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Papaya ( Carica papaya L.) is grown throughout the equatorial regions of the world ( Crane, 2008 ; Morton, 1987 ; Nakasone and Paull, 1998 ), and the species is an important horticultural crop on Guam and other nearby islands. Many of the regions

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Papaya (Carica papaya L.) fruit flesh and seed growth, fruit respiration, sugar accumulation, and the activities of sucrose phosphate synthase (SPS), sucrose synthase (SS), and acid invertase (AI) were determined from anthesis for ≈150 days after anthesis (DAA), the full ripe stage. Sugar began to accumulate in the fruit flesh between 100 and 140 DAA, after seed maturation had occurred. SPS activity remained low throughout fruit development. The activity of SS was high 14 DAA and decreased to less than one-fourth within 56 DAA, then remained constant during the remainder of fruit development. AI activity was low in young fruit and began to increase 90 DAA and reached a peak more than 10-fold higher, 125 DAA, as sugar accumulated in the flesh. Results suggest that SS and AI are two major enzymes that may determine papaya fruit sink strength in the early and late fruit development phases, respectively. AI activity paralleled sugar accumulation and may be involved in phloem sugar unloading.

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Flowering plants of `Kapoho' papaya were sprayed with aqueous solutions of kinetin and folcysteine. Plants were treated four times at 3-week intervals with 0-, 50-, 90-, or 130-ppm solutions of either biostimulant or their combinations. Fruit number, size, and weight were recorded weekly during 15 weeks after treatment. Folcysteine treatment at 90 to 130 ppm significantly increased `Kapoho' papaya yield. Kinetin treatment alone did not significantly affect fruit yield at any rate tested. Moreover, none of the kinetin plus folcysteine combinations significantly differed from the control in terms of fruit yield. These findings suggest that folcysteine rates of 90 to 130 ppm can increase fruit yield in this cultivar, and that kinetin had an antagonistic effect on the activity of folcysteine on the yield of `Kapoho' papaya.

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Papaya ( Carica papaya Linn), in the family Caricaceae, is native to the lowlands of eastern Central America and is a semiherbaceous tropical tree. The main cultivar grown in Taiwan is ‘Tainung No.2’, which accounts for about 90% of the total

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of PRSV ( Baker et al., 1991 ; Purcifull and Hiebert, 1979 ; Purcifull et al., 1984 ). The main reason for the early confusion about the taxonomic status of the W isolate was that it does not infect papaya. However, the P isolates infect cucurbits

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Abstract

Even at the turn of the century, the papaya (cover photo) was the universal breakfast fruit in Hawaii and was considered as one of the most wholesome of fruits. Early horticulturists predicted a strong economic future. Today, it ranks third after pineapple and macadamia in acreage and value in Hawaii. Of the 32.8 million pounds produced from 1,430 acres in 1973, about half was exported with a total farm value of over 4 million dollars with promise of increased acreage and value in the near term.

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The Caricaceae family consists of six genera, including Vasconcellea , which contains 21 of the 35 Caricaceae species, and Carica papaya L., which is the most economically important species attributable largely to its cultivation in the tropics

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Four papaya (Carica papaya L.) lines that may have commercial value were surveyed for variability in ripening characteristics. Skin and flesh yellowing, fruit softening, respiration rate, and ethylene production were compared. Skin yellowing and flesh softening followed a similar sigmoid pattern for all lines. However, the temporal relationship between skin yellowing and flesh softening differed among the lines. Fruit from lines RL-1-3 and RL-1-12 did not begin to soften until the skin was 80% yellow, compared to 40% yellow for the commercial cultivars Kapoho and Sunrise. Fruit from RL-1-3 and RL-1-12 took 12 and 16 days, respectively, to reach 100% yellow from color break, which was two to three times as long as that of `Kapoho' and `Sunrise' at 22C. All lines showed typical climacteric respiration and ethylene patterns. The time between the start of skin yellowing and the rise in respiration varied from ≈2 days in `Kapoho' and `Sunrise' to ≈4 days in line RL-1-3 and 8 days in line RL-1-12. The respiratory peak was greatly reduced in RL-1-12. The patterns of softening in lines RL-1-3 and RL-1-12 differed from `Kapoho' and `Sunrise': RL-1-3 softened slowly, but reached similar firmness values to other lines 4 days after 100% yellow skin color; RL-1-12 had a much slower rate of softening and the fruit were still firm 4 days after the fruit reached 100% yellow. The ripening patterns of line RL-1-3 and RL-1-12 could be useful in postharvest handling and provide material for studying the genetic control of fruit softening.

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the United States papaya plantings are generally irrigated, the producing region in Florida lies between an urban area with high demand for water, and a protected natural area facing water quality challenges due to agricultural irrigation ( Williamson

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Abstract

Suspension cultures derived from Carica papaya L. ovular callus were subcultured on modified Murashige and Skoog medium containing 60 g·liter−1 sucrose, 400 mg·liter−1 glutamine, 9 μm 2,4-D, and either 0–0.45 m sodium chloride (NaCl) or the osmotically equivalent concentrations of mannitol. After 4 successive subcultures (120 days), the suspensions from each NaCl treatment were inoculated into the entire range of salt-containing media, and were subcultured on the same media formulations for 4 months. Cultures grown in the presence of mannitol were treated in the same manner. Sodium chloride generally inhibited somatic enbryogenesis; however, somatic embryogenesis was stimulated greatly following subculture from media with 0.18 m NaCl into media containing lower concentrations of salt. Enhancement of somatic embryogenesis also occurred following preconditioning with 0.30 m and 0.45 m mannitol. The increased rate of somatic embryogenesis was lost after 2 to 3 subcultures in media having lower osmolarities. Chemical names used: (2,4-dichlorophenoxy)acetic acid (2,4-D).

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