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Burcu Begüm Kenanoglu, Ibrahim Demir, and Henk Jalink

variation in seed maturity results in variation in plant growth and development. Therefore, separating out less mature seeds would enhance the overall quality of a seed lot. Chlorophyll content of the seedcoat in many species decreases as seed matures

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Teresa L. Walker, Justin R. Morris, Renee T. Threlfall, Gary L. Main, Olusola Lamikanra, and Stephen Leong

Muscadine grapes (Vitis rotundifolia Michx.), native to the southeastern United States, have a distinct flavor, and grocers are interested in marketing them as table grapes. Two studies using 'Fry' muscadines were conducted to assist the muscadine industry in providing quality table grapes. Study 1 (1998 and 1999) evaluated density sorting and relationships between maturity, color, soluble solids, firmness, shelf life, and sensory evaluation of grapes. Study 2 (1998) determined the effect of storage on quality attributes of different maturities of grapes and evaluated use of polyethylene bags to extend their storage. Density separation successfully sorted grapes by maturity. Muscadine berry color may allow for visual or electronic sorting to eliminate immature fruit. Sensory panelists could distinguish differences in maturities for all sensory attributes. In 1999 maturities 3 and 4 (≈24-33 soluble solids: acid ratio) were preferred overall by panelists. As maturity increased, soluble solids and pH increased, and acidity decreased. Firmness decreased as maturity and storage at 2 °C increased. Percent decay increased with maturity and storage time. Grapes stored in polyethylene bags had reduced decay. A chart developed from the 1999 data related berry color to soluble solids: acid ratio, soluble solids, tartaric acid, and pH. Data from these studies can be used by industry to establish harvest parameters and enhance marketability of 'Fry' muscadine grapes.

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D.O. Ketchie, R. Kammereck, and E. Fairchild

In the past, the laborious and time-consuming method of defoliation was used to determine vegetative maturity (VM) of various deciduous plants. Other methods such as water potential and electrotrical impedence have been explored without a positive response. A change of freezing events of water in plant tissue may be associated with VM. Differential thermal analysis (DTA) was tried to determine if the freezing events of water are related to VM. `Golden Delicious', `Gala', `Red Fuji' and `Antonovka' apple (Malus domestica Borkh.) trees were used to determine VM by defoliation. Different sets of 1-year-old trees grown in pots in the greenhouse were defoliated weekly from 1 Aug. until it was assured the trees had reached VM. Samples from the same trees were taken for DTA. The trees were observed for regrowth 2 weeks after they were defoliated, and the exothermic patterns from DTA were examined for the appearance of an exotherm at about –35 to –40°C. The comparison of regrowth from trees defoliated from a specific date were compared to the exothermic pattern of the same date. An exotherm appeared between –35 and –40°C ≈2 weeks before the apple trees ceased to show regrowth from the defoliation treatment. The exotherm appeared on 30 Aug. for Antonovka and `Golden Delicious' and regrowth of the trees ceased on 12 Sept. Regrowth ceased on 9 Oct. for `Gala' and `Fuji' preceded by the exotherm on 2 Oct. The conclusion was that the appearance of the exotherm at –35 to –40 °C could be used to determine VM.

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Huicong Wang and Lailiang Cheng

coloration of apples has been well documented, much less attention has been paid to its effect on other aspects of fruit maturity. Because maturity at harvest greatly affects apple fruit quality and storage performance, starch hydrolysis indices (starch

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Charles A. Mullins and Richard A. Straw

Harvest maturity of round-podded snap beans is based on pod diameter. Flat-podded cultivars such as `Roma II' require a different maturity index. Pod fiber and seed development are two leading indicators of maturity and pod quality and both are highly dependent upon environmental conditions. Experiments were conducted at the Plateau Experiment Station at Crossville in 1993 to evaluate changes in pod characteristics as the crop matured. The objectives were to evaluate indices for field use to determine optimum maturity of `Roma II' bush beans for processing usage. Harvests were made at two day intervals starting before optimum maturity and continuing until a decline in maximum yields had occurred. Seed length of 100 mm for 10 seeds extracted from the most mature pods appeared to be an acceptable guide for harvest maturity to assure maximum yields and excellent pod quality.

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R. Roger Ruan, Paul L. Chen, and Simon Almaer

This paper describes the relationship between the maturity stages and nuclear magnetic resonance (NMR) characteristics of sweet corn (Zea mays L.). The NMR parameter T2, which is the spin–spin relaxation time constant, and two conventional maturity parameters, moisture content and alcohol insoluble solids (AIS), of sweet corn samples during maturation, were determined and correlated with reference maturity indices, namely, heat units and sensory maturity scores. The relationships between T2 and the heat unit and sensory maturity score of the samples were linear, suggesting that T2 can be used to establish mathematical models for the prediction of sweet corn maturity to determine harvest time. The major advantages of using NMR are the nondestructive nature, the speed, and the simplicity of the method.

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Elena de Castro, William V. Biasi, and Elizabeth J. Mitcham

effect of harvest maturity of Pink Lady apples on the quality attributes after storage and to determine the most appropriate postharvest treatments and storage conditions to maintain quality during storage. Material and Methods Fruit material

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Stephen A. Carver and Harry K. Tayama

The influence of poinsettia (Euphorbia pulcherrima Wild. ex Klotzsch) stock plant shoot maturity on subsequent splitting of cuttings taken from the shoots was evaluated. Terminal cuttings (7.5 cm) taken from `Lilo' poinsettia stock plant axillary shoots that had 4, 8, or 12 nodes were rooted, planted, then observed for initial signs of splitting (conversion of the vegetative terminal buds into floral buds). The percentages of cuttings that split were 22, 77, and 100 for those taken from shoots with 4, 8, and 12 nodes, respectively. By implication, cuttings should be taken just as stock plant axillaries reach a size adequate for propagation to help reduce the incidence of splitting.

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Marisa M. Wall and Joe N. Corgan

A 2-year field study was conducted to evaluate the effects of maturity and storage on fresh-market onion (Allium cepa L.) quality. Four short-day onion cultivars (`NuMex BR1', `NuMex Sunlite', `NuMex Starlite', and `Buffalo') were seeded in early October each year. Bulbs were harvested at five times; the first and second harvests were when 20% and 80 %, respectively, of the bulbs in a plot had mature necks; the third, fourth, and fifth harvests were at 5,10, and 15 days after the second harvest date, respectively. After curing for 3 days, bulb firmness, weight, and incidence of disease were evaluated for all harvests. Bulbs were re-evaluated after 10 and 20 days storage in a shed under ambient conditions. `Buffalo' and `NuMex Surdite' bulbs had the lowest incidence of disease before storage. For all cultivars, average bulb weight increased and firmness decreased with delayed harvest. Percent diseased bulbs increased for all cultivars as harvest was delayed in 1991 but not in 1992. The optimum harvest time was at 80% maturity. In storage, average bulb weight and firmness decreased, and the incidence of bulb diseases increased.

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Randolph M. Beaudry and Sylvia M. Blankenship

The reasons for knowing the maturity of fruit center around controlling fruit quality after harvest. Farmers are usually concerned with trying to determine harvest date to fit their labor, storage, and marketing needs, whereas research scientists are typically trying to account for the effects of maturity as a variable in experiments. Specific goals for farmer and researcher will, in part, govern what maturity indices are used and what values are acceptable. Restrictions in time and equipment will also affect choice of maturity assessment methods. In some instances, internal or external characteristics might be more important. Because changes in a number of characteristics comprise ripening, there is no single criteria or method that can be termed “best.” However, for each situation, an optimal choice of criteria or method may exist. The logic and information necessary to reach those optimal choices, from the perspective of the researcher and the commercial horticulture operation, is presented and contrasted.