Functional Soil Biological Measurements to Support Healthy Soils

Soil microorganisms contribute significantly to terrestrial ecosystem functioning through their activities. Various methods exist to characterize soil microbial activity and functional diversity including those that focus on potential enzyme activities and the respiratory responses of microbes to different substrates. Here, we describe: (1) the fluorescein diacetate hydrolysis assay for total potential microbial enzyme activity; (2) measurement of beta-glucosidase activity using ρ-nitrophenyl (pNP); (3) multienzyme assay using 4-methylumbelliferone (MUB); and (4) MicroResp assays to measure the respiratory responses of microbes to different substrates and generate a community level physiological profile (CLPP)

Genetic analysis of fiber dimensions and their correlation with stem diameter and solid-wood properties in Norway spruce

Adverse genetic correlations between growth traits and solid-wood, as well as fiber traits are a concern in conifer breeding programs. To evaluate the impact of selection for growth and solid-wood properties on fiber dimensions, we investigated the inheritance and efficiency of early selection for different wood-fiber traits and their correlations with stem diameter, wood density, modulus of elasticity (MOE), and microfibril angle (MFA) in Norway spruce (Picea abies L). The study was based on two large open-pollinated progeny trials established in southern Sweden in 1990 with material from 524 families comprising 5618 trees. Two increment cores were sampled from each tree. Radial variations from pith to bark were determined for rings 3â\u80\u9315 with SilviScan for fiber widths in the radial (RFW) and tangential (TFW) direction, fiber wall thickness (FWT), and fiber coarseness (FC). Fiber length (FL) was determined for rings 8â\u80\u9311. Heritabilities based on rings 8â\u80\u9311 using joint-site data were moderate to high (0.24â\u80\u930.51) for all fiber-dimension traits. Heritabilities based on stem cross-sectional averages varied from 0.34 to 0.48 and reached a plateau at rings 6â\u80\u939. The â\u80\u9cage-ageâ\u80\u9d genetic correlations for RFW, TFW, FWT, and FC cross-sectional averages at a particular age with cross-sectional averages at ring 15 reached 0.9 at rings 4â\u80\u937. Our results indicated a moderate to high positive genetic correlation for density and MOE with FC and FWT, moderate and negative with RFW, and low with TFW and FL. Comparison of several selection scenarios indicated that the highest profitability is reached when diameter and MOE are considered jointly, in which case, the effect on any fiber dimension is negligible. Early selection was highly efficient from ring 5 for RFW and from rings 8â\u80\u9310 for TFW, FWT, and FC