| Summary: | 碩士 === 國立中興大學 === 園藝學系所 === 97 === The flowering seasons of Euphorbia spp. were investigated. Beside E. millotii blossomed from September to May, E. milii‘Olympus’, E. geroldii, and Euphorbia sp. ‘Thornless’ blossomed year round. The optimum sucrose concentration in medium for pollen germination were tested. The medium containing 20％ sucrose was suitable for E. geroldii pollen germination and 10％ for E. milii ‘Olympus’, E. millotii and Euphorbia sp.‘Thornless’. Moreover, the optimum temperature for pollen germination of all treated ones was 25℃.
The seed harvested from the cross of E. milii ‘Olympus’× Euphorbia sp. ‘Thornless’ were more than other cross combinations. The immature embryos of E. milii ‘Olympus’ × E. geroldii and E. milii ‘Supo Roek’ × E. geroldii were taken from ovaries after 7 days of crossing and could be rescued in the medium of 1/4 MS formula with better radical elongation rate.
The thorns from the cross of E. milii ‘Olympus’× Euphorbia sp.‘Thornless’ progenies were less and softer. In cross of E. geroldii × E. milii ‘Olympus’, thorns of progenies were toothed but not harmful. Thorns from E. milii ‘Supo Roek’× E. geroldii progenies became softer and broken easily.
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