effect of enhanced UV-B radiation on fruit maturity and quality and leaf photosynthetic capacity in ‘Guifei’ mango. Our results reveal the response of ‘Guifei’ mango to enhanced UV-B radiation, which will be helpful for improving tolerance to UV-B stress
replications. One tree within each plot was designated for fruit drop counts and the remaining two trees per plot designated for sequential sampling for fruit maturity and quality assessments after storage. The mixing and application procedures described
A mechanical impulse system for determining tomato fruit maturity and size was tested, for development of a rapid, nondestructive fruit testing instrument. Fruit were grouped into various maturity categories, ranging from immature green to red, and impulse spectra were obtained at a site over the locule at marked locations. Resistance to puncture was measured on the locular side of the pericarp wall at the same locations. A sonic resonant frequency band was weakly correlated with fruit maturity category. Stronger correlations existed with pericarp puncture resistance and fruit weight. A description of essential components and utilization of the instrument for fruit firmness determination will be presented. Supported by OCAST (Oklahoma Center for the Advancement of Science and Technology) grant AR2-069, USDA grant 92-34150-7190 and the Oklahoma Agricultural Experiment Station.
Abstract
Fruit maturity induced by (2-chloroethyl)phosphonic acid (ethephon) in apples (Malus domestica Borkh.) and sour cherries (Prunus cerasus L.) was enhanced by tetrachloroisophthalonitrile (chlorothalonil). Chlorothalonil alone had no effect on any of the fruit maturity parameters measured, but in combination with ethephon, enhanced ripening in apple (color development, soluble solids, softening, and loosening) and loosening of sour cherries. Apple fruit ethylene production was advanced by this combination. The addition of chlorothalonil to ethephon sprays to loosen sour cherries permitted the use of lower ethephon concentration and eliminated gummosis in branches caused by standard rates of ethephon.
The susceptibility of five apple cultivars to bitter rot was examined by inoculating fruit with multiple isolates of Colletotrichum gloeosporioides and C. acutatum. Fruit were inoculated at three maturity dates in 1994. Fruit maturity was analyzed for firmness, soluble solids, and acidity. `Smoothee' and `Red Rome' were wounded-inoculated by placing 0.1 ml of inoculum (106 conidia/ml) into wounds while `Granny Smith', `Golden Delicious', and `Red Delicious' were inoculated by spraying unwounded fruit with inoculum until runoff. Free moisture was maintained on fruit for 15 h by enclosing fruit in a plastic bag. Bitter rot was quantified by counting lesion number and measuring lesion diameter. In general, more-mature fruit had a higher number and larger lesions than younger fruit. Lesion diameter was highly correlated with increased fruit soluble solids (r = 0.76) and decreased firmness (r = –0.77). The results indicate that fruit susceptibility increases as fruit ages. Differences in susceptibility were observed among apple cultivars and differences in virulence were observed among bitter rot pathogens.
Superoxide dismutase (SOD: EC 1.1.15.1.1) and peroxidase (POD: EC 1.11.1.7) activities were evaluated during maturity, ripening, and senescence of `Red Spur Delicious' (Malus domestica Borkh.) apple fruits. SOD and POD activities did not exhibit uniform changes during fruit maturity; however, during fruit ripening, activities of both enzymes increased significantly. During fruit senescence, SOD activity continued to increase, while POD activity declined by 24% to 50%. Fruit maturity at harvest significantly affected SOD and POD activities during the progression of ripening and senescence. SOD activity was significantly higher during ripening and senescence of fruits that were harvested at full and over-mature stages than in fruits harvested at early mature stage. In contrast, POD activity was lower in fruits that were harvested at full and over-mature stages than in fruits harvested at early mature stage. Increase in SOD and POD activities during fruit ripening suggest that these enzymes are actively involved in scavenging free-radicals generated during this developmental stage. However, the decline in POD activity during fruit senescence suggest a possible disruption of the breakdown of H2O2 free-radicals. This disruption may have contributed to tissue senescence and the induction of a physiological disorder called senescence scald.
Abstract
Flowering occurred over a 5-week period in semi-erect, tetraploid thornless blackberries (Rubus spp.) (cvs. Black Satin, Hull Thornless, and Dirksen Thornless). The harvest durations were slightly longer. The terminal flower bud of the primary axis (A1) of the inflorescence was first to open, followed by the terminal flower bud on one of basal secondary axes (A2). Remaining terminal flower buds on A2 axes opened sequentially in acropetal direction at a constant rate (two flowers/day). However, bloom pattern of flower buds located laterally on A2 axes was less definite. Within a floricane, the bloom on the primary fruiting laterals began at the distal end and progressed basipetally to the cane base. Ripening sequence of berries in a cluster followed that of the bloom. The time difference in anthesis between fruiting laterals and among flower buds within inflorescences was a major factor affecting the range of fruit maturity.
Abstract
A factorial study was designed to examine the effects of fruit maturities, juice extraction temperatures, storage time, and storage temperature on the quality of ‘Concord’ grape (Vitis labrusca L.) juice. Mature grapes produced juice with superior sensory quality and better objective color initially than less-mature grapes, but juice from grapes at both maturities had similar sensory quality after 18 months. The high extraction temperature (99°C) resulted in juice with better color initially than extraction at 60°, but juice extracted at 85° or 99° resulted in greater browning and loss of total anthocyanins during storage than extraction at 60°. High storage temperature (35°) greatly accelerated quality loss. Sensory color ratings correlated better with a ratio of absorbances at 520/430 nm (r = 0.95) and a/b (r = 0.92) than other objective color measurements.
Paclobutrazol (PB) was sprayed on hedged `Riesling' (Vitis vinifera L.) vines at one of five concentrations (0, 1000, 2000, 3000, or 4000 mg·liter-1) as single annual applications over 3 years (1987-89). Observations were made on growth, yield, and fruit composition during the years of application and 1 year thereafter (1990) to test carryover effects. PB had no effect on vine vigor, expressed as weight of cane prunings, during the three application years, but reduced vine vigor linearly with concentration in 1990. Yield was reduced by PB in the first 2 years of the trial, while in one season cluster weight and berries per cluster were also reduced. °Brix was increased by PB during all 3 years of application; titratable acidity was reduced and pH increased in the first year of application. PB sprays significantly reduced lateral shoot length, mean leaf size on both main and lateral shoots, and total leaf area on main and lateral shoots. Winter injury to buds, cordons, and trunks was also reduced with increasing PB level. Residues of PB in fruit in the first year of application ranged from 9 μg·kg-1 at the 0-m·gliter-1 level to 638 μg·kg-1 at the 4000-mg·liter-1 level. PB shows promise as a viticultural tool for advancement of fruit maturity, with possible additional benefits such as improved vine winter hardiness. Chemical name used β -[(4-chlorophenyl) methyl]-α -dimethylethyl)-1-H-1,2,4-triazole-l-ethanol (paclobutrazol, PB).
`Chandler' strawberries (Fragaria ×ananassa Duch.) harvested three-quarter colored or fully red were stored in air or a controlled atmosphere (CA) of 5% O2 + 15% CO2 at 4 or 10 °C to evaluate the influence of fruit maturity and storage temperature on the response to CA. Quality evaluations were made after 1 and 2 weeks in air or CA, and also after 1 and 2 weeks in air or CA plus 1 day in air at 20 °C. By 2 weeks, strawberries of both maturities stored in air at 10 °C were decayed, however, strawberries stored in CA at 4 or 10 °C or air at 4 °C had no decay even after 2 weeks plus 1 day at 20 °C. Three-quarter colored fruit stored in either air or CA remained firmer, lighter (higher L* value) and purer red (higher hue and chroma values) than fully red fruit, with the most pronounced effect being on CA-stored fruit at 4 °C. CA was more effective than air storage in maintaining initial anthocyanin and soluble solids contents (SSC) of three-quarter colored fruit and fruit stored at 10 °C. Strawberries harvested three-quarter colored maintained initial hue and chroma values for 2 weeks in CA at 4 °C, becoming fully red only when transferred to air at 20 °C. Although three-quarter colored fruit darkened and softened in 10 °C storage, the CA-stored fruit remained lighter colored and as firm as the at-harvest values of fully red fruit. After 1 or 2 weeks in CA at either 4 or 10 °C plus 1 day at 20 °C, three-quarter colored fruit also had similar SSC levels but lower total anthocyanin contents than the initial levels in fully red fruit. CA maintained better strawberry quality than air storage even at an above optimum storage temperature of 10 °C, but CA was more effective at the lower temperature of 4 °C. Three-quarter colored fruit responded better to CA than fully red fruit, maintaining better appearance, firmness, and color over 2 weeks storage, while achieving similar acidity and SSC with minimal decay development.