Abbreviations: FMP, fruit maturation period; SFM, shortened fruit maturation. 1 Graduate Research Assistant. 2 Professor. Current address: Mountain Horticultural Crops Research Center, 2016 Fanning Bridge Rd. Fletcher, NC 28732-9629. This research
Joseph M. Kemble and Randolph G. Gardner
T.G. Beckman, W.R. Okie, and S.C. Meyers
Rootstock influence on bloom date and fruit maturation of `Redhaven' peach [Prunus persica (L.) Batsch] was studied over a 3-year period. Rootstock included seedlings (Lovell, Halford, Bailey, and Siberian C) and cuttings (GF677, GF655.2, Damas 1869, and `Redhaven'). Bloom dates of the various combinations differed in all 3 years, with a range of 3.6, 9.1, and 7.3 days in 1988, 1989, and 1990, respectively. Fruit development period differed each year with a range of 3.9, 5.8, and 4.4 days in 1988, 1989, and 1990, respectively. `Weighted-average harvest date also differed with a range of 3.6,2.9, and 5.6 days in 1988, 1989, and 1990, respectively. `Redhaven'/Lovell was the latest blooming and maturing combination in all 3 years of the study.
Torrance R. Schmidt, Don C. Elfving, James R. McFerson, and Matthew D. Whiting
effects of GA on apple fruit present during treatment (i.e., current season fruit). In sweet cherry ( Prunus avium ), GA 3 can delay fruit maturation ( Proebsting, 1972 ). The Pacific northwestern U.S. industry widely uses 10 to 20 mg·L −1 to increase
Lili Zhou, Ching-Cheng Chen, Ray Ming, David A. Christopher, and Robert E. Paull
An invertase gene was isolated and its mRNA activity and protein levels were determined during papaya (Carica papaya L.) fruit development. A complete invertase cDNA (AF420223) and a partial sucrose synthase cDNA (AF420224) were isolated from papaya fruit cDNA libraries. The invertase cDNA encoded a predicted polypeptide of 582 residues (MW 65,537 Da), and was 68% and 45% identical with carrot apoplastic and vacuolar invertases, respectively. Key amino acids indicative of an apoplastic invertase were conserved. A full-length gene corresponding to the putative apoplastic invertase cDNA was isolated and was organized into seven exons and six introns. Exon 2 (9 bp long) encoded part of a highly conserved region (NDPNG/A). Invertase mRNA and activity levels increased during fruit maturation and sugar accumulation just before ripening. In contrast, sucrose synthase mRNA levels were high during early fruit growth and low during the fruit sugar accumulation stage. A 73-kDa cell wall extractable protein that cross-reacted with carrot apoplastic invertase antisera substantially increased during papaya fruit maturation and declined in full ripe fruit. The increase in invertase protein levels occurred 2 to 4 weeks before maturity and was markedly higher than the overall increase in enzyme activity at this stage. Subsequently, the increase in enzyme activity was higher than the increase in protein levels between 2 weeks before maturity and fully ripe. The results suggested that mRNA level and invertase activity were related to maturity. The data suggested that the invertase was apoplastic, and that post-translational control of enzyme activity occurred, in which a significant accumulation of invertase occurred before the peak of enzymes activity.
Joseph. M. Kemble and Randolph G. Gardner
Experiments were conducted in 1989 to determine the heritability of shortened fruit maturation (SFM) period in 871213-1, an inbred cherry tomato line (Lycopersicon esculentum var. cerasiforme (Dunal.) A. Gray), and to determine the relationship between this trait and fruit size. In the first study, a cross was made between 871213-1 and NC 21C-1, an inbred cherry line. NC 21C-1 had a mean maturation period of 40.8 days compared to 32.0 days for 871213-1. A mean maturation period for the F1 hybrid of 32.9 days and 32.2 days was found using 871213-1 as the female and male parent, respectively. Analysis of the data from parental, F1, F2 and backcross generations yielded estimates of broad-sense and narrow-sense heritabilities for SFM as 0.72 and 0.56, respectively. Further analysis indicated that genetic control of SFM was quantitative in nature and highly dominant. A test for epistatic interaction showed significance. In the second study, an F2 population from the cross 871213-1 x NC 309-1, a large-fruited tomato line (Lycopersicon esculentum Mill.), was evaluated to determine if any correlations existed between fruit size and SFM. Two fruit characteristics, locule number and fruit weight, were used as estimates of fruit size. Correlations between SFM and these two characteristics were +0.28 and +0.61, respectively. Broad-sense heritability of SFM was estimated as 0.64.
Ross E. Byers, Frank H. Emerson, and Herbert C. Dostal
Succinic-acid-2,2-dimethylhydrazide (SADH) applications hastened the maturity of peach fruit when trees were sprayed during fruit growth stages I, II and III. The greatest hastening of fruit maturity was evident with high concn of SADH (4000 and 8000 ppm) applied between the mid-point and the end of stage I. The optimum concn during stage II for hastening maturity was 1000 ppm. Applications of SADH in stage III hastened fruit color development but had little effect on other indices of maturation. Five of 6 SADH analogues were effective in hastening fruit maturation when applied in the first half of stage II. The growth retardants Amo 1618 and £CC did not hasten peach fruit maturation.
M.D. White, D.S. Tustin, K.F. Foote, R.K. Volz, J. Stokes, J. Campbell, R. Marshall, and C. Howard
ReTain™ is a plant bioregulator containing the active ingredient aminoethoxyvinylglycine (AVG), which inhibits the ethylene biosynthesis pathway. In 1997, the first efficacy studies on `Royal Gala' apple with ReTain™ were conducted under New Zealand conditions in Hawkes Bay. ReTain™ was applied 4 weeks before the anticipated start of harvest on `Royal Gala' at 850 and 1700 g·ha–1 with or without adjuvants. ReTain™ application delayed the onset of `Royal Gala' fruit maturation between 1 and 2 weeks, resulting in enhanced fruit size and fruit flesh firmness at harvest. The optimum response for delaying the onset of fruit maturation was achieved using ReTain™ at 850 g·ha–1 if applied in combination with a wetter. Fruit were also graded for fruit quality and air-stored at 0.5 °C. Fruit after 10 weeks of storage showed no difference in fruit flesh firmness, but all ReTain™ treatments had fruit with less yellow background colour compared with untreated fruit. In 1998, efficacy studies were undertaken in three geographical locations on `Royal Gala'. ReTain™ was applied at a rate of 830 g·ha–1 in combination with Silwet L-77 at 0.1%. All trees with the exception of `Royal Gala' grown in the Hawkes Bay had not received any ReTain™ previously. In all regions, seasonal changes in background color and starch pattern index were delayed by ReTain™ treatment. A concurrent delay of an increase in soluble solids concentration and retention of higher flesh firmness were also induced by ReTain™ treatment.
Daniel Ferreira Holderbaum, Tomoyuki Kon, Tsuyoshi Kudo, and Miguel Pedro Guerra
( P < 0.01) among cultivars and FDSs and a significant interaction between both factors was detected. According to the SNK multiple means comparison test, all cultivars showed a decrease on ΔE during fruit maturation. A clear difference was observed
Gregory E. Welbaum
Muskmelon (Cucumis melo L.) seed crops sometimes contain seeds with split coats that expand to twice their normal water content. These expanded seeds are often referred to as “fishmouth” seeds, because the split seed coat resembles an open fish's mouth when viewed longitudinally. “Fishmouth” seeds are dead seeds. However, little is known about why death occurs inside the fruit before harvest. Hermaphroditic flowers were tagged at anthesis and fruits were harvested at various intervals during the later stages of development and decay. Seeds were removed from the fruits and incubated in water on germination blotter paper for 14 days. The percentage of germinable, dead and “fishmouth” seeds were averaged for each Harvest date. Fruit pericarp samples were analyzed for pH, ethanol, and acetic acid content. At 50 days after anthesis (DAA), just past edible maturity, 100% of the seeds germinated. However, at 60 and 78 DAA germination dropped to 60 and 17%, respectively, while the occurrence of “fishmouth” seeds increased from 2 to 54% over the same period. The ethanol content of the tissue increased from 0.11 to 0.28%, the pH dropped from 6.2 to 5.1, and acetic acid concentration increased from 3.0 to 3.7 mM from 50 to 60 DAA, respectively. However, when dried seeds were incubated in the laboratory under conditions similar to those within the fruit, the formation of “fishmouth” seeds was related to the ageing effects of long term hydration and was not correlated with any chemical product within the fruit.
James Velasco and Allan K. Stoner
Abscisic acid (ABA) levels in seeds of tomato (Lycopersicon esculentum Mill.) fell about 10-fold during fermentation to remove mucilaginous tissue. Imbibing seeds in 20 µg/ml ABA prevented germination and increased ABA content of the seed 15-fold. Subsequent germination in water averaged greater than 90%.