A laboratory exercise is outlined and discussed for embryo culture of bean, corn, and pea embryos. Fresh, inexpensive material is generally available for these crop species throughout the year. The exercise gives students experience in embryo excision and exposure to some benefits of embryo rescue. Embryos from the three species are identified easily and can be removed without magnification, and data can be obtained within 3 weeks after culture. Further investigations using embryos are suggested.
We evaluated height growth, diameter growth, and survival of newly planted fraser fir and colorado blue spruce Christmas trees in southwest Michigan in response to mulch, weed control, and irrigation. Mulches included black polyethylene, white polyethylene, VisPore mulch mats, and wood chips. Seedlings were also established with or without raised beds and with or without complete weed control. Weed control (mulches or a combination of chemical weed control and hand weeding) improved survival and growth of both species after 2 years. Growth was similar for trees in irrigated plots or with wood chip mulch without irrigation. Polyethylene mulch increased growth compared with similar production systems with raised beds and bare ground. Among production systems, variation in growth and survival reflected patterns of predawn water potential and midday shoot gas exchange, suggesting that differences were largely related to plant moisture stress. White mulch improved growth relative to similar production systems with black mulch and wood chip mulch improved growth compared with similar production systems without irrigation. Overall, the ranking of magnitude of growth response effects were weed control > irrigation > mulch. These results underscore the importance of weed control for establishment and maintenance of high-quality Christmas tree plantations.
Embryos from five seedless Vitis vinifera L. clones were cultured in ovulo 6 weeks after pollination with V. rotundifolia Michx. A total of 19 hybrid seedlings from about 16,000 pollinations were identified using leaf morphology and starch-gel electrophoresis. Efforts to obtain more V. vinifera/V. rotundifolia hybrids carrying the seedless gene(s) using embryo rescue should be increased and these plants could act as breeding stock to introduce the seedless gene(s) from V. vinifera into V. rotundifolia.
Three seeded V. vinifera (‘Royalty’, ‘Cabernet Sauvignon’, and B46-76) clones were pollinated with pollen from four clones of V. rotundifolia (‘Tarheel’, ‘Noble’, ‘Carlos’, or ‘Bountiful’). Resulting embryos were cultured in ovulo either 6 weeks after pollination or at veraison. For comparison, fruit from controlled pollinations were also allowed to mature on the vine, and resulting seed was removed and stratified in moist 1 sand : 1 sphagnum (v/v). Of the 52 hybrids produced from 5010 emasculations, 39 (75%) came from cultured ovules, and 34 (65%) came from ovules cultured at veraison. Although preliminary, data from ‘Royalty’ × ‘Noble’ and ‘Tarheel’, and ‘Cabernet Sauvignon’ × ‘Noble’ and ‘Tarheel’ indicates embryo-rescue techniques may be useful in increasing numbers of V. vinifera × V. rotundifolia hybrids.