This article appeared in the Winter 2013 issue of Pulse Crop News.

Holly Gelech, BioVision Seed Labs

Seed labs issue hundreds of reports each week that provide valuable information that drives seed selection and seed treatment decisions. Seed testing is a well-known agricultural service, but the processes and skill set required to perform testing is not understood. In this article, we will answer your questions on internal processes implemented from sample receipt to analysis.

Germination

Germination is by far the most requested and valued test in the seed industry. Today’s germination test methods have not changed in the last 20 years and continue to be managed by the Canadian Food Inspection Agency. Through CFIA’s “Canadian Methods and Procedures for Testing Seed”, planting media, chamber temperatures, and even analysis rules are outlined in this document, to be followed by all accredited seed analysts.

Sample Preparation

• Roll Towel Planting Method: 200 seeds planted at 50 seeds / replicate
• Growth Chamber Conditions: 20°C for 7 days with alternating photoperiod

Germination Analysis

Complexity of analysis ranges from sample to sample based on disease, seed moisture during harvest, and storage conditions. From a pulse standpoint, the most impactful farm operation that affects germination is handling of the pulses. Seed coat cracks and embryo damage can occur quickly and are not often visible to the naked eye. Accredited analysts are trained, and then tested by CFIA, to ensure their skills are proficient.

The analysis procedure commences with division of seedlings into the various categories. This is conducted on each of the four replicates. Final signoff of the tests is wrapped up when all four replicates meet statistical tolerances and are averaged for reporting.

• Normal Seedlings: All structures required to produce a healthy plant are present.
• Abnormal Seedlings: Structures are missing. Roots or shoots are stunted or deformed. Cotyledons are detached from each other.
• Dead Seeds: Seed show no signs of sprouting. Cotyledons are split apart.

If the seedlings show signs of chemical damage, which can occur when glyphosate is applied pre-harvest, then retesting the germination in soil is an option. This may mitigate some tell-tale chemical damage symptoms, which is very short roots with little root hair and very minimal shoot elongation.

Disease

Culture media disease testing is the predominant testing method utilized in analyzing seed borne infection, as it detects viable pathogen presence and will communicate the infection level to the client. These test benefits gives clients the tools needed to choose a seed lot and to target seed protection products. The marketplace typically requests Ascochyta, Botrytis, and Anthracnose (lentil, bean, chickpea) for pulses. Seed borne Ascochyta infection is higher in the 2012 seed crop, which was also observed in the growing crop.

• Culture Media (potato dextrose agar) Plating Method: 200 seeds plated at 10 seeds/plate in Laminar flow cabinet
• Incubation Chamber Conditions: 27°C for 5 days with alternating photoperiod

Disease Analysis

Disease analysis requires a unique skill set which includes lab procedures proficiency and analytical competency. Identification of pathogens includes visual analysis of each fungal colony for morphological characteristics including color, mycelial growth pattern, and pycnidia presence. Follow-up compound microscopic spore analysis (at 400X magnification) is often required to distinguish species, as spores are not visible by the naked eye.

Fungal presence is recorded at the workbench for each seed. Test completion is finalized when all 200 seed are analyzed and infection is reported as a percent. The lowest level of detection is 0.5 per cent, which is one seed infected out of 200 seeds tested.

The Report of Analysis is the end product of lab service delivery. Knowing what tests impact your seed decisions are the first step, followed by how to interpret the results. Each testing season brings different challenges, so contact your seed lab to benchmark how your results stack up against typical results for that year.