Einfluss der physiologischen Alterung bei Pflanzknollen verschiedener Sorten auf Wachstumcharakteristika im Laborversuch

Zusammenfassung

Die Wachstumskapazität (GC=g Spross- plus Wurzelmasse pro Knolle nach 20 Tagen bei 22°C) beschreibt im Verlauf der physiologischen Alterung eine Optimumskurve. Das Maximum der Wurzelmasse wurde in der Regel früher durchlaufen als das Maximum der Spross- bzw. Gesamtmasse. In 2 Jahren konnten Sortenunterschiede für die Alterungsrate in der Lage des Optimums der GC auf der physiologischen Zeitachse, in der Breite des optimalen Bereiches der GC und in der Höhe der GC direkt nach der Beendigung der Dormanz festgestellt werden.

Summary

The following test was carried out in two years: during physiological ageing, samples of 15 tubers of each of eight cultivars were desprouted, planted into a mixture of compost and peat, and placed in darkness at a temperature of 22°C. Averaged over cultivars, the number and length of sprouts increased with increasing physiological age of the seed tubers until a maximum was reached. Beyond this, a slight decline in the number of sprouts was observed (Fig. 1a,b). With advanced physiological age, the diameter (Fig. 1c) and dry-matter content (Fig. 1d) of the sprouts decreased. However, these characteristics could not be used to monitor differences in the rate of physiological ageing between the potato cultivars.

The growth capacity (GC=sprout and root mass) (g) per tuber after 20 days at 22°C) showed an optimum in the course of physiological ageing (Fig. 3). Root mass reached optimum levels earlier than sprout mass (Fig. 2) and in most cases also earlier than the total mass (Fig. 3). Despite year-to-year variation cultivar differences in the rate of ageing could be noted from the timing of the GC optima (based on temperature sum), from the maximum values of GC and from the GC values immediately after the end of dormancy. For three pairs of cultivars the differences in rate of physiological ageing—as observed in field trials—were confirmed by differences in growth capacity in the laboratory tests (Figs. 2, 3a, 3c). For one pair of cultivars the laboratory test did not predict the different behaviour in the field (Fig. 3b).