Commercial Harvest Time Research Articles

Cell cycle and germination of fresh, dried and deteriorated sugarbeet seeds as indicators of optimal harvest time

AbstractSeeds of sugar beet (Beta vulgarisL.) were collected at weekly intervals from 3 weeks before to 1 week after commercial harvest time, dried and stored at room temperature (18–22°C). Laboratory germination tests and flow cytometric analyses were performed immediately after harvest (fresh seeds) and five times at weekly intervals during storage (dry seeds). After 6 months of storage, seeds were exposed to a controlled deterioration treatment (CD). The proportion of G2nuclei in the embryo was constant in the fresh seeds, regardless of their maturity. It decreased, however, after drying and CD, especially in those seeds harvested before maturation drying had commenced. The proportion of endosperm cells in the seed decreased with maturation, and a further decrease was observed after drying and CD. These observations suggest that nuclei with a higher nuclear DNA content were more sensitive to water stress caused by premature desiccation and to deterioration than nuclei with a lower DNA content. Fresh seeds exhibited some germination, but this increased after drying, suggesting that desiccation induced a switch from the developmental to the germination mode. Germination percentages were the highest in dry seeds collected at the commercial harvest time and a week after. This high germinability coincided with the highest proportion of G2cells in the embryo. It is concluded that flow cytometry provides information about the status of sugarbeet seed maturation, seed quality and storage potential, and can be used for estimation of optimal harvest time.

Possible involvement of hydrogen peroxide in the development of resistance mechanisms in ‘Golden Delicious’ apple fruit

Apples (Malus domestica L. cv Golden Delicious) were picked 7 days before (harvest 1), or after (harvest 2) the commercial harvest time. Changes in H2O2 levels and in the activity of the H2O2-generating enzyme superoxide dismutase (SOD) and H2O2-scavenging enzymes catalase (CAT) and unspecific peroxidase (POX) were estimated immediately after harvest and during the first 24 h following wounding and inoculation with Penicillium expansum. Fruit from harvest 1 had lower decay incidence and severity of infection than those from harvest 2. Immediately after wounding or inoculation, the less susceptible fruit (harvest 1) showed a significant increase in H2O2 levels concomitantly with higher activity of SOD. No significant changes in CAT and POX were found. In susceptible fruit (harvest 2), both H2O2 levels and SOD activity in wounded/inoculated fruit remained similar to those in control fruit. In contrast, CAT and POX activity significantly increased as a consequence of wounding and inoculation. Collectively, these results provide evidence that harvest date is important in determining the susceptibility of ‘Golden Delicious’ fruit to P. expansum, and that H2O2 and associated metabolism induced by wounding could play a role in defence mechanisms in this fruit.

EFFECT OF AMINOETHOXYVINYLGLYCINE (AVG) ON ETHYLENE EVOLUTION AND FRUIT QUALITY OF JAPANESE PEARS AT HARVEST STAGE

The effect of aminoethoxyvinylglycine (AVG) applications on delaying fruit maturity in Japanese pear (Pyrus serotina) was investigated. A field experiment was conducted using (15-year-old) Japanese pear 'Kousui' and 'Housui' trees during the 2000 season, to investigate the effect of AVG on ethylene evolution and fruit quality parameters at harvests. The fruits were sprayed with 250 and 500 ppm concentrations of AVG, along with 0.1% Approach BI as a surfactant, 2 and 4 weeks before the commercial harvest time. Fruits were harvested at 2 different times, i.e. commercial harvest and 2 weeks after the commercial harvest time. Ethylene evolution was suppressed in both cultivars compared to the control, during both harvests. The decrease in ethylene evolution was more obvious following application of the higher concentration of AVG (500 ppm). Pre-harvest application of AVG had no significant effect on fruit quality parameters at either harvests. However, treatment effects on fruit firmness were evident: AVG applied 2 and 4 weeks before the commercial harvest at 250 and 500 ppm increased fruit flesh firmness at both harvests Fruit skin color tended to be greener in AVG treated fruit at both harvests for the 'Kousui' and 'Housui' cultivars.

Mango fruit calcium levels and the effect of postharvest calcium infiltration at different maturities

Calcium concentrations in ‘Kensington’ and ‘Sensation’ mango fruits were measured throughout fruit development on the tree. Flesh calcium concentrations fell from 2.1 to 0.8 mg/g d.w. for ‘Kensington’ and 1.6 to 0.8 mg/g d.w. for ‘Sensation’ as the fruits grew into maturity. Cuticle thickness in both cultivars varied only slightly during growth. Increases in cell wall thickness and in cell length and breadth were similar for both cultivars. Cell wall thickness was greatest in the outer flesh, while cell size increased most in the inner flesh of the fruit. Calcium concentration profiles were determined in ‘Kensington’ fruit harvested at normal commercial maturity for untreated fruit and fruit vacuum infiltrated (−33 kPa) with 4% (w/v) calcium chloride. Similar profiles were obtained for both cases. The skin, outer flesh, middle flesh and inner flesh had sequentially decreasing calcium concentrations. Concentrations ranged between 0.371 mg/g d.w. (skin) and 0.095 mg/g d.w. (inner flesh) for untreated ripened fruit. Corresponding concentrations for calcium-treated ripened fruits were 0.547–0.086 mg/g d.w. Calcium-treated fruits exhibited no differences in colour or firmness changes and weight loss during shelf life as compared to control fruit. Some lenticel damage was observed as a result of calcium infiltration. Shelf life studies were undertaken on control and vacuum infiltrated ‘Kensington’ and ‘Sensation’ mango fruits harvested at early (−3 weeks), middle, and late (+3 weeks) stages of maturity and on ‘Irwin’ and ‘Palmer’ mangoes harvested at middle maturity, i.e. normal commercial harvest time. Calcium levels in skin tissue of only ‘Kensington’ and ‘Palmer’ mangoes were slightly higher for calcium-treated than for untreated fruits. Calcium levels in flesh tissue were not increased by vacuum infiltration of calcium into any of the cultivars or maturities. Treatment with 4% (w/v) calcium chloride did not extend the shelf life of fruits of any of the four cultivars.

Leatheriness and mealiness of peaches in relation to fruit maturity and storage temperature

Summary`Huangjin' peaches (Prunus persica Batsch) were harvested at commercial harvest time (commercial) and 20 d before (early) or after (later) commercial harvest. Fruit from each harvest were stored at three temperature regimes (0, 5 and 10°C) at 95% r.h. After four weeks of storage at 0 or 5°C, early harvested fruit developed more leatheriness but less mealiness and later harvested fruit did not develop leatheriness but developed more mealiness comparedwith fruit from commercial harvest. Overall, fruit stored at 5°C developed more mealiness but less leatheriness than fruitat 0°C for the same period of storage. When stored at 10°C for two weeks, after which fruit were senescent, fruit did not develop any leatheriness or mealiness regardless of harvest times. Fruit with leatheriness were firmer (>30 N) thanjuicy or mealy fruit (<10 N) after the same period of cold storage and 4 d at 20°C. Mealy fruit were as soft as juicy fruit. 1-Aminocyclopropane-1-carboxylate oxidase (ACO) activity, 1-aminocyclopropane-1-carboxylic acid (ACC) content, and polygalacturonase (PG) and galactosidase (GAL) activities were lower, and insoluble pectin content was higher in leathery fruit than that in juicy or mealy fruit. ACO, PG and GAL activity, ACC, and insoluble pectin content were similar between mealy and juicy fruit.

Effect of harvest time and soaking treatment on cell cycle activity in sugarbeet seeds

AbstractCell cycle activity in dry and germinating untreated and treated (soaked in water and subsequently in fungicide) seeds of two sugarbeet cultivars, collected at commercial harvest time (late mature seeds) and about 2 weeks before this (immature seeds), was investigated by flow cytometry, and by immuno-detection of β-tubulin and the B-subunit of the 11 S globulin. Germination capacity and field emergence were tested. With dry seeds of both cultivars, higher G2/ G1ratios were observed in the radicle tips of late mature seeds, as compared with those from immature seeds. The late mature seeds contained more partly degraded (soluble) B-subunit of 11 S globulin, typical of germinating or primed sugarbeet seeds. Thus events associated with the onset of germination had occurred in the seed lots collected at commercial harvest time. The cytoskeleton protein β-tubulin was not detectable in dry seeds from either harvest. Western blotting revealed an accumulation of β-tubulin during germination and this was faster in the late mature harvested seeds which was correlated with the onset of DNA replication. Soaking enhanced the rate of cell cycle activation during germination as well as vigour, germination capacity, and field emergence. There was positive correlation between the G2/ G1ratio and the traits examined in laboratory and field tests. It is concluded that a combined analysis of proteins and cell-cycle-related events can be used in understanding and predicting sugarbeet seed quality.

Using Incidence ofBotrytis cinereain Kiwifruit Sepals and Receptacles to Predict Gray Mold Decay in Storage

A field-monitoring system has been developed to predict the incidence in storage of gray mold decay of kiwifruit caused by Botrytis cinerea. Kiwifruits were harvested from nine vineyards in 1993 and 1994, and their sepals and receptacles (stem ends) were surface sterilized and placed on acidified potato dextrose agar. The incidence of B. cinerea was determined after incubating dishes at 6 to 7°C for 6 days followed by 3 days at 23°C. At commercial harvest time, kiwifruits were harvested from these vineyards and stored at a controlled-atmosphere, cold (-0.5°C) facility. Postharvest gray mold was recorded after 3 and 5 months of storage. In both years, the incidence of sepal colonization decreased 3 months after fruit set and then increased until harvest time. In contrast, the incidence of receptacle colonization increased continuously from 4 and I months after fruit set until harvest in 1993 and 1994, respectively. In 1993, the relationship between incidence of B. cinerea in fruit sepals or receptacles and incidence of gray mold after 3 and 5 months of fruit storage was significant, as determined by linear regression, for most sampling dates from 4 months after fruit set until harvest. In 1994, all regressions were significant (R 2 = 0.55 - 0.96, P 50%) incidence of sepal or receptacle colonization by B. cinerea distinguished (predicted) the majority of the vineyards as having low ( 6%) incidence of postharvest gray mold decay after 5 months of storage, respectively. In vineyards where the incidence of gray mold decay was low to moderate ( 6%) incidence of gray mold significantly reduced fruit decay in storage.

A comparison of ethylene production, maturity and controlled atmosphere storage life of Gala, Fuji and Lady Williams apples (Malus domestica, Borkh.)

Gala and Lady Williams apples have distinct climacteric patterns of ethylene production but ethylene production remains low during ripening of Fuji apples. The Induced Ethylene Climacteric (IEC) method was found to accurately predict optimum harvest maturity for long-term CA storage of Gala apples. Alternative maturity indices are reported for Fuji and Lady Williams apples. Samples of the apple cultivars Gala, Fuji and Lady Williams were picked over a three week period around the commercial harvest time for each cultivar in the Harcourt area (Victoria, Australia). The fruit were stored under controlled atmosphere (CA) conditions (1.5% O2 at 0–1 °C). Samples were removed for analysis at 0, 3 or 4, 5, 7 and 9 months. Ethylene production rates were measured at harvest, and internal ethylene levels after various storage intervals. Firmness was assessed at harvest and after 7 and 9 months of CA storage and 18 or 25 days at 20 °C. Gala and Lady Williams cultivars showed climacteric ethylene patterns with ripening, but this was much less obvious with the cultivar Fuji. Gala apples maintained a higher level of firmness if put into CA storage in a preclimacteric state. For the other cultivars, edible quality after CA storage was much less affected by pick date. Consumer tests have suggested that Fuji and Lady Williams apples were improved by being harvested later than the presently used commercial harvest dates, and explanations for those findings are put forward.

Time of harvesting and storage of soyabeans: influence on oil quality

Soybean var. IAC-8 was harvested in five different times, two previous (R7 and R8) and two subsequent (C1 and C2) to the usual commercial harvest time (H). The seeds were air dried at normal ambient temperature before storage. Those with 15% moisture could be kept for only three months. Those with 12% moisture were kept for six months. Initial characterization of the seeds revealed the least oil content in seeds from the harvest of R8. In addition, the sample R8 had the least acidity and the oil had better storage properties regarding peroxide value. During storage a general increase in acidity has been observed in the oil from seeds from all the samples and at the two moisture levels. Peroxide value of the oil decreased after three months of storage, except for R8 oils, and were even lower in the 15% moisture seeds. Spectrophotometric absorption in the ultraviolet range indicated the formation of conjugated double bonds as the period of storage increased, independently of the harvest time and seed moisture. There was little change in the iodine values of any of the samples during the storage period. The oils from R8 were the ones that showed the least oxidative deterioration during the period studied, whereas R7 and C2 seed oils were considered to have deteriorated the most.

Effect of harvesting time on seed physiological quality, chemical composition and storability of soybeans

Soybeans IAC-8 were harvested in the growth stages R7 and R8 commercial harvesting time and at two other subsequent times to compare their physiological and technological characteristics. Seeds were stored at two moisture levels, 12% and 15%, for 6 months. Germination and vigor (acelerated aging, electrical conductivity), oil and free fatty acids, peroxide and iodine values were evaluated periodically. As expected, the time of harvesting and seed moisture content affected seed performance, while oil content did not correlate to physiological quality as did acidity, peroxide value and iodine number.

Skin Permeability to Oxygen in Apples Stored in Controlled Atmosphere

Abstract The skin permeability to O2-diffusion and the mass transfer equilibrium constant for ‘Super Golden Delicious’ spur and ‘Red Stark’ (Malus domestica Borkh.) have been studied using a kinetic approach. A direct proportionality between the O2-exchange initial rate and the environmental PO2 is shown by a linear regression line passing near the origin of the axes. This confirms the suitability of the adopted mass-transfer equations and allows the calculation of the two involved constants: the equilibrium mass-transfer constant and the kinetic constant, which represents a suitable measure of permeability of the apple skin. As apple-skin permeability to O2 increases with fruit ripening, to reach a maximum near the commercial harvesting time, this parameter could be used as a ripening index.

Changes of Organic Acids in Bartlett Pears during After-ripening

Changes in organic acids of Bartlett pears during after-ripening were investigated with elution chromatography on silicagel column. The pears picked at commercial harvest time in Yamagata prefecture were divided into two lots; Lot A was after-ripened at 20°-22°C immediately after harvest, and Lot B after seven days storage at 0-1°C. During cold storage for seven days, citric and malic acids and titratable acidity decreased to a slight extent. During after-ripening of both lots, citric acid decreased rapidly, malic acid increased in the first two days and decreased rapidly thereafter, and some acids which were assumed to be acetic, formic, oxalic, and glycolic acids increased remarkably at over-ripe stage. Lot A took eight days and Lot B six days for the optimum extent of after-ripening. At the optimum ripe stage, citric and malic acids contents in the fruits of Lot A were lower than those of Lot B.