidly

The situation of soybean production in Vietnam has changed from year to year in terms of area, production, and annual yield According to the Vietnam General Statistics Office, the figures from certain years are shown in Table 2.4 below to help better comprehend that change