Table 1. Regression parameters estimated from the three-parameter log-logistic model (Eq 1: d = upper limit, b = slope) for percent cumulative germination of dicamba-fluroxypyr–susceptible (S) and –resistant (R) K. scoparia at various constant temperatures averaged over experimental runs.
| Temperature (°C) | Regression parameter estimates | ||||
|---|---|---|---|---|---|
| Selected linea | d (± SE)b | b (± SE) | I50 (95% CI)c, d | I90 (95% CI)c, d | |
| 5 | S | 89.2 (1.2) a | - 4.3 (0.4) | 88 (84–92) a | 146 (130–162) b |
| R | 53.2 (1.9) b | - 2.7 (0.3) | 93 (83–103) a | 210 (170–250) a | |
| 10 | S | 87.3 (2.5) a | - 1.9 (0.1) | 69 (62–76) b | 181 (134–228) b |
| R | 47.0 (1.2) b | -2.3 (0.3) | 100 (91–109) a | 318 (244–392) a | |
| 15 | S | 91.8 (0.9) a | -2.2 (0.2) | 32 (29–35) b | 186 (170–202) b |
| R | 75.6 (1.4) b | -0.9 (0.1) | 98 (50–146) a | 331 (210–452) a | |
| 20 | S | 108.3 (3.4) a | - 1.4 (0.1) | 55 (47–63) a | 252 (155–349) a |
| R | 90.0 (3.7) b | 1.4 (0.2) | 58 (49–67) a | 276 (145–407) a | |
| 25 | S | 100.9 (1.2) a | - 2.0 (0.1) | 39 (36–42) a | 113 (94–132) b |
| R | 94.8 (2.6) a | - 1.4 (0.2) | 43 (38–48) a | 201 (175–227) a | |
| 30 | S | 93.8 (1.2) a | -2.4 (0.4) | 24 (21–27) b | 58 (42–74) b |
| R | 78.3 (3.0) b | -1.4 (0.2) | 36 (30–42) a | 169 (90–248) a | |
| 35 | S | 97.6 (1.4) a | -1.6 (0.2) | 23 (20–26) b | 87 (60–114) b |
| R | 71.3 (2.1) b | -1.5 (0.2) | 35 (30–40) a | 148 (138–158) a | |
a S, dicamba-fluroxypyr–susceptible K. scoparia selected line; R, dicamba-fluroxypyr–resistant K. scoparia selected line; SE, standard error of mean; CI, confidence interval.
b Value in parenthesis represent standard error of the mean.
c I50 is the time (h) of incubation required for 50% cumulative seed germination; I90 is the time (h) of incubation required for 90% cumulative seed germination.
d Within each temperature, d, I50, or I90 values followed by the same letter are not significantly different based on the approximate t test using the “CompParm” command in the drc package, R software [32].