Central Experimental Platform


Soil

Two substrates differing in texture have been selected for the central experimental platform (SPE, SCEs), a loam (L ) and a sand (S). The loam is derived from the 0 to 50 cm depth of a Haplic Phaeozem close to Schladebach in Saxony Anhalt. The sand is derived from an excavation site (3-5 m depth) close to Oppin in Saxony Anhalt. It is mixed with 5% (w/w) of the loam. Through this procedure both substrates are inoculated with the same microbiome and share to some extent the composition of soil minerals and organic matter although amounts differ. The table presents preliminary results. Analyses will be repeated once the substrates (about 400 t each) have been excavated, transported to field station, mixed and sieved at the start of PP 2089. Their characteristics are summarized in Table 1 for orientation.


Origin Texture
Class (WRB)
Sand
[%]
Silt
[%]
Clay
[%]
pH Ct
[%]
Nt
[%]
Carbonate
[%]
Haplic Phaeozem Loam
(L)
37 45 18 6.8 0.7 0.09 < 0.1
95% Sand
5% Haplic Phaeozem
Sand
(S)
97 2 1 6.5     < 0.1





Two Zea mays genotypes will be compared; the wildtype and the rth3 mutant.


 rth3 mutant:

Zea mays mutant with normal root hair initiation but disturbed elongation. The mutant, first described by Wen & Schnable (1994) shows no apparent aberrant shoot phenotype, but yield is reduced by 20 to 40 % compared to the wildtype (Hochholdinger et al. 2008). When grown under field conditions less soil adheres to the root system. The mutant phenotype remains stable under field conditions.




Hochholdinger F, Wen T-J, Zimmermann R, Chimot-Marolle P, da Costa e Silva O, Bruce W, Lamkey KR, Wienand U, Schnabel PS (2008) The maize (Zea mays L.) roothairless3 gene encodes a putative GPI-anchord, monocot-specific, COBRA-like protein that significantly affects grain yield. The Plant J 54, 888-898.

Wen T-J, Schnable PS (1994) Analyses of mutants of three genes that influence root hair development in Zea mays (Gramineae) suggest that root hairs are dispensable. American Journal of Botany 81, 833-842.

Li L., Hey S., Liu S., Liu Q., McNinch C., Hu H.C., Wen T.J., Marcon C., Paschold A., Bruce W., Schnable P.S., Hochholdinger F. (2016) Characterization of maize roothairless6 which encodes a D-type cellulose synthase and controls the switch from bulge formation to tip growth. Sci. Rep. 6, 34395.

Soil plot experiments2 (SPE) will be conducted with the same genotypes/textures next to each other (i.e. size of individual plots 9x3 metres, substrates will be excavated at the original sites, homogenized and disposed on a drainage layer with a thickness of 75 cm). Plants will be grown up to maturity in a randomized block design established for consecutive years. From harvest to next seeding soil will be kept fallow (compare H1, H2, H4).

I. This will enable measurements at later time points avoiding artefacts created by volume restriction (which is the case for pot experiments with large plants)

    • Destructive sampling maintaining spatial context3
    • Destructive point sampling relating to available spatial information
    • Destructive sampling following classical approaches

II. This will enable measurement of emerging properties at later stages

III. This will enable to measure temporal evolution of spatial patterns for 6-year duration of PP; starting from completely homogeneous conditions (compare H2).


2 Soil plot experiment will be set up at the experimental station Bad Lauchstädt, which belongs to the Helmholtz Centre for Environmental Research – UFZ. The required space is set aside and is available for the 6-year period of the PP
3 Extraction of undisturbed soil columns

Soil column experiments (SCE) with the two genotypes/textures will be conducted in climate chambers under well-defined and standardized conditions to study the pattern development during the first weeks of plant growth (compare H1).


I. These will enable to combine different in situ measurements

II. These will enable to link in situ measurements to

    • Destructive sampling maintaining spatial context1
    • Minimum invasive point sampling relating to available spatial information
    • Destructive sampling following classical approaches

III. These will enable measurement of emerging properties in the early stage


1 Resin embedding of the whole column or parts of the columns