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.