Search Results

You are looking at 111 - 120 of 1,153 items for :

  • "maturation" x
Clear All

Muskmelon [Cucumis melo L. (Reticulatus Group)] fruit sugar content is the single most important consumer preference attribute. During fruit ripening, sucrose accumulates when soluble acid invertase (AI) activity is less then sucrose phosphate synthase (SPS) activity. To genetically heighten fruit sugar content, knowledge of sugar accumulation during fruit development in conjunction with AI and SPS enzyme activities and their peptide immunodetection profiles is needed. Two netted muskmelon cultivars [`Valley Gold' (VG), a high sugar accumulator, and `North Star' (NS), a low sugar accumulator] with similar maturity indices were assayed for fruit sugars, AI, and SPS activity and immunodetection of AI and SPS polypeptides following 2, 5, 10, 15, 20, 25, 30, 35, and 40 (abscission) days after anthesis (DAA). Both cultivars, grown in spring and fall, showed similar total sugar accumulation profiles. Total sugars increased 1.5 fold, from 2 through 5 DAA and then remained unchanged until 30 DAA. From 30 DAA until abscission, total sugar content increased, with VG accumulating significantly more sugar then NS. In both cultivars, during both seasons, sucrose was detected at 2 DAA, which coincided with higher SPS activity than AI activity. At 5 through 25 DAA, SPS activity was less then AI activity resulting in little or no sucrose detection. It was not until 30 DAA that SPS activity was greater than AI activity resulting in increased sucrose accumulation. VG at abscission had higher total sugar content and SPS activity and lower AI activity than NS. Total polypeptides from both cultivars 2 through 40 DAA, were immunodetected with antibodies: anti-AI and anti-SPS. NS had Al isoforms bands at 75, 52, 38, and 25 kDa that generally decreased wtih DAA. One isoform at 52 kDa remained detectable up to anthesis (40 DAA) VG had the same four Al isoforms, all decreased with DAA and became undetectable by 20 DAA. It is unclear if one or all AI isoforms correspond with detected enzyme activity. VG and NS had one SPS band at 58 kDa that increased with DAA and concomitantly with SPS activity. VG had a more intense SPS polypeptide band at abscission then did NS. Thus, netted muskmelon sugar accumulation may be increased by selecting for cultivars with a specific number of AI isoforms, which are down-regulated, and with high SPS activity during fruit ripening.

Free access

Fruit maturity was hastened by 5 to 7 days with the application of GA3 and GA4+7 paste on petioles 4 weeks after full bloom and 3 to 4 days with the spray of both ethephon (1,000ppm) and dichroprop(30ppm) 62 days after full bloom. Fruit size was significantly increased by GAs treatment but there was a tendency of decreasing fruit size by ethephon and dichroprop treatments. Excessive softening of flesh was found in ethephon or dichroprop treated fruits while no significant difference was observed with GAs treatment until maturity. Calcium acetate partially prevented the enhancement of fruit softening and fruit size decrease induced by ethephon and dichroprop. Other fruit qualities such as soluble solids contents were not affected by the addition of calcium acetate except some delay in fruit maturity.

Free access

Abstract

Vegetative and fruit responses of ‘Montmorency’ sour cherries to Alar were evaluated from 1966 to 1968. Mature trees were treated with from 1000 to 8000 ppm of Alar at 2 weeks after full bloom. Alar significantly increased fruit color and decreased the force required to separate the fruit from its pedicel early in the harvest season. These differences were sufficient to advance the start of commercial harvesting one week. Fruit firmness was significantly increased in both handpicked and mechanically harvested fruit. Alar treated fruit showed a significant ability to resist softening when mechanically harvested. Fruit color and firmness enhancement was evident in both canned and frozen processed fruit.

Alar altered the fruit growth curve and contributed to a more uniform size. Fruit acidity and respiration were significantly reduced. Alar reduced terminal growth, by reducing internode length, but increased flower bud initiation.

Open Access

Abstract

Fruits were collected on weekly intervals in 1980, beginning at fruit set (ovary shatter) and continuing through harvest. Additional samples collected at harvest in 1980 and veraison in 1981 were sorted into preveraison green, postveraison green, and ripening categories. Seed number per berry was directly related to accumulation of 14C-photosynthate, fresh weight, and dry weight. Seed number had little relationship with berry content of indoleacetic acid (IAA), abscisic acid (ABA) or percentage of acidity. Percentage of soluble solids was not affected by seed number prior to veraison, but after veraison, percentage of soluble solids and intensity of juice color were inversely related to seed number. Nonripe fruit at the time of harvest had fewer seeds per berry, and fruit containing an immature seed did not accumulate ABA or enter veraison. IAA levels were similar in ripening and nonripening fruit. IAA declined to basal levels by about 55 days after peak bloom. ABA began to increase after 65 days from peak bloom and berry changes associated with veraison occurred after 72 days.

Open Access

This study was performed to characterize the physiological responses of tomato (Lycopersicon esculentum L.) fruit harvested at either 10% to 30% or 30% to 60% color change and treated with two forms of 1-methylcyclopropene (1-MCP). Tomato fruit were treated either by submersion for 1 min in 1-MCP aqueous solution at the ambient temperature or by exposure for 12 h at 20 °C in air with 1-MCP gas, then stored at 20 °C. The concentrations (1.0, 5.0, or 10.0 μL·L-1) in 1-MCP aqueous solution were achieved through addition of 0.5, 2.5, or 5.0 g of AFxRD-300 powder (2.0% formulation, Agro-Fresh, Inc.) to 10 L of the de-ionized water, following manufacturer's instructions. 1-MCP (0.5 μL·L-1) gas in a 174-L container was achieved through addition of 0.22 g of SmartFresh® powder (0.14% formulation, Agro-Fresh, Inc.) to 100 mL of tap water. Both forms of 1-MCP significantly delayed ripening of fruit at the two initial ripeness stages, as noted by a significant delay in fruit softening and peel color change. The firmness of 30% to 60% color change tomatoes was significantly retained in response to gaseous or aqueous 1-MCP. Control fruit softened rapidly and reached the minimum marketable firmness value (about 5 N) within 8 days of storage at 20 °C, whereas fruit treated with gaseous 1-MCP (0.5 μL·L-1) or aqueous 1-MCP (1.0 or 5.0 μL·L-1) reached the same stage after 16, 20, or 24 days, respectively. Firmness retention was also highly significant for 10% to 30% color change tomatoes treated with both forms of 1-MCP. The highest concentration of aqueous 1-MCP (10.0 μL·L-1) did not result in a further delay in ripening compared with treatment at 5.0 or 1.0 μL·L-1 1-MCP.

Free access

Plants were grown in a greenhouse in controlled hydroponic conditions, and fruit were harvested at different intervals from 18 to 94 days from fruit set (DFFS). AsA was higher in pepper than in tomato fruit. In pepper fruit, it increased very fast and reached a maximum at 50 DFFS and then decreased suddenly and reached a minimum about 60 DFFS. AsA in tomato fruit increased slowly and reached a maximum after about 75 DFFS and then declined slowly. The decrease in AsA is correlated with the initiation of ripening and with an increase in the activity of AAO. There was more putrescine in pepper than in tomato fruit. There were no major changes in spermine and spermidine in pepper and spermidine in tomato fruit. However, putrescine in pepper fruit and spermine in tomato fruit increased very early until about 30 to 38 DFFS and then decreased in a manner similar to the decrease in AsA. Putrescine in tomato fruit increased consistently and did not decrease even during the senescence of the fruit. We conclude that AsA decreases in tomato and pepper fruit after 75 and 50 DFFS, respectively, and this decrease is related to an increase in AAO and a decrease in putrescine in pepper and spermine in tomato fruit.

Free access

To compare the effects of growth regulators on preharvest fruit drop and fruit maturity, aminoethoxyvinylglycine (AVG) was applied to `McIntosh' apple trees at 75, 150, or 225 mg·L-1, at 8, 4, or 2 weeks before harvest (WBH). These treatments were compared to NAA, daminozide, and to an untreated control. All AVG treatments and timings except 75 mg·L-1 applied 8 WBH delayed preharvest drop and fruit maturity. AVG applied at 225 mg·L-1was more effective in delaying drop and development of maturity than other rates when applied 8 or 2 WBH, but at 4 WBH, 150 mg·L-1 gave equivalent results to 225 mg·L-1. AVG at 150 mg·L-1 was superior to NAA or daminozide as a stop-drop agent. No concentration, or time of application of AVG influenced fruit size at harvest. AVG reduced internal ethylene concentration (IEC) in `McIntosh' apples linearly with increasing AVG concentration. There was a linear relationship between time of AVG application (8, 4, or 2 WBH) and IEC in the fruit after harvest, and the time required for harvested fruit to enter the ethylene climacteric. Development of red color was delayed by AVG. This was attributed to a delay in ripening as determined by a slower increase in IEC and starch hydrolysis. In general, earlier application of AVG resulted in reduced effectiveness of lowering IEC following harvest. Chemical names used: aminoethoxyvinylglycine (AVG), naphthaleneacetic acid (NAA), succinic acid-2,2-dimethylhydrazide (daminozide).

Free access

AVG was evaluated for its effect on controlling preharvest drop and influencing ripening of `McIntosh' apples in Maine and Massachusetts. AVG consistently and effectively retarded preharvest drop. AVG was superior to NAA and comparable to daminozide in drop control. Dilute or 2× applications were more effective than applications made at lower water volumes. One application of AVG made 4 weeks before anticipated normal harvest was more effective in controlling preharvest drop than split applications of the same amount made earlier or later. In general, AVG delayed ripening as assessed by a retardation in the development of red color, maintenance of flesh firmness, delayed degradation of starch, and a delayed onset of the ethylene climacteric. We conclude that AVG is an effective drop control compound that is also useful as a management tool to extend the harvest window for blocks of `McIntosh' that would otherwise ripen simultaneously. Chemical names used: aminoethoxyvinylglycine (AVG), naphthaleneacetic acid (NAA), succinic acid-2,2-dimethylhydrazide (daminozide, Alar).

Free access

Abstract

SADH affected color enhancement of ‘Canino’ apricot (Prunus armeniaca L.) thereby increasing the percentage of fruit harvested during the first 2 harvests. The sprays at and after pit hardening had a greater effect on color than “after bloom” spray. Other parameters of ripening, however, were unaffected, or were even retarded, indicating the different effects of SADH on various species of stone fruits.

Open Access

for the successful culture of zygotic mango embryos. In this context, Pateña et al. (2002) effectively controlled browning of nucellar explants by adding coconut water to the embryogenesis induction medium. In addition, maturation of somatic embryos

Free access