1. Unit 9: Seed & Grain Quality
CROP PRODUCTION
Unit 9: Seed & Grain Quality

2. Seed Quality--Importance (211)
Viability—ability of seed to germinate
Vigor—ability of the seed to produce strong, rapidly emerging seedlings
Varietal purity—seed of only one variety or hybrid
Free of weed seed

3. Seed Germination (212) Dormancy External requirements
Physical—seed coats may not imbibe water; sometimes solved by scarification
Physiological—due to hormonal inhibition or immature embryos
External requirements
Temperature
Moisture
Oxygen
Light

4. Seed Germination (213) Seed treatments
Protect seeds from microbial attack
Treatments include fungicides and herbicides
Care must be taken, as some treatments may be toxic to humans & animals
Seed coatings—multitude of reasons for use
Coat small or irregular seeds for uniformity for planting
Impregnate treatment chemicals to reduce environmental hazards like leaching and dust
Artificially program seed germination for specific interval or conditions
Improve injury resistance and storability

5. Germination Test (214) (under optimal conditions)
Conducted in warm, moist setting
Estimates maximum percentage of seeds capable for developing healthy seedlings
Both normal and abnormal seedlings as well as hard seeds are recorded

6. Vigor test (215) (because field conditions are not usually ideal)
Cold test—help estimate germination under moist, cool conditions (50° F)
Accelerated aging test—used to estimate germination under optimum conditions after exposure to heat & humidity (106° F & 100% humidity)

7. Tetrazolium test (215) Rapid test for seed viability;
Not recognized as official for seed sales purposes

8. Purity Analysis (215)
Seed is split into fractions based on the following (all recorded as percentages by weight):
Pure seed
Other crop seed—ex: barley seed in wheat
Weed seed—names and number of state secondary noxious weeds recorded; primary noxious weeds render the entire lot not for sale
Inert matter—chaff, stones, stems, and other materials

9. Mechanical Damage in Seeds (218)
Injury caused by harvest, conditioning, and handling of seed
Sodium hypochlorite test for cracked seed coats in soybeans

10. Determination of PLS (219)
% PLS = (% Germination x % Purity)/100
Real Cost (of PLS) =
(Quoted price of seed/unit)/(PLS/100)
Actual seeding rate =
(Recommended seed rate of PLS)/(%PLS/100)

11. Increasing Seed Supplies (220)
Federal and state laws and seed certification programs ensure purity
How can the supply be increased for customers?
How can genetic purity be maintained?
How can high quality, weed-free supplies be continuously obtained?

12. Increasing Seed Supplies (221)
Legal seed—laws that must be followed; vary state to state
Valid seed label
Tested for germination and purity
No primary noxious weed seed present
Name and number of secondary noxious weed seed printed on label
Less than 1.5% total weed seed

13. Increasing Seed Supplies (221)
Certification agency
Usually State Crop Improvement Assoc. (SCIA)
Persons engaged in ag work—mainly seed producers and dealers
Encourage availability of high quality seed

14. Increasing Seed Supplies (221)
Certification requirements:
High germination percentage
No primary noxious weed seed
Limited secondary noxious weed seed
No more than 0.5% total weed seed
Limited inert matter
Limited number of other crop seed

15. Increasing Seed Supplies (221)
Certification classes and sources of certified seed
Breeder seed—developed by breeder, controlled by institution—source for foundation seed
Foundation seed—supervised by Ag Experiment Station—handled to maintain purity and ID—source for Registered and/or Certified seed
Registered seed—progeny of foundation, used to produce certified seed
Certified seed—genetic purity and ID acceptable to certifying agency
Bin run seed

16. Increasing Seed Supplies (222)
Seed increase of new varieties
Plant variety protection act—1970
Passed to enable developers of a new variety to protect the variety from unauthorized sale by others—guaranteeing a return on research investment

17. Grain Quality--Standards (223)
U.S. Grain Standards Act of 1916
Established official grain standards and grading procedures
Established Federal Grain Inspection Service to license and supervise grain inspection and weighing
Established an appeal procedure if grain grades are challenged

18. Grain Grading (224) Procedure
Sampling—obtain representative sample to be graded; probes and other samplers used
Preliminary examination—visual observation determines class of grain
Preparation of sample portions—
smaller samples; Boerner Divider
Inspecting work sample—final
grade determined

19. Grain Grading (226) Various determinations in grain grading
Class and subclass—use kernel characteristics and color
Special grade designations—characterize grain quality in addition to numerical grade
Dockage—foreign material, such as hulls, weed seed, and dust that is readily removed
Moisture—noted on grading ticket; does not influence numerical grade

20. Grain Grading (227) Various determinations in grain grading
Grade factors—items that affect numerical grade: test weight, total damage, foreign materials, and heat-damaged kernels
Test weight—measure of weight filling a standard volume; higher weights = higher flour and starch and plumper kernels
Analytical determinations—total damaged kernels and other by-weight determinations

21. Grain Grading (228) Placing the final grade
Procedure—factors individually graded before summarizing overall grade
Hypothetical example—lowest individual grade is final grade of sample
Writing the grade—numerical grade, class or subclass, special grade designations and factors determining grade

22. Website resources: Chapter 9 http://www.mwseed.com/grass-legume.htm
Chapter 9
Review Questions (p. 231 – 232)
Thinker