Performance of an elite,hybrid family of a northern × southern highbush cross (‘Draper’ × ‘Jewel’)

A family of the cross of the northern highbush blueberry ‘Draper’?×?the southern highbush ‘Jewel’ (D?×?J) was propagated and phenotyped for plant size, yield, rate of flower, bud, and fruit development, leafing ability, winter hardiness, and fruit quality for 2 years in the field in Florida (FL), Georgia (GA), Michigan (MI), and Oregon (OR). In addition, a controlled greenhouse study was conducted on these progenies to estimate their chilling requirements. Significant levels of genotypic variability were observed for all the traits and the majority showed significant location and genotype?×?environmental interactions. Most of these traits were normally distributed across genotypes. There were many more flower buds per cane in GA than FL and OR, and many more vegetative buds broke in OR than in the southeastern states. Most of the various yield and growth traits were significantly correlated, except for flower buds per cane with plant height and width, and strength of leafing with plant width and flower buds/cane. Plants in OR developed much more slowly than those in FL and GA. There was a significant G?×?E effect on days to early green tip, floral bud break, and full bloom. Significant correlations were observed between all the developmental rates except between floral bud break and the days to full flowering and first blue fruit. Most individuals were severely damaged by winter cold in MI, although a few showed good tolerance. Significant location effects were observed for pH, titratable acidity (TA), soluble solids (SS), and SS/TA. Fruit in FL were a little softer and had higher SS/TA ratios than those in GA. There were significant interactions between genotype and environment for all the fruit quality traits except for fruit scar, firmness, anthocyanin content (ACY), and % juice. Fruit scar had a significant positive relationship with firmness and a significant negative relationship with flavor. Fruit color was significantly associated positively with soluble solids and ACY. Firmer fruit had significantly lower levels of ACYs. Fruit pH showed significant positive correlations with TA, TA/SS, and % juice, and significant negative relationship with SS and ACY. TA was significantly associated negatively with TA/SS and positively with ACY and % juice. TA/SS and ACY were positively correlated significantly with % juice. Two or three individuals were identified at each location that had high yields, were very early or late ripening and had excellent overall fruit quality. There were significant levels of genotypic, environmental (chilling hours) and G?×?E interaction among vegetative and floral buds for numbers of buds per shoot, percentage that developed and their developmental rate. The chilling requirement of highbush blueberry appears to be regulated polygenically as the D?×?J family segregated normally. On average, genotypes did more poorly at 250 and 350 chilling hours than the other chilling treatments.     

Physiology of fresh-cut ‘Galia’ (Cucumis melo var. reticulatus) from ripe fruit treated with 1-methylcyclopropene

‘Galia’ (Cucumis melo var. reticulatus L. Naud. cv. Galia) fruit were harvested at the three-quarter slip stage and treated with 1 μL L⁻¹ 1-methylcyclopropene (1-MCP) at 20 °C for 24 h. The fruit were processed and stored as fresh-cut cubes and intact fruit for 10 d at 5 °C. Ethylene production of fresh-cut cubes was approximately 4–5-fold higher than intact fruit at day 1. Afterward, the ethylene production of fresh-cut cubes declined significantly whereas that of intact fruit remained relatively constant at about 0.69–1.04 ng kg⁻¹ s⁻¹. 1-MCP delayed mesocarp softening in both fresh-cut and intact fruit and the symptoms of watersoaking in fresh-cut fruit. Continuously stored fresh-cut cubes and cubes derived from intact fruit not treated with the ethylene antagonist softened 27% and 25.6%, respectively, during 10 d storage at 5 °C while cubes derived from 1-MCP-treated fruit softened 9% and 17%, respectively. Fresh-cut tissue from 1-MCP-treated fruit exhibited slightly reduced populations of both total aerobic organisms and Enterobacterium, although the differences did not appear to be sufficient to explain the differences in keeping quality between 1-MCP-treated and control fruit. Based primarily on firmness retention and reduced watersoaking, 1-MCP treatment deferred loss of physical deterioration of fresh-cut ‘Galia’ cubes at 5 °C by 2–3 d compared with controls.     

Discrimination of four different postharvest treatments of ‘Red Delicious’ apples based on their volatile organic compound (VOC) emissions during shelf-life measured by proton transfer reaction mass spectrometry (PTR-MS)

Storage methods extend the postharvest life of apples from weeks to up to one year; however, these methods also alter the production of volatile organic compounds (VOCs), which amongst others, are important for aroma attributes. While the impact of storage on particular aroma components has been established, high throughput methods for determining the storage history during shelf-life are elusive. Here we show the potential of proton transfer reaction-mass spectrometry (PTR-MS), an MS-based metabolic fingerprinting technique, for characterizing fruit in the postharvest chain. The VOC fingerprint of apples (Malus × domestica Borkh. ‘Red Delicious’) was analyzed by PTR-MS during four weeks of shelf-life ripening after storage under four different storage conditions: ULO (ultra-low oxygen), DCA-CF (dynamic controlled atmosphere monitored by chlorophyll fluorescence), RLOS (repeated low oxygen stress) and 1-MCP (1-methylcyclopropene) in ULO. PTR fingerprint mass spectra of the apple headspace, obtained in short time without sample preparation or preconcentration, were sufficient to discriminate the four storage conditions during shelf-life. Moreover, we were able to monitor the changes in quality-critical VOC classes, including esters and terpenes, during shelf-life and observe the differential impact of the storage history on these VOCs. This work emphasizes the potential of PTR-MS as a valuable addition to targeted GC–MS-based approaches in postharvest research.     

Identification of a novel gene (Apq1) from the indica rice cultivar ‘Habataki’ that improves the quality of grains produced under high temperature stress

The appearance of brown rice grown under high temperature conditions is an important characteristic for improvement in Japanese rice breeding programs. We performed a QTL analysis of the appearance quality of brown rice using chromosome segment substitution lines of the indica cultivar ‘Habataki’ in the ‘Koshihikari’ genetic background. A line carrying a ‘Habataki’ segment on chromosome 7 showed a high percentage of perfect grains produced under high temperature conditions during the ripening period. To verify the role of this segment, and to narrow down the region containing the useful allele, substitution mapping was performed using multiple paired lines. As a result, the chromosomal location of a gene that we named Appearance quality of brown rice 1 (Apq1) was delimited to a 48-kb region. In addition, we developed an Apq1-near isogenic line (NIL) to evaluate the effect of Apq1 on various agronomic traits. Under high temperature conditions during the ripening period, the Apq1-NIL produced significantly higher percentages of perfect grains than ‘Koshihikari’. Other agronomic traits, including yield and palatability, were similar between the Apq1-NIL and ‘Koshihikari’. Therefore, the ‘Habataki’ allele of Apq1 will be useful in breeding programs aimed at improving the quality of grains ripened under high temperature conditions.     

In vitro induction of tetraploid plants from callus cultures of diploid bananas (<Emphasis Type="Italic">Musa acuminata</Emphasis>, AA group) ‘Kluai Leb Mu Nang’ and ‘Kluai Sa’

Tetraploid plants were induced successfully from diploid bananas Musa acuminata (AA genome) ‘Kluai Leb Mu Nang’ and ‘Kluai Sa’ (2n = 2x = 22) with in vitro oryzalin treatment. Calluses from in vitro-grown shoot tips of both cultivars were treated with oryzalin at concentrations of 1.5 or 3 mg l⁻¹ for 24, 48 and 72 h, respectively. The oryzalin treatments produced tetraploids at a frequency of 15.6% in ‘Kluai Leb Mu Nang’ and 16.7% in ‘Kluai Sa’ as detected by flow cytometry. Chromosome counting showed that the tetraploid plant chromosome number was (2n = 4x = 44). The selected tetraploid plants were transplanted in the field and variations in the morphological characteristic of leaf shape and fruit bunch compared to normal diploid plants were found under the same growing condition even after 3 years of cultivation.