Exploiting Genetic Diversity in Potato (Solanum tuberosum) to Overcome Soil Constraints to Tuber Yields

Skilleter, Patrick and Dodd, Ian and Nelson, David (2023) Exploiting Genetic Diversity in Potato (Solanum tuberosum) to Overcome Soil Constraints to Tuber Yields. PhD thesis, Lancaster University.

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Abstract

Potato fields are highly susceptible to soil compaction, with two-thirds of UK fields severely affected. Compacted soils impede root growth and decrease crop yields. This thesis’s goal was to identify ways to improve potato yields in compacted soil. Genotypic diversity in compaction tolerance was determined by growing six potato cultivars in loose and compacted soil in containers. Compacted soil delayed emergence, reduced leaf area and root length, and increased root diameter differently between cultivars. When cultivars varying in compaction tolerance were reciprocally grafted, rootstock affected leaf area and root growth more than the scion, indicating the root system’s importance. Root production of, and sensitivity to, ethylene were measured in cultivars that showed high (Charlotte), intermediate (Maris Piper), and low (Pentland Dell) sensitivity to soil compaction. Soil compaction and cultivar did not affect root ethylene evolution. Exogenous ethylene increased root diameter of Maris Piper and Charlotte similarly, but Pentland Dell was unresponsive. Applying ACC deaminase-containing rhizobacteria lowered root ethylene evolution of Maris Piper roots and increased root growth in compacted soil to comparable levels as roots in uncompacted soil. Thus, variation in ethylene production and ethylene sensitivity mediate root growth in compacted soil. Two cultivars with higher (Inca Bella) or lower (Maris Piper) sensitivity to soil compaction were grown in field trials comparing compacted and uncompacted soil. Irrespective of initial soil resistance, soil resistance consistently increased to cultivar-dependent maxima during the growing season. Compacted soil decreased Inca Bella yields, but not Maris Piper yields. Inca Bella better maintained shoot growth whilst Maris Piper root growth was unaffected by compaction. Thus, maintaining root growth is more important for maintaining yields in compacted soil produced by pressure on the soil surface.iv This thesis is the first to identify compaction- and cultivar-dependent changes in soil resistance in potato fields, and to utilise ACC deaminase-containing rhizobacteria to enhance potato tolerance to compaction.