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F R Harker, C B Watkins, B A Cregoe, P L Brookfield, and W J Bramlage

The apple growing districts of New Zealand are spread across a wide range of latitudes. Differences in growing conditions associated with these various districts may influence the way fruit mature on the tree. In this study, the relationships between background colour and physiological maturity of Royal Gala apples have been compared in four major production areas. Royal Gala apples were strip picked from trees in three orchards during the commercial harvest period Hawkes Bay, Canterbury, Nelson and Otago. The maturity of these fruit was assessed, and fruit stored at 0°C for 12 weeks. Following removal from “storage, the quality of the fruit was assessed paying particular attention to -greasiness. Results from this trial indicate that the relationship between background colour and fruit maturity is not consistent. Indeed, the maturity of apples of a particular background colour may differ according to district and harvest date. Greasiness of fruit was related to harvest maturity in Hawkes Bay. However, fruit from Canterbury and Otago became severely greasy even when harvested at early maturities.

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Shiva Ram Bhandari, Bo-Deul Jung, Hum-Young Baek, and Young-Sang Lee

) among the maturity stages in sweet pepper cultivars. More prominent β-carotene accumulation could be observed between the BR and RR stages in that β-carotene content was low in the GM stage, exhibited a slight increase during the BR stage, and increased

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Gaétan Bourgeois, Sylvie Jenni, Hélène Laurence, and Nicolas Tremblay

The heat-unit system, involving the sum of daily mean temperatures above a given base temperature, is used with processing pea (Pisum sativum L.) to predict relative maturity during the growing season and to schedule planting dates based on average temperature data. The Quebec pea processing industry uses a base temperature of 5 °C to compute growing-degree days (GDD) between sowing and maturity. This study was initiated to verify if the current model, which uses a base temperature of 5 °C, can be improved to predict maturity in Quebec. Four pea cultivars, `Bolero', `Rally', `Flair', and `Kriter', were grown between 1985 and 1997 on an experimental farm in Quebec. For all cultivars, when using a limited number of years, a base temperature between 0.0 and 0.8 °C reduced the coefficient of variation (cv) as compared with 5.0 °C, indicating that the base temperature used commercially is probably not the most appropriate for Quebec climatic conditions. The division of the developmental period into different stages (sowing until emergence, emergence until flowering, and flowering until maturity) was also investigated for some years. Use of base temperatures specific for each crop phase did not improve the prediction of maturity when compared with the use of an overall base temperature. All years for a given cultivar were then used to determine the base temperature with the lowest cv for predicting the time from sowing to maturity. A base temperature from 0 to 5 °C was generally adequate for all cultivars, and a common base temperature of 3.0 °C was selected for all cultivars. For the years and cultivars used in this study, the computation of GDD with a base temperature of 3 °C gave an overall prediction of maturity of 2.0, 2.4, 2.2, and 2.5 days based on the average of the absolute values of the differences for the cultivars Bolero, Rally, Flair, and Kriter, respectively.

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Arthur D. Wall, Marisa M. Wall, and Joe N. Corgan

Onions (Allium cepa L.) with ≥18% bulb dry weight are dehydrated and used for spices and food ingredients. Bulb weight characteristics and water-soluble carbohydrates (WSC) of two commercial dehydrator cultivars, GS02 and GS04, and a breeding population, NM9335, were studied before and after maturity to observe phenotypic traits that may be useful for selection during breeding programs, and to study dehydrator onion carbohydrate physiology. At maturity, NM9335, GS02, and GS04 bulbs had 11.9 ± 0.33%, 18.6 ± 0.27%, and 19.4 ± 0.40% dry weight, respectively. Mature GS04 plants had 76.5 ± 0.01% of whole plant dry weight in bulbs, which is an extraordinarily high crop harvest index. NM9335 bulbs had higher fresh (hydrated) weight than bulbs of GS04 and GS02, but bulbs in all populations accumulated similar amounts of dry weight. Bulb percent dry weight before maturity did not indicate percent dry weight at maturity in the high-solids commercial onion cultivars. Bulb percent dry weight declined slightly after maturity in all populations. Glucose, fructose, and sucrose were relatively low, and fructans with degree of polymerization ≥6 were relatively high in GS04, but the converse was observed in NM9335. Relative amounts of GSO4 bulb fructan increased sequentially, in order of rank, from DP4 to DP6, but the converse was observed for NM9335.

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D. Gerasopoulos and B. Chebli

`Testarossa' gerbera (Gerbera jamesonii Bolus) scapes were injected with distilled water (control), or 0.3, 0.6, and 0.9 mm ACC at harvest, then held at 20 °C for 15 days in a preservative solution. PAL activity and ethylene production increased within 1 day proportionally to injected ACC. ACC injection reduced bending incidence, inhibited flower scape elongation, enhanced firmness of the flower scapes and increased vase life. Flower scapes treated with ACC reached full maturity 3 days before the end of vase life of the control, which bent before reaching full maturity.

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W.A. Dozier Jr., R. Rodriguez-Kabana, A.W. Caylor, D.G. Himelrick, N.R. McDaniel, and J.A. McGuire

The yellow passionfruit (Passiflora edulis f flavicarpa Degener), a perennial vine grown in the tropics and subtropics, was successfully grown as an annual crop in a temperate zone. Fruit maturity was hastened by ethephon treatments to allow harvest before the mean date of the first killing frost. Maturity was advanced in a linear manner with application rates of 150, 300, and 600 ppm ethephon. Total yield was not affected by ethephon treatment; however, cull fruit producing no juice increased with increasing rates of ethephon, thereby reducing marketable yields. Soluble solids and ascorbic acid contents of the juice were not affected by ethephon treatment. Purple passionfruit (Passiflora edulis Sims) did not produce blossoms.

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Harry S. Paris

Most cultivars of acorn squash (Cucurbita pepo), such as `Table Queen', have fruit that are light green when young, become dark green by intermediate age, and remain dark green through maturity, carrying genotype D/D l-l/l-1 L-2/L-2. Many other forms of C. pepo that carry this genotype, the most familiar being the Halloween and pie pumpkins, turn orange at maturity. The genetic basis for green color retention of acorn squash was investigated by crossing `Table Queen' with `Vegetable Spaghetti', `Fordhook Zucchini', and accession 85k-9-107-2 (the parental, filial, backcross, and testcross generation progenies being grown out in the field and observed and scored for fruit color at maturity, between 40 and 44 days past anthesis). The results indicated that the three stocks crossed with `Table Queen' carry two recessive genes, designated mature orange-1 (mo-1) and mature orange-2 (mo-2), which act in concert to result in complete loss of green color before maturity in 1-1/1-1 plants. `Table Queen' is Mo-l/Mo-1 Mo-2∼o-2. Genes D and mo-2 are linked, ≈15 map units apart.

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Monica Ozores-Hampton, Thomas A. Bewick, Peter Stoffella, Daniel J. Cantliffe, and Thomas A. Obreza

The influence of compost (derived from MSW and biosolids) maturity on seed germination of several weed species was evaluated. A bioassay was developed by extracting 20 g of compost of different maturities with various volumes of water, then measuring germination percentage of ivyleaf morningglory (Ipomoea hederacea) seeds placed on extract-saturated filter paper in a petri dish. A 20 g (dry weight) compost: 50 mL of water generated an extract that produced the widest percentage seed germination variation in response to composts of different maturity. Ivyleaf morningglory, barnyardgrass (Echinochloa crus-galli L.), purslane (Potulaca oleracea L.), and corn (Zea mays L) were selected as plant indicators to determine the compost maturity stage with maximum germination inhibition. Compost 8-week-old decreased percent germination, root growth, and germination index (combines germination rate and root growth), and increased mean days to germination (MDG) of each plant indicator. Immature 8 week-old compost extract effect on MDG and germination percent of 15 weed species was evaluated. Extract from 8-week-old compost inhibited germination in most weed species, except yellow nutsedge (Cyperus esculentus). Compost extracts derided from immature (3-day, 4-, and 8-week-old) compost resulted in delayed and reduced germination percent of important economic weed species.

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Sylvie Jenni, Gaétan Bourgeois, Hélène Laurence, Geneviève Roy, and Nicolas Tremblay

Four snap bean (Phaseolus vulgaris L.) cultivars, Goldrush, Teseo, Labrador, and Flevoro, were grown in irrigated fields of southern Quebec between 1985 and 1998. Data on phenology collected from these fields were used to determine which base temperature would best predict time from sowing to maturity. The optimal base temperature was 0 °C for `Goldrush', `Teseo', and `Labrador' and 6.7 °C for `Flevoro'. Adjusting different base temperatures for intermediate developmental stages (emergence, flowering) did not improve the prediction model. All years for a given cultivar were then used to determine the base temperature with the lowest coefficient of variation (CV) for predicting the time from sowing to maturity. A common base temperature of 0 °C was selected for all cultivars, since `Flevoro' was not very sensitive to changes in base temperature. This method improved the prediction of maturity compared with the conventional computation growing-degree days (GDD) with a base of 10 °C. For the years and cultivars used in this study, calculating GDD with a base of 0 °C gave an overall prediction of maturity of 1.7, 1.5, 2.0, and 1.4 days based on average absolute differences, for `Flevoro', `Goldrush', `Teseo', and `Labrador', respectively.

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Floyd M. Woods, William A. Dozier, Robert C. Ebel, Raymond Thomas, Monte Nesbitt, Bryan S. Wilkins, and David G. Himelrick

Changes in fruit quality attributes and antioxidative properties from six cultivars of thornless blackberries (Rubus sp.) (`Apache', `Arapaho', `Chester', `Loch Ness', `Navaho', and `Triple Crown') during four different ripening stages (red, mottled, shiny-black, and dull-black) were determined under Alabama growing conditions. Berry fruit samples were evaluated for pH, titratable acidity, total soluble solids, TSS/TA ratio, soluble sugars, vitamin C (reduced, oxidized and total), and antioxidant capacity (measured as trolox equivalent antioxidant capacity, TEAC). Significant variation among cultivars were noted in fruit quality attributes and antioxidative properties, which were influenced by maturity at harvest. An increase in fruit pH concomitant with a decline in titratable acidity (TA) was observed during ripening for all cultivars. Total soluble solids (TSS) values increased from 5.7% to 11.6%, with associated TSS/TA ratio values ranging from 11.92 to 63.56 in ripening fruit. Highest reducing and total sugar content were contained in dull-black fruit. Vitamin C content either declined or remained unchanged with ripening, and the pattern was dependent on cultivar, maturity at harvest and form determined. In general, antioxidant activity declined between red and dull-black ripening stages. The results suggest that the TSS/TA ratio may provide the best maturity index in determining optimal eating quality and antioxidant capacity in terms of TEAC value the best indicator of optimal nutritional quality as influenced by maturity at harvest.