Table 3.

Estimated ED50 values (± 95% C.I.) for germination, radicle extension, and cotyledon formation for major biochar aqueous extract constituents in four target plant species (combining results from experiments 1 and 2)

Chemical	Species	Germination ED50 (mmol L−1)		P	Radicle extension ED50 (mmol L−1)		P	Cotyledon formation ED50 (mmol L−1)		P
Acetic acid	Lettuce	1.52	± 0.18	< 0.001	1.00	± 0.00	< 0.001	1.33	± 2.01	0.516
	Ryegrass	7.16	± 0.85	< 0.001	3.36	± 0.56	< 0.001	3.29	± 4.12	0.004
	Radish	16.72	± 0.49	< 0.001	3.08	± 0.36	< 0.001	3.82	± 24.71	0.879
	Basil	3.73	± 0.99	< 0.001	1.76	± 0.26	< 0.001	1.86	± 0.48	< 0.001
Propionic acid	Lettuce	3.87	± 0.09*	< 0.001	0.91	± 0.10	< 0.001	1.35	± 0.15	< 0.001
	Ryegrass	3.50	± 0.19*	< 0.001	1.57	± 0.25	< 0.001	4.79	± 5.19	0.365
	Radish	10.76	± 4.26	0.019	7.02	± 4.45	0.127	4.45	± 3.55	0.222
	Basil	2.58	± 0.44	< 0.001	0.58	± 0.06	< 0.001	1.19	± 0.17	< 0.001
Butyric acid	Lettuce	2.44	± 0.35	< 0.001	0.87	± 0.32	0.013	1.23	± 1.11	0.278
	Ryegrass	3.38	± 1.45	0.029	1.24	± 0.19	< 0.001	3.73	± 2.09	0.088
	Radish	9.79	± 0.31	< 0.001	2.42	± 0.58	< 0.001	8.20	± 2.47	0.003
	Basil	7.16	± 3.03*	0.022	0.81	± 0.10	< 0.001	1.77	± 0.67	0.010
Valeric acid	Lettuce	1.59	± 0.08*	< 0.001	0.93	± 0.16	< 0.001	1.18	± 3.09	0.703
	Ryegrass	1.85	± 0.08	< 0.001	0.97	± 0.08	< 0.001	3.36	± 2.32	0.154
	Radish	8.42	± 0.93	< 0.001	2.75	± 0.75	0.001	6.64	± 0.78	< 0.001
	Basil	2.07	± 0.51*	< 0.001	0.52	± 0.04	< 0.001	1.06	± 0.29	< 0.001
Caproic acid	Lettuce	1.46	± 0.53	0.008	0.33	± 0.04	< 0.001	1.02	± 0.12	< 0.001
	Ryegrass	2.86	± 0.32	< 0.001	1.39	± 0.15	< 0.001	2.44	± 1.68	0.152
	Basil	4.00	± 1.04	< 0.001	0.66	± 0.07	< 0.001	1.84	± 0.36	< 0.001
2-ethylbutyric acid	Lettuce	0.741	± 1.161	< 0.001	0.203	± 0.039	< 0.001	0.658	± 0.170	< 0.001
	Ryegrass	1.084	± 0.292	< 0.001	0.114	± 0.013	< 0.001	0.887	± 0.247	< 0.001
	Radish	0.708	± 0.120*	< 0.001	0.085	± 0.008	< 0.001	0.371	± 0.090	< 0.001
Acetone	Lettuce	2,365	± 513	< 0.001	269	± 123	0.035	513	± 189	0.010
	Ryegrass	2,597	± 140	< 0.001	2,449	± 437	< 0.001	4,902	± 197	< 0.001
	Radish	4,632	± 3,890	0.242	2,399	± 854	0.008	5,606	± 98	< 0.001
Phenol	Lettuce	0.62	± 0.05	< 0.001	0.44	± 0.32	0.191	2.12	± 3.66	0.878
	Ryegrass	3.14	± 0.19	< 0.001	2.14	± 0.27	< 0.001	3.83	± 1.33	0.008
	Radish	5.80	± 0.68	< 0.001	1.25	± 0.32	0.001	2.13	± 0.15	< 0.001
Benzene	Lettuce	9.74	± 1.03	< 0.001	NA	NA	NA	9.67	± 1.80	0.010
	Ryegrass	NA	NA	NA	NA	NA	NA	NA	NA	NA
	Radish	NA	NA	NA	NA	NA	NA	NA	NA	NA
Methyl ethyl ketone	Lettuce	42.0	± 11.7	< 0.001	77.8	± 30.9	0.018	39.3	± 10.1	< 0.001
	Ryegrass	NA	NA	NA	185.4	± 88.1	0.045	NA	NA	NA
	Radish	137.0	± 57.8	0.025	57.8	± 62. 7	0.037	NA	NA	NA

All values listed are based on a log-logistic dose–response model as shown in Figs. 2, 3, 4, with exceptions (*) based on the logistic dose–response model where this showed a lower AIC value. Cases in which ED50 values were not estimable are marked “NA” and compounds tested that did not show significant ED50 values in any test species are excluded