Abschlussbericht Projekt: „Verminderung der ... - BLE

of potato tubers (Wulkow et al. in preparation) and might overrule nutritional interactions
towards blackspot susceptibility.
Statistics. The obtained data were analysed with Sigma Stat statistical program (STAT32).
Preliminary all data sets were tested for normal distribution and variance homogeneity (p=
0.05). Following analyses of variance were calculated for cultivar and specific gravity.
Calculated means were compared by Tukey-test (p ≤0.05). Correlation and multiple regression
procedures between normally distributed quality parameters were performed using
Pearson correlation coefficients. This technique does not determine significant differences
between specific gravities within one cultivar but rather gives an overall indication
of relative importance of both the genetic factor and tuber mass. Graphics were prepared
with Sigma Plot 2001 (SPSS Inc. SigmaPlot for Windows).
Results
Weather conditions during both years of investigation 2006 and 2007 were not significantly
different and did not depart from the average weather conditions metered for this
typical potato-growing region. In both years the sunshine duration amounted approximately
1252 hours associated with a mean temperature of 15°C and a water supply of 564
mm particularly mediated through irrigation. Depending on the soil conditions the time of
planting and harvesting differed slightly. In 2006 the vegetation period comprised 161 days
contrary to 2007 where the period of vegetation was 168 days long. In both years 2006 and
2007 tubers were partially harvested two weeks before the main harvest (in the following
named as pre-harvest) with the aim of investigate tubers at different stages of maturity.
Relationship between specific gravity, nutrient concentration and BSI. The relationship
between tuber specific gravity, as determinant of tuber dry matter concentration
(Haase 2003/2004) and BSI as well as the relationship between nutrient concentrations and
BSI are illustrated in Figure 1. Moreover, absolute concentrations of nutrients in potato
tubers did not always reflect imbalanced nutrient conditions, therefore the ratios between
macro and micro nutrients were calculated according to Bergmann (1993) (Tab. 1).
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