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Specific Work Instructions (SWI 142.1.2-6): Soybean Seed Crop Inspection Procedures

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Date

This version of the Soybean Seed Crop Inspection Procedures was issued May 1, 2020.

Contact

The contact for this Seed Program Specific Work Instruction (SWI) is the National Manager, Seed Section. Comments regarding the content of this document should be addressed to the National Manager at cfia.seed-semence.acia@canada.ca.

Review

This Seed Program Specific Work Instructions (SWI) is subject to periodic review. Amendments will be issued to ensure the SWI continues to meet current needs.

Endorsement

This Seed Program Specific Work Instruction is hereby approved.

____________________
Director, Plant Production Division

____________________
Date

Distribution

The most up to date version of this document will be maintained on the CFIA website. In addition, the signed original will be maintained by the National Manager, Seed Section. A copy of the latest version is available upon request to cfia.seed-semence.acia@canada.ca.

0.0 Introduction

The purpose of pedigreed seed crop inspection is to provide an unbiased inspection of a seed crop and complete a Report of Seed Crop Inspection for the Canadian Seed Growers' Association (CSGA) on the isolation, condition, and purity of the crop. It is the inspector's responsibility to describe the crop as observed at the time of inspection.

1.0 Scope

This Seed Program Specific Work Instruction (SWI) outlines the procedures that a seed crop inspector will follow in inspecting soybean seed crops for pedigreed seed status. The seed crop inspection program ensures that seed crops grown for pedigreed status meet the requirements for varietal purity and seed crop standards as specified by the CSGA's Canadian Regulations and Procedures for Pedigreed Seed Crop Production (Circular 6).

These procedures apply not only to oilseed soybeans that are subject to variety registration under Part III of the Seeds Regulations, but also miso type, tofu type, and natto-type soybeans as well as vegetable-type and high protein soybean varieties destined for roasting for livestock feed. These latter types are not subject to variety registration.

2.0 References

The publications referred to in this SWI are those identified in SPRA 101 – Definitions, Acronyms, and References for the Seed Program. In addition, the following were used in the development of this SWI:

3.0 Definitions

For the purposes of this SWI the definitions given in SPRA 101 and the following apply:

Abscission layer
in soybeans, the layer of parenchyma cells formed at the point of attachment of the seed and the seed pod; as the parenchyma disintegrates, the seed becomes separated from the pod
Bushy type
soybeans with determinate growth type, 90 to 100 cm tall, drying more slowly than normal soybeans
Determinate growth habit
the terminal bud ceases vegetative activity when flowering begins
Herbicide tolerant soybean variety
a variety of soybeans that is tolerant of a herbicide for which tolerance is not ubiquitous throughout the traditional North American soybean gene pool
Hilum colour
the colour of the hilum or center spot on the seed can range from, yellow, gray, brown, or black (see Appendix I); hilum colour and shape can be affected by plant maturity, environment and disease
Indeterminate growth habit
the terminal bud continues vegetative activity throughout the growing season
Maturity
for inspection purposes, maturity means that at least 90% of the plants in the inspected field have dropped their leaves. Soybean varieties are classified early, medium or late maturing
Miso type soybean varieties
soybean varieties which are fermented to make a paste with barley or rice malt
Natto type soybean varieties
small seeded soybeans varieties with high sugar content used for food purposes
Pubescence colour
colour of the short hairs on soybean plant stems and pods at maturity; the colour can vary from gray, light brown, to brown and dark brown and is best observed on the bottom 1/3 of the plant
Semi-determinate growth habit
the terminal bud continues vegetative growth after flowering but terminates this growth before indeterminate types
Soybean kinds
include Oilseed, High Protein, Natto, Tofu/Soymilk, Sprouting, and Miso
Tofu type soybean varieties
soybeans soaked and mashed to produce a curd
Tall
a plant can be considered tall when the top petiole is removed/absent, and the main stem is approximately 15 cm above other main stems of the general plant population

4.0 Specific inspection procedures

Inspection of pedigreed seed crops of soybeans should be carried out as described in SWI 142.1.1 Pedigreed Seed Crop Inspection, with the additional conditions and information provided in the following sections.

4.1 Inspection requirements

Seed crop inspection for soybeans must be made at maturity. As a general guide, and based on harvest pressures, inspection could be conducted when a minimum of 90% of the plants have dropped all their leaves and the mature plants have developed distinguishing pod, pubescence, and hilum colour characteristics. Beginning in 2016, descriptors provided in the variety description for pubescence, mature pod and hilum colour follow a standardized colour scheme. See Appendix VI. Only standardized colour descriptors for pubescence, mature pod and hilum may be reported. Crop inspectors do not need to report talls that are shorter than the SWI definition (and that otherwise conform) even if they are described in the variety description as variants.

4.2 Field inspection

The soybean is a highly self-pollinating crop with an outcrossing rate of less than 1% among fertile plants. In Canada, most soybean varieties have an indeterminate growth habit. Indeterminate varieties begin to flower when less than half of the nodes on the main stem have developed such that vegetative and reproductive development occur simultaneously for a considerable portion of the plant's life. Pod and seed development begin at the bottom of the plant and progress toward the top as new nodes form, but all seeds reach maturity at the same time.

Oilseed soybean varieties are required to be registered for sale in Canada. Variety descriptions for miso type, natto type, tofu type, vegetable and other specialty use soybeans may be obtained from the CSGA. Variety descriptions for unregistered oilseed soybean varieties must be provided by the grower.

When inspecting soybean seed crops, some key varietal characteristics at maturity are determined by colour and, therefore, it is important that light conditions for colour and contrast be maximized. This is important when determining off type characteristics such as pubescence and pod colour during inspection. The time of day, shadows, direction and the light angle may also be crucial. Sometimes cloudy or overcast conditions allow for more contrast in colours and easier identification of variants and off-types than bright overhead sunlight. It should be noted that with the passing of time after maturity, the colour characteristics can be affected by weather and may not be as distinguishable. Pod colour at maturity can vary from light brown to black.

Picture A - These are examples of the SAME pod colour, but different pubescence colours.
Picture B - These are examples of the SAME pod colour, but different pubescence colours.
Figure 1 – The pictures A and B (above) demonstrate that a lighter pubescence colour can be deceiving and may make the pod colour appear lighter. These are examples of the same pod colour, but different pubescence colours.
Picture C - These are examples of different pod colours, but the same pubescence colours.
Picture D - These are examples of different pod colours, but the same pubescence colours.
Figure 2 – The pictures C and D (above) are examples of different pod colours, but the same pubescence colours.

Seed coat lustre can vary from dull to glossy. Soybean seed coat exists in a range of colours including yellow, green, brown, black and bicolour, however the most common colours are yellow, black and brown. The seed coat colour can be affected by environmental factors and diseases. When colour pigmentation, like black or brown, is present in the seed coat, it will be visible on all of the plant's seeds. In contrast, when the seed coat colour varies on the seed, the plant, and from one plant to another, the seed coat colour variation is likely caused by a disease or frost.

Seed shapes may be round and spherical to elliptical and flattened. See Appendix III. It should be noted that while seed characteristics should be used to confirm the variety, seed characteristics should only be used to confirm variant or off-type plants in counts based on other visible morphological off-type characteristics.

Other factors to watch for include maturity with later maturing plants often retaining their leaves and being taller than the other plants in the field (Figure 3; Appendix V). The time of emergence, soil type, disease, herbicide injury and weather conditions can cause variability in plant height and maturity, making off-types for these factors difficult to distinguish at maturity. Plants that are immature due to environmental factors should not be included in counts. Appendix IV provides information on diseases that may alter the plant's appearance.

Figure 3 – Example of an immature soybean plant in a field.
Figure 3 – Example of an immature soybean plant in a field
 
Figure 4 – Although the hilum colour is not fully developed in an immature plant, the developing colour may be helpful in determining if the plant will conform to the variety i.e. the colour is developing into a light versus a dark hilum.
Figure 4 – Although the hilum colour is not fully developed in an immature plant, the developing colour may be helpful in determining if the plant will conform to the variety for example, the colour is developing into a light vs a dark hilum.

For soybean inspections, 2 off-type characteristics must be identified and reported. If only 1 off-type characteristic differs from the norm of the variety, then the second characteristic can be stated as "otherwise conforms." "Tall and immature" is not acceptable for the 2 off-type characteristics requirement. If using "tall and immature," another morphological characteristic such as pubescence colour or hilum colour will need to be provided.

Where the previous land use was soybean, particular attention should be paid to the possibility of volunteers.

Note: The maximum field size for production of Breeder and Select status seed is 2.5 acres (1 ha). Probation plots of pedigreed soybean seed must be smaller than 0.5 ha.

If off-types are found in a number of fields of a variety, seed crop inspectors should notify their supervisor and the CFIA as it may be indicative of contaminated parent seed.

Appendix I: Soybean hilum colour

Soybean hilum colour
image - Soybean hilum colour. Description follows.
Description of photo of soybean hilum colour:

This photo shows rows of soybeans seeds of each hilum colour option: black, imperfect black, dark brown, brown, grey, light brown, imperfect yellow, and yellow.

Range of soybean hilum colours
Photo 1 - Range of Soybean Hilum Colours. Description follows.
Photo 2 - Range of Soybean Hilum Colours. Description follows.
Photo 5 - Range of Soybean Hilum Colours. Description follows.
Photo 3 - Range of Soybean Hilum Colours. Description follows.
Photo 4 - Range of Soybean Hilum Colours. Description follows.
Description of photos of soybean hilum colour range:

Five photos of soybean seeds depicting soybean hilum colour variations within the same hilum colour and between different hilum colours.

Appendix II: Abscission layer

Lacking an abscission layer is a single gene trait in soybean. If the abscission layer between the seed and the seed pod is lacking, you cannot remove the adhering material from the seed easily. The adhering material can be polished off some seeds in a combine but in general it should be a constant trait in a variety. The description of the variety will characterize the abscission layer as lacking or normal. If "-" is provided on the variety description, that indicates that the breeder has not provided information on this characteristic. Due to its variability, using hilum abscission layer as an off-type characteristic is only recommended in situations where no other supporting secondary characteristic is available and the trait is stable in the variety. The characteristic is considered stable when the abscission layer presents in the same way (lacking or normal) and not partially, on all the seeds in all the pods from the top to the bottom of the plant. If this is not the case, this characteristic is not stable and should not be used.

image - soybeans where abscission layer is lacking or present
image - soybeans where abscission layer is lacking or present
Description of photos of soybean abscission layers

Two photos of 6 soybeans each depict 3 seeds each with material clearly still attached to the soy bean seed (lacking abscission layer) on the right, and 3 seeds each on the left where no material is attached (abscission layer is normal).

Appendix III: Soybean characteristics diagrams

Terminal leaflet shape

Terminal leaflet shape - Lanceolate.
lanceolate

Terminal leaflet shape - triangular.
triangular

Terminal leaflet shape - pointed ovate.
pointed ovate

Terminal leaflet shape - rounded ovate.
rounded ovate

Stem termination type

Stem termination type - determinate.
Determinate - The terminal bud ceases vegetative activity when flowering begins.

Stem termination type - indeterminate.
Indeterminate - The terminal bud continues vegetative activity throughout the growing season.

Semi-determinate - The terminal bud continues vegetative growth after flowering but terminates this growth before indeterminate types.

Plant growth habit

Plant growth habit - erect.
erect

Plant growth habit - semi-erect.
semi-erect

Plant growth habit - intermediate.
intermediate

Plant growth habit - semi-prostrate.
semi-prostrate

prostrate.
prostrate

Seed shape

Seed shape - length.
length

Seed shape - width.
width

Seed shape - thickness.
thickness

Spherical rounded (length/width, length/thickness, and thickness/width Ratios = < 1.2)

Spherical flattened (length/width Ratio > 1.2; length/thickness Ratio < 1.2)

Elongate (length/thickness Ratio > 1.2; thickness/width Ratio < 1.2)

Elongate flattened (length/thickness Ratio > 1.2; thickness/width Ratio > 1.2)

Appendix IV: Diseases that may influence soybean plant appearance

Plant is normal height but leaves are discoloured:

Plants die prematurely / mature plants retain dead leaves:

Pods and/or seeds abnormal in appearance:

Plants stunted with crinkly or ruffled leaves:

Appendix V: Potential causes of green, immature plants

Green, immature plants should not be assumed to be off-types. There can be many causes of green, immature plants as outlined in the chart below. The shaded column on the left of Appendix V contains titles of parts of the plant (leaves, stem, pods, seeds) or the plant population that are examined for identifying characteristics of the green, immature plant. The top shaded row contains titles of the causes of green, immature plants. Based on the described characteristics to identify environmental stress, green stem syndrome, male sterile, and bud blight, these plants should not be counted as off-types. Only off-types, as described in the last column should be noted on the report.

Table of potential causes of green, immature plants
Environmental stress Green stem syndrome Male sterile Bud blight Off-type
Leaves Green, present, can be diseased None to present on upper nodes Green Green, leaflets may be smaller than normal and cupped Green, 80-90% present
Stem Green Green Green May be stunted, brown discolouration of pith Green
Pods Present, immature Mature, few to none Largely absent, small on top of the plant Developed poorly or aborted, may have brown patches Present, immature
Seeds Present, immature Mature 0-1 present in a pod Few, if any Present, immature
Plant population Either plant population uniformly impacted by stress, or a number of plants in certain locations Distributed randomly or clustered in a field Rare in population Varies Isolated individual plants

Appendix VI: Pre-2016 and current colour descriptors used for soybean pubescence, pod and hilum colours

Standardized pubescence colour descriptors

soybean light brown. Description follows.
soybean brown. Description follows.
soybean dark brown. Description follows.
soybean grey. Description follows.
Description of photos of soybean pod pubescence colour:

Four photos of mature soybeans pods with the different pubescence colour.

If non-standardized pubescence colour descriptors are encountered in a description of the variety (not included in the list directly above), use the following chart to convert them to the closest acceptable colour descriptor.

Pre-2016 to current pubescence colour descriptor conversion chart
Pre-2016 pubescence colour descriptors Current pubescence colour descriptors
tawny or brown tawny brown
gray at top to tawny at bottom brown
light tawny, very light tawny, very light brown, or near grey light brown
light tawny with some darker gold tawny light brown to dark brown

Standardized hilum colour descriptors

  1. black
  2. imperfect black
  3. grey
  4. dark brown
  5. brown
  6. light brown
  7. imperfect yellow
  8. yellow
soybean colours. Description follows.
Description soybean hilum colour descriptors photo:

This photo shows 8 soybean seeds with the different hilum colour.

If non-standardized hilum colour descriptors are encountered in a description of the variety (not included in the list directly above), use the following chart to convert them to the closest acceptable colour descriptor.

Pre-2016 to current hilum colour descriptor conversion chart
Pre-2016 hilum colour descriptors Current hilum colour descriptors
brownish black brown to black
buff light brown
dark buff light brown to brown
grey to imperfect black with brown tint imperfect black
light buff light brown
light gray gray
mid-light brown light brown
tan light brown
very light brown light brown
clear yellow
medium brown brown

Standardized mature pod colour descriptors

When describing off-types with "brown to dark brown pods," inspectors should use the full descriptor if possible, or they can write "brown pod" or "dark brown pod" if space is limited.

soybean pods light brown. Description follows.
Soybeans with a light brown pod will generally have a consistent light brown colour across the whole pod.

soybean pods brown. Description follows.
soybean pods dark brown. Description follows.
Soybeans with brown to dark brown pods will generally have a slightly lighter colour on the portion of the pod in between the seeds.

soybean pods black. Description follows.
Soybeans with a black pod will generally have a consistent black colour across the whole pod.
Description of photos of soybean pod colour:

Four photos showing the different mature soybean pod colours.

If non-standardized mature pod colour descriptors are encountered in a description of the variety (not included in the list directly above), use the following chart to convert them to the closest acceptable colour descriptor.

Pre-2016 to current mature pod colour descriptor conversion chart
Pre-2016 mature pod colour descriptors Current mature pod colour descriptors
tan light brown
beige light brown
mixed light brown and brown to dark brown
pale tan light brown
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