Morphology and Physiology of Soybean

Botany and structure of soybean plant
growth stages of soybean plant
growth and development of soybean plant

1. MORPHOLOGY AND PHYSIOLOGY OF SOYBEAN Baffour Asafo-Adjei IITA, Ibadan July 28, 2015

2. OUTLINE Introduction Botany and structure of soybean plant Growth stages of soybean plant Growth and development

3. INTRODUCTION Importance Why is soybean important? Geographic Distribution How widely is it produced?

4. INTRODUCTION Importance Soybean is the most important grain legume in the world in terms of production and use. It is important in Africa and Nigeria for three key reasons. - Employment and incomes to people (farmers, processors, marketers) - Nutrition and health benefits - Role in sustainable farming systems (N2 organic carbon, cereal striga management)

5. INTRODUCTION contd.

6. INTRODUCTION contd. Geographic Distribution Currently grown in various environments throughout the world . Extensively cultivated in tropical Brazil; sub-tropical Central America and Southern USA; temperate Northern USA and Canada, and sub-arctic Sweden and Siberia Introduction of soybean in most African countries is very recent (mostly in the 20th century).

7. BOTANY AND STRUCTURE OF SOYBEAN PLANT Botany Cultivated soybean ( Glycin max ) is an annual crop. It belongs to the family Leguminosae Sub - family Papilionoideae and tribe Phaseolae. It is a diploid with chromosome number 2n=2x=40. Some of the wild and semi-wild relatives e.g. G. falcata and G. latifolia are also diploid Others such as G. tabacina and G. tomentella are tetraploids (2n = 4x = 80).

8. BOTANY AND STRUCTURE OF SOYBEAN PLANT contd. Botany Some of the wild species may have genes controlling useful traits that may be lacking in the cultivated specie It has not been easy to transfer such traits Into cultivated soybean due to the difficulty in obtaining fertile/viable seed from Inter- specific hybridization.

9. BOTANY AND STRUCTURE OF SOYBEAN PLANT Structure of soybean plant Cultivated soybean is generally an erect, sparsely branched bush type – unlike the spreading sometimes vinery characteristics of wild and semi-wild species

10. BOTANY AND STRUCTURE OF SOYBEAN PLANT Structure of soybean plant There are two types of stem growth habit and floral initiation in soybean . These are the determinate and indeterminate types. Most of the varieties cultivated in the tropics are determinate while those in the temperate regions are indeterminate

11. BOTANY AND STRUCTURE OF SOYBEAN PLANT Determinate Vegetative growth of terminal bud ceases when it becomes an inflorescence. Flowering occurs about the same time along the length of the plant, hence pod and seed development and maturation occur uniformly throughout the plant. Terminal leaves are of the same size as those at the bottom of the main stem. Indeterminate Plant may have achieved less than half its final height when it starts flowering. Plant continues to grow taller while flowering also continue. Flowering/pod and seed development are spread over a longer period Pod and seed development on lower parts of the plant are more advanced than those at the top. They do not have terminal inflorescence. Terminal leaves are smaller than those which are lower on the plant

12. BOTANY AND STRUCTURE OF SOYBEAN PLANT Root Consists of a taproot that may go deep into the soil depending on cultural conditions The root system is usually in the top 30-60 cm of soil with about 80-90 of dry weight occurring in the top 15 cm of the soil. Nodules may be visible 10 days after planting if the appropriate rhizobia are present in the soil. Stem Well-developed main stem, may have 0-6 lateral branches and grow to a height of 20 cm to over 100 cm depending on variety and cultural/environmental conditions Structure of soybean plant

13. BOTANY AND STRUCTURE OF SOYBEAN PLANT Leaves Two main types: Primary and Trifoliate leaves. The primary leaves are ovate with 1-2 cm length petioles and a pair of stipules at its point of attachment to the stem The trifoliate leaves are alternate and have long petioles. Leaflets have entire margins and are broadly ovate to elliptic- Ianceolate in shape Primary and Trifoliate leaves

14. BOTANY AND STRUCTURE OF SOYBEAN PLANT Inflorescence Soybean has a typical papilionaceous flower . It consists of a tabular calyx with five sepal lobes; a corolla made up of a standard petal, two lateral wing petals, and two anterior keel petals. Nine of the ten stamens are fused leaving the posterior one separate The pistil is made of an ovary that contains 1-5 ovules, a style that accrues towards the standard and a capitate stigma. Pollination occurs before the flower opens Soybean flowers

15. BOTANY AND STRUCTURE OF SOYBEAN PLANT Pod Pods are borne in clusters on short stalks, pubescent and of varied colours depending on cultivar. They may be straight or slightly curved, about 1 cm in width and 3-7 cm long when matured Seeds Matured soybean seed may be spherical in shape or may be flattened and elongated to various degrees depending on variety Seed size may range from 5 - 40 g per 100 seeds with most varieties between 10 and 20 g per 100 seeds

16. GROWTH STAGES

17. DESCRIPTION OF VEGETATIVE STAGES

18. DESCRIPTION OF REPRODUCTIVE STAGES

19. DESCRIPTION OF REPRODUCTIVE STAGES

20. DESCRIPTION OF REPRODUCTIVE STAGES V2 Fully developed trifoliate leaf at node above the unifoliate

21. DESCRIPTION OF VEGETATIVE STAGES V5 Five nodes on main stem with fully developed leaves beginning with the unifoliate

22. DESCRIPTION OF VEGETATIVE STAGES R1 One open flower at any node on main stem

23. DESCRIPTION OF VEGETATIVE STAGES R2 Open flower at one of the two uppermost nodes on main stem with a fully developed leaf

24. DESCRIPTION OF VEGETATIVE STAGES R3 Pods 5 mm long at one of the four uppermost nodes on main stem with fully developed leaf

25. DESCRIPTION OF VEGETATIVE STAGES R4 Pods 2 cm long at one of the four uppermost nodes on main stem with fully developed leaf

26. DESCRIPTION OF VEGETATIVE STAGES R5 Seeds 3 mm long in a pod at one of the four uppermost nodes on main stem with fully developed leaf

27. DESCRIPTION OF VEGETATIVE STAGES R6 Pod containing a green seed that fills the pod cavity at one of the four uppermost nodes on main stem with fully developed leaf

28. DESCRIPTION OF VEGETATIVE STAGES R7 One normal pod on main stem that has reached its mature pod colour

29. DESCRIPTION OF VEGETATIVE STAGES R8 95% of pods have reached their matured pod colour

30. GROWTH AND DEVELOPMENT

31. GROWTH AND DEVELOPMENT Growth : May be defined as a gain in dry matter production. It is affected by two main factors .   Genetic or Internal factors, and Environmental or external factors

32. GROWTH AND DEVELOPMENT Genetic or Internal factors Resistance tolerance to biotic (e.g. diseases/insects), and abiotic (e.g. heat/shade and soil pH/ nutrient toxicity). Enzyme activity Rate and type of various biochemical reactions (e.g. photosynthesis, respiration, partitioning of assimilates) Cell differentiation etc

33. GROWTH AND DEVELOPMENT Genetic or Internal factors Breeding for resistance /tolerance to biotic & abiotic stresses are major breeding objectives of most soybean programs – cost effective / efficient, sustainable & environmentally friendly.

34. GROWTH AND DEVELOPMENT Environmental or external factors Biological: Diseases, Insects, weeds and soil micro- organisms (e.g. Nitrogen fixing bacteria, denitrifying bacteria mycorrhiza) Climatic: Light, temperature, water, day length, gases (C0 2, O 2, SO 2 , Cl etc.) Soil: Texture, structure, organic matter content, CEC, pH, Nutrient availability

35. IMPORTANT FACTORS THAT AFFECT SOYBEAN GROWTH AND DEVELOPMENT Light The effect of light on plant growth is expressed primarily through photosynthesis and other related processes. Reduced radiation reduces photosynthetic rates and consequently dry matter accumulation In a soybean field, leaves near the surface of the canopy intercept more light than lower leaves. Vertical leaf orientation is also known to enhance light interception when leaf area index (LA I) is greater than 3.0. Varieties with vertical leaf orientation would thus be expected to be more productive because light interception is improved and photosynthetic activity is also increased . Breeding implications?

36. IMPORTANT FACTORS THAT AFFECT SOYBEAN GROWTH AND DEVELOPMENT Temperature Plant growth depends on several biochemical processes taking place in the plant. The rates at which these processes take place are influenced by temperature. Different biochemical processes require different optimum temperature e.g. the optimum rate of photosynthesis in Individual soybean leaves is achieved at about 35°C to 40°C. Respiration however continues to increase above these temperatures. On the other hand the optimum temperature for dry matter accumulation is about 30°C. Effect of temperature depends also on the stage of crop development. Seed germinates between 10°C -40°C however, low soil temperature at planting results in low germination and seedling development. Seed developed in hot weather ( > 33°C) tend to have poor germination, while seed viability deteriorates rapidly when stored in warm temperature ( >30°C) conditions.

37. IMPORTANT FACTORS THAT AFFECT SOYBEAN GROWTH AND DEVELOPMENT Temperature Vegetative growth is affected by both soil and air temperatures. Soil temperatures of about 22°C - 27°C are considered the most favourable for soybean root growth Flowering pod and seed development: Flowering is poor below 20 C and increases up to about 32 C beyond which flower abortion results. Generally high temperature and excessive heat tend to increase flower and pod abortion

38. IMPORTANT FACTORS THAT AFFECT SOYBEAN GROWTH AND DEVELOPMENT Photoperiod Soybean is naturally a short day plant but cultivars differ in critical day-length requirements. Photoperiod affects plant height and the number of nodes produced. Both characters increase with increasing day length Thus, cultivars adapted to the long-day (14-16hrs) summer conditions in the temperate regions will be shorter, have fewer nodes, flower earlier and will produce less dry matter when planted in tropical environment (shorter day lengths 12 hrs.). Conversely, cultivars adapted to the tropics when planted in temperate environments, grow taller, produce more nodes and flowering is delayed until the day length shortens

39. IMPORTANT FACTORS THAT AFFECT SOYBEAN GROWTH AND DEVELOPMENT Moisture Soybean will experience water stress when there is either excess moisture in the soil or there is a deficit in available soil moisture. Excess soil moisture injures root system by reducing aeration, and soil moisture deficit results in dehydration of the shoot. Soybean requires about 580g of water per gram of dry matter produced For soybean seed to germinate, it has to imbibe about 500g I kg of dry weight. Thus both low soil moisture content and excessive soil moisture will result in poor germination

40. IMPORTANT FACTORS THAT AFFECT SOYBEAN GROWTH AND DEVELOPMENT Soil The physical, chemical and biological properties of the soil affect plant growth and development. Soybean requires a well-drained loamy soil for proper growth Heavy soils impede seed emergence, resulting in poor stands root development is also restricted. Light or loamy soils however encourage good root development Sandy soils low in organic matter, have low moisture holding capacity and plants growing on such soils tend to experience drought stress. Soybean requires the 16 essential elements for its growth and development. Absence or non-availability of any of these elements results in abnormal or sub-normal plant growth. Plants show characteristic nutrient deficiency symptoms.

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