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Abstract
Seeds of Asparagus densiflorus (Kunth) Jessop ‘Sprengen’, Brassaia actinophylla Endl., and Musa balbisiana Colla., were exposed to 5 durations of ultrasonics at a frequency of 60 Hz. Some seeds were then given a 12 hour water soak before sowing. No differences were noted in germination rates for all species. The only significantly improved germination percentage occurred with seeds of Musa balbisiana given a 30 second exposure and no water soak. Seeds of Asparagus densiflorus ‘Sprengeri’, Brassaia actinophylla, Cordyline australis (G. Forst.) Hook, f., and Philodendron lundii Warm., were given 15 minute soaks in 3 concentrations of 3 fungicides before sowing but no significant differences in final germination percentage or germination rate were observed among treatments.
Abstract
Effects of 5 soilless media and 2 sowing depths, 4 pH levels and 3 medium temperatures on tropical foliage plant seed germination were analyzed using germination rate and final percentage germination. Cordyline australis had highest germination percentages in highly organic media, Philodendron selloum germinated well in all media at a depth of twice the seed diameter, Asparagus densiflorus ‘Sprengeri’ and Brassaia actinophylla germinated equally well in all media and at depths of 2 and 4 times the seed diameter. Most deeper sown seeds took longer to emerge. Best germination occurred in Brassaia actinophylla, C. australis and Philodendron lundii without bottom heat (27°C), and in Nephthytis ‘Emerald Gem’ with bottom heat (30°-33°). Species germinated well between pH 3.7 and pH 6.2 except for Musa balbisiana at pH 3.7.
Abstract
Three diploid taxons (Vaccinium darrowi Camp, V. elliottii Chapm., and interspecific V. darrowi x V. elliottii) were treated with various colchicine concentrations and treatment durations to determine the best method for inducing autopolyploidy in in vitro blueberry cultures. Shoot-tip cuttings were the best in vitro planting material for induction of shoots with increased diameter, an indicator of polyploidy. Tetraploids were produced at colchicine concentrations from 0% to 0.20%. The best treatment combinations were genotype-dependent.
The influence of rootstock on average fruit weight was evaluated for a subset of data from a multilocation NC-140 apple [Malus sylvestris (L.) Mill. var. domestica (Borkh.) Mansf.] rootstock trial. Data for eight dwarf rootstocks were collected at four locations for 2 years. Analysis of covariance was used to evaluate the effect of rootstock on average fruit weight when crop density or number of fruit per tree was included in the linear model as a covariate. When number of fruit harvested per tree was used as a covariate, average fruit weight was not affected by rootstock in either year in Ontario. In Michigan and Virginia, rootstock and number of fruit per tree, but not the rootstock × number of fruit interaction, were significant, so common slopes models were used to estimate least squares means for average fruit weight. In general, trees on M.27 and P.1 produced the smallest fruit, and trees on B.9, M.9 EMLA, and Mac.39 produced the largest fruit. In New York the interaction of rootstock × number of fruit was significant, so least squares means were estimated at three levels of number of fruit per tree. Both years, at all levels of number of fruit, trees on M.26 EMLA produced the smallest fruit and trees on M.27 EMLA produced the largest fruit. Average fruit weight was most affected by number of fruit per tree when Mark was the rootstock. In general, results were similar when crop density was used as the covariate, except that trees on M.27 EMLA did not produce small fruit in Michigan and Ontario.