Abstract
Ethylene is known to accelerate the respiration and to hasten the loss of chlorophyll from lemons (3). In addition, ethylene-treated lemons, are more subject to decay than untreated fruit and, as a consequence, show a shortened storage life (1). Fruits exhibiting a respiratory climacteric typically show a concomitant increase in volatile production, including ethvlene (4). The present paper reports the effect of added ethylene on volatile production by lemons, a non-climacteric fruit (2). Although sound lemons have little or no odor, no previous study has been made of the volatile production of lemons.
Scatchard plots for ethylene binding in apples (Malus domestica Borkh.), which were harvested weekly for 5 weeks to include the ethylene climacteric rise, showed C50 values (concentration of ethylene needed to occupy 50% of the ethylene binding sites) of 0.10, 0.11, 0.34, 0.40, and 0.57 μl ethylene/liter-1, respectively, for each of the 5 weeks. Higher ethylene concentrations were required to saturate the binding sites during the climacteric rise than at other times. Diffusion of 14C-ethylene from the binding sites was curvilinear and did not show any indication of multiple binding sites. Ethylene was not metabolized by apple tissue.
Abstract
A 10-minute soak in 1.0 mm vitamin K5 reduced ethylene production over 90%, while doubling carbon dioxide production by cortical tissue from pre-climacteric apples (Malus domestica Borkh.). Reduced ethylene production persisted for at least 4 hours, while carbon dioxide production declined to rates not significantly different from the controls. Vitamin K5 also reduced ethylene production by 50% from quartered fruit of tomato (Lycopersicon esculentum Mill.) at different stages of maturity, and from cortex tissue from apples at or near their climacteric peak of ethylene production.
Abstract
Aqueous sprays of NH4F applied to ‘Early Improved Elberta’ peach trees significantly increased the % of abnormal fruits. Tissue firmness was increased on the dorsal side but decreased on the suture side. Suture tissues contained more F than dorsal tissues and both had higher F levels as the F spray concn increased. The climacteric of treated fruits was initiated before the untreated fruits at every sampling date where a climacteric occurred. Both malic and citric acids were decreased in the suture tissues of F treated fruits.
Abstract
My aim in this brief presentation is to illustrate how the interplay of senescence and homoeostasis can offer a context within which to question and, in part, explain various postharvest phenomena. I should like to begin by briefly noting the status of principal phenomena and related paradigms that have influenced postharvest research, namely the respiratory climacteric, ethylene, and molecular (genetic) determinants.
`Granny Smith' apples were stored at 1 °C, 5 °C and 20 °C, then treated at the preclimacteric stage with 2 ppm MCP, various O2 concentrations, and MCP + low O2. All the treatments greatly retarded the onset of the C2 H4 climacteric, and hence ripening. MCP + low O2 was much more effective than were the applications of MCP and low O2 singly. Even at 20 °C, 4.04 kPa O2 inhibited the rise in C2 H4 evolution for 145 d. Neither low O2 nor MCP inhibited the System 1 C2 H4 evolution. The suppression of the climacteric rise in C2 H4 evolution was accompanied by a strong inhibition of the accumulation of ERS1 C2 H4 receptor and ACS transcripts. On the other hand, ETR1 receptor was constitutively expressed. When climacteric fruits were treated with MCP, and with low O2 + MCP the rate of C2 H4 evolution decreased sharply. This occurred simultaneously with a decrease in ERS1 mRNA. Moreover, the decrease in ERS1 mRNA paralleled the decrease in C2 H4 evolution. The data thus indicate that the initiation and sustainment of the C2 H4 climacteric requires the presence of functional C2 H4 receptors. The expression of ETR2 and ERS2 is also under investigation.
To determine the ability of `d' Anjou' pear fruit to produce climacteric ethylene postharvest, fruit were harvested at a mature green stage, chilled at -1 °C for various times, then transferred to 20 °C to ripen. In addition, fruit were first held at 20 °C for various times, then at –1 °C for various durations, followed by transfer to 20 °C for 11 days. As storage time at –1 °C increased from 0 to 70 days, the time required to induce climacteric ethylene when transferred to 20 °C progressively decreased from 90 to 0 days. The total storage time (sum of d at chilling and nonchilling temperature) needed to induce climacteric ethylene remained nearly constant (70 to 90 days). However, this was not the case with fruit held initially at 20 °C, then transferred to –1 °C. The total storage time needed before the pears produced climacteric ethylene ranged from 70 to 110 days and increased with time of storage at 20 °C. These fruit required more time at –1 °C than those first stored at –1 °C. The chilling requirement mechanism of `d' Anjou' pears remains intact even during storage at nonchilling temperature and diminishes with senescence.
Abstract
Respiration and ethylene production were determined daily on fruit of A. atemoya Hort. stored at 20°C from preclimacteric to postclimacteric stages. At 5 stages, fruit were analyzed for water, sugars, starch, organic acids, Vitamin C, thiamin, titratable acidity, pH, and total soluble solids. The major changes during ripening were a continuous decrease in starch, a continuous increase in fructose and glucose, an increase in sucrose to a maximum at the climacteric, an increase in malic acid early in the climacteric rise, and a decrease in Vitamin C after the climacteric. Eating quality was optimal 2 days after the climacteric and the levels of protein, fat, dietary fiber, ash, sodium, potassium, iron, calcium, magnesium, zinc, riboflavin, niacin, α-carotene, β-carotene, cryptoxanathin, energy content, and edible portion were determined at this stage. Fruit were stored at temperatures from 0° to 25°. The safe range of storage temperature was between 15° and 25° with 20° being the optimum for the development of eating quality but with 15° giving the longest delay in ripening. Storage at lower temperatures gave rise to symptoms typical of chilling injury.
Abstract
The effect of controlled atmospheres on the regulation of ethylene biosynthesis during the senescence of broccoli flower buds (Brassica oleracea, L. Italica group cv. Green Valiant) was assessed. The broccoli buds wee stored in the dark at 25C under a continuous stream of nitrogen containing the following percentages of CO2-O2 : 0-20 (air), 0-2.5, 6-20, and 10-20. Generally, respiration, ethylene production, and ethylene-forming enzyme (EFE) activity followed a climacteric like pattern in all atmospheres. The ACC content changed little during the “climacteric”, but increased dramatically during the “post-climacteric” period, when ethylene production and EFE activity decreased. Under high CO2, respiration was reduced, but ethylene production and EFE activity were temporarily stimulated early during treatment. Under low O2, respiration, ethylene production, EFE activity, and ACC content were reduced, and the “climacteric” and chlorophyll losses were delayed to a greater extent than under high CO2. Whatever the treatment, ACC level was not the limiting factor in ethylene biosynthesis in broccoli; the reduction in ethylene production during senescence resulted from the degradation of the system that converts ACC to ethylene. Chemical name used: 1-aminocyclopropane-1-carboxylic acid (ACC).
Abstract
The ripening rate of tomato fruit with high pigment and/or crimson characteristic was about the same as that with normal pigment; however, the lycopene content of the former fruit was much greater. Shelf life of fruit containing high pigment and crimson characteristic was significantly greater than that of other fruit. All fruit exhibited a typical climacteric in the respiration pattern.