Eggplant relatives as sources of variation for developing new rootstocks: Effects of grafting on eggplant yield and fruit apparent quality and composition

We propose the utilization of eggplant (Solanum melongena L.) interspecific hybrids derived from crosses with closely related species as an approach for developing new improved rootstocks for eggplant. Here we investigate rootstock effects on fruit yield, apparent quality and proximate and mineral composition of S. melongena ‘Black Beauty’ (BB) scions grafted on interspecific hybrid rootstocks developed from crosses of S. melongena with Solanum incanum L. (SI × SM) and Solanum aethiopicum L. (SM × SA). The results are compared with non-grafted (BB control) and self-grafted (BB/BB) controls and with S. melongena ‘Black Beauty’ scions grafted onto Solanum torvum Sw. (STO) and Solanum macrocarpon L. (SMA) rootstocks. All treatments were grown in a soil naturally infested with root-knot nematodes (mostly Meloidogyne incognita (Kofoid and White) Chitwood). SI × SM and SM × SA interspecific hybrids had high germination (≥90%) and total graft success (100%). Contrary to what occurred with all other treatments, no plants from scions grafted onto these hybrid rootstocks died during the experiment. In particular, the SI × SM hybrid rootstock conferred the highest vigour to the scion, which resulted in the highest values for fruit earliness and early and total yield. Little difference was observed among treatments for apparent fruit quality traits, except for a greater fruit calyx length and prickliness of fruit grafted onto SMA rootstocks. A similar result was obtained for fruit composition where phenolics content was higher in fruit from plants grafted onto SMA rootstocks. Grafting eggplant onto interspecific eggplant hybrids, especially on the SI × SM hybrid, has proved advantageous for eggplant production, as the high vigour and good compatibility of the rootstock with scion results in improved early and total yield without negative effects on apparent fruit quality or composition. Interspecific hybrids represent an alternative to the commonly used STO rootstock, which is a wild species with irregular germination.     

Effects of simple and double grafting melon plants on mineral absorption,photosynthesis, biomass and yield

The Spanish type cultivar ‘Piel de Sapo’ (Cucumis melo L. var. saccharinus), has a limited compatibility with the Cucurbita maxima × Cucurbita moschata hybrids currently used as rootstocks. Double grafting can be used to improve compatibility between rootstock and scion by means of an intermediate rootstock compatible with both. Non-grafted, single, and double grafted melon plants of the cultivar Piel de Sapo were evaluated for water, nutrient absorption, photosynthesis activity, biomass production in early phases, as well as for yields and fruit quality in a long term trial. The hybrid ‘Shintoza’ (C. maxima × C. moschata) was used as rootstock, and the cantaloupe type melon cultivar ‘Sienne’ as an intermediate scion. Grafting did not affect net photosynthetic values, yet increased water use efficiency (35%). Double grafted plants increased aerial dry weights (66% and 31% with respect to non-grafted and simple graft plants, respectively), and also increased capacity for uptaking beneficial minerals (between 61% and 13% and particularly for NO₃⁻, P, K, Ca, Mn, and Zn) with respect to non-grafted and single grafted plants. The quantum efficiency PSII photochemistry values increased in double grafted plants (12%) with respect to the control plants. Consequently, double grafting on a vigorous rootstock such as ‘Shintoza’, with an intermediate scion, results in improved mineral and water absorption and achieves an increase in ion influx to the scion – so enabling an increase in light photosynthetic reaction and biomass. Double grafted plants increased fruit yield when compared to simple grafted and non-grafted plants (12% and 56%, respectively) and did not affect fruit quality in terms of °Brix and colour. In conclusion, double grafting presents several beneficial aspects that are counter-balanced by the extra cost of the technique. The difference in yields reflects compatibility problems.     

Effects of low temperature storage on growth and transplant quality of non-grafted and grafted cantaloupe-type muskmelon seedlings

Grafting is a unique horticultural technology that allows the grower to select an alternate, compatible root system with natural disease resistance for their desired crop. Short-term storage of grafted seedlings under low temperature may extend the production window of grafted seedlings, reduce the labor input and increase production of grafted seedlings with a small propagation capacity. To evaluate the low temperature storage conditions, Cucumis melo ‘Olympic Gold’ seedlings were grafted onto Cucurbita maxima x Cucurbita moschata ‘Tetsukabuto’ rootstock and stored for a period of 2 or 4 weeks at 9, 12, or 15 °C under 12 μmol m⁻² s⁻¹ photosynthetic photon flux (PPF). The study demonstrated that grafted seedlings could be stored at 12 °C for 4 weeks without significant dry mass accumulation or effects on post-storage growth and development. Grafted seedlings stored at 15 °C for 4 weeks had a significant increase in dry mass and stem elongation; this was not observed for the non-grafted seedlings stored under the same conditions, suggesting that the rootstock enhanced the scion growth at lower temperatures than optimal for muskmelon. Storing muskmelon seedlings at 9 °C caused chilling damage but the damage was pronounced for non-grafted seedlings than grafted seedlings. ‘Tetsukabuto’ rootstock, an interspecific squash, presumably has a chilling tolerance and increased the storability of muskmelon seedlings. Further optimization is needed but there is potential for using this technique as a tool for mass production of grafted muskmelon seedlings.     

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.     

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.     

Fruit quality in ‘Cripp's Pink’ apple,especially colour,as affected by preharvest sprays of aminoethoxyvinylglycine and ethephon

‘Cripp's Pink’ apple grown in Western Australia often develops poor colour at commercial harvest resulting in economic losses. To determine if fruit colour could be improved without advancing ripening, ‘Cripp's Pink’ apple fruit on trees were sprayed with aminoethoxyvinylglycine (AVG) alone, ethephon alone, or AVG followed by ethephon. The experiments were conducted at two different locations in Western Australia in 2002 and 2003. Fruit sprayed with AVG alone had retarded colour development at harvest. However, ethephon applied after AVG enhanced percent red blush, anthocyanin concentration and reduced chlorophyll concentration in the fruit skin in both locations. These fruit had similar colour to those treated with ethephon alone. Internal ethylene concentration and fruit firmness were unaffected by the different treatments in 2002. However, in 2003 AVG with or without ethephon reduced internal ethylene concentration and maintained firmness compared to ethephon alone. In conclusion, AVG treatment alone delayed colour development and ripening of ‘Cripp's Pink’, while AVG application 5 weeks before harvest followed by an ethephon application 2 weeks later enhanced red colour at commercial harvest. This is, therefore, an effective tool for improving colour of ‘Cripp's Pink’ apples at commercial harvest without adversely affecting other fruit quality attributes.     

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.     

Yield performance,quality characteristics and fruit storability of winter squash cultivars in sub-humid areas

This research investigated the quality traits of eight winter squash cultivars (Cucurbita maxima, C. moschata, C. pepo and interspecific hybrids of C. moschata × C. pepo) during three years, but only ‘Tetsukabuto’ and ‘Violina’ were tested each year. In 2005 these two varieties were compared to ‘Butternut’; in 2006 to ‘Red Kury’, ‘Tan Cheese’ and ‘Kabosha’; in 2007 to ‘Red Kury’, ‘Mooregold’, and ‘Winter Luxury’. The characteristics recorded were: fruit yield, storage ability, chemical composition and sensory quality. Following harvest and sorting of marketable winter squash, 50 fruits for each cultivar were stored at 12 °C for 12 weeks the 1st year, and for over 20 weeks in 2nd and 3rd years, during which rotten fruits were counted. Compositional analyses regarding sugar concentration, starch, carotenoids and dry matter content at harvest and after storage were carried out; a panel test was organised to assess sensory traits. The most interesting cultivars were ‘Tetsukabuto’ for yield, ‘Tetsukabuto’ and ‘Mooregold’ for storability, ‘Red Kury’ and the same ‘Tetsukabuto’ particularly for soluble sugars and carotenoids and sensory appreciation.     

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.     

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.     

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.     

Harvest and post-harvest apple fruit quality following applications of kaolin particle film in South African orchards

Sunburn on apples in the Western Cape region of South Africa can result in yield losses of up to 50%. Application of kaolin-based particle film (Surround^® WP) increases leaf and fruit surface reflectivity, thus potentially reducing heat load and sunburn. Trials were performed during 2002/2003 and 2003/2004 to assess the effectiveness of kaolin particle film in controlling sunburn on ‘Granny Smith’, ‘Braeburn’, ‘Fuji’, ‘Royal Gala’ and ‘Cripps’ Pink’ apples. Fruit quality and ripening were monitored following 1–4 months in regular atmosphere cold storage at −0.5 °C. Sunburn on exposed fruit was significantly reduced in ‘Granny Smith’ and ‘Fuji’. Kaolin treatment improved fruit colour of ‘Granny Smith’ and ‘Royal Gala’, and delayed starch conversion in ‘Granny Smith’ at harvest and during the early storage period but not thereafter. Incidence of watercore at harvest was significantly reduced by kaolin treatment, but this disorder disappeared during cold storage in both treatments. There were no effects on skin anthocyanin or phenolic concentrations in any cultivar compared to unsprayed fruit.     

Effect of synthetic auxins on fruit size of five cultivars of Japanese plum (Prunus salicina Lindl.)

Most of the Japanese plum (Prunus salicina) cultivars grown in Israel produce relatively small fruit. Application of 2 l solution tree⁻¹ of 25 mg l⁻¹ 2,4-dichlorophenoxypropionic acid (2,4-DP) as butoxyethyl ester (Power™), 15 mg l⁻¹ 3,5,6-trichloro-2-pyridyloxyacetic acid (3,5,6-TPA) as free acid (Maxim^®), or 25 mg l⁻¹ 2,4-dichlorophenoxyacetic acid (2,4-D) + 30 mg l⁻¹ naphthaleneacetic acid (NAA) (0.3% Amigo™) at the beginning of pit-hardening, when fruitlet diameter was ca. 22 mm, caused an appreciable and significant increase in fruit size. The yield of large fruit per cv.: ‘Kesselmen’ (100% increase), ‘Songold’ (100%), ‘Black Diamond’ (800%), ‘Royal Diamond’ (160%) and ‘Royal Zee’ (100%). As a result, the total yield of all five cultivars was also increased dramatically. Anatomical studies with ‘Songold’ revealed that the main effect of these synthetic auxins was via direct stimulation of fruit cell enlargement. The above auxins had no negative effect either on fruit quality at harvest (and after 1 week in shelf-life), or on return yield in the following year.     

Growth,yield and fruit quality of ‘Van’ and ‘Stark Hardy Giant’ sweet cherry cultivars as influenced by grafting on different rootstocks

The influence of Adara, CAB 6P, Gisela 5, MaxMa 14, Saint Lucie GF 64 (SL 64), Saint Lucie GF 405 (SL 405), and Tabel rootstocks onto vegetative growth, yield and fruit quality of ‘Van’ and ‘Stark Hardy Giant’ (SHG) sweet cherry cultivars was studied during 10 years after grafting. The experiment was performed in the Ebro Valley (Zaragoza, Spain), on a heavy and calcareous soil. Significant differences in some of these parameters such as vigour, yield, fruit size, soluble solids content (SSC), titratable acidity (TA), skin colour and fruit firmness were examined among rootstocks. In general, the highest vigour, annual and cumulative yield were induced by Adara rootstock, whereas Gisela 5 induced the lowest when grafted with both cultivars. The highest yield efficiency was induced by Gisela 5 due to its low trunk cross-sectional area (TCSA), together with Adara, CAB 6P and Tabel for ‘SHG’ cultivar. Regarding fruit quality, Adara, CAB 6P and MaxMa 14 showed, in general, the highest fruit weight and the more attractive skin colour for both sweet cherry cultivars. Furthermore, the high yield shown by Adara did not significantly affect its fruit size. Cherries of trees grafted on Adara also showed high firmness, which implies a better resistance to post-harvest damage. CAB 6P showed a tendency to induce higher TA. Despite the higher firmness of fruits on Gisela 5 and its tendency to induce higher SSC and ripening index, the smaller size fruits together with the less attractive skin colour resulted in a non-interesting rootstock in terms of fruit quality for our growing conditions. Interesting correlations were found among quality parameters, such as the positive correlation showed by SSC with fruit weight and TA. The work demonstrates that the scion–rootstock combination influences some important sweet cherry attributes such as vigour, yield, fruit size, acidity, skin colour and firmness.     

Carbohydrate profiles in the graft union of young sweet cherry trees grown on dwarfing and vigorous rootstocks

In composite (scion–rootstock) dwarfing fruit trees, an overgrowth at the graft union is often observed, the severity of which is correlated with degree of dwarfing. The graft union of dwarfing sweet cherry (Prunus avium L.) rootstocks may limit soluble sugar transport or starch mobilization, leading to localized accumulation. Soluble sugars and starch were measured in the tissues surrounding the graft union of young ‘Rainier’ (2002) and ‘Lapins’ (2003) sweet cherry trees on ‘Gisela 5’ (‘Gi 5’; dwarfing) and ‘Colt’ (vigorous) rootstocks. Separate rootstock shank, rootstock, graft union, and scion tissues were analyzed for both starch and soluble sugar content throughout the growing season in both years. Starch concentrations did not vary among locations within the graft union for ‘Rainier’ on either the dwarfing or vigorous rootstock, or for ‘Lapins’ on the dwarfing stock. However, for ‘Lapins’ on ‘Colt’, starch was highest in the rootstock shank and declined vertically (rootstock shank ? rootstock > union > scion). Soluble sugar concentrations were generally similar to or higher in scions on ‘Gi 5’ than on ‘Colt’, and were similar to or lower in the rootstock and rootstock shank on ‘Gi 5’ than on ‘Colt’. Results suggest that rootstock has a significant effect of localized accumulations of carbohydrates above and within the graft union of ‘Gi 5’ and below the graft union of ‘Colt’.     

1-MCP处理对不同采收成熟度‘徐香’猕猴桃保鲜效果的影响

以‘徐香’猕猴桃为试材,研究了4个采收期(盛花期后1301、381、46和154 d)1-MCP(1-甲基环丙烯)浓度为0.5μL/L处理24 h后,在(2±1)℃下贮藏后的保鲜效果。结果表明:1-MCP能够显著降低‘徐香’果实低温贮藏过程中呼吸速率、乙烯释放速率,延缓果实硬度、可滴定酸的下降以及可溶性固形物的上升;4个采收期的1-MCP处理果实出库后均能正常后熟,但品质和保鲜效果存在差异,其中Ⅱ、Ⅲ期处理果实在贮藏期结束时保持较高的硬度、可滴定酸和VC含量,并且110 d时失重和腐烂率较低;货架期末硬度、糖酸比相对较高,失重率和腐烂率较低。由此推断‘徐香’猕猴桃盛花期后138~146 d采收品质好,此时的1-MCP处理效果最佳。     

Influence of 1-methylcyclopropene on pectic enzyme activities,gene expression,and cell wall modification in papaya (Carica papaya cv. ‘Sunrise’) fruit

SUMMARY

‘Sunrise’ papaya fruit harvested at two stages of maturity [colour break (< 10% yellow peel colour) and 25% yellow peel colour] were treated with 100 nl l^–1 1-methylcyclopropene (1-MCP) to determine its effects on ripening, on the activities and levels of gene expression of polygalacturonase (PG), pectin methyl esterase (PME), and βgalactosidase ( βGal), and on the degradation of cell wall components. 1-MCP delayed ripening and the onset of the climacteric, although the peak in the respiration rate was almost the same as that in untreated control fruit. Colour-break fruit treated with 1-MCP exhibited a continuous increase in ethylene production, but at a lower rate than in control fruit. Consequently, 1-MCP-treated fruit ripened with a concomitant reduction in firmness, which was accompanied by an increase in PG and βGal enzyme activities and gene expression. On the other hand, fruit treated with 1-MCP at the 25% yellow stage exhibited lower levels of ethylene production and developed pulp with a rubbery texture at the ripe stage which was attributed to reduced PG, βGal, and PME enzyme activities and gene expression. This was consistent with the higher level of cell wall polysaccharides measured in 1-MCP-treated fruit. The above results indicated that ‘Sunrise’ papaya fruit can be treated with 1-MCP at the colour break stage since they have a greater capacity to recover from the effects of 1-MCP than fruit treated at the 25% yellow stage.     

Physicochemical changes in Mazafati date fruits incubated in hot acetic acid for accelerated ripening to prevent diseases and decay

A method was developed and optimized for the accelerated ripening of date fruits of cultivar ‘Mazafati’ to prevent diseases and decay. The date fruits were incubated in hot acetic acid solution 0.5% at 40 + 1 °C for 72 h. During the process some physicochemical changes in the fruits were studied and were found to be comparable with the changes in the fruits that naturally ripened on the tree. Fruit firmness, water insoluble solid (WIS), protein, pH, L*a*b* and E decreased during accelerated ripening whereas in control samples at 4 °C increased. Total solid (TS), total soluble solid (TSS) and acidity were slightly higher in treated fruits compared to control fruits. The greatest loss of fruit firmness occurred during the first 12 h of incubation. Organoleptic tests also showed little difference between the naturally ripened fruits on trees and accelerated ripened fruits in hot acetic acid. Overall there was no difference between the fruits and were readily acceptable to consumers.     

1-MCP对不同成熟度白凤桃冷害发生的影响

以白凤桃果实为材料,研究了1-甲基环丙烯(1-MCP)对低温冷藏条件下果实成熟生理和冷害发生的影响。实验采用25μL/L1-MCP分别对底色转白期(MG)和成熟期(RR)桃果实进行处理,然后置于(0±1)℃冷库中贮藏24d。结果表明,1-MCP处理都能够延缓MG和RR果实的后熟软化进程,降低乙烯释放量,并抑制了果实快速软化阶段的PG酶活性;1-MCP处理提高了贮藏后期MG果实的硬度,降低了出汁率,加剧了冷害的发生程度,1-MCP处理对RR果实的冷害发生率没有显著影响,表明1-MCP对桃冷害的发生程度与果实成熟度有关。     

‘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.