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

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

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

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

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

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)

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

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

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

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)

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?

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

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

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

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

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

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

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

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

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

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

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