Date of this Version
Agronomy Journal, Volume 104, Issue 2, 2012; doi:10.2134/agronj2011.0168
The effect of switchgrass (Panicum virgatum L.) seed quality tests on field establishment has been addressed inadequately. Our objective was to evaluate the ability of seed quality tests to predict field establishment. Standard Association of Official Seed Analysts (AOSA) tests are based on the percentage of seeds in a seedlot that germinate under standard laboratory conditions, whereas the seedlot establishment tests (SETs) are based on the number of seeds that emerge per gram of seed using different germination or stress test conditions. The SET was determined using six laboratory tests and the results validated in three replicated field trials. Treatments were: (i) AOSA pure live seed (PLS) test assuming 858 seeds g–1; (ii) AOSA test with no prechill; (iii) AOSA test with prechill; (iv) heat stressed at 50°C for 12 h; (v) emergence from 4 cm of sand; and (vi) heat stressed plus emergence from 2 cm of sand. Data from non-control tests were on a SET per-gram basis. Field establishment differed by the seed quality test on which the seeding rate was based. The best predictor of field establishment was emergence from 4 cm of sand, which had an establishment index (ratio of field-emerged seeds to seeds planted) that was 3.5 times greater than the PLS method and 36% greater than no prechill. Stands on which planting rates were based on SET that included stress tests were better predictors of field establishment than the standard PLS method. Switchgrass seeding rates based on SET are recommended to reduce the risk of failure during stand establishment.