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  • Author or Editor: Sachiko Matsubara x
  • Journal of the American Society for Horticultural Science x
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Abstract

Self-incompatibility of Raphanus sativus L. was partially overcome by exposing plants to temperature of 30 to 50°C. The most effective treatment was 50°C for 25 minutes. Scanning electron microscopical (SEM) observation of pollen tubes on the papillae surface have shown that exposure of the gynoecium to 50°C for 25 minutes resulted in pollen tube growth following self-pollination that resembled that of cross-pollination. Openings of papillae and detached pollen grains and tubes were found as the result of successful pollen tube penetration of papillae. Fluorescence microscopical (FM) observation served to confirm these observations made by SEM. However, incompatible pollen failed to germinate although pollen grains were attached to the papillae by aid of their waxy surface substances.

Open Access

Abstract

A high concentration of inhibitors which were as high as that of gibberellin (GA)-like substances was found in young asparagus (Asparagus officinalis L.) spears using the rice seedling bioassay, and one of inhibitors was identified as abscisic acid (ABA) by gas chromatography. Endogenous ABA was extracted more thoroughly from the lyophilized materials than from frozen tissue. ABA level was the highest in tops including growing points of spears, and was always higher in the distal half than in the proximal, and higher in the cortex than in the pith. Free ABA levels tended to increase with the development of spears, while bound ABA levels remained the same irrespective of age. Three peaks of ABA were found in crown buds and root tips in March or April, August and December. Presumably asparagus crowns were in the deepest dormancy around the middle of December. Clearly the degree of dormancy from October to January paralleled ABA levels in crown buds and root tips. Endogenous levels of ABA in buds at developing stages was found highest in the resting buds.

Open Access