Twenty-one selections consisting of 13 numbered hybrids, one ornamental, and seven named cultivars were tested as rootstocks for `Valencia' orange, Citrus sinensis L. Osbeck. The test included six, four-tree replications in randomized complete blocks on sandy soil typical of the center of the Florida peninsula. Trees propagated on Vangasay lemon, HRS 812 (Sunki × Benecke trifoliate orange), and HRS 942 (Sunki × Flying Dragon trifoliate orange) produced more fruit than trees on the other 18 rootstocks in the test. Trees on 10 rootstocks, including the widely used commercial rootstocks, Swingle citrumelo and Carrizo citrange, were intermediate in cumulative fruit production. Trees on five rootstocks, including Sun Chu Sha, Gou Tou #1, and Tachibana, had low yields and trees on HRS 939 (Flying Dragon trifoliate orange × Nakorn pummelo) and sour orange #2 were extremely dwarfed and were minimally productive because of tristeza virus disease. Fouryear cumulative fruit production ranged from 52 to 317 kg per tree. Fruit from trees on HRS 954 and HRS 952 (Pearl tangelo × Flying Dragon trifoliate orange) had the highest, and fruit from trees on Vangasay and Gou Tou #1 had the lowest total soluble solids concentration.
H.K. Wutscher and K.D. Bowman
Jennifer R. DeEll and Robert K. Prange
Postharvest quality and sensory attributes of organically and conventionally grown `McIntosh' and `Cortland' apples (Malus domestica Borkh.) stored at 3C in ambient air or in controlled atmospheres were evaluated. Organically grown apples had higher soluble solids concentration than conventionally grown apples, while there were no significant differences in firmness or titratable acids content. Organically grown `McIntosh' were perceived by sensory panelists as firmer than conventionally grown `McIntosh' at harvest but not after storage, which may have been due to maturity differences. No significant differences were perceived in juiciness, sweetness, tartness, and off-flavor of apples at harvest or after storage.
Kevin M. Keener, Richard L. Stroshine and John A. Nyenhuis
A 5.40-MHz NMR system was used for measuring the self-diffusion coefficient of water (Dw) and the spin-spin relaxation constant (T2) in apple (Malus ×domestica Borkh.) tissue. The pulsed field gradient spin echo (PFGSE) technique was used to measure Dw, and the Carr-Purcell-Meiboom-Gill (CPMG) technique was used to measure T2. T2 and Dw values were compared for apples with differing amounts of soluble solids concentration (SSC) and with and without internal defects, such as bruising, watercore, and internal browning. `Granny Smith', `Golden Delicious', and `Delicious' apples were tested. In `Golden Delicious', Dw highly correlated with apple tissue SSC (P < 0.002, r 2 = 0.68). This indicates that Dw could potentially be used for sorting `Golden Delicious” apples based on SSC, but the coefficient of determination needs to be improved before it would be commercially viable. There were no measurable differences in Dw among healthy apple tissue and tissue affected by either watercore or internal browning. T2 values showed no relationship between healthy apple tissue and bruised tissue in `Golden Delicious' and `Granny Smith'. However, in `Delicious' tissue, T2 values were statistically different between healthy and bruised tissue (P < 0.02). Further comparisons in `Delicious' between watercore and healthy apple tissue showed no differences. But, there were statistical differences found between T2 in healthy apple tissue and tissue with internal browning (P < 0.01). These results indicate that T2 could potentially be used for separating `Delicious' apples with internal browning or with bruising from healthy apples. Titratable acids and pH were correlated for `Golden Delicious' (P < 0.08). This correlation is significant because one may be able to noninvasively measure pH in `Golden Delicious' apples using NMR, which could then be correlated to titratable acids.
Gene E. Lester, John L. Jifon and D. J. Makus
Netted muskmelon [Cucumis melo L. (Reticulatus Group)] fruit quality (ascorbic acid, β-carotene, total free sugars, and soluble solids concentration (SSC)) is directly related to plant potassium (K) concentration during fruit growth and maturation. During reproductive development, soil K fertilization alone is often inadequate due to poor root uptake and competitive uptake inhibition from calcium and magnesium. Foliar applications of glycine-complexed K during muskmelon fruit development has been shown to improve fruit quality, however, the influence of organic-complexed K vs. an inorganic salt form has not been determined. This glasshouse study investigated the effects of two K sources: a glycine-complexed K (potassium metalosate, KM) and potassium chloride (KCl) (both containing 800 mg K/L) with or without a non-ionic surfactant (Silwet L-77) on melon quality. Orange-flesh muskmelon `Cruiser' was grown in a glasshouse and fertilized throughout the study with soil-applied N–P–K fertilizer. Starting at 3 to 5 d after fruit set, and up to 3 to 5 d before fruit maturity at full slip, entire plants were sprayed weekly, including the fruit, with KM or KCl with or without a surfactant. Fruit from plants receiving supplemental foliar K had significantly higher K concentrations in the edible middle mesocarp fruit tissue compared to control untreated fruit. Fruit from treated plants were also firmer, both externally and internally, than those from non-treated control plants. Increased fruit tissue firmness was accompanied by higher tissue pressure potentials of K treated plants vs. control. In general, K treated fruit had significantly higher SSC, total sugars, total ascorbic acid, and β-carotene than control fruit. Fall-grown fruit generally had higher SSC, total sugars, total ascorbic acid and β-carotene concentrations than spring-grown fruit regardless of K treatment. The effects of surfactant were not consistent but in general, addition of a surfactant tended to affect higher SSC and β-carotene concentrations.
Morris Ingle, Mervyn C. D'Souza and E.C. Townsend
Firmness, soluble solids concentration (SSC), starch index (SI), internal ethylene concentration (IE), and titratable acid concentration (TA) of `York Imperial' apple (Malus ×domestica Borkh.) fruit changed linearly with harvest date between 152 and 173 days after full bloom (DAFB). Firmness was positively correlated with TA, SSC was correlated with SI, and SI was negatively correlated with TA. After 150 days of refrigerated-air (RA) storage, there was no relationship between DAFB at harvest and firmness or superficial scald, but the malic acid concentration declined linearly and storage decay increased linearly with DAFB. Firmness had declined to a plateau and was not correlated with any variable at harvest. Malic acid concentration after CA storage was correlated with DAFB, firmness, SSC, and SI; scald was correlated with firmness and SI; and decay was correlated with DAFB, firmness, SSC, and SI. During 150 days of controlled-atmosphere (CA) storage (2.5% O2, 1.0% CO2), firmness and TA decreased as a linear function of DAFB. Percentage of fruit with scald and scald rating changed quadratically with DAFB, and decay increased linearly with DAFB. After 150 days of CA, firmness was correlated with DAFB, SI, and IE at harvest; TA was correlated with DAFB, firmness, SSC, TA, and SI; scald was correlated with firmness and SI; and decay was correlated with DAFB, SSC, and scald index at harvest. During 250 days of CA storage, firmness, TA, scald, and decay changed linearly with DAFB in only 1 or 2 years out of 3. Formulas were created to predict firmness after CA within 10 to 12 N (2.0–2.5 lb-f) and TA to within 25%.
Anton J. Bongers, Lawrence A. Risse and Vincent G. Bus
Comparisons were made of the major physical and chemical characteristics of seven cultivars of apples (Malus domestica Borkh.) produced and imported into Western Europe from 13 origins. During the 1990-91 marketing season, `Delicious', `Golden Delicious', `Granny Smith', `Elstar', `Jonagold', `Gala', and `Fuji' apples were included in the study. Physical characteristics evaluated were length-to-diameter ratio, shape, external defects, internal defects, water core, bruises, firmness, blush surface, and color. Chemical characteristics evaluated were starch, juice content, soluble solids, acids, and ascorbic acid. Significant differences in some of these quality characteristics were found between the different origins. Apples produced in the United States, particularly `Delicious', had some superior quality characteristics compared to fruit from other origins.
D. Michael Glenn, Stephen Drake, Judith A. Abbott, Gary J. Puterka and Patricia Gundrum
Experiments were performed over 3 years to examine the effect that particle film (PF) treatment had on fruit quality of several apple (Malus ×domestica) cultivars in Washington and West Virginia. In the first study, a highly reflective, white, hydrophilic particle-based kaolin mineral (Surround WP) was applied to `Empire' apple in May and June, on a season-long basis, or not at all. Red fruit color was increased by both the PF treatments compared with no treatment in all years. In a second study, the PF material was applied, starting at petal fall, every week for 6 weeks and then every 2 weeks until harvest to `Empire', `Gala', and `Fuji' trees in West Virginia and to `Cameo', `Fuji', and `Gala' trees in Washington. In the latter study, cultivar response to season-long applications varied by year and location. `Empire' consistently had improved red color with season-long applications of PF materials. `Gala' had greater fruit weight and red color with PF application in 1 of 2 years in West Virginia but not in Washington. `Fuji' had greater fruit weight and soluble solids content and `Cameo' had greater soluble solids, higher starch indices, and greater red color in Washington with the PF application. In these studies, application of a PF never reduced the surface red color in apples. A taste panel did not identify quality differences in `Empire' apples treated with PF vs. the control. Cultivar responses to PF applications were variable due to location and yearly environmental characteristics. While particle film technology has value for insect control and reducing sunburn, it has limited value to enhance fruit color due to the inconsistent response.
Edna Pesis and Rosa Marinansky
Abbreviations: AA, acetaldehyde; RQ, respiratory quotient; TSS, total soluble solids content. Supported by grant no. 1-900-85 from BARD, the U.S.-Israel Binational Agricultural Research and Development Fund. Contribution from the Agr. Res
Todd C. Wehner, Rachel P. Naegele and Penelope Perkins-Veazie
directly evaluated in watermelon to date. Watermelon breeding has resulted in a diversity of fruit sizes, rind color, rind patterns, and flesh color. Most cultivars have soluble solids content (°Brix) between 8% and 15% and acidity (flesh pH) of 5
Paul M. Chen, Diane M. Varga and Eugene A. Mielke
Abbreviations: EJ, extractable juice; FF, flesh firmness; SSC, soluble solids concentration; TA, titratable acidity. Oregon State Agricultural Experiment Station Technical Paper no. 9834. This study was supported by the Winter Pear Control Committee