Individual plant trait response to domestication and soil microbiome
The four aboveground plant traits (dry shoot weight, LNC, LCC, Chl) varied between wild and modern barley, however, we found no evidence of the effects of soil microbiome treatment (DSM versus NSM) on the above ground traits measured (Fig. 3a-d). For instance, the average shoot dry weight of wild barley was 0.87 g plant-1 and decreased by 32% (p = 0.01) for modern barley (Fig. 3a). Similarly, the LCC was, on average, 41% for wild barley and decreased to 40.2% for modern barley (p = 0.002) (Fig. 3b). In contrast, the LNC and Chl concentrations were greater in modern than wild barley. The LNC was, on average, 4.47% in wild barley and increased by 19% in modern barley (p < 0.001) (Fig. 3c). The Chl concentration in wild barley leaves was 170.8 mg m-2 whereas values for modern barley were up to 17% greater (p = 0.02) (Fig. 3d).
In comparison to plant aboveground traits, the belowground traits were more variable and responded distinctly to soil microbiome for both wild and modern barley (Fig. 3e-o). For instance, we found no evidence of the impact of soil microbiome (DSM versus NSM) and barley type (wild versus modern) on root dry weight, RCC, SRL, and FRD. However, our results showed that the RNC for wild barley was 1.15% and the values increased on average by 0.22% for modern barley (p = 0.03) (Fig. 3g). Similarly, the SRA and PHOEXU activity were greater for modern than wild barley with an increase of 15% for SRA (p = 0.045) (Fig. 3j) and 71% for PHOEXU (p< 0.001) (Fig. 3n). Our results further indicated that the RTD, RGR, root AMF colonization, and OCEXU responded to both barley species and soil microbiome. For instance, the root AMF colonization was close to 0 for both barley species under DSM but increased (up to 15%) only for wild barley under NSM (Fig.3h). The RTD for wild barley was 74.5 mg cm-3 and decreased on average by 10% for modern barley (p = 0.03). We found a very weak effect of soil microbiome on RTD where DSM led to a decrease of RTD by 9% (Fig. 3k). In contrast, our results showed that the RGR and OCEXU values were greater for modern barley and disturbing soil microbiome (DSM) had facilitative effects on them (values increased). For instance, DSM led to an increase in RGR by 36% (p = 0.007) (Fig. 3o). Our results provided only weak evidence on differences in RGR between two barley species where the roots of modern barely tended to grow slightly faster than that of wild barley (p= 0.08) (Fig. 3o). Lastly, the root OCEXU was, on average, 0.98 µg-C h-1 cm-2 for wild barley and the values increased by 0.32 µg-C h-1cm-2 for modern barley (p = 0.07) providing weak evidence of the difference between exudation rates of two barley species. Disturbing the soil microbiome led to an increase in the root exudation rate of organic C, on average, by 32% (Fig. 3m).