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Abstract

The effect of waxes and plastic shrink wraps on weight loss from papaya (Carica papaya L.) fruit during ripening was determined. Loss of ≈8% of initial weight from mature-green papaya produced “rubbery”, low-gloss, unsalable fruit. The rate of weight loss from ripening papaya was ≈0.1% initial weight/day per mbar. The highest rate of weight loss occurred via the stem scar (nearly 3500 mg·cm−2·day−1) while 4.4 mg·cm−2·day−1 was lost through the skin. The major mode of weight loss was the skin because of its larger surface area. The stomata did not appear to function in ripening fruit. The skin's resistance to water movement increased at the start of ripening, then declined with no apparent change in the rate of total water loss. Part of the decline in resistance was associated with the disruption of the cuticle with latex, especially after the 50% ripe stage. These results suggest that the major site of resistance to weight loss changed late in ripening. Fruit waxing reduced weight loss by 14% to 40%, while plastic shrink wraps reduced loss by ≈90%. The loss of water was the major component of weight loss. Some waxes and one wrap delayed ripening by 1 to 2 days at ambient temperatures, after storage for up to 2 weeks at 10C. Occasionally, off-flavors occurred in waxed and wrapped fruit when the fruit cavity CO2 level exceeded ≈7% at the full-ripe stage.

Open Access
Authors: and

Abstract

A phosphorus fertilizer experiment at Puna, Hawaii comprising 3 application rates was conducted over a period of 11/2 years in “aa” lava soil on fruiting papaya trees (Carica papaya L. ‘Solo’). Leaves at 3 stages of maturity were sampled 4 times a year, and the dried ground leaves were chemically analyzed for P. The weight of fruits was obtained at weekly intervals. A curvilinear regression of yield on concentration of P was determined for each leaf tissue at each stage, at each sampling date. A multiple correlation coefficient was then obtained from each of these calculations.

In general, the highest multiple correlation coefficients were obtained with the “recently matured” petiole. Thus, the concentration of P in this tissue on a dry weight basis was selected as the P index of papaya. The critical levels which related yield to the P index and the weights of leaves to the P index were determined for April and May and were found to be about the same. They were 0.25% P for the maximum yield or weight of leaves and 0.213% P for 5% off the maximum. These levels can serve tentatively as a basis for P fertilization of papaya in the Puna area of Hawaii.

Open Access

Sources of resistance to the watermelon strain of papaya ringspot virus (PRSV-W) have been identified within the watermelon (Citrullus lanatus) germplasm collection. Inheritance of resistance to papaya ringspot virus-watermelon strain was studied in three C. lanatus var. citroides accessions: PI 244017, PI 244019, and PI 485583. The susceptible parent lines `Allsweet', `Calhoun Gray', and `New Hampshire Midget' were crossed with resistant accessions to develop F1, F2, and BC1 generations for six families. A single recessive gene was found to control resistance to PRSV-W. The gene symbol `prv' is proposed for PRSV-W resistance in watermelon. Additional work is needed to determine whether the genes in PI 244017, PI 244019, and PI 485583 are allelic for resistance to PRSV-W.

Free access

Extended storage studies were conducted on papaya, Carica papaya L. `Kapoho Solo', seeds to observe the effect of KNO3 preconditioning treatment when seeds were stored under ambient (25 C) and refrigerated (10 C) temperatures for 0, 2, 6, and 12 months. KN03 treated seeds maintained a constant germination percentage of 46.7 ± 2.7% throughout the 12 month period at both storage temperatures. Non-treated seeds stored at 25 C, however, had increased germination percentages (from 11 to 40% germination) after 2 months storage. Nontreated seeds stored at 10 C displayed a slower increase in germination percentages. The beneficial effects of KNO3 preconditioning treatments over nontreated seeds is observed only when seeds are sown immediately or within 2 months of storage at 25 C.

Free access

Studies were conducted in the Dominican Republic to determine the short-term response of young `Cartagena Ombligua' papaya (Carica papaya) plants to nitrogen (N), phosphorus (P), and potassium (K) fertilization. N, P2O5, K2O were individually applied 20 days after transplanting at rates 0, 6, 12, 18, and 24 g per plant. Plant height, stem diameter, leaf area, and root and shoot dry weight responded to N and K in a quadratic fashion (N:Y= 30.79+ 1.35X-0.07X2; K20:Y = 30.02 +1.6X - 0.06X2). Maximum growth was obtained with 6 and 18 g of N and K2O, respectively. P fertilization did not significantly affect shoot growth, but it stimulated root growth (Y = 2.02 + 0.41X - 0.013X2).

Free access

The effect of varying calcium (Ca), magnesium (Mg), boron (B), and molybdenum (Mo) rates on the growth of young `Cartagena Ombligua' papaya (Carica papaya) plants was studied in experiments conducted in the Dominican Republic. Rates of 0, 3, 6, 9, and 12 g Ca; 0, 0.85, 1.7, 2.55, and 3.4 g Mg; 0, 20, 40, 60, and 80 mg B; and 0, 0.05 0.1,0.15 and 0.2 mg Mo per plant were applied to the soil 20 days after transplanting. Ca did not stimulate plant growth, but instead was toxic at rates of 9-12 g per plant. Mg fertilization significantly stimulated root growth (Y = 2.35 + 0.48X, r 2 = 0.95), but not shoot growth. Mo applications decreased plant growth, whereas B enhanced overall plant growth (Y = 10.64 + 70.5X, r 2 = 0.96).

Free access

Abstract

Papayas (Carica papaya L.) were stored at 5° or 10°C for 1, 4, 7, 14, or 21 days. Chilling injury was detectable as visible skin discolorations after 4 days at 5°. Differences in electrolyte leakage and Hunter “L” values between fruit stored at 5° and 10° were not significant until after 7 days of storage. Fruit stored at 5° for more than 4 days also produced more ethylene upon transfer to warmer temperatures than did fruit stored at 10°. Differences in ethylene production between fruit stored under chilling temperatures, 5°, and nonchilling temperatures, 10°, increased with length of storage. Papayas chilled for 14 days at 5° retained a capacity to convert ACC to ethylene.

Open Access
Authors: , , and

Abstract

Papaya plants, Carica papaya L. cv. Solo, were treated with 3 levels of lime combined with 3 levels of P in a split-plot arrangement. Optimal yield of papaya was maintained when the pH of the surface soil ranged from 5.5 to 6.7. Liming lowered petiole concentrations of Mn, K, and Mg and raised those of Ca and P; petiole P was raised when P was applied only. Phosphorus fertilization increased the growth rate of the tree-trunk circumference only at the early stage of growth, while liming affected growth later than P. Phosphorus fertilization raised the petiole concentrations of P, N, Mn, and Zn and lowered petiole concentrations of K and Cu.

Open Access
Authors: and

Abstract

Nitrogen fertilizers as urea and ammonium-nitrate-sulphate were supplied at 2 rates to fruiting papaya trees. Control trees were untreated. Concentrations of petiole N and fruit yield increased with N applications. Petiole N and petiole water affected fruit yield in June. In December tree size and petiole N affected yield. Although N application rate was the dominant variable which affected the concn of petiole N in both June and December, petiole K also affected petiole N in June. The December data were used to determine the petiole N level (1.45% N) which gave max yield. This N level can be used as a basis for applying N fertilizers to fruiting papaya trees in Hawaii.

Open Access
Authors: and

Abstract

N and P fertilizers in factorial combinations were applied to flowering and bearing papaya (Carica papaya L.) grown on aa lava soil. An increase in N fertilization increased the number of harvested fruit and yield of marketable fruit and culls but decreased fruit size. P fertilization increased the number of harvested fruit and yield of culls but did not affect yield of marketable fruit. N fertilization increased petiole concentrations of N, Mg, S, Fe, Mn, Zn, and Cu and decreased those of K and B. P fertilization increased petiole concentrations of P, N, and Mn, and decreased those of Ca, S, and Cu. Petiole N concentrations associated with maximum yield of marketable fruits were determined under low P (41 kg P/ha) and the combined medium (186 kg P/ha) and high P (723 kg P/ha) plots.

Open Access