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Open access

David Mason Pharr and Yoshie Motomura

Abstract

The effect of anaerobiosis, imposed during germination of ‘Calypso’ cucumber (Cucumis sativas L.) seeds, was studied. Anaerobic conditions inhibited reserve mobilization from the cotyledons and dry weight gain by the embryonic axis. Within the embryonic axis, lipid degradation was stopped and use of all readily metabolizable carbohydrate reserves was strongly stimulated. By 48 hr of exposure to an anaerobic environment, the axis was nearly depleted of endogenous carbohydrate reserves. Aerobically germinating seeds accumulated a massive concentration of hexose sugars within the axis during the same time period. Thus, growth inhibition within cucumber seeds during anaerobiosis may result in part from carbohydrate deprivation of the embryonic axis.

Free access

Wilawan Kumpoun, Takashi Nishizawa, Yoshie Motomura, Tanidchaya Puthmee, and Toshiyuki Aikawa

Green mango (Mangifera indica L.) ‘Nam Doc Mai See Thong’ fruit were dipped in 2-chloroethylphosphonic acid solution (50 ppm) for 5 minutes, kept at 25 °C for 3 days, cold stored at 5 °C for 35 days and then transferred to 25 °C for 7 days. The skin color of the cold-stored fruit partly changed to dark-brown with surface depression. In addition, desiccated white-corky pulp tissues developed mainly along to the dark-brownish skin. Histological and biochemical analyses revealed that the formation of white-corky pulp tissues was correlated with starch accumulation in the hypodermal cells. Cell wall polymers of the white-corky pulp tissues were characterized by both a lower amount of solubilized pectins and higher amount of hemicelluloses than those of normally ripened (NR) tissues. The highest fatty acid unsaturation was observed in the NR pulps under chilling conditions followed by the white-corky pulp tissues under chilling conditions and the NR tissues without chilling. These results suggested that the disordered membrane caused by chilling inhibited the subsequent cascade of secondary reactions, such as the cell wall degradation. The skin damage derived from chilling injury (CI) is a direct factor inducing abnormal desiccation in the adjacent pulp, resulting in the formation of white-corky pulp tissues.

Open access

Eric Young, Yoshie Motomura, and C. Richard Unrath

Abstract

Apple (Malus domestica Borkh.) (‘MM 111’ rooted layers) and peach (Prunus persica L. Batsch) (‘Lovell’ seedlings) trees were subjected to two root temperatures (5° and 16°C) in a cold room during dormancy with the shoot maintained at 5°. Trees were removed after specific cold treatments (5°), ranging from 0 to 1870 hr. Respiration and carbohydrate fractions were determined on shoots and roots immediately upon removal from the temperature treatments. A second set of trees treated identically were placed in a greenhouse for 30 days, and respiration, budbreak, new root number, and new root and shoot dry weights were determined. Warm (16°) root temperature reduced total soluble carbohydrates and respiration in roots of apple and peach after removal from the cold room, and this response did not change with additional chilling. Root starch levels of both species decreased with increased chilling time, but were not affected by root temperature. After 30 days in the greenhouse, budbreak, new shoot dry weight, and new root number and weight were significantly higher in apple trees that had their roots chilled as compared to those with unchilled roots. These parameters were independent of root temperature in peach. Respiration rates showed greater increases during the greenhouse phase, with increased shoot chilling in peach and root and shoot chilling in apple after the chilling requirements were surpassed. Shoot and root respiration rates did not rise in apple when the roots were not chilled.

Free access

Takashi Nishizawa, Satoshi Taira, Masanori Nakanishi, Masanori Ito, Masahiro Togashi, and Yoshie Motomura

Acetaldehyde and ethanol production by muskmelon fruit were promoted by short-term shading of the plants for 5 days from 10 to 15 days prior to fruit maturation. Sucrose concentrations in the fruit flesh were reduced by shading, while fructose and glucose concentrations did not differ. Shading also accelerated the development of a “water-soaked” appearance in the flesh.

Free access

Thanidchaya Puthmee, Kenji Takahashi, Midori Sugawara, Rieko Kawamata, Yoshie Motomura, Takashi Nishizawa, Toshiyuki Aikawa, and Wilawan Kumpoun

The transpiration rate of cuticular membrane and fissures that comprise the netting on fruits of three netted melon cultivars, Life, Andesu, and Gurandoru, were measured during fruit development. Fissures in the equatorial region first developed vertically, then became interconnected by horizontal fissures as the fruit developed. Some cracks remained along the net, even at the fruit ripening stage, regardless of cultivar. Both lignified and suberized cell wall layers in the net tissues of the cultivar Life were thinner than those of the other cultivars, probably because of the shorter developmental period of fruits in the variety. Nevertheless, net transpiration rate did not differ significantly among cultivars at the fruit ripening stage. Peroxidase (POD) activity in the skin tissues of ‘Life’ was lower than that in ‘Andesu’ and ‘Gurandoru’ throughout fruit development and was not correlated with climacteric ethylene production. Among these cultivars, significantly higher ethylene production occurred in ‘Life’ fruit at the ripening stage. This can accelerate membrane permeability of hypodermal tissues, resulting in rapid fruit softening. Our results indicate that the net tissues of netted melons can be as waterproof as cutinized membranes if suberized cell wall layers with wax depositions develop below the net fissures at the fruit ripening stage.