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Switchgrass seedlot establishment tests (SETs) applied to 20 seedlots planted in field trials near Mead, NE, in 2002 and 2003.

 
Set Protocol
Pure live seed (PLS) standard PLS test (germination × purity) following Association of Official Seed Analysts (AOSA) rules for testing seeds with prechill using published number of 858 seeds g−1
No prechill (NP) SET-germinated seeds per gram for each seedlot using AOSA rules for testing seeds with no prechill
Prechill (P) SET-germinated seeds per gram for each seedlot using AOSA rules for testing seeds with prechill
Heat stress (H) SET-germinated seeds per gram for each seedlot using AOSA rules for testing seeds with no prechill following a heat stress treatment (0.25 g of seed placed on top of two layers of dry blotter paper in open germination boxes and kept in a dark germination cabinet [95% relative humidity, 50°C] for 12 h)
Emergence through 4 cm of sand (E4) SET emerged seedlings 21 d after planting 0.25 g of seed 4 cm deep in sand in germination trays drenched with captan (1g L−1 H2O) and watered daily; sand particle size was 10% coarse (0.5–1.0 mm), 40% medium (0.25–0.5 mm), 40% fine (0.10–0.25 mm), and 10% very fine (0.05–0.10 mm)
Heat + emergence through 2 cm of sand (H+2) combination of heat stress procedure combined with emergence through 2 cm of sand; emerged seedlings counted after 21 d to determine emerged seedlings per gram



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Number of seeds per gram, seed establishment test seedlings germinated or emerged per gram of seed, and Association of Official Seed Analysts (AOSA) germination percentages (germinated seeds per 100 seeds) for 10 switchgrass seedlots evaluated in greenhouse trials using no prechill (NP), prechill (P), heat stress (H), emergence through 4 cm of sand (E4), and heat stress plus emergence through 2 cm of sand (H+2) in 2002 and 2003.

 
Seeds germinated or emerged
AOSA germination
Cultivar Seedlot Seeds NP P H E4 H+2 NP P H
no. g−1 no. g−1 of seed %
2002
Sunburst 2199 552 375 445 476 304 413 68.1 83.1 83.8
Sunburst 2221 507 447 455 439 341 429 85.3 90.3 88.7
Sunburst 98063 481 422 426 408 355 403 87.1 89.1 84.6
Cave-in-Rock 12169 652 456 423 436 391 457 70.0 66.0 65.9
Cave-in-Rock 1712 473 399 438 407 387 419 84.6 92.8 85.7
Shawnee 2061 662 357 462 339 269 419 53.6 71.7 50.1
Trailblazer 2243 526 464 504 491 440 485 90.3 93.7 93.5
Trailblazer 91149 702 386 300 405 242 331 55.9 42.5 57.4
Trailblazer 7771 525 299 285 290 226 286 57.1 55.1 54.5
Trailblazer 91101 482 129 40 129 75 93 26.7 7.9 27.4
Mean 556 373 378 382 303 374 67.9 69.2 69.2
LSD(0.05) 25 19 3.6
2003
Sunburst 2275 513 302 443 415 229 370 59.5 86.0 80.4
Sunburst 2276 537 249 442 366 226 365 46.3 81.0 69.7
Cave-in-Rock 2277 529 272 286 150 183 105 51.8 53.8 28.2
Trailblazer 2278 622 487 485 477 388 396 74.9 82.5 76.1
Trailblazer 2279 657 415 482 469 252 379 60.3 75.8 72.8
Trailblazer 2280 618 450 475 484 264 420 72.3 76.5 72.3
Trailblazer 2289 666 260 309 228 136 157 39.0 45.7 35.3
Shawnee 2290 677 192 514 317 99 212 28.7 71.0 49.3
Shawnee 2291 686 371 391 448 321 371 53.6 55.4 67.8
Cave-in-Rock 12169 689 437 421 139 261 121 66.4 55.8 20.9
Mean 619 344 425 349 236 290 55.3 68.4 58.0
LSD(0.05) 31 28 2.1



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Mean switchgrass seedlings per meter of row ∼30 d after planting, aboveground biomass dry matter (DM) 5 mo after planting, and aboveground biomass DM 14 mo after planting at Site 1, a field site seeded in 2002 near Mead, NE, using planting rates based on five seedlot establishment tests (SETs) averaged across 10 seedlots. A seeding rate of 200 germinated or emerged seeds m−2 was used, with the amount of seed planted dependent on the results of each specific SET.

 
Seed quality test† Seedlings Biomass 5 mo after planting Biomass 14 mo after planting
no. m−1 of row Mg ha−1
NP 15.3 1.45 11.28
P 14.9 1.70 10.91
H 12.5 1.39 10.51
E4 18.0 1.82 10.94
H+2 12.5 1.32 10.08
LSD(0.05) 4.2 0.33 0.86
NP, no prechill; P, prechill; H, heat stress; E4, emergence through 4 cm of sand; H+2, heat stress plus emergence through 2 cm of sand.



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Frequency of occurrence of switchgrass seedlings 5 mo after field planting in 2002 at Site 1 near Mead, NE, for 10 seedlots planted using rates based on five seedlot establishment tests (SETs). A seeding rate of 200 germinated or emerged seeds m−2 of plot area was used, with the amount of seed planted dependent on the results of each specific SET (NP, no prechill; P, prechill; H, heat stress; E4, emergence through 4 cm of sand; H+2, heat stress plus emergence through 2 cm of sand).

 
Frequency of occurrence
Cultivar Seedlot NP P H E4 H+2
%
Cave-in-Rock 1712 62 58 70 66 57
Shawnee 2061 49 49 68 70 60
Sunburst 2199 44 48 46 37 43
Sunburst 2221 52 69 42 66 71
Trailblazer 2243 73 69 63 64 40
Trailblazer 7771 27 36 32 35 35
Cave-in-Rock 12169 39 46 32 57 46
Trailblazer 91101 19 46 21 20 19
Trailblazer 91149 55 45 49 76 49
Sunburst 98063 61 42 54 66 45
Mean 48 51 48 56 47
LSD(0.05) 7



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Effects of seedlot establishment test (SET) based planting rates and switchgrass seedlots on seedlings per meter of row, frequency of occurrence 5 mo after planting, and frequency of occurrence 14 mo after planting at Site 2 seeded in 2003 near Mead, NE, using SETs including pure live seed (PLS), no prechill (NP), prechill (P), heat stress (H), emergence through 4 cm of sand (E4), and heat stress plus emergence through 2 cm of sand (H+2).

 
Cultivar Seedlot PLS NP P H E4 H+2
Seedlings, no. m−1 of row
Sunburst 2275 10.3 14.3 12.5 14.3 23.8 6.3
Sunburst 2276 4.8 21.5 8.3 18.5 27.5 14.8
Cave-in-Rock 2277 1.5 3.8 10.5 23.0 13.3 23.8
Trailblazer 2278 5.5 19.3 16.8 8.3 10.8 23.3
Trailblazer 2279 11.8 10.5 6.8 19.5 25.3 17.3
Trailblazer 2280 8.8 19.3 12.3 17.0 28.5 22.8
Trailblazer 2289 4.0 14.5 10.3 11.0 25.0 18.0
Shawnee 2290 2.5 13.5 2.8 6.3 20.5 20.0
Shawnee 2291 7.0 13.3 13.0 13.8 16.0 6.3
CIR 12169 3.5 4.3 11.0 17.0 9.5 27.3
Mean 6.0 13.4 10.4 14.9 20.0 18.0
LSD(0.05) 8.1
Frequency of occurrence 5 mo after planting, %
Sunburst 2275 37.5 42.5 34.5 42.0 45.0 35.5
Sunburst 2276 15.5 48.5 37.0 38.5 46.5 48.0
Cave-in-Rock 2277 17.5 34.0 28.5 53.5 48.0 44.0
Trailblazer 2278 22.5 42.0 38.5 30.0 38.3 50.5
Trailblazer 2279 34.0 34.0 27.0 36.5 49.5 34.0
Trailblazer 2280 26.5 47.0 40.5 39.5 55.0 42.0
Trailblazer 2289 12.5 35.0 33.0 53.5 56.5 41.5
Shawnee 2290 16.0 40.5 18.5 25.0 58.5 40.0
Shawnee 2291 29.5 36.0 43.0 30.0 35.5 31.5
CIR 12169 16.0 19.5 22.0 47.5 30.0 54.0
Mean 22.8 37.9 32.3 39.6 46.3 42.1
LSD(0.05) 12.6
Frequency of occurrence 14 mo after planting, %
Sunburst 2275 30.3 31.3 23.8 32.3 45.8 35.3
Sunburst 2276 20.0 43.8 29.0 50.0 47.0 45.5
Cave-in-Rock 2277 25.3 37.5 28.5 56.3 53.8 56.3
Trailblazer 2278 29.3 47.0 49.8 34.0 39.5 64.3
Trailblazer 2279 40.3 39.5 39.0 38.3 54.5 35.0
Trailblazer 2280 26.5 53.3 49.0 43.8 51.5 49.8
Trailblazer 2289 19.0 47.0 32.3 54.5 47.0 40.0
Shawnee 2290 23.3 55.3 17.5 24.5 41.8 30.8
Shawnee 2291 31.5 33.8 41.8 33.0 45.0 27.5
CIR 12169 22.5 23.0 29.0 44.5 31.3 43.5
Mean 26.8 41.1 34.0 41.1 45.7 42.8
LSD(0.05) 12.7