Einfluß eines Wachstumsregulators auf die ‘Sink’‐Kapazität von Raps (Brassica napus L.)

Abstract

Influence of a Plant Growth Regulator on the ‘Sink’ Capacity of Oilseed Rape (Brassica napus L.) A pot experiment was carried out to examine the effect of the plant growth regulator Triapenthenol (RSW) on the apical dominance of oilseed rape and its corresponding effect on the plant's ‘sink’ capacity. RSW's influence on the number of flower primordia, flowers, pods, yield and yield structure of the whole plant and of different fractions of the plant (main shoot, lateral shoots 1–3, lateral shoots >3; 1st, 2nd and 3rd‐order lateral shoots) and its effect on gibberellin content and shoot height was measured. RSW diminished dominance of the main shoot and of 1st‐order lateral shoots: the initiation of flower primordia was increased to about 34% and 116%, respectively, in fraction lateral shoots higher than 3 and 3rd‐order lateral shoots. Buds developed in a more synchronized pattern leading to a significantly improved number of flowers and pods in fraction lateral shoots higher than 3. Despite an increased number of pods per plant, grain yield remained unchanged because of a decrease in the number of seeds per pod and an unaffected thousand‐kernel weight. A decreased content of gibberelhn A19 (GA19), GA20, GA1 and GA8 was evident after application of RSW, and a correlation between gibberellin‐content and shoot height was found. The results of this study suggest that high levels of such GAs, that primarily promote shoot elongation and strengthen the apical dominance within the plant, limit the plant's ‘sink’ capacity. These effects may be due to a gibberellin‐promoted auxin‐synthesis.