Abstract:
Potatoes are widely consumed in UK and many other countries. There is a continuous
demand for potatoes all year around both from consumers and retailers such that several
postharvest technologies are being used to meet this demand. Sprouting is the main
phenomenon affecting both the quality and marketability of potatoes during long term
storage. Several sprout suppressants are widely used (e.g. maleic hydrazide and
chloropropham, but there are concerns over their toxicity such that alternatives have
been sought. Continuous exposure of potato tubers to ethylene (usually 10 µL L-
1
)
during storage was approved by the Chemicals Regulation Directorate since 2003. Even
though potatoes have been regarded as non climacteric, this study aimed to examine the
effect of different ethylene regimes in combination with or without
1-methylcyclopropene on physiological, biochemical and mechanical characteristics of
a selection of important UK cultivars. In 2008-2009, ten potato cultivars were examined
for their response to four different ethylene regimes during storage. Storage time and
ethylene treatments had a cultivar specific effect on all the measured parameters
(sprouting, sugars, texture). Ethylene applied after first indication of sprouting was as
effective at sprout inhibition as when applied continuously for certain potato cultivars;
therefore this could be considered as a more environmentally and economical
alternative for sprouting inhibition. In addition, sugar accumulation was retarded when
tubers were subjected to ethylene at the first indication of sprouting compared to those
treated with continuous ethylene. In 2009-2010, four potato cultivars were studied and
the effect of 1-MCP either before or after ethylene treatment on sprouting, respiration
rate, endogenous ethylene production and texture was investigated. 1-MCP is believed
to interact with ethylene receptors and therefore prevent or retard ethylene dependent
responses. 1-MCP seemed to effectively block ethylene binding sites when applied
before storage of tubers in ethylene resulting in less tuber sugar accumulation. In 2010-
2011, the effect and timings of 1-MCP and ethylene treatments on sprouting, tuber
respiration, endogenous ethylene production and sugars on two potato cultivars was
studied. 1-MCP effectively suppressed the action of ethylene in terms of the increase in
the respiration rate or ethylene production and sugar accumulation. Selected potato
samples were also analysed quantitavely for an array of phytohormone using a newly
developed UPLC QToF MS method. This method had the advantage of quantifying
simultaneously a significant number of plant growth regulators that are present in potato
(ABA and its metabolites, cytokinins and gibberellins).