Muskmelon [Cucumis melo L. (Reticulatus Group)] fruit sugar content is directly related to potassium (K)-mediated phloem transport of sucrose into the fruit. However, during fruit growth and maturation, soil fertilization alone is often inadequate (due to poor root uptake and competitive uptake inhibition from calcium and magnesium) to satisfy the numerous K-dependent processes, such as photosynthesis, phloem transport, and fruit growth. Experiments were conducted during Spring 2003 and 2004 to determine if supplemental foliar K applications during the fruit growth and maturation period would alleviate this apparent inadequate K availability in orange-flesh muskmelon `Cruiser'. Plants were grown in a greenhouse and fertilized throughout the study with a soil-applied N-P-K fertilizer. Flowers were hand pollinated and only one fruit per plant was allowed to develop. Starting at 3 to 5 days after fruit set, and up to 3 to 5 days prior to fruit maturity (full slip), entire plants, including the fruit, were sprayed with a glycine amino acid-complexed potassium (potassium metalosate, 24% K) solution, diluted to 4.0 mL·L-1. Three sets of plants were sprayed either weekly (once per week), biweekly (once every 2 weeks) or not sprayed (control). Fruit from plants receiving supplemental foliar K matured on average 2 days earlier than those from control plants. In general, there were no differences in fruit maturity or quality aspects between the weekly and biweekly treatments except for fruit sugar and beta-carotene concentrations, which were significantly higher in the weekly compared to the biweekly or control treatments. Supplemental foliar K applications also resulted in significantly firmer fruit with higher K, soluble solids, total sugars, ascorbic acid (vitamin C) and beta-carotene concentrations than fruit from control plants. These results demonstrate that carefully timed foliar K nutrition can alleviate the developmentally induced K deficiency effects on fruit quality and marketability.
Gene E. Lester, John L. Jifon, and Gordon Rogers
Patricia S. Holloway and Roxie Rodgers Dinstel
Frozen lingonberries (Vaccinium vitis-idaea subsp. minus) and bog blueberries (V. uliginosum) were processed using recipes of the Alaska Cooperative Extension Service. Overall antioxidant activity (H-ORAC) was 71 μmol·g-1 of TE for frozen bog blueberries and for lingonberries, 160–165 μmol·g-1 of TE. Processing into fruit leather and drying increased levels in bog blueberries to 260–430 μmol·g-1 of TE and lingonberries to 457–939 μmol·g-1 of TE. Leathers and dried fruit had significantly higher levels of total anthocyanins (frozen bog blueberries: 2.1 μg·g-1, leather: 8.0 μg·g-1, dried: 9.8 μg·g-1; frozen lingonberries 1.4 μg·g-1, leather: 4 μg·g-1, dried: 5.2 μg·g-1); total phenolics (frozen bog blueberries: 4.8 μg·g-1, leather: 19 μg·g-1, dried: 26 μg·g-1; frozen lingonberries 7.7 μg·g-1, leather 24 μg·g-1, dried: 38 μg·g-1); and quercetin (frozen bog blueberries: 6.7 μg·g-1, leather: 86 μg·g-1, dried: 150 μg·g-1; frozen lingonberries 7.7 μg·g-1, leather 110 μg·g-1, dried: 430 μg·g-1). Bog blueberries did not have detectible levels of p-coumeric acid or benzoic acid, but lingonberries showed a significant increase in dried fruit and leather (frozen fruit p-coumeric: 0.18 μg·g-1g, leather: 0.45 μg·g-1, dried: 1.4 μg·g-1; frozen fruit benzoic: 0.41 μg·g-1, leather: 0.84 μg·g-1, dried: 0.71 μg·g-1). Frozen and processed lingonberries had little or no vitamin C. Bog blueberries had detectible levels in all treatments [highest in leather (440 μg·g-1), frozen berries (220 μg·g-1)]. ORAC, total anthocyanins, total phenolics, and quercetin were detected in all other processing methods (canned fruit, syrup, canned juice, jam, sauce, frozen j uice, and freezer jam). Levels were similar to or lower than frozen fruit.
Daniel I. Leskovar*, Darrin J. Moore, Libbie Johnson, Julio Loaiza, and Giovanni Piccinni
Regulations restricting water use, competition for water with large urban sector, coupled with extreme high temperatures have placed a large strain on farming areas in south Texas. In addition, consumer demand for healthy vegetables has increased. The objective of this work was to determine yield and fruit quality to deficit irrigation rates and irrigation systems on poblano pepper cv. Tiburon. In 2002, an experiment was conducted at the TAES-Uvalde with a Center pivot using three irrigation rates, 100%, 80%, and 60% evapotranspiration rates (ETc). Transplants were established on beds 1.0 m apart with plants within rows 45 cm apart. In 2003, we compared production efficiency of four irrigation systems in a urban-rural environment near San Antonio. Beds were 0.9 m (single-row) or 1.8 m (double-row) between centers. Irrigation systems were: 1) furrow irrigation with one line/single beds, 2) subsurface drip (SDI)-no mulch, with one line/single bed, 3) SDI-no mulch, with two lines/double bed, and 4) SDI-white mulch with two lines/double bed. In 2002, summer ratooning of the spring-planted crop under deficit irrigation (<100% ETc) allowed a fall crop with a 2.0 fold yield increase, larger fruit size (greater than 10 cm length) and significantly lower defects caused by sunburn or blossom end rot compared to summer production. In 2003, SDI-white mulch had a 2.4-fold yield increase and 760 mm water savings compared to furrow. Fruit vitamin C content was not affected by irrigation, however, mature red fruits had a 3.6 fold increase compared to mature green fruits. Combining deficit irrigation with ratooning we were able to produce marketable poblano fruits. Additional water savings and increased yield were demonstrated by SDI technology.
Donald J. Makus* and Gene E. Lester
Field-grown mustard greens, Brassica juncea, were used to validate several observations of a greenhouse study which reported nutrient changes in mustard greens grown, in part, under ambient and reduced light. The cultivar Florida Broadleaf was transplanted into a Hildago sandy clay soil near Weslaco, Texas (26° 08' Lat.) on 6 Nov 2003. Greens were fertigated with 30 kg·ha-1 of N on 1 Dec. Plants 14 days before harvest were grown under the following four light regimes: (1) continuous ambient light; (2) 7 days of 50% shade then 7 days of ambient light; (3) 7 days of ambient light then 7 days of 50% shade; and (4) 14 days of 50% shade. Cumulative solar light was 28.9 and 19.4 kW/m2 during the first and second 7 days, respectively. Measured cumulative light, as PPFD, for treatments 1-4 were 108, 67, 78, and 44 mm·m-2·s-1, respectively. Plants were harvested at 0800, 1100, and 1400 h on 2 Jan. 2004. Shade during the last 7 days generally evoked the greatest responses. Increased shade duration did not significantly effect the agronomic performance, but did increase leaf total carotenoids, chlorophylls, water content, and reduced total ascorbate levels. As time of daylight progressed, sample plant weight and average leaf weight decreased in shaded plants only. Free ascorbic acid, chlorophyll a:b ratio, and the chlorophyll to carotenoid ratio decreased with time of day. Cumulative sunlight, as PPFD, was significantly correlated with total ascorbate (fresh weight basis), chlorophyll a:b ratio, and plant weight (P < 0.06) and negatively correlated with chlorophylls and total carotenoids (dry weight basis). Thus, cloudy weather prior to harvest can reduce leaf Vitamin C and alter leaf greenness
Peter M. Hanson, Ray-yu Yang, Jane Wu, Jen-tzu Chen, Dolores Ledesma, Samson C.S. Tsou, and Tung-Ching Lee
Tomato (Lycopersicon esculentum Mill.) is among the most widely consumed vegetables worldwide and an important source of certain antioxidants (AO) including lycopene, β-carotene, and vitamin C. Improvement of tomato for content of AO and overall antioxidant activity (AOA) could potentially benefit human health in many countries. We evaluated 50 L. esculentum and three L. pimpinellifolium (L.) Mill. entries for contents of lycopene, β-carotene, ascorbic acid, total phenolics, and two assays for antioxidant activity [anti-radical power (ARP) and inhibition of lipid peroxidation (ILP)] for 2 years during the same period in south Taiwan. We detected high levels of genetic diversity for the AO and AOA measured in this study. Group means of the L. pimpinellifolium entries were significantly higher than L. esculentum group means for ARP, ILP, lycopene, ascorbic acid, phenolics, and soluble solids concentration, suggesting that introgression of alleles from L. pimpinellifolium may have potential to improve cultivated tomato for these traits. Ranking of entries for ILP and ARP were consistent between years, particularly for those entries with the highest means and these assays could be adopted by tomato breeders. Results from ILP and ARP assays were highly correlated (r = 0.82**) and it would be unnecessary to use both assays for tomato. Lycopene, β-carotene, ascorbic acid, soluble solids, and total phenolics were all positively correlated with ARP. Among AO, total phenolics content was most closely associated with ARP (r = 0.90**) and ILP (r = 0.83**); this suggests that phenolics make a major contribution to AOA in tomato fruit. Fruit size was negatively correlated with ARP (r = -0.74**) and ILP (r = -0.71**), indicating that combining large fruit size and high AOA will be challenging.
John Beaulieu and Jeanne Lea
Cantaloupe (Cucumis melo Var. reticulatus, Naudin) were evaluated during development and then fresh-cuts were stored after preparation from various maturities to track quality changes during storage. Flowers were anthesis tagged one morning and developing fruit were harvested weekly at 13, 20, 27–28, and 34–35 days after anthesis (DAA). Mature fruit were harvested at 37–38 DAA with five distinct maturities: 1/4-, 1/2-, 3/4-slip, full-slip and over-ripe. Hunter L* and a* color values indicated change from pale green to light orange that occurred after 28 DAA. There were significant decreases in L*, a* and b* by day 9 in storage as fresh-cuts. After 28 DAA, sucrose dramatically increased, and this was positively correlated with increases in both total sugars (r = 0.882, P = 0.084) and °Brix (r = 0.939, P = 0.041). Gradual subjective deterioration occurred during storage, which was independent of maturity. There was a negative linear trend over the length of storage in hand-held firmness for each maturity level and the slopes decreased significantly with increasing maturity; indicating the effect of storage duration decreased as maturity increased. Vitamin C had a significant increasing trend (P-value = 0.042) during development from 12 through 35 DAA, then losses were greater in fresh-cuts prepared from full-slip fruit (65%) than in less mature fruits, quarter-slip 40%, half-slip 48%, and three quarter-slip 50%. The pH of mesocarp tissue dropped to the lowest value (5.25) just prior to physiological maturity, then peaked after harvest (6.51–6.79), and generally declined by the end of freshcut storage. In sum, considering other publications on this study, and herein, fruit should be harvested at greater than or equal to 1/2-slip to attain optimum quality and storability.
The genus Actinidia contains more than 66 species and 118 taxa. The best-known species is A. deliciosa C.F. Liang et A.R. Ferguson, the commercially developed kiwifruit. The natural range of Actinidia is remarkably wide, extending from the tropics (latitude 0°0′) to cold temperate regions (500°N). However, the original distribution of most taxa of Actinidia is centered around the mountains and hills of south-central and southeast China, with the QinLing mountain as its northern boundary and the HengDuan mountain as its western boundary. Sixty-two species, 114 taxa have been found in China. Genetic variation ranging from morphological traits to DNA is discussed in here. 1) Morphological variation (mainly horticulturally important traits): fruit size varies from 2 to 100 g, fruit skin color ranges from brown to green to white to purple, fruit surface from setose to villose, and flesh color from green to purple. 2) Nutritional value and flavor: vitamin C content varies from 10 mg/100 g to 1000 mg/100 g fresh fruit, soluble solids ranges from 2% to 22%, and flavor includes variation form bitter and astringent to desirable sour-sweet. 3) Gender variation includes six phenotype/genotypes of female, inconstant female, male, fruiting male, neuter and hermaphrodite. 4) Ploidy variation is consist of 2x, 4x, 6x, 8x in both intra- and inter-taxa variation. 5) Isozyme genetic variation: high polymorphisms were detected in commercial cultivated species and 28 wild species. 6) Genetic diversity was evaluated by RAPD, SSR, PCR-RFLP of mtDNA and cpDNA, a high level of genetic diversity was found in both inter-taxa and intra-taxa. Conservation strategy for diverse genetic resources of Actinidia in China is also discussed.
J. Farías-Larios, J.G. López-Aguirre, J.L. Miranda, and L.A. Bayardo-Vizcaino
Acerola (Malpighia glabra L.) is a small, red fruit that is native to the West Indies, but is also grown in South and Central America. In western Mexico, this crop is very important because acerola is the richest known natural source of vitamin C, with a content of 1000 to 4500 mg/100 g of fruit. In nursery and field conditions, acerola growth is severely affected by root-knot nematode. The objective of this study was to evaluate the use of commercial formulations of Bacillus spp. on root-knot nematode management. This study was carried out in the Farm Santa Clara Maria in Colima State. Acerola plants, 60 days old were used. They were grown in 3-L pots with soil, compost, and pumice stone mixture as substrate. Treatments evaluated were: 5, 10, 15 and 30 mL/pot of Activate 2001, Tri-Mat (5 mL/pot) and control, without application. Activate 2001® is a concentrated liquid in water suspension of Bacillus chitinosporus, B. laterosporus, and B. licheniformis. Initial nematode population was of 3,305 in 50 g of roots. Acerola plants were harvested at 30, 60, and 90 days after application. Results show that Activate 2001 at 10 and 30 mL rates reduce significantly root-knot populations in acerola plants 60 days after application with 135 and 178 nematodes/50 g of roots, respectively. Diameter stem, shoot fresh and dry weight and root production were also increased by rhizobacteria application. These results are promising and confirmed the potential of Bacillus as a biological agent for nematode management.
Gene E. Lester, John L. Jifon, and Gordon Rogers
Muskmelonfruit[Cucumis melo L. (Retiulatus Goup)] sugar content is related to potassium (K)-mediated phloem loading and unloading of sucrose into the fruit. During fruit growth and maturation, soil fertility is often inadequate (due to poor root uptake) to satisfy the demand for K. Potassium uptake also competes with the uptake of Ca and Mg, two essential minerals needed for melon fruit membrane structure, function and postharvest shelf-life. Supplemental foliar-applied K could alleviate this problem especially during the critical fruit growth/maturation period. We conducted experiments to determine the effects of timing of supplemental foliar K applications on fruit quality and health attributes of orange-flesh muskmelon `Cruiser'. Plants were grown in a greenhouse and fertilized with a regular soil-applied N–P–K fertilizer throughout the study. Entire plants, including the fruit were sprayed with a solution of a novel glycine amino acid-complexed potassium (Potassium Metalosate, 24% K), diluted to 4.0 mL·L-1, 3 to 5 d after anthesis (fruit set) and up to 3 to 5 d prior to abscission (full-slip). Three sets of plants were either sprayed weekly, or bi-weekly or not sprayed (control). Fruit from plants receiving supplemental foliar K matured on average 2 days earlier, and had significantly higher fruit K concentrations, soluble solids, total sugars, ascorbic acid (vitamin C), beta-carotene, and were firmer than fruit from control plants. In general, there were few differences in fruit quality aspects between bi-weekly or weekly treatments. The data demonstrate that fruit quality and marketability as well as some of the developmentally induced K deficiency effects can be alleviated through foliar nutrition.
A. Talaie, B. Goleyn, A. Vezvaei, and Y. Ebrahimi
`Page' mandarin is a complex hybrid between `Minneola' tangelo and `Clementine' mandarin. Because of self-incompatibility, this cultivar severely needs pollinizers and, if a suitable pollinizer does not exist, it will produce few and small fruit. In this study, the effects of pollen grains of nine cultivars of citrus ['Sour' orange, `Duncan' grapefruit, `Sweet' lemon, `Salustiana' orange, `Local' mandarin, `Hamlin' orange, `Siavaraz III Locan' orange, `Marrs' orange, and `Shell' mahaleh (natural hybrid)] on the quantitative and qualitative characteristics of fruit (weight, diameter, length, volume, peel thickness, juice content, developed seeds, undeveloped seeds, total soluble solids, acidity, pH, vitamin C, and percentage of final fruit set) were investigated and evaluated. After artificial pollination and during fruit growth and development, seven times abscission and fruit color and diameter were recorded. Fruit were harvested 29 weeks after pollination and were analyzed. The results showed that this cultivar, in addition to the complete self-incompatibility, has the ability of week parthenocarpy, which results in small and low-quality fruit and also parthenocarpy is induced. `Page' mandarin is cross-compatible with some cultivars, such as `Marrs' orange. There is a positive and significant correlation between developed seed number and fruit weight. The pollen of `Siavaraz III Local' orange has the most effects on percentage of final fruit set. The pollen of `Shell' mahaleh (natural hybrid) has the most effect of the quantitative characteristics, and the pollen of `Marrs' orange has the most effects on qualitative characteristics. It was concluded that `Hamlin' orange is the best pollinizer for `Page' mandarin in northern Iran. The results of this study were analyzed with the use of a randomized complete-block design.