Effect of distance from early flowering pollinizers ‘Maypole’ and ‘Dolgo’ on ‘Fiji’ fruit set

An apple orchard consisting of a single cultivar under the condition of natural pollination must have suitable pollinizers such as Crab apples to ensure stable fruit production. We selected ‘Maypole’ and ‘Dolgo’ as pollinizers for the cultivar ‘Fuji’, and investigated the rate of fruit and seeds in ‘Fuji’ fruits produced by pollen of the pollinizers. We developed a method for tracing pollen flow based on the leaf color of progeny and S-RNase allele of ‘Maypole’, and on Simple Sequence Repeat (SSR) analyses of ‘Maypole’ and ‘Dolgo’. These were powerful tools for determining the distance insects (mainly Osmia cornifrons) carry pollen from the pollinizers to ‘Fuji’. Although the fruit set of ‘Fuji’ apples was not reduced with increasing distance between ‘Fuji’ apple trees and pollinizers (probably due to pollen flow from other commercial cultivars planted outside the area), the rate of ‘Fuji’ apple fruit produced by the pollen of the pollinizers decreased with increasing distance. The rate of fruit produced by the pollinizers was 84% and 77% when ‘Fuji’ was 2.5 m from ‘Maypole’ and ‘Dolgo’, respectively, and 71% and 64% when ‘Fuji’ was 5 m from ‘Maypole’ and ‘Dolgo’, respectively, but was reduced to 47% and 39% when ‘Fuji’ was 10 m from ‘Maypole’ and ‘Dolgo’, respectively. However, the spacing could cause reduced fruit size, and require extra fruit thinning for producing large fruits. It could also cause reduction of the yield for increasing the planting area of pollinizers. We recommend that pollinizers should be planted not more than 10 m from ‘Fuji’.     

Differential structure and physiological response to canker challenge between ‘Meiwa’ kumquat and ‘Newhall’ navel orange with contrasting resistance

Asiatic citrus canker caused by Xanthomonas citri subsp. citri (Xcc) is one of the most detrimental diseases affecting citrus production. ‘Meiwa’ kumquat (Fortunella crassifolia) and ‘Newhall’ navel orange (Citrus sinensis) are two genotypes with contrasting Xcc resistance. In the current study, efforts were made to perform pairwise comparison between them in terms of structural difference and biochemical response to Xcc attack. Pinprick inoculation demonstrated that ‘Meiwa’ had lower disease incidence rate and smaller lesion size, concurrent with significantly less bacterial number at the inoculation sites relative to ‘Newhall’. Microscopic observation demonstrated that stomatal density and size of ‘Meiwa’ were significantly smaller than ‘Newhall’. Stomatal apertures of ‘Meiwa’ were smaller than ‘Newhall’ measured at 2 h after their leaves were immersed in Xcc suspension, consistent with the bacteria number in the internal tissues counted at 4 d. Epicuticular wax content of ‘Meiwa’ was significantly higher than that of ‘Newhall’, while no difference in palisade and spongy tissue was observed between them. Enzymatic activity assay showed that after Xcc inoculation, ‘Meiwa’ exhibited significantly higher activities of catalase (CAT), peroxidase (POD) and phenylalanine ammonia-lyase (PAL) in comparison with ‘Newhall’ at most of the sampling time points. Our data showed that the two genotypes with contrasting Xcc resistance exhibited clear difference in the structure and physiological response, which may provide information to facilitate our understanding of Xcc resistance.     

Horticultural performance of ‘Folha Murcha’ sweet orange onto twelve rootstocks

Despite its outstanding position, the Brazilian citriculture is established on a very limited pool of varieties that limits its expansion and restricts the fruit availability throughout the year. This situation determines the urgent necessity of developing alternative scion and rootstock cultivars, with good performance under local conditions. ‘Folha Murcha’ sweet orange (Citrus sinensis (L.) Osbeck) is a late-harvest cultivar, suitable both for the juice processing industry and the fresh fruit market, being described as tolerant to citrus canker (Xanthomonas citri subsp. citri Schaad et al.), and less affected by citrus variegated chlorosis (Xylella fastidiosa Wells et al.). A study was conducted in Bebedouro, São Paulo State, Brazil, to evaluate the horticultural performance of ‘Folha Murcha’ sweet orange budded onto 12 rootstocks: the citrandarin ‘Changsha’ mandarin (Citrus reticulata Blanco) × Poncirus trifoliata ‘English Small’; the hybrid ‘Rangpur’ lime (Citrus limonia Osbeck) × ‘Swingle’ citrumelo (P. trifoliata (L.) Raf. × Citrus paradisi Macfad.); the trifoliates (P. trifoliata (L.) Raf.) ‘Rubidoux’, ‘FCAV’, and ‘Flying Dragon’ (P. trifoliata var. monstrosa); the ‘Sun Chu Sha Kat’ mandarin (C. reticulata Blanco); the ‘Sunki’ mandarin (Citrus sunki (Hayata) Hort. ex. Tanaka); the ‘Rangpur’ limes (C. limonia Osbeck) ‘Cravo Limeira’ and ‘Cravo FCAV’; ‘Carrizo’ citrange (C. sinensis × P. trifoliata), ‘Swingle’ citrumelo (P. trifoliata × C. paradisi), and ‘Orlando’ tangelo (C. paradisi × Citrus tangerina cv. ‘Dancy’). The experimental grove was planted in 2001, using a 7 m × 4 m spacing, in a randomized block design, with five replications and two plants per plot. No supplementary irrigation was applied. Fruit yield, canopy volume, tree tolerance to drought and to citrus variegated chlorosis, and fruit quality were assessed for each rootstock. Trees grafted onto the ‘Flying Dragon’ trifoliate were smaller in size, but had largest yield efficiency when compared to those grafted onto other rootstocks. Lower alternate bearing index was observed on trees budded onto ‘Cravo FCAV’ ‘Rangpur’ lime. Both ‘Rangpur’ lime rootstocks and the ‘Sunki’ mandarin induced higher tree tolerance to drought. The ‘Flying Dragon’ trifoliate induced better fruit quality and higher tolerance to citrus variegated chlorosis (CVC) to ‘Folha Murcha’ trees. A cluster multivariate analysis identified three groups of rootstocks with similar effects on ‘Folha Murcha’ tree performance. Among the 12 evaluated rootstocks, the ‘Flying Dragon’ trifoliate has a unique effect on plant growth, tolerance to drought and CVC, fruit yield and fruit quality of ‘Folha Murcha’ trees, and may be better suited for high-density plantings.     

Tree performance and fruit yield and quality of ‘Okitsu’ Satsuma mandarin grafted on 12 rootstocks

The citriculture in Brazil, as well as in other important regions in the world, is based on very few mandarin cultivars. This fact leads to a short harvest period and higher prices for off-season fruit. The ‘Okitsu’ Satsuma (Citrus unshiu Marc.) is among the earliest ripening mandarin cultivars, and it is considered to be tolerant to citrus canker (Xanthomonas citri subsp. citri Schaad et al.) and to citrus variegated chlorosis (Xylella fastidiosa Wells et al.). Despite having regular fruit quality under hot climate conditions, the early fruit maturation and absence of seeds of ‘Okitsu’ fruits are well suited for the local market in the summer (December through March), when the availability of citrus fruits for fresh consumption is limited. Yet, only a few studies have been conducted in Brazil on rootstocks for ‘Okitsu’. Consequently, a field trial was carried out in Bebedouro, São Paulo State, to evaluate the horticultural performance of ‘Okitsu’ Satsuma mandarin budded onto 12 rootstocks: the citrandarin ‘Changsha’ mandarin (Citrus reticulata Blanco) × Poncirus trifoliata ‘English Small’; the hybrid Rangpur lime (Citrus limonia Osbeck) × ‘Swingle’ citrumelo (P. trifoliata (L.) Raf. × Citrus paradisi Macfad.); the trifoliates (P. trifoliata (L.) Raf.) ‘Rubidoux’, ‘FCAV’ and ‘Flying Dragon’ (P. trifoliata var. monstrosa); the mandarins ‘Sun Chu Sha Kat’ (C. reticulata Blanco) and ‘Sunki’ (Citrus sunki (Hayata) Hort. ex. Tanaka); the Rangpur limes (C. limonia Osbeck) ‘Cravo Limeira’ and ‘Cravo FCAV’; ‘Carrizo’ citrange (Citrus sinensis × P. trifoliata), ‘Swingle’ citrumelo (P. trifoliata × C. paradisi), and ‘Orlando’ tangelo (C. paradisi × Citrus tangerina cv. ‘Dancy’). The experimental grove was planted in 2001, using a 6 m × 3 m spacing, in a randomized block design. No supplementary irrigation was applied. Fruit yield, canopy volume, and fruit quality were assessed for each rootstock. A cluster multivariate analysis identified three different rootstock pairs with similar effects on plant growth, yield and fruit quality of ‘Okitsu’ mandarin. The ‘Flying Dragon’ trifoliate had a unique effect over the ‘Okitsu’ trees performance, inducing lower canopy volume and higher yield efficiency and fruit quality, and might be suitable for high-density plantings. The ‘Cravo Limeira’ and ‘Cravo FCAV’ Rangpur limes induced early-ripening of fruits, with low fruit quality. ‘Sun Chu Sha Kat’ and ‘Sunki’ mandarins and the ‘Orlando’ tangelo conferred lower yield efficiency and less content of soluble solids for the latter rootstock.     

Comparative forcing of Hydrangea macrophylla ‘Bailer’ as a florist's hydrangea

‘Bailer’ (Endless Summer™) is a new, pink- or blue-flowered hydrangea that flowers on new wood continuously throughout the growing season. It is also winter-hardy in northern, temperate climates (USDA Z4). Use of Endless Summer as a florist's potted hydrangea would provide consumers with a dual-use product (flowering potted plant, landscape shrub). The objectives were to determine if Endless Summer could be forced as a florist's hydrangea using two forcing regimes (immediate, standard), two soil pH regimes, and two pinching treatments. ‘Merritt Supreme Pink’ (pink), ‘Blue Danube’ (blue), and Endless Summer (blue, pink) were forced under immediate (no cold treatment, short- and long-day photoperiods) and standard (6 weeks cold, 4 °C to overcome dormancy) conditions. Since commercial liners were not yet available, cuttings of Endless Summer were used in the immediate forcing experiment. Days to visible flower bud, first color, full flower were recorded, as well as height, no. of branches, no. of flowers, and flower size. In the immediate forcing experiment, only Endless Summer produced flowers. Cultivars differed significantly (P < 0.001) for days to visible flower bud, days to first color, days to full flower, and height. The number of flowers and flower size were not significantly different among pink cultivars. In the standard forcing experiment, Endless Summer reached days to visible flower bud, days to first color, and days to full flower significantly earlier than either comparison, although it exhibited weaker stems and less intense flower pigmentation. Pinching (blue pH) had a significant effect on all traits except the days to full flower and flower size, although no pinching treatment was significant for pink pH. Photoperiod was significant only for the days to visible flower bud (pink pH), days to full flower (blue pH), and final height (blue pH). Further research is needed before Endless Summer can be grown as a dual-use florist's potted hydrangea with acceptable quality.     

Evaluation of ‘Hamlin’ sweet orange + ‘Montenegrina’ mandarin somatic hybrid for tolerance to Xanthomonas axonopodis pv. citri and Xylella fastidiosa

Asiatic citrus canker (ACC), caused by Xanthomonas axonopodis Starr & Garces pv. citri (Hasse) Vauterin et al., and citrus variegated chlorosis (CVC), caused by Xylella fastidiosa Wells et al., are considered the main diseases affecting sweet orange scion varieties in Brazil. Among commercial varieties, mandarins and tangerines are recognized as tolerant to these pathogens. We report herein the production of ‘Hamlin’ sweet orange (Citrus sinensis L. Osbeck) + ‘Montenegrina’ mandarin (Citrus deliciosa Ten.) allotetraploid somatic hybrid plants by protoplast fusion with improved disease tolerance that could be used as a donor of resistance genes in interploid hybridisation. Somatic hybridisation was confirmed by leaf morphology, flow cytometry and RAPD analyses. The somatic hybrid was propagated by grafting and cultivated in a screenhouse for tolerance assays. For X. axonopodis pv. citri assays, buds were collected from both ‘Hamlin’ sweet orange and the somatic hybrid and grafted onto ‘Cleopatra’ mandarin (Citrus reshni hort. ex Tanaka). As a negative control, buds from ‘Mexerica Tardia’ mandarin (C. deliciosa) were collected and grafted onto ‘Cleopatra’ mandarin. Two-month old plants with at least one young vegetative flush were individually spray-inoculated with a 10⁶ CFU mL⁻¹X. axonopodis pv. citri suspension and incubated in a growth chamber, at 27 °C, under 16-h photoperiod. The somatic hybrid showed a statistically significant reduction in susceptibility to ACC 30 days after inoculation. Compared to ‘Hamlin’ sweet orange, disease severity was reduced by 70%, with similar tolerance to that of the mandarin negative control. For X. fastidiosa assays, buds were collected from the somatic hybrid and its parental plants and grafted onto ‘Rangpur’ lime (Citrus limonia Osbeck). The developed plants were needle-inoculated with a X. fastidiosa suspension (8.7 × 10¹⁰ CFU mL⁻¹) into the new growth flush stem. Bacterial population was quantified both at 4 (at the inoculation point) and 8 months (50 cm above the inoculation point) after inoculation. The first evaluation detected X. fastidiosa in 63% of ‘Hamlin’ sweet orange and ‘Hamlin’ + ‘Montenegrina’ mandarin samples. In the second evaluation, X. fastidiosa was detected in 47.4% of ‘Hamlin’ sweet orange and 10.5% of ‘Hamlin’ + ‘Montenegrina’ somatic hybrid samples, suggesting that bacterial movement was restricted in the somatic hybrid. X. fastidiosa was not detected in both evaluations in samples collected from leaves of ‘Montenegrina’ mandarin. These results indicate that the ‘Hamlin’ sweet orange + ‘Montenegrina’ mandarin somatic hybrid has potential for improved disease tolerance that should enhance its value regarding future use in citrus breeding programs.     

Effect of the expression level of an AGAMOUS-like gene on the petaloidy of stamens in the double-flowered lily, ‘Elodie’

Double-flowered lilies, in which stamens are converted to petaloid organs, are valuable for horticulturists. ‘Elodie’ is a double-flowered lily cultivar in which stamens are homeotically converted into petaloid organs in whorl 3. The ‘Elodie’ cultivar shows individual variation in stamen structure and it was therefore classified into the following three types according to the strength of petaloidy of the stamens: weak (type-I), intermediate (type-II), and strong (type-III) phenotypes. The AGAMOUS (AG) gene is a class C floral identity gene in Arabidopsis thaliana that is involved in the formation of stamens and carpels. An AG-like gene was isolated from ‘Elodie’ (LelAG1) and its expression was compared between flower types. The LelAG1 gene was expressed in whorls 3 and 4, but not in whorls 1 and 2 in all flower types. In type-I flowers, LelAG1 was expressed strongly in whorls 3 and 4, while its expression was significantly decreased in whorl 3 in type-III flowers. In type-II intermediate phenotype flowers, the expression level of LelAG1 in whorl 3 was reduced by 60%. These results suggest that the expression level of AG-like genes is correlated with the degree of petaloidy of the stamens.     

Delayed harvest improves red blush development and quality of ‘Cripps Pink’ apple

The poor red blush development on ‘Cripps Pink’ (Malus x domestica Borkh.) apple fruit at commercial maturity (CM) reduces the economic return to apple growers in warmer regions of the world. The effects of delayed harvest maturity up to 6 weeks following CM on the development of red blush and fruit quality of ‘Cripps Pink’ apple were investigated at two locations in Western Australia during 2003 and 2004. The red blush, export-grade fruit, total anthocyanin, cyanidin 3-galactoside, chlorogenic acid, catechin, and epicatechin of apple fruit skin tissues increased with advancement of harvest maturity at both locations in both years, whereas hue angle, concentration of phloridzin, fruit firmness, and titratable acidity (TA) of apple fruit tissues decreased with delayed harvest. The internal ethylene concentration was elevated with the delayed harvest. The concentrations of quercetin 3-galactoside, quercetin 3-arabinoside, quercetin 3-rutinoside, quercetin 3-rhamnoside, and quercetin 3-glucoside increased up to 2 weeks following CM, and then declined in 2003 at both locations and at Perth Hills in 2004. Delayed harvest resulted in improved development of red blush on the fruit surface, accumulation of total anthocyanin, cyanidin 3-galactoside, chlorogenic acid, catechin, epicatechin, and quercetin glycosides in fruit skin, SSC:TA ratio and reduced fruit firmness possibly due to the increased ethylene production.     

Identification of S-alleles in pear (Pyrus communis L.) cv. ‘Rocha’ and other European cultivars

In this work we report the cloning and identification of S-RNase alleles responsible for gametophytic self-incompatibility (GSI) of ‘Rocha’ pear and of 13 other European pear cultivars that might be used as its pollinators. Partial sequences of S-RNase alleles were amplified by PCR with specific primers hybridising in conserved regions of previously identified S-RNase alleles of Pyrus communis, cloned and sequenced and the S-genotype of eight pear cultivars was fully determined. Three cultivars (‘General Léclerc’ (SqSl), ‘Tosca’ (SbSl) and ‘Alexandrine Douillard’ (SbSk)) shared no S-alleles with ‘Rocha’ (SaSe) and shall be totally compatible with this cultivar. None of the cultivars analysed showed an identical amplification pattern to the one observed in ‘Rocha’, so the other cultivars shall be at least semi-compatible. One new allele was identified in P. communis cv. ‘Beurré d’Avril’ (designated as St). The determination of both S-RNase alleles of cvs ‘Rocha’, ‘Beurré Precoce Morettini’ (SeSk) and ‘Tosca’ and the identification of one S-RNase allele in cvs ‘Carapinheira’ (Sb), ‘Amêndoa’ (Se), ‘Pérola’ (Sk) and ‘Beurré d’Avril’ (St) are important contributions for the effort recently developed worldwide to establish groups of sexual compatibility among European pears.     

Alterations in flower and seed morphologies and meiotic chromosome behaviors of micropropagated rhubarb (Rheum rhaponticum L.) ‘PC49’

Variations in flower and seed and meiotic chromosome behaviors were investigated in micropropagated rhubarb (Rheum rhaponticum L.) ‘PC49’. The results showed that micropropagated plants had significantly higher variations in flower and seed morphologies and chromosome behaviors than plants derived from crown division. The results demonstrated that micropropagated plants grew 2–5 stamens, 8–13 stigmas, and 2–7 seed-wing, compared to 3 stamens, 9 stigmas and 3 (rarely 4) seed-wing in crown-derived plants. Additionally, alteration in chromosome behaviors (i.e. lagging and bridging) was observed only in micropropagated plants. All the results suggest that somaclonal variation may have been involved in micropropagated rhubarb ‘PC49’.     

Yield and fruit quality of ‘Gala’ and ‘Fuji’ apple trees protected by white anti-hail net

Covering apple orchards with nets protects them from hailstorms but this changes the amount and quality of the light supplied to the trees. This study was carried out to assess the effects of shade provided by white protection net on yield and fruit quality of apple orchards in Southern Brazil, along three growing seasons (2002/2003, 2003/2004, and 2004/2005). ‘Gala’ and ‘Fuji’ apple trees (on MM111 rootstock, raised as slender spindles, with a spacing of 5.5 m × 3 m) were left uncovered (control trees) or covered with white net. The white net reduced the photosynthetically active radiation (λ = 400–700 nm) accumulated over the trees’ canopy along a day by 18.4%, leading to a higher leaf chlorophyll content in both cultivars, and a higher specific leaf area in ‘Gala’. The shade provided by the net did not affect yield and increased fruit average weight in both cultivars. At harvest, the number of seeds per fruit and severity of russet were not affected by netting in both cultivars, as well as the incidence of watercore in ‘Fuji’. The main beneficial effects of the white net were the reduced incidence of sunburn on ‘Gala’, reduced incidence of bitter pit during cold storage in both cultivars, and reduced incidence of apple scab at harvest and of decay after cold storage in ‘Fuji’. Fruit fly damage in ‘Gala’ (assessed in one season) was reduced by netting. However, netting affected negatively some fruit quality attributes. ‘Gala’ and ‘Fuji’ apples from trees protected by the net had a poor skin color (pale blush and a more intense green background color) at harvest. The net reduced flesh firmness and SSC, and increased the starch index of ‘Gala’ apples at harvest, and reduced flesh firmness and SSC, assessed after cold storage and shelf life, in fruits of both cultivars.     

Rootstock effect on budburst of ‘Premier’ low-chill peach cultivar

To determine the effect of rootstock with different chilling requirements on the bud break of the low-chill ‘Premier’ peach cultivar (150 CH), the trees grafted on ‘Newbelle’ (150 CH) and ‘O’Henry’ (750 CH) seedling rootstocks were forced in a glasshouse after being subjected to 100, 200 and 300 CU chilling. The percentage of flower bud burst was slightly higher on ‘Newbelle’ than on ‘O’Henry’, although the difference was not significant. There was little leaf bud burst with 100 CU chilling on both rootstocks. With 200 and 300 CU chilling, the percentage of leaf bud burst and the total leaf number per tree was higher on the ‘Newbelle’ than on the ‘O’Henry’ rootstocks.     

Bract browning in waratahs (Telopea spp.) is not a localised calcium deficiency disorder

Bract browning in waratahs [Telopea spp. (Smith) R.Br.; Proteaceae] is a physiological disorder causing discoloration and necrosis of the margins and tips of exposed bracts. Experiments were carried out to determine whether calcium was involved in waratah bract browning, as browning and necrosis of leaf and bract tissue in other species such as lettuce and poinsettia has been attributed to a localised calcium deficiency. However, the inconsistent response of waratahs to calcium applied as a spray or to the potting media, and the lack of reduction in bract browning, suggests that factors other than calcium nutrition have a greater impact on the development and control of bract browning. This response corroborates reports questioning the role of calcium in late onset browning disorders.     

‘Swingle’ citrumelo propagation by cuttings for citrus nursery tree production or inarching

‘Swingle’ citrumelo [Citrus paradisi MacFaden × Poncirus trifoliata (L.) Raf.] has been extensively used as a rootstock in several citrus growing regions of the World, including Southern Brazil where ‘Rangpur’ lime (Citrus limonia Osbeck) is still the predominant variety despite being affected by several important pathogens. In this case, ‘Swingle’ citrumelo is used to produce nursery trees to establish new orchards or to be inarched in adult and healthy groves in order to change the rootstock. We report herein a system to produce trees on ‘Swingle’ citrumelo more rapidly by budding onto non-rooted cuttings, as well as assessing potential to rapidly multiply ‘Swingle’ through rooting of non-budded cuttings. Therefore, two potential products are described: budded trees and rooted rootstock cuttings. ‘Valencia’ sweet orange [Citrus sinensis (L.) Osbeck] was budded at different heights on cuttings derived from eight-month old rootstocks. Grafted and additional non-budded cuttings were then treated with indole-3-butyric acid (500 mg L⁻¹) or left untreated before rooting. Three types of cuttings were evaluated: softwood, semi-hardwood and hardwood. The use of nursery trees derived from pre-budded hardwood cuttings of ‘Swingle’ citrumelo is an alternative grafting method on this cultivar. Softwood cuttings with one leaf pair were considered the most adequate material for rapid multiplication of ‘Swingle’ citrumelo by cutting. This could be particularly useful for inarching production or conventional budding after transplant of cutting-derived rootstocks.     

Effects of nitrogen deficiency on leaf photosynthesis,carbohydrate status and biomass production in two olive cultivars ‘Meski’ and ‘Koroneiki’

The effects of nitrogen deficiency on CO₂ assimilation, carbohydrate content and biomass were studied in two olive (Olea europaea L.) cultivars (‘Meski’ and ‘Koroneiki’). One-year-old plants were grown in pots and subjected to four nitrogen levels for 58 days.     

Study on nutraceutical properties of different cultivars Ipomoea aquatica Forsskal (‘Chunbai’ and ‘Liulv’) in an eutrophic water body

Ipomoea aquatica Forsskal is a fast-growing aquatic economic plant and has been applied widely to purify eutrophic water, but little is known about the edible safety of it for humans or animals. The main purpose of our research was to assess the metal (copper, zinc, lead, cadmium and chromium) concentration and nutritional quality in the edible part of I. aquatica Forsskal (‘Chunbai’ and ‘Liulv’) growing in eutrophic water. The results showed that all levels of these metals were within the acceptable levels in our present studies, and the metal accumulating potential varied mainly depending upon levels of metal contamination in the water body in which they were growing. In the present investigation, nitrate content (NO₃–N) had no significant differences between ‘Chunbai’ and ‘Liulv’, but had significant differences (p < 0.001) between eutrophic water and Hoagland nutrient solution. Soluble protein, soluble sugar, and vitamin C content were affected greatly by variety and solution (treatments). The soluble protein and vitamin C content in ‘Liulv’ were one time higher but the soluble sugar content was one time lower than that in ‘Chunbai.’ The soluble protein and soluble sugar of plants cultivated in nutrient solutions were one time lower than that in eutrophic water. In addition, the vitamin C content of plants grown in Hoagland nutrient solution was approximately two times higher than that in eutrophic water. The possible utilization of these aquatic vegetables to meet the demands of food and health perspectives for consumers is discussed.     

An intact mitochondrial cox1 gene and a pseudogene with different genomic configurations are present in apple cultivars ‘Golden Delicious’ and ‘Delicious’: Evolutionary aspects

We have characterized the mitochondrial cox1 gene copies in two apple cultivars ‘Golden Delicious’ and ‘Delicious’. Both the cultivars contained an intact copy and a truncated copy of cox1. The intact ‘Golden Delicious’ and ‘Delicious’ cox1 genes, designated G-cox1 and D-cox1, respectively, were both found to be actually transcribed to give an RNA of approximately 1.7 kb. The two intact cox1 and two truncated copies (G-φcox1 and D-φcox1) shared a common 1115-bp segment flanked by four combinations of two different 5′- and 3′-sequences. PCR assay demonstrated that the configurations bearing G-cox1 and G-φcox1 existed in substoichiometric amounts within the mitochondrial genome of ‘Delicious’ whereas substoichiometric molecules carrying D-φcox1 were present in the ‘Golden Delicious’ mitochondrial genome. Although ancestor/descendant relationships cannot be inferred between the G-cox1 and D-cox1 arrangements, the results led us to hypothesize that (1) the 1115-bp segment containing part of the progenitor cox1 was duplicated, thereby generating a pseudo-cox1 copy, and (2) this was followed by homologous recombination across a portion of the 1115-bp repeats which gave rise to the descendant cox1 and pseudo-cox1 arrangements.     

Selection of potential pollinizers for ‘Hass’ avocado based on flowering time and male–female overlapping

Avocado production is dependent on the singular synchronous protogynous dichogamy of the species that promotes outcrossing. With the objective of selecting potential pollinizer avocado genotypes for ‘Hass’, the most important avocado cultivar worldwide, we have monitored during two consecutive years the flowering phenology of 27 avocado genotypes in South-eastern Spain. The average length of the flowering season was 45 days ranging from 18 days for ‘Harvest’ to 50 days for ‘Fuerte’. The earliest genotypes to flower were ‘Fuerte’ and ‘Shepard’ that started blooming during the third week of March. The latest genotypes to flower were ‘Colin V-33’, ‘Adi’, ‘OA184’ and ‘Harvest’, which started blooming in the second week of April. ‘Hass’ blooming lasted 30 days, from the first week of April until the second week of May. Since a good pollinizer must present not only an overlapping in the flowering season but also an overlapping in sexual stages with the pollinated cultivar, a group of 12 genotypes (‘Hass’, ‘Fuerte’ and 10 genotypes producing ‘Hass-like’ fruit with good overlapping in the flowering season with ‘Hass’) was studied with more detail determining daily the stages of male and female overlapping every 2 h. Results herein indicate that ‘Marvel’ and ‘Nobel’ showed a high sexual overlapping with ‘Hass’. Taking into account the flowering phenology, the overlapping in sexual stages and the fruit set obtained with hand-pollinated flowers in the field, those two genotypes could be an interesting alternative to the current use of ‘Fuerte’ as pollinizer for ‘Hass’ in South-eastern Spain.     

Preharvest aminoethoxyvinylglycine treatments reduce internal browning and prolong the shelf-life of early ripening pears

The effect of aminoethoxyvinylglycine (AVG) on internal browning (IB) and keeping quality of early maturing European pears cv ‘Camusina di Genova’ and ‘Camusina di Bonarcado’ was examined over 10 days of storage at 18 °C. AVG was applied at 125 or 250 mg/L 2 weeks before harvest. At harvest fruit treated with AVG was less ripe than control fruit, being significantly firmer and experiencing lower values of maturity stage (based on ground color), maturity index (calculated value) and IB, depending on the AVG dose and cultivar. During storage, there was no treatment-dependent difference in titratable acidity and total soluble solids of juice, while both treatments reduced ethylene and respiration rates, delayed the ripening process and lowered the incidence of IB and the loss of firmness, especially when applied at 250 mg/L. In addition, AVG treatment significantly reduced decay development in both cultivars, mainly when it was applied at 250 mg/L. This effect was related to the delay of ripen and to possible inhibition of ethylene production by the pathogens and/or infected tissues.