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Abstract
Three pot/mulch combinations and 2 pot spacings were evaluated as to their effects on growing-media temperatures and growth of ‘Hershey’s Red’ azalea (Rhododendron Xsp.). The highest, maximum temperature and least root and shoot growth occurred in black pots on white clam shell mulch compared to white pots on black polyethylene and to white plywood-shielded pots. Close spacings of pots increased root growth with black pots on white mulch but not with white pots on black mulch. Plants in black pots on white mulch developed the greatest winter foliage discoloration and leaf abscission.
Abstract
Dwarf Japanese euonymus (Euonymus japonica Thunb. ‘Microphylla’) and Japanese holly (Ilex crenata Thunb. ‘Compacta’), grown in fresh or aged (1 year) pine bark amended with a slow-release complete fertilizer, were supplied with NH4NO3 weekly at 0, 100, 200, or 300 ppm N. Plant growth, foliar color, leaf tissue N, and leachate soluble salts increased with increasing levels of supplemental N while tissue K, Ca, and Mg decreased. Plant growth, foliar color, and leaf tissue N, P, Ca, and Mg in fresh pine bark equaled or exceeded that in aged pine bark at all levels of supplemental N. Leachate soluble salts, pH, and leaf tissue K was higher in aged pine bark.
Abstract
Overhead irrigation during the day reduced maximum temperatures and their duration within the plant canopy and the container growth medium, and resulted in increased top and root growth of ‘Hershey’s Red’ azalea (Rhododendron × ‘Hershey’s Red’). Intermittent irrigation for 2.5 min/hr during the day reduced canopy temperature but did not affect growth medium temperature or plant growth.
Abstract
Dwarf Japanese euonymus (Euonymus japonica Thunb. ‘Microphylla’) and ‘Pink Supreme’ azalea (Rhododendron Xsp.) grown in containers of three diameters (10.2, 15.2, and 20.3 cm), were given three rates of Osmocote 17N-3P-10K (3.6, 7.1, and 10.7 kg·m-3). Response to container volume and fertility was species-dependent. Top growth of euonymus increased in response to both increased medium volume and fertility and was closely related to foliar levels of N, P, and K. Top growth of azalea increased in response to increasing fertility rates in the smallest pots, and to increasing medium volume at the lowest fertilizer rates. With an increase in both fertilizer rate and medium volume, growth of azalea was reduced. Top growth was inversely related to foliar K, but was unrelated to foliar N and P.
Abstract
Dwarf Burford holly (Ilex cornuta Lindl. & Paxt. ‘Burfordii Nana’), dwarf Japanese euonymus (Euonymus japonica Thunb. ‘Microphylla’), and ‘Hershey’s Red’ azalea (Rhododendron x sp.) were grown in containers in all combinations of 3 diameters (10.2, 15.2, and 20.3 cm) and 3 depths (7.6, 15.2, and 30.5 cm). Top growth of Burford holly, a species with coarse, lateral, and deep roots, increased as pot depth and width increased; root growth was increased in deep pots. Euonymus, a species with a densely branched, medium fine root system, increased in top growth as pot depth and width increased, although the response to pot depth was less than to width. Top growth of azalea, a fibrous and shallow-rooted species, increased as pot width increased but was not affected by pot depth. Root density of euonymus and azalea decreased as pot depth and width increased, whereas relative root depth of azalea was reduced in deep pots.
Plant response to time of transplanting from 0.53-qt (OS-liter) to l-gal (3.8-liter) containers was influenced by cultivar and severity of winter. Transplanting of `Formosa' from Sept. through Dec. 1983 resulted in injury and death of many plants due to a low temperature of 8F (-13.3C) in Dec. 1983. Injury or death of `Hino Crimson' was higher when plants were transplanted in December. Survival and growth indices of both cultivars were higher when transplanted in January through March. During 1986-87, when minimum temperature was 26F (-3.3C), transplanting between September and April had minimal effect on growth of `Formosa', but plant quality was better when plants were transplanted between December and April. Transplanting date had little effect on size of `Hino Crimson', except smaller plants were produced when transplanted in April; quality was highest of plants transplanted from November through March.
Triploid watermelon [Citrullus lanatus (Thunb.) Matsum & Nakai] consumption is increasing in the U.S. However, some of the original problems, poor and inconsistent germination, still exist. Seeds of several triploid and diploid watermelon cultivars were subjected to a variety of treatments to improve germination. Control and scarified seeds, by nicking, were incubated at 25 or 30 °C in either 5 or 10 mL H2O or hydrogen peroxide (H2O2). Triploid seed germination was strongly inhibited in all cultivars when seeds were at 10 mL of the H2O or H2O2; both nicking and H2O2 increased germination, but not equal to rate of the control in 5 mL H2O or H2O2. Germination of diploid cultivars was unaffected by any treatment. Seed morphological measurments indicated that triploid seed has a smaller embryo with a large and highly variable (CV = 105%) air space surrounding the embryonic axis as compared with the diploid seed. These data suggests that triploid watermelon seed germination is not inhibited by the seedcoat thickness alone. Seed moisture plays a significant role in germination, emergence, and stand uniformity.
Triploid watermelon [Citrullus lanatus (Thunb.) Matsum & Nakai] consumption is increasing in the United States However, some of the original problems, poor and inconsistent germination, still exist. Seeds of several triploid and diploid watermelon cultivars were subjected to a variety of treatments to improve germination. Control and scarified seeds, by nicking, were incubated at 25 or 30 °C in either 5 or 10 mL H2O or hydrogen peroxide (H2O2). Triploid seed germination was strongly inhibited in all cultivars when seeds were at 10 mL of H2O or H2O2; both nicking and H2O2 increased germination but not equal to rate of the control in 5 mL H2O or H2O2. Germination of diploid cultivars was unaffected by any treatment. Seed morphological measurments indicated that triploid seed has a smaller embryo with a large and highly variable (cv = 105%) air space surrounding the embryonic axis as compared with the diploid seed. These data suggests that triploid watermelon seed germination is not inhibited by the seed coat thickness alone. Seed moisture plays a significant role in germination, emergence, and stand uniformity.
Poor and inconsistent germination is a problem in triploid watermelon. Nicking was shown effective in improving germination in triploid cultivars. In this experiment, we examined the effects of high and low medium moisture, and nicking on diploid and triploid seed germination. Germination for the diploid cultivar was unaffected by any treatment. At high moisture conditions, triploid seed germination was severely reduced to less than 15%, while nicking significantly improved germination up to 40%. However, this increase is still not commercially acceptable. When seed morphological components were measured for each cultivar, triploid seeds had a larger and highly variable air space as compared to the diploid seed. The data confirm that seed germination is not inhibited by the seedcoat alone, but appears to be highly sensitive to excessive water conditions.