Response of climacteric-type guava (Psidium guajava L.) to postharvest treatment with 1-MCP

Guava (Psidium guajava L. cv. ‘Allahabad Safeda’) fruit harvested at the mature light-green stage were exposed to 300 and 600 nL L⁻¹ 1-methylcyclopropene (1-MCP) for 6, 12 and 24 h at 20 ± 1 °C, and held in either cold storage (10 °C) for 25 days or ambient conditions (25–29 °C) for 9 days. Most of the physiological and biochemical changes during storage and ripening were affected by 1-MCP in a dose dependent manner. Ethylene production and respiratory rates were significantly suppressed during storage as well as ripening under both the storage conditions depending upon 1-MCP concentration and exposure duration. 1-MCP treatment had a pronounced effect on fruit firmness changes during storage under both the conditions. The reduced changes in the soluble solids contents (SSC), titratable acidity (TA) and vitamin C content showed the effectiveness of 1-MCP in retarding fruit ripening. Vitamin C content in 1-MCP-treated fruit was significantly higher than in non-treated fruit, and those treated with 300 nL L⁻¹ 1-MCP for 6 h. The development of chilling injury symptoms was ameliorated to a greater extent in 1-MCP-treated fruit during cold storage and ripening. A significant reduction in the decay incidence of 1-MCP-treated fruit was observed under both the storage conditions. 1-MCP at 600 nL L⁻¹ for 12 h, in combination with cold storage (10 °C) seems a promising way to extend the storage life of guava cv. ‘Allahabad Safeda’ while 1-MCP at 300 nL L⁻¹ for 12 and 24 h or 600 nL L⁻¹ for 6 h, may be used to provide 4–5 days extended marketability of fruit under ambient conditions.     

番石榴SRAP反应体系的建立与正交优化

采用正交设计方法,对影响番石榴SRAP反应体系的Mg2+、dNTPs、引物、Taq DNA聚合酶和模板DNA浓度等进行了优化,建立了适用于番石榴的SRAP反应体系。该优化的20 μL反应体系中包含2.5 mmol/L Mg2+,0.15 mmol/L dNTPs,0.4 μmol/L引物,1.5 U Taq DNA聚合酶和20 ng模板DNA。利用该优化体系通过64对SRAP引物组合对5份番石榴材料进行了SRAP-PCR扩增,结果表明SRAP引物及优化后的反应体系能够有效地用于番石榴种质资源鉴定及遗传多样性分析等研究。     

台湾软枝杨桃的引种及其适应性研究

研究了若干杨桃品种的生物学特性、适应性及其经济效益，结果表明：软枝杨桃、香蜜杨桃等品种适宜在漳州地区栽培，尤其以台湾软枝杨桃最为适宜。台湾软枝杨桃平均果重210g，可溶性固形物8.5%、总酸0.04%，平均种子数10个，周年开花结果，品质优异，市场批发价6~8元/kg，效益好。并提出了该品种配套栽培技术要点。     

1-MCP extends the storage and shelf life of mangosteen (Garcinia mangostana L.) fruit

Mangosteen (Garcinia mangostana L.) fruit were harvested when the peel (pericarp) was light greenish yellow with scattered pinkish spots. Fruit were exposed to 1 μL L⁻¹ 1-methylcyclopropene (1-MCP) for 6 h at 25 °C and were then stored at 25 °C (control) or 15 °C. The 1-MCP treatment only temporarily delayed softening of the fruit flesh, during storage. Storage life, defined as the time until the pericarp was dark purple, was much longer in fruit stored at 15 °C than in fruit stored at 25 °C. It was also longer in 1-MCP treated fruit (storage life at 15 °C: control 18 d, 1-MCP-treated fruit 27 d). The 1-MCP treatment also increased the length of shelf life, defined as the time until the pericarp turned blackish purple or showed calyx wilting, at 25 °C. 1-MCP treatment reduced ethylene production. It also reduced pericarp levels of 1-aminocyclopropane-1-carboxylic acid (ACC), and the pericarp activities of ACC synthase (ACS) and ACC oxidase (ACO). In the fruit flesh, in contrast, 1-MCP did not affect ACC levels and ACS activity, but the treatment reduced ACO activity. Taken together, both the storage life and the shelf life of the fruit were extended by the 1-MCP treatment. A decrease in ACO activity largely accounted for the effects of the 1-MCP on ethylene production in the pericarp.     

Calcium chloride extends the keeping quality of fig fruit (Ficus carica L.) during storage and shelf-life

The effects of postharvest application of fruit hardening chemical agents on fig (Ficus carica L. cv. Poona) fruit were compared with untreated figs during storage. The impact of calcium chloride (4%) was notable in terms of retention of fruit color, texture and increased accumulation of ascorbic acid, compared to untreated control figs. Pretreatment with calcium chloride (4%) was found to be most effective in checking the growth of both mesophilic aerobic bacteria and yeast and molds at low temperature (1 ± 0.5 °C; 95–98% RH) storage and it further delayed ripening and senescence of figs and was beneficial in prolonging the postharvest life twofold. Treated figs without microbial spoilage could be used for short term storage, transportation, distribution and marketing for long distance domestic markets in India.     

Controlled atmosphere storage of rabbiteye blueberries enhances postharvest quality aspects

Blueberries are highly perishable and therefore it is necessary to develop strategies to increase their storage life. Two rabbiteye cultivars (‘Centurion’ and ‘Maru’) were stored at 1.5 °C in either regular air or controlled atmosphere (2.5 kPa O₂ + 15 kPa CO₂) for up to 6 weeks. Measurements of firmness, soluble solids content, titratable acidity, weight loss, shrivel and blemishes were combined with determinations of antioxidant activities and total phenolic content. Weight loss and shrivel were not affected by storage atmosphere or storage duration. After 28 days, controlled atmosphere storage resulted in only half as much blemished fruit compared with storage in regular air. Additionally, fungal development in ‘Maru’ fruit was minimised by controlled atmosphere storage.Water-soluble extracts from ‘Centurion’ fruit had higher antioxidant activities and total phenolic content than those from ‘Maru’ fruit at harvest and after storage in regular air and controlled atmosphere. The highest increases in antioxidant activity and total phenolic content occurred during the additional 6 days of shelf-life at 20 °C.     

The effect of delaying harvest date on fruit quality and storage of late highbush blueberry cultivars (Vaccinium corymbosum L.)

The effect of delaying harvest on fruit quality and storage life was measured for the late-season highbush blueberry cultivars ‘Aurora’, ‘Elliott’ and ‘Liberty’. In all three cultivars as fruit ripened, there was a steady decline in TA while SS remained stable, indicating that the fruit were becoming sweeter. This was supported by taste panel perceptions of greater sweetness associated with later harvested fruit. There was also a significant overall reduction in fruit firmness and storage life as the percentage of blue fruit at harvest increased; however, a significant interaction for storage life between crop ripeness and cultivar was observed, indicating that the fruit of some cultivars were less influenced by overall crop ripeness than others. The storage life of ‘Elliott’ was significantly affected negatively by crop ripeness, while ‘Aurora’ and ‘Liberty’ were not. ‘Liberty’ produced the highest percentage of sound fruit of the three cultivars and its fruit stored the longest, suggesting that ‘Liberty’ and ‘Aurora’ fruit can be left longer on the bush before harvesting than ‘Elliott’ without significantly damaging storage life. This would allow ‘Aurora’ to develop a sweeter flavor before shipping. The physicochemical and sensory evaluations were highly correlated, suggesting that TA, SS and firmness can be used as predictors of consumer preferences.     

Effect of gum arabic as an edible coating on antioxidant capacity of tomato (Solanum lycopersicum L.) fruit during storage

Coating of tomato fruit with gum arabic has been found to delay the ripening process and maintain the antioxidant capacity. Gum arabic in aqueous solutions of 5, 10, 15 and 20% was applied as an edible coating to green-mature tomatoes which were stored at 20 °C and 80–90% RH for 20 days. Fruit coated with 10% gum arabic delayed the ripening process by slowing down the rate of respiration and ethylene production and also maintained total antioxidant capacity, lycopene content, total phenolics and total carotenoids during storage as compared to the uncoated control and fruit treated with 5% gum arabic concentration. The results suggest that by using 10% gum arabic as an edible coating, the ripening process of tomatoes can be delayed and the antioxidant can be preserved for up to 20 days during storage at 20 °C without any negative effects on postharvest quality.     

Inheritance of firmness in raw cucumber (Cucumis sativus L.) fruit

Summary Inheritance of raw cucumber fruit texture (Magness-Taylor Fruit Pressure Tester firmness) was investigated over a 4-year period from 1971–1974. Results from 2 separate but related experiments suggested that firmness was quantitatively inherited with sufficient additive effects to permit gain from selection. In a selection study within 4 F₂ populations derived from crosses between firm (Chipper and Gy3) and soft (Mincu and Green F) fruit type cultivars, variation among and within F₃ and F₄ families was significant but overall family means were not significantly higher than the high parent in any of the 4 crosses. Narrow sense heritability estimates for fruit texture were 0.80 in the Mincu × Chipper population and 0.77 in the Green F × Chipper, Mincu × Gy3, and Gy3 × Green F crosses. In a separate experiment, generation means analysis was used to assess the mode of gene action in 2 crosses: Green F × Chipper, and Gy3 × Green F. Additive genetic effects accounted for 98.8% and 99.3% of the total genetic variation within each cross, respectively.Scientific Journal Series Paper No. 9794.     

Pollen storage in cocoyam (Xanthosoma sagittifolium (L.) Schott)

Summary The effect of different storage conditions on cocoyam pollen viability was investigated. Two levels of temperature (0° and 5°C) and four levels of relative humidity (0, 10, 20 and 30 percent) represented the storage environments.Viable cocoyam pollen could be obtained after 28 days in storage. The best storage condition was 5°C and 30% relative humidity.     

Repeated treatment of apple fruit with 1-methylcyclopropene (1-MCP) prior to controlled atmosphere storage

The effect of multiple 1-MCP treatments prior to the establishment of controlled atmosphere (CA) storage on the quality of ‘McIntosh’ and ‘Empire’ apples [Malus × sylvestris (L.) Mill. var. domestica (Borkh.) Mansf.] was investigated. Fruit were harvested on three occasions over a 1 week period, and at each harvest cooled overnight and 1-MCP applied the following day. Fruit from the first or second harvests were treated again or for the first time when fruit from each successive harvest was treated. CA conditions were established after the last 1-MCP treatment and fruit were stored for up to 8 months. Delays in 1-MCP application generally resulted in progressively higher internal ethylene concentrations (IECs) at the time of treatment and lower firmness both at the time of treatment and after storage. Multiple 1-MCP applications kept IECs low and maintained firmness compared with single applications that were applied after 4 d. For ‘McIntosh’, external CO₂ injury was more prevalent after storage if fruit were treated without delays after harvest for earlier harvests while later harvests were less affected. For ‘Empire’, flesh browning was more prevalent in fruit from later harvests and 1-MCP treated fruit had higher levels than untreated fruit. Either early 1-MCP treatment or multiple treatments reduced senescent breakdown in ‘McIntosh’, and core browning and greasiness in ‘Empire’.     

Texture profiling of blueberries (Vaccinium spp.) during fruit development,ripening and storage

Blueberries are ‘soft fruit’, a name which underlies the impact that fruit texture plays in their marketability. Worldwide blueberry production has been increasing in the last years, and they are now the second most economically important soft fruit after strawberry. During pre- and postharvest ripening, fruit softening represents the most dramatic change, leading to important losses in quality during storage. To support the FEM breeding program toward the creation of new blueberry accessions with superior texture, we used a novel texture analyzer TAXTplus to improve the phenotyping resolution, a fundamental step for a more reliable and precise selection of the most suitable ideotypes. In this work change in the mechanical profile of the blueberry cultivar ‘Brigitta Blue’ was initially assessed during berry development, maturation and postharvest ripening, revealing important textural variations. In addition, this novel equipment was exploited to compare the fruit texture behavior at two specific stages, maturity and after postharvest cold storage, on a set of 49 different blueberry and hybrids cultivars and selections. A multivariate statistical approach, including principal component analysis, was employed to analyze the dataset related to the textural parameters, according to their performance. Finally a storage index, originally defined for apple fruit texture, was adopted to depict the different storage potential of a set of blueberry cultivars.     

Phyllochron Dynamics Under Controlled Environments in Rice (Oryza Sativa L.)

Previously, we reported that phyllochron of rice greatly fluctuated in the course of development under natural conditions. The present study was carried out to examine the phyllochron dynamics using the five near-isogenic lines (NILs) for heading time and the recurrent parent. The change of phyllochron was investigated under four different controlled conditions regarding daylength and temperature. Growth duration (days to heading) showed a large variation among different growth regimes as well as genotypes. Changes of phyllochron were evaluated in the genotypes by using a quartic polynomial regression that was well fitted to the change of phyllochron in the present controlled environments as previously observed under natural conditions. Phyllochron began to drastically increase after around the 5th phytomer order and decreased with the progress of reproductive development in similar manners under different environments. The pattern of phyllochron change varied from a flat to non-flat shape. The shape of the equation was affected by genotypes as well as daylengths and temperatures. In addition, the shape was closely related to the growth duration (days to heading) of the genotype, suggesting that the phyllochron might internally increase depending on the genotype controlling the heading date. Therefore, the present results showed that the sufficient examination of phyllochron dynamics is necessary for understanding a variation in the heading date of rice.     

Quality attributes of stored koubo (Cereus peruvianus (L.) Miller) fruit

Cereus peruvianus (L.) Miller (koubo, also known as apple cactus) is a new fruit crop in Israel. When the fruit reach full maturity, they tend to crack due to uncoordinated growth of the different fruit tissues. This phenomenon normally causes heavy fruit losses, as much as 90% of the total yield. To prevent this problem, fruit are usually harvested before they reach full ripening, i.e. at the violet stage, a practice that effectively prevents cracking, but also reduces the overall quality of the marketed fruit. In order to establish optimal harvesting protocols and storage conditions, we characterized fruit ripening under storage, comparing purple-harvested fruit, stored fruit (purple and red-ripe) and tree-ripened red-split fruit. Organoleptic tests indicated that the overall flavor increased concomitantly with the development of the red peel color. During ripening, the pH slightly increased, while titratable acidity and the content of malic acid decreased. These changes were more marked in stored than in tree-ripened fruit. The levels of polysaccharides, glucose and fructose did not change significantly during storage. The content of linalool and linalool derivatives increased dramatically during storage, being much higher than that of cracked tree-ripened fruit. Our results indicated that the overall quality of the fruit increased during storage as expressed by color change, decreased acidity and enhanced levels of aroma compounds, while the content of carbohydrates was practically unaffected.     

Some consequences of pollen storage in the raspberry (Rubus idaeus L.)

Summary Raspberry pollen was stored at 5°C and –13°C for six months and then tested for its ability to induce pyrene set and the production of viable seedlings, and for its effect upon the segregation of a major gene s. Only pollen stored at –13°C gave a pyrene set and germination percentage adequate to produce sufficient seedlings for a breeding programme. It is suggested that tests of pollen viability in the raspberry should include studies of pollen germination, and the effect of this pollen on pyrene set and seed germination. Possible causes of the loss of viability in the pollen stored at 5°C are discussed.     

Assessing guava maturity by statistical analyses of dropped fruit impact responses

A non-destructive method for assessing the maturity of guava fruit was developed based on the mechanical properties obtained from dropped fruit impact responses. The levels of maturity were classified with cluster and discriminant analyses on the raw impact measurements and their derived indices. The number of indices being processed was reduced with stepwise regression analysis. The accuracy of classification was improved using linear discriminant analysis to 76.3% with the penetrometer stiffness as a calibrator and to 84.2% with postharvest days as a calibrator. The performance shows that falling impact together with adequate statistical analyses provides a promising non-destructive approach in assessing the maturity of guava. The non-destructive nature was validated by repeating the test on the same specimen. The test mechanism is mechanical and can therefore be integrated as the maturity inference engine on an automated guava sorter.     

Importance of sepals in fruit and seed development in linseed (Linum usitatissimum L.)

Summary The green sepals in linseed (Linum usitatissimum L.) persist till almost the time of fruit ripening. Since the plant retains very few leaves and the fruits are better exposed to receive sunlight, the green sepals may be important in fruit and seed development. Influence of the removal of 0, 1, 3 and 5 sepals on the day of anthesis, 7, 15 and 25 days after anthesis on fruit and seed development was examined. Excision of all the fine sepals on the day of anthesis stopped fruit and seed development in the varieties M 10 and NP (RR) 45 but in Mukta the reduction was about 55%. Removal of three sepals also decreased fruit growth in Mukta and NP (RR) 45. The effect of removal of sepals was more pronounced on the number of seeds per fruit than on seed weight. Sepals fixed ¹⁴CO₂ and translocated ¹⁴C to seeds. However, the ¹⁴CO₂ fixation was maximum at early stages of fruit development, whereas a higher percentage of the fixed ¹⁴C was translocated at later stages of growth. It is suggested that the sepal size in linseed could be a useful selection criterion.     

Inheritance of resistance to fruit rot (Phytophthora capsici Leon.) and induction of resistance in bell pepper (Capsicum annuum L.)

Summary Fruit rot in bell pepper caused by Phytopthora capsici Leon. is a limiting factor in its commercial production. Crosses were made between Waxy Globe, a small fruited hot type, resistant to fruit rot and four highly susceptible bell pepper commercial cultivars (Chinese Giant, California Wonder, Osh, Kosh and Yolo Wonder). Studies of the F₁'s, F₂'s and backcrosses indicated that Waxy Globe carries a dominant gene imparting resistance to fruit rot. After three backcrosses with California Wonder, lines were obtained combining the resistance gene of Waxy Globe with the large fruit size and low capsaicin of California Wonder.     

Phenotypic diversity and relationships of fruit quality traits in apricot (Prunus armeniaca L.) germplasm

Fruit quality attributes were studied for two consecutive years in forty-three apricot cultivars and selections grown in a Mediterranean climate. Physical parameters (weight, size, flesh and skin colour, percentage of blush, firmness and percentage of dry matter), chemical parameters (total soluble solids content and acidity) and sensory parameters (attractiveness, taste, aroma and texture) were evaluated. A high variability was found in the set of the evaluated apricot genotypes and significant differences were found among them in all studied quality attributes. Year-by-year variations were observed for some pomological traits such as harvest date, flesh colour, fruit weight, firmness and soluble solids content. A high correlation was found among some apricot quality attributes. In addition, principal component analysis (PCA) made it possible to establish similar groups of genotypes depending on their quality characteristics as well as to study relationships among pomological traits in the set of apricot genotypes evaluated.