|Author: ||J.J. Burke|
|Keywords: ||leaf chlorophyll, sucrose, reducing sugar, fry colour|
The effect on canopy integrity, tuber bulking rate, tuber size distribution, dry matter concentration, Maillard reaction substrates and fry colour, from restricting the growing season, by advancing the desiccation date, was investigated for the potato cultivars, ‘Fianna’, ‘Maris Piper’, ‘Navan’ and ‘Rooster’ during 1996 and 1997. Haulm was desiccated on three dates, with intervals of 10-12 days between desiccations and the tubers graded into nine size categories.
Rate of decline in canopy integrity over time, expressed as reduction in radiation interception or in SPAD values, was remarkably consistent between the cultivars ‘Fianna’, ‘Maris Piper’, ‘Navan’ and ‘Rooster’ over both years.
Yield ranking and tuber bulking rate for the cultivars varied between years and between desiccation dates within years.
Advancing the desiccation date induced the greatest reductions in yield in the 60-70 mm tuber size grade for cv. ‘Maris Piper’ and ‘Rooster’ in 1997 and in the 70-80 mm grade for cv. ‘Navan’ and ‘Fianna’. Restricting the duration of the growing season decreased tuber dry-matter content.
Sucrose concentration varied with cultivar, desiccation date and year.
Reducing sugar and amino-N concentrations were not consistently effected by the applied treatments.
Fry colour following storage was not consistently effected by cultivar or desiccation date and furthermore, concentrations of Maillard reaction substrates were not useful as predictors of chip fry colour following extended storage.
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