A major challenge in terms of commercializing 1-methylclopropene (1-MCP) to extend the storage life and control physiological disorders in European pears is that it irreversibly inhibits fruit ripening in some cultivars, particularly flesh softening that is necessary for optimal consumption quality. In this study, we examined the effect of 1-MCP pretreatments on fruit ripening and associated transcriptomic changes in ‘La France’ (Pyrus communis L.) pears during storage at 20°C and 5°C. Compared to non-treated controls, 1-MCP pretreatment suppressed fruit respiration and ethylene production rates, and markedly delayed flesh softening. Normal ripening (ethylene production and flesh softening to eating quality firmness) was observed in 1-MCP treated fruit after 42 d at 20°C, and 112 d at 5°C. Subsequent RNA-Seq analysis revealed that 6,427 genes, including those associated with ethylene biosynthesis (ACS1, ACS1b, ACO1, and ACO2), cell wall degrading enzymes (PG3, β-GAL, EG, and EXP1), and transcription factors (AGL18 and NAC29) were up- or down-regulated in non-treated fruit both at 20°C and 5°C. The expression patterns of these genes were disrupted by 1-MCP pretreatment, but up- or down-regulation was also observed when ethylene was detected in 1-MCP-treated fruit. Together, these findings demonstrate the potential for practical use of 1-MCP to extend storage life in ‘La France’ pears given that (i) a single application markedly extended storage life to 56 d at 20°C and 112 d at 5°C, and (ii) treated fruit could regain their softening capacity, thus eliminating previous irreversible ripening blockage concerns.
Young coconut shell cracking is a significant problem reported during trimming and polishing. By studying the shell structure, fruit development, pressure inside the shell (internal pressure) of young fruits, dissolved carbon dioxide in the coconut water and cracking incidence, as well as postharvest treatments to manipulate the pressure and carbon dioxide concentration, it was revealed that cracking depended on the physical property of the shell and the internal pressure. Cracking was principally found on the large carpel where the shell was the thinnest. The growing area presenting a high cracking incidence was found to have fruits with a thinner shell than fruits from a nearby area. The younger fruits had a weaker, thinner shell and high internal pressure. Once the fruits were 28 weeks old, the internal pressure dropped to slightly above atmospheric pressure. The level of internal pressure did not depend on rainfall or growing area. However, postharvest heating, dipping in water and exposure to carbon dioxide increased the internal pressure. To reduce shell cracking incidence, it is recommended to delay harvesting to allow shell strengthening, delay the trimming and polishing processes to allow water loss from the fruit and reduce the internal pressure. Dipping fruit in an anti-browning solution should also be brief to avoid water absorption.
Limes (Citrus aurantifolia Swingle) have a short postharvest life. Therefore, effective treatments increasing storage life to lengthen the time that produce remains fresh is desirable. This study evaluated the effects of postharvest treatments of 1-methylcyclopropene (1-MCP), gibberellic acid (GA3), and Aloe vera on lime storage life and fruit quality. The optimum individual treatments of 50% Aloe vera coating, 300 mL·L−1 GA3, and 750 nL·L−1 1-MCP were identified as most effective in extending lime postharvest life. Under ambient conditions (26.4 ± 1.0°C, 64.4 ± 7.4% RH), 1-MCP fumigation was the best treatment, increasing lime postharvest life to 28.2 days. The 1-MCP-treated fruit had a higher juice content than the control fruit. Also, soluble solid contents and titratable acidity were not significantly different, while ascorbic acid was lower than the control. Under cold room conditions (10.0 ± 0.3°C, 68.9 ± 12.4% RH), 1-MCP fumigation followed by Aloe vera coating was the best treatment, increasing lime storage life by 38.7 days. The longer storage time did reduce juice content in treated limes compared to untreated fruit. However, the treatment did not affect the soluble solid contents, titratable acidity, or ascorbic acid level. In conclusion, for optimum postharvest life in limes stored under ambient conditions, fumigation with 1-MCP is best. While for limes stored in cold rooms, a cotreatment of 1-MCP fumigation followed by Aloe vera coating maximizes postharvest life.
Self-incompatibility and compatibility of Citrus depressa (Shiikuwasha) and its related species were determined by pollen tube growth within the style. Among the 30 accessions investigated, twelve C. depressa, two C. ryukyuensis (Tanibuta), and three species derived from C. depressa, C. keraji, C. oto, and C. tarogayo, were self-incompatible, while ten C. depressa, one C. tachibana (Tachibana), and two C. tachibana relatives showed self-compatibility. Of the self-incompatible accessions, some cross-incompatible relationships were discovered. All self-incompatible C. depressa except “Ishikunibu” were cross-incompatible with each other. Two C. ryukyuensis were cross-incompatible. This species showed cross-compatibility with C. depressa. C. depressa “Ishikunibu” was cross-compatible with all self-incompatible C. depressa and C. ryukyuensis. From the above, three genotypes determining incompatibility were found in C. depressa and C. ryukyuensis. In addition, all self-incompatible C. depressa and C. ryukyuensis accessions were cross-compatible with self-incompatible C. keraji, C. oto, and C. tarogayo which are related to C. depressa. The present study suggests that S (self-incompatible) alleles of C. depressa and C. ryukyuensis are derivatives of themselves and not from C. maxima (pummelo), major source of citrus S alleles.
Papaya cultivators in northeast Thailand deal with dry conditions that dramatically affect growth, yield, and fruit quality. The use of intercropping fruit crops, especially banana, should improve papaya production. This study evaluated intercropping papaya and banana in terms of papaya growth, fruit quality, and nutrient content. Experiments were conducted at the Fruit Tree Experimental Field, Faculty of Agriculture, Khon Kaen University between January 2019 and July 2020. The mono-papaya and intercropped papaya with banana used 3 × 2 m spacing, and the intercropped papaya used 1 row of banana with 3 rows of papaya. Plant growth was analyzed between the 5th and 19th month post-transplantation, while fruit yield and nutrient status were evaluated between the 14th and 19th month after transplantation. Plant height, number of leaves, and girth were not different between mono- and intercropped papaya. All plant growth patterns were sigmoidal, reaching stable growth rates between the 15th and 19th month after transplantation. Fruit numbers were not significantly different, but banana-intercropping with papaya increased papaya yield through fruit length and pulp thickness. Nutrient levels in all plant parts were not significantly different. In addition, nutrient analysis identified that papaya fruit extracted N, K, and B at higher levels than other parts, while P and Ca were the highest removed by the stem.
Artificial pollination is essential in pears (Pyrus spp.) for stable fruit set and the production of high-quality fruit. Low temperatures in the early spring before bud flowering can damage pear pollen and pose a special risk to pollen production for artificial pollination. In this study, we sought to identify, in pears, the flower bud stage most susceptible to low-temperature pollen damage, observe anther development abnormalities, compare pollen sensitivities among seven pear cultivars, and evaluate the pollen cold injury inhibition efficacy of a coffee extract treatment for flower buds. The most cold-sensitive flower bud stage for the Japanese pear ‘Kosui’ pollen was the scale-separation stage, with pollen in that stage ranging from the pollen mother cell to the tetrad stage. In the ‘Kosui’ flower bud treated at −3°C over 10 h, the typical cold-induced anther development abnormalities were tapetum hypertrophy, cell debris, and anther locule shrinkage. Flower buds at the scale-separation stage of seven pear cultivars were treated with low temperatures in a model based on daily temperature changes during the winter season in Saitama, Japan, to reach daily minimum temperatures of 0, −1, −2, −3, −4, −5, and −6°C. The pollen germination rates of ‘Hosui’ were unaffected by low-temperature treatments between 0 and −6°C. Overall ‘Hosui’ showed the least reduction in pollen germination rate than the other cultivars evaluated. Our results strongly suggest that ‘Hosui’ is the most tolerant to low temperatures among the tested cultivars. In the laboratory environment, the application of a coffee extract before cold treatment delayed flower bud freezing and preserved pollen germination. These results are helpful in selecting varieties and treatments for the prevention of cold injury in pear pollen production.
Winged bean seeds require imbibition treatment to ensure fast and uniform germination. Seed soaking has been commonly used; however, it is unclear if this is a safe method for winged bean seeds. Solid matrix priming (SMP) is an imbibition treatment that combines seeds, a matrix and water in a specific ratio. It allows seeds to imbibe under controlled water uptake. We investigated the effect of imbibition treatments on seed germination of white winged bean. Soaked seeds had significantly reduced germination and emergence as a result of imbibition injury due to rapid imbibition. SMP at a seed: vermiculite: water ratio of 7:12:9 (w/w/w) was the most effective treatment that allowed seeds to imbibe slowly without the occurrence of imbibition injury. SMP significantly reduced the mean germination time from 4.63 days to 2.01 days, and mean emergence time from 7.21 days to 5.78 days, compared to the control, as well as having a high germination rate of 98% and uniform emergence. The fast imbibition rate of white winged bean seeds was likely the result of cracks present on the permeable seed coat.
Borecole (curly kale) was cultivated without heating during autumn and winter in a multi-film-covered greenhouse in Hokkaido, Japan. Borecole survived even when the greenhouse air temperature dropped to −6.2°C with an accompanying drastic increase in Brix value. This rapid increase of Brix value was observed under conditions where the minimum air temperature in the greenhouse was less than 0°C. Cold temperatures caused the plant to freeze, inducing extracellular freezing. Although the Brix value increased at low temperatures irrespective of leaf order, the Brix values for leaves of lower order, at the top of the plant, were much larger than the higher order leaves, closer to the base of the plant. Leaf Brix values started to increase when the average minimum temperature was 1.3°C or less for 10 days before harvest. Moreover, the nitrate concentration, reported to correlate with bitterness intensity, decreased at low temperatures. These results revealed that leaves with reduced bitterness and improved sweetness can be produced in low temperatures from the upper portions of borecole plants.
Supplemental interlighting is a technique to improve horticultural light conditions. However, optimal methods for energy-efficient supplemental lighting are not yet established. Therefore, this study investigated the influence of supplemental light canopy position during the tomato fruit enlargement stage on photosynthetic function and aboveground dry-matter weight. A supplementary interlighting module was fixed at the initial irradiation position, then the irradiation position for three other modules were raised to 10 cm above each fruit truss at different developmental stages. These stages were the early enlargement stage (ES), from flowering until the first fruit reached a diameter of 10 mm, then the vigorously enlarging stage (VES), with tomato fruit diameter from 10 to 30 mm, and the late enlargement stage (LS) with a tomato fruit diameter greater than 30 mm. Cultivation was carried out using a D-tray system with a planting density of 5.5 plants·m−2. The LED supplemental interlighting reduced specific leaf area (SLA), altering the plant canopy structure. This increased the canopy light transmittance from 40% to 70% at 20 cm from the canopy and from 20% to 40% at 40 cm from the canopy, especially during the ES. The total chlorophyll (Chl) content of leaves was higher under all irradiated treatments compared to the untreated control. However, Chl a/b ratios decreased for all treatments except in leaves under continuous LED irradiation. The maximum photosynthetic rate was higher in leaves closer to the supplemental interlighting exposure, but was lower in the 17th and 13th leaves at 6 μmol·m2·s−1 and 4 μmol·m2·s−1, respectively. Fruit dry-matter weight increased significantly to 143.2–156.5 g in all supplemental interlighting treatments compared with 119.6 g for the control. Interlighting treatment during VES achieved the highest yield and the greatest increase in fruit and total dry-matter weight. Therefore, VES-irradiation is most efficient to increase dry-matter weight.
Rosa foetida Herrm. is an important wild rose that contributed to the birth of modern yellow cultivars. It is also well known for the unpleasant odor, not prevalent in other roses, emanating from its petals. We analyzed the floral scent of R. foetida and its sport cultivars, R. foetida var. bicolor (Jacq.) Willm. and R. foetida f. persiana (Lem.) Rehd., to identify the causative compounds for their offensive odor. Fatty acid derivatives 2,4-decadienal (2,4-DA), 2,4-decadienol (2,4-DO), and (Z)-jasmone were detected by gas chromatography-mass spectrometry along with several terpenoids, phenylpropanoids, and hydrocarbons. Among them, 2,4-DA and 2,4-DO were identified as the causative compounds of the offensive odor. This is the first detection of these fatty acid derivatives in the scent of rose flowers. We also analyzed the floral scent of eight descendant cultivars of R. foetida: ‘Agnes’, ‘Harison’s Yellow’, ‘Rhodophile Gravereaux’, ‘Schloss Seusslitz’, ‘Soleil d’Or’, ‘Star of Persia’, ‘The Queen Alexandra Rose’, and ‘Williams’ Double Yellow’. 2,4-DA and 2,4-DO were only detected in the smell of ‘Star of Persia’. No other descendant was found to emit these fatty acids. This is the first analysis of an unpleasant odor in roses.