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  • Author or Editor: Mark P. Widrlechner x
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Abstract

The relationship between in vivo pollen germination and vital staining was tested for 7 genotypes of deciduous azalea (Rhododendron sp.) differing in fertility. Fluorescein diacetate, 3-amino-9-ethylcarbazole (AEC), and 3-(4,5-dimethylthiazolyl-2)-2,5-diphenyl tetrazolium bromide (MTT) all showed significant correlations between staining and germination. AEC produced the highest significant correlation (r = 0.96). AEC and MTT were the most suitable vital stains for azalea pollen.

Open Access

Seed germination patterns were studied in Echinacea purpurea (L.) Moench grouped by seed source, one group of seven lots from commercially cultivated populations and a second group of nine lots regenerated from ex situ conserved wild populations. Germination tests were conducted in a growth chamber in light (40 μmol·m–2·s–1) or darkness at 25 °C for 20 days after soaking the seeds in water for 10 minutes. Except for two seed lots from wild populations, better germination was observed for commercially cultivated populations in light (90% mean among seed lots, ranging from 82% to 95%) and in darkness (88% mean among seed lots, ranging from 82% to 97%) than for wild populations in light (56% mean among seed lots, ranging from 9% to 92%) or in darkness (37% mean among seed lots, ranging from 4% to 78%). No germination difference was measured between treatments in light and darkness in the commercially cultivated populations, but significant differences were noted for treatments among wild populations. These results suggest that repeated cycles of sowing seeds during cultivation without treatments for dormancy release resulted in reduced seed dormancy in E. purpurea.

Free access

Abstract

Bacterial wilt, caused by the soil-borne pathogen Pseudomonas solanacearum E, F. Sm., causes major economic losses in tomato (Lycopersicon esculentum Mill.) production in many warm, humid regions of the world (6, 8). Selections of L. esculentum (GA 1565-2-4 BWT, GA 219-1-2 BWT and GA 1095-1-4 BWT) and of L. esculentum × L. pimpinellifolium (Jusl.) Mill. (GA 14051-2 BWT), all possessing high tolerance levels to P. solanacearum, are jointly released by the ARS/USDA and the Univ. of Georgia.

Open Access