Search Results
The purpose of this work was to investigate the influence of O2 and CO2 partial pressures on glycolytic carbon flux, phosphorylated intermediates, phosphate, pyrophosphate, and phosporylated nucleotides in asparagus spears tips stores at 1 °C. The effects of CO2 (0, 5, 10, and 20 kPa) combined with O2 pressures ranging from 0.1 to 16 kPa (1% O2 = 1.013 kPa O2 at 1 atm) were investigated. Spears were enclosed within a low-density polyethylene (LDPE) package (for the 5-, 10-, and 20-kPa CO2 treatments) having a surface area of 462 cm2 and enclosed in 1.95-L glass jars. Low O2 enhanced the interconversion of phosphoenolpyruvate (PEP) to pyruvate (PYR) and F6P to F1,6P2 relative to high O2. When spears tips at 16 kPa O2 were compared to those at harvest, little change occurred in the adenylate or phosphate pools. PPi and ATP contents decreased as the O2 partial pressure declined below 16 kPa O2. In general, as CO2 increased, PPi and ATP decreased, while Pi, ADP, and AMP increased. The adenylate energy charge (AEC) declined with a decline in the O2 partial pressure, declining most rapidly below 2 kPa O2. Low O2 reduced AEC relative to high O2. Increasing CO2 partial pressure reduced AEC, an effect not evident at lower O2. The data suggest low O2 and elevated CO2 impair oxidative phosphorylation and induce nonsustaining carbon metabolism, which may limit asparagus spear survival under O2-deficient conditions.
Asparagus (Asparagus officinallis L. `Giant Jersey') was stored a in flow-through system at 0°C under levels of O2 ranging from 0.1 to 21 kPa in combination with three levels of CO2 (0, 10 and 20 kPa) for 21 d. The resulting changes in RQ and soluble sugars were monitored. The levels of sucrose were higher at 0 kPa of CO2 and at O2 levels >2 kPa; however, those levels were extremely reduced at combinations of high CO2 and low O2. Glucose levels were higher at 0 kPa CO2 when O2 concentrations levels were >1.5 kPa compared to CO2 at 10 and 20 kPa. Fructose levels were maintained higher with CO2 at 20 kPa for all levels of O2, showing lower levels as CO2 decreased. Glycolytic intermediates were evaluated to support the sugar accumulation data. Phosphorylated intermediate levels were altered in spears by CO2 and O2 treatments. Glycolytic control point enzymes were analyzed and may account for sugar accumulation and/or degradation induced by the atmospheric treatments.
To help elucidate of the relationship between decline in sugar (especially sucrose) and senescence in asparagus (Asparagus officinallis L.), spears with or without tips were treated with 6-benzylaminopurine (6-BAP) and stored during 25 days at 0°C. 6-BAP was applied using a cheesecloth soaked with 100 ppm solution (30-s contact) immediately after harvesting to the tip or to the cut surface for spears that had 2 cm of the tip removed. Time-dependent profile of fluorescence, chlorophyll content, amount of fructose, glucose, and sucrose were measured for four segments from tip to the base of the spears over. Respiration rate and general visual quality were also evaluated for the whole spear on a daily basis. Three replications were used for all evaluations. 6-BAP reduced respiration rate of spears with intact tips, slowed the decline in fluorescence, and slowed chlorophyll degradation for the tip during 25 days of storage at 0°C. Respiration rate was higher in spears that had the tip removed, regardless the use of 6-BAP; however, the decline of fluorescence and chlorophyll degradation were lower in 6-BAP-treated spears. Application of 6-BAP also slowed the decline in sucrose content. 6-BAP effects were more marked when comparing with spears lacking their tip. The visual quality was higher in spears with tips that were treated with 6-BAP.
Abstract
Modified atmosphere (MA) packages of tulip bulbs (Tulipa gesneriana L. ‘Kees Nelis’) composed of 5 bulbs sealed in low-density polyethylene film (LDF-301, Dow Chemical) were exposed to 20°C for one week followed by 3 weeks of temperature regimes between 15° and 25°. The temperature changes resulted in little change in package CO2 and O2 equilibrium levels. Bulbs held in air flowered poorly after 3 or 4 weeks at most of the temperature regimes. Packaged bulbs held below 25°C yielded 80–100% normal flowers after 3 or 4 weeks storage. The dry weight (DW) of daughter bulbs within bulbs in air increased 7-fold during 4 weeks storage. These bulbs also lost 25% of total bulb DW, 35% of scale DW, and 20% of floral shoot DW. There was little daughter bulb enlargement and few significant changes in DW of other bulb organs in film-packaged bulbs during storage.
Abstract
Flowering of ‘Kees Nelis’ (Tulipa gesneriana L.) tulip bulbs was not impaired after 4 weeks of storage at 17°C in either 3 or 5% oxygen. ‘Kees Nelis’ bulbs stored in air or 1% O2 for 4 or 6 weeks and ‘Prominence’ bulbs stored at any reduced O2 level for 4 or 6 weeks flowered unsatisfactorily. Bulbs specially precooled later in the forcing season yielded unsatisfactory flowering after storage at 17°C regardless of cultivar. Low O2 levels (1 to 5%) reduced the respiration rate of bulbs stored at 17°C for 6 weeks compared to bulbs stored in air. Storage of ‘Kees Nelis’ bulbs for 3 weeks in air with 5 ppm ethylene caused flower abortion upon forcing. Three or 5% O2 reduced ethylene-induced flower abortion during storage.
Abstract
Intact plants of four Lycopersicon species, Solanum lycopersicoides Dun. and a L. esculentum Mill. × S. lycopersicoides intergeneric hybrid at the four- to 11-leaf developmental stage were subjected to temperatures of 20° or 2.5°C for 72 hr. Plants were assayed for chilling injury by a visual rating of damage on specified leaflets (VRL), chlorophyll fluorescence (CF), electrolyte leakage (EL), and a visual rating of plants (VRP). Correlations of genotypic effects were significant between a) CF and VRL, b) CF and VRP, c) VRL and VRP, and d) VRP and EL. Correlations of the temperature × genotype interactions were highly significant between a) CF and VRL, b) CF and VRP, and c) VRL and VRP. CF was the most precise assay to quantify chilling injury. The means for CF for each of five leaflets from a single leaf produced similar separation of genotypes. Chilling resistance of an intergeneric hybrid between sensitive L. esculentum Mill. cv Sub-Arctic Maxi and resistant S. lycopersicoides suggested dominant, nuclear gene control.
Abstract
Terms describing or identifying developmental stages of horticultural crops are not used consistently, thus the meaning of each term becomes ambiguous. The cause for this discrepancy is speculative; however, the discrepancy could be minimized if a set of widely applicable definitions were available as guides in selecting the appropriate terms. Lott (2) recommended definitions for the terms “mature” and “ripening” and their derivatives. However, his definitions of the term “mature” and its derivatives were restricted to fruit while it is still attached to the plant, and the definitions of the term “ripe” and its derivatives were restricted to physiological changes and conditions which occur in fruit following harvest, which limit the use of terms only to specific fruits and exclude any of those ripening prior to harvest.