Evaluation of spring wheat genotypic response to soil health promoting management practices
Growing efforts to restore soil organic matter and overall soil health are likely to enhance soil biological communities and promote positive interactions between plants and soil communities. However, modern genotypes bred under intensive management practices may not be able to benefit fully from soil health promoting practices if they have lost their ability to effectively interact with key soil organisms. The purpose of this study was to explore this idea by studying how spring wheat genotypes with different breeding contexts and histories respond to improved soil health achieved via additions of organic matter and soil fauna. A greenhouse experiment with a full factorial complete randomized design was carried out at Colorado State University, Fort Collins, between June and November, 2016. The treatment factors included spring wheat genotype, as well as compost and earthworm additions. The genotypes included a wild ancestor of wheat, Aegilops tauschii, two older genotypes of spring wheat, Gypsum and Red Fife, and two near-isogenic modern genotypes, Scholar Rht2M and Scholar Rht2W, that differ only by the presence of the semi-dwarf allele Rht-D1b in ScholarRht2M. Each wheat genotype was grown in rootboxes (24.5 x 3.5 x 38.0 cm) that received either soils amended with composted manure or not, and with or without the addition of earthworms (two Aporrectodea caliginosa per box). Measurements included plant growth (heading date, number of tillers), biomass (aboveground and root biomass, root:shoot ratio), root morphology (root length and diameter), yield-related traits (number of seeds, seeds weight, average weight per seed, harvest index), nitrogen content (vegetative aboveground and grains), and nitrogen uptake. Findings indicate that interactions between genotypes and soil treatments were inconsistent, and the original hypothesis, that older wheat genotypes would show a greater response to improved soil biological conditions relative to newer genotypes, was not well supported. Overall, the aboveground and yield responses to compost were small compared to the root responses. Composted manure additions, increased root length, biomass, and diameter only in the wild accession (Ae. tauschii) and older Gypsum wheat variety. Modern genotypes, on the other hand, exhibited little root trait plasticity except in root diameter, which decreased with compost additions. Except for a decrease observed in Red Fife, compost effects on aboveground biomass were not significant for most genotypes. Genotype x earthworm interactions were only observed in the vegetative biomass N uptake, and earthworm effects in general were low due to low survival of the earthworms. Ae. tauschii and Gypsum had a more positive response to compost addition for both aboveground and root biomass, indicating that these genotypes may better take advantage of soil health promoting practices. While Gypsum had a similar response to the wild accession when compost was added, Red Fife tended to respond more like the modern genotypes. Overall, my findings suggest that different wheat genotypes can respond distinctly to changes in soil management and biological activity. Only a few genotypes were tested, but a number of clear genotype x soil biology interactions highlights the importance of considering soil management practices, environmental context, and breeding history for different wheat lines, so that we can better manage plant x soil interactions.
Includes bibliographical references.
Includes bibliographical references.