Zone 5 Southern 2018 Argentine Bahiagrass Referee Proposal Presentation: Roger Cross (North Carolina Seed Laboratory, NCDA&CS)

Introduction The objective of this referee is to explore a better germination testing method for varieties of bahiagrass other than Pensacola bahiagrass. It is the hope of the Zone 5 referee committee that upon conclusion of this referee a rules change proposal to discontinue the removal of enclosing structures for germination testing of Argentine Bahiagrass can be put to the membership for a vote.

Background Argentine Bahiagrass (Paspalum notatum flugge) is a forage grass commonly grown in the Southeastern United States. The AOSA Rules for Testing Seeds Volume 1, Principles and Procedures, Section 6.8b requires the removal of the glumes covering the internal seed structures for germination testing. The primary concern is the time required to hand peel (de-gluming) 400 seeds for an AOSA germination test.

Background (continued) Non-uniform results from analysts when hand peeling Argentine Bahiagrass is a potential problem since the removal of enclosing structures requires skill, dexterity and patience. An additional issue is older and lower quality Argentine Bahiagrass seed typically has a lower moisture content and possess caryopsis which are brittle and difficult to remove intact which adds a potential for bias in a germination test.

Proposal Addressing the Argentine Bahiagrass germination testing concerns presented in the background section, it was proposed by the Zone 5 Southern Referee Committee to initiate a referee consisting of six lots of Argentine Bahiagrass for germination testing using two testing methods involving unpeeled and hand peeled (de-glumed) seed.

Procedure Each participant was sent six lots of Argentine Bahiagrass containing pure seed which was both hand peeled (400 seeds de-glumed) and left unhulled (400 seeds). At the end of 21 days the number of normal and abnormal seedlings were recorded, and a tetrazolium test was conducted on the remaining un-germinated firm seed. The number of viable and non-viable seed was recorded.

Results The amount of time needed to de-glume 400 seeds averaged 5 hours 6 minutes. The amount of time that was needed to complete the task ranged from 1 hour 35 minutes to 2 hour 30 minutes on the low end and over 10 hours on the high end (various). No solid connection could be made between the experience of the person de-gluming seeds and the time needed to complete the task because many groups reported ranges of experience for the entire lab in the questionnaire rather than the experience of the individual tester per seed lot. The number of seeds damaged during peeling averaged 13.8 seeds. There is no noticeable correlation between the time needed to de-glume the seeds and the amount of seed damage.

Results

Results

Conclusions The difference between the hand peeled treatment and the unpeeled seed treatment, both combined with TZ results, is 1.15% (a difference of slightly over 1 seed per 100) with the higher result of positives leaning toward the hand peeled treatment. Given the average time (5 hours 6 minutes) to hand peel seeds and the small amount of variation between the peeled/unpeeled treatments, it may be advantageous to test the seed unpeeled and combine that count with the results of a TZ test for a final count.

Thank you! Kevin Buis Mansour Asghare David Johnston Lan Chi Trinh Stan Akagi Andrae McMillian AB Seed Laboratory Alabama Seed Lab Louisiana Seed Lab North Carolina Seed Lab Oregon State University Seed Lab Pennsylvania Seed Lab Federal Seed Lab, Gastonia NC All staff and testers who participated