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- Author or Editor: John M. Smagula x
- Journal of the American Society for Horticultural Science x
Abstract
Fertilization with 98 and 196 kg N/ha from urea or sulfur-coated urea (SCU) resulted in higher amounts of K2SO4-extractable ammonium N in the 0-7.6 cm but not the 7.6-15.2 cm soil layer. There was no difference due to sources of N. Application of 98 kg N/ha from either urea or SCU to portions of 5 clones of lowbush blueberry (Vaccinium augustifolium Ait.) increased N concentration, size and weight of leaves, flower bud formation, and yield.
Abstract
A new method for analyzing acetaldehyde concentration in apple (Malus domestica Borkh.) tissues was used to measure its accumulation in senescing fruits. Initially low levels (1 µg/g fresh weight) increased as the fruits ripened, but only at advanced senescence did they reach relatively high levels (14 µg/g fresh weight). Acetaldehyde did not accumulate in advance of tissue disorganization. Watercored ‘Delicious’ apple tissue accumulated significantly more acetaldehyde than tissue of non-watercored fruits during storage, but watercore breakdown did not result. There was no consistent difference in acetaldehyde levels of ethephon-treated and non-treated ‘McIntosh’ apples after long-term storage, although the ethephon-treated fruits developed more senescent breakdown. However, the acetaldehyde level in fruits after breakdown occurred was about 20% higher than that in corresponding sound fruit. Acetaldehyde accumulation appeared to be a consequence of tissue disorganization rather than a cause of senescent breakdown in the fruits.
Abstract
Cuttings of 2 clones of lowbush blueberry (Vaccinium angustifolium Ait.) treated with increasing rates of urea (0, 40, 80 kg N/ha) during rooting resulted in increased levels of total stem nitrogen in the respective treatments. Fall flowering and vegetative growth of cuttings in the propagation beds were stimulated by nitrogen treatments. Plants moved to cold storage (5°C) for 3 months and then grown under long day (16 hours) greenhouse conditions for 2 months did not produce more rhizomes in response to nitrogen treatments. However, plants which remained in the propagation beds during the winter and which were grown under field conditions for 6 months, responded to the nitrogen treatments by producing larger root systems, more aerial growth and more rhizomes.
In a managed field of native Vaccinium angustifolium Ait. clones, the effect of fall foliar sprays of B at 345 g·ha-1 and/or Ca at 3,450 g·ha-1 in remedying tissue deficiency of B varied among 12 clones, as seen in pollen germinability and on individual stems as seen in flower number, fruit set, and number of harvestable berries. With Ca applied alone, increased berry size did not overcome yield reduction due to fewer flowers and berries per stem. Berry diameter and mass correlated better to number of seeds of germinable size than to total number of seeds. Pollen germination averaged 17.4% on stigmata from untreated clones, and all three treatments (B, Ca, B + Ca) increased that average by 8%. More seeds per berry with the B-alone treatment implies more ovules fertilized when B deficiency is remedied. No relation was found between in vitro and in vivo pollen germination.
Abstract
A light requirement for improved seed germination of lowbush blueberry (Vaccinium angustifolium Ait.) was partially overcome by GA treatments; GA at 500, 1000, 2000, and 4000 ppm stimulated early germination of seeds kept in the dark. The germination rate of seeds exposed to an 8 hour light period was also enhanced by GA treatments. Continuous exposure to concentrations above 1000 ppm resulted in abnormally curled seedlings with necrotic root tips.