Growth and Flowering of Gypsophila paniculata L.'Bristol Fairy'Selections as Influenced by Temperature and Shoot-Root Interactions.

Abstract

Four vegetative lines of Gypsophila paniculata L. 'Bristol Fairy' were grown under natural conditions in autumn. Shoots of lines 09 and 13 initiated flower bud. In contrast, shoots of lines 04 and 20 formed rosette. However, rosette formation was not accompanied by decreased new root growth.Lines 13 and 20 which were grafted on their own roots and reciprocally, produced the scion/stock combinations of 13/13, 13/20, 20/13 and 20/20. The grafted plants were then exposed to chilling which was sufficient to promote flowering for ungrafted line 13 rooted cuttings but insufficient for those of line 20. The onset of shoot elongation was delayed and the percentage of blooming plants was decreased on 13/20, 20/13 and 20/20 graft combinations.Shoot elongation of 13/20 combination was delayed nearly 6 weeks compared with that of 13/13 plants.Plants of line 04 showed rapid growth after their shoot and root were chilled. All the plants with their shoot unchilled and root chilled bloomed during the chilling treatment. In this case, removal of the flower stalks after the chilling treatment resulted in rapid growth and high percentage of blooming in lateral shoots which had not been chilled. This suggests that the chilling effects were translocated from root to shoot and retained in basal nodes.These results indicate that chilled roots have the great influence on shoot growth and consequent flowering in gypsophila.