For three Asiatic hybrid lily cultivars ('Bright Beauty', 'Fashion', 'Orlito') the potential postharvest performance of floral buds in terms of growth, anthesis and longevity was studied in relation to tepal carbohydrate status. To determine the importance of carbohydrate redistribution within lily inflorescences, the postharvest performance of several attached and detached buds was compared at the time of anthesis of the most mature floral bud of the inflorescence. Detachment of buds increased failure of opening in small buds, whereas in the largest buds tepal size at anthesis and longevity were improved. In lily inflorescences, postharvest translocation of substrate from the basal to the upper buds takes place. Five bud classes have been characterised, comparing the postharvest performance of attached and detached buds. Classes were based on differences in tepal growth rate, absolute growth and the potential to reach anthesis. A bud length of about 60 mm at harvest, appeared to be critical for reaching anthesis of detached buds. Comparable bud development and flower longevity of inflorescence-attached and inflorescence-detached floral buds was determined in buds of 70-75 mm. At this bud length the total carbohydrate content (fructose, glucose, glycerol glucoside, starch, sucrose) covered about three-fourths of the total tepal carbohydrate content found in the largest bud stage just prior to anthesis. Per cultivar, postharvest flower longevity after anthesis of detached buds was well correlated with total carbohydrate content of the tepals at harvest. Longevity of inflorescence-attached flowers remained constant within the inflorescence, likely due to postharvest redistribution of tepal carbohydrate. These findings indicate an important role for tepal carbohydrate content in postharvest bud development and flower longevity of Asiatic hybrid lilies. Carbohydrate redistribution is suggested to play a major role in the postharvest performance of Asiatic lily inflorescences.

This paper describes the analysis of the elimination of potato DNA from potato-tomato somatic cell hybrids. The hybrids were obtained by fusion of protoplasts of a cytoplasmic albino tomato genotype with leaf mesophyll protoplasts of a potato genotype carrying the β-glucuronidase (GUS) gene of Escherichia coli. The potato protoplasts were either isolated from unirradiated plants or from plants irradiated with 50 or 500 Gy of γ-rays. Green calli were selected as putative fusion products. The hybridity of these calli was confirmed by isoenzyme analysis. All of the green calli tested contained a potato-specific chloroplast DNA restriction fragment, and most of the calli analysed were positive for β-glucuronidase activity. In 72 of the hybrid calli we determined the percentage of potato nuclear DNA using species-specific probes. All of the tested green calli contained a considerable amount of potato genomic DNA, irrespective of the dose of irradiation of the potato parent. The limited degree of potato DNA elimination and the absence of true cybrids are discussed.

Genotypic variation in postharvest flower longevity was determined for 63 Asiatic lily hybrids (Lilium L.). The reliability of standardized test conditions for longevity screening was also examined. Improvement of lily flower longevity by breeding appears feasible. Considerable genotypic variation in individual flower longevity was obtained and estimates of the degree of genotypic determination were high. The rank order of the genotypes with respect to individual flower longevity was similar between years using standardized test conditions. Screening results for flowers forced in a growth chamber were similar to those obtained in a greenhouse. No plant traits suitable for indirect selection on flower longevity were detected.

This paper describes the aggregation of nuclei in heterokaryons of tomato and unirradiated or irradiated potato protoplasts and the effects of gamma irradiation of potato and tomato protoplasts on single- and double-stranded DNA fragmentation, DNA repair and DNA synthesis as revealed by alkaline and pulsed field gel electrophoresis and an immunocytochemical technique. The prospects for obtaining highly asymmetric somatic hybrids of tomato and gamma-irradiated potato are discussed.

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