# Evaluation of Biochar and Composit Mixes as Substitutes to a Commercial Propagation Mix
## 3 Results and Discussion  
### The Effect of the Biochar and Compost Mix on Seed Germination Stage  
In Experiment 1, it was observed that all seeds in the BC and VC mixes had similar EPs to the control's except for cowpea and corn in the mix with 70% BC and 30% VC (by volume; 7 BC:3 VC) and pumpkin in both BC:VC mixes, which were lower than the control (Figure 1a). Celosia in 8 BC:2 VC and pumpkin in both BC:VC mixes had lower EIs than the control's, with the other seeds having better or equal EIs (Figure 1b). In Experiment 2, it was observed that all seeds had similar EPs and EIs in both BC:VC mixes when compared to the control's (Figure 2). This indicated that all the seeds in both BC:VC mixes had similar germination rates and speeds compared to the ones in the commercial propagation mix. Most of the results were similar in Experiments 1 and 2 except for the EP of cowpea, corn, and pumpkin and the EI of pumpkin. The different cultivars of the cowpea seeds could have led to different EPs. For corn and pumpkin, the different result could be due to the different batches of the seeds, temperatures of the days when conducting Experiments 1 and 2, and different amounts of water applied for germination. Figure 1: Seeds’ emergence percentages (**a**) and emergence indexes (**b**) (mean \(\pm\) standard error) in commercial propagation mix (control), 70% biochar:30% vermicompost (7 BC:3 VC, by volume), or 8 BC:2 VC in Experiment 1. The asterisks (*) indicate differences from the control using [PERSON]’s test at \(p<0.05\) (\(n=4\)). Means indicated by “\(\mathbf{\psi}\)” are 100% \(\pm\) 0. The results from Experiments 1 and 2 demonstrate that mixes of 70% or 80% (by volume) BC with the rest being VC have the potential to be substituted into the commercial seed propagation mixes for basil, coleus, edamame, marigold, okra, petunia, radish, salvia, tomato, vinca, and zinnia seeds with similar or higher EPs and EIs compared to the control's. Similar to our results, [PERSON] et al. [39] tested and indicated that the germination rate of the lettuce seeds in mixes with 75% BC (from pruning waste at 300 or 500 \({}^{\circ}\)C) and peat were similar to the 100% peat control. [PERSON] et al. [23] also showed that the substrate with 70% (by volume) softwood BC and 30% perlite without pH adjustment had no negative effect on the germination rate of marigold seeds compared to the 70:30 peat:perlite mixture. [PERSON] et al. [20] concluded that the percentage of seedling establishment for green beans (_Phaseolus vulgaris_ var. 'Bowie') in mixes of 75% sugarcane bagasse BC or pine BC, with the rest being commercial growing media, was similar to that of the control. The reason for the lower EPs and EIs for cowpea, corn, and pumpkin seeds in Experiment 1 could be that these relatively bigger seeds do not have close contact with relatively big BC particles in the mixes. The uptake of the water, available from substrate particles in the case of container substrate, is required for the seeds to germinate [40]. In Experiment 3, all the seeds in mixes with the BC and CM had lower EPs than the ones in the control except for the edamame and watermelon seeds in 8 BC:2 CM, which were similar to the control (Figure 3). Similarly, the EIs of all the seeds in BC:CM mixes were lower than the ones in the control except for the edamame seeds in 8 BC:2 CM and corn in both BC:CM mixes. Therefore, all the seeds in either 7 BC:3 CM or 8 BC:2 CM mixes had lower EPs or EIs than those of the control, except for EI of corn. The reason for the suppressed seed germination could be the high pH of the germination mix (pH of the BC: 11.18; pH of the CM: 7.5) and/or high EC (32.9 dS m\({}^{-1}\)) of the CM, which led to salinity stress for the seeds. A similar result has been found in other research, which showed slow and poor germination of the seeds induced by a pig slurry compost due to the detrimental effect of high salinity [41].