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Abstract

‘Thompson Seedless’ fruits from vines that received gibberellin or auxin treatment were separated into different maturity classes and stored at 0° for 98 days. Samples were withdrawn at about monthly intervals and soluble solids, total acidity, malic acid, arginine and proline were measured. Fruits with differing soluble solids concn had the same soluble solids content per berry. After 30 days of storage, the soluble solids concn and total acidity of non-GA₃ treated fruits began to increase, probably as a result of water loss. Malic acid concn and content increased for 30 days in storage, remained stable for the next 28 days, and then decreased during the remainder of the storage period. The amino acids, arginine and proline, remained relatively constant during the 1st 58 days of storage and then increased greatly both in concn and content.

Abstract

Strawberry plants (Fragaria ×ananassa Duch. ‘Dover’ and ‘Florida Belle’) produced increased December fruit yields during 2 seasons when stored at 2°C for 1 week prior to transplanting rather than transplanting directly from the nursery. The total fruit yield of ‘Dover’ decreased with storage the 2nd season, whereas the total fruit yield of ‘Florida Belle’ was unaffected by storage. Lowering the soil fertility in the nursery prior to plant harvest increased ‘Dover’ December fruit yield the 2nd season, and increased ‘Florida Belle’ December yield both seasons. Total fruit yields of both cultivars as related to nursery fertility were inconsistent. Total fruit yields of ‘Dover’ in both seasons were greater with a fertilizer application in the fruit production field of 224N-50P-224K kg·ha^-1 than with double this application. Total fruit yield of ‘Florida Belle’ was not affected by fertilization in a fruiting field. During the first season, both cultivars produced more misshapen fruit with the 448N-100P-448K kg·ha^-1 application than with the 224N-50P-224K kg·ha^-1 application.

Abstract

Root regeneration and time to first budbreak of two-year white ash (Fraxinus americana L.) seedlings were strongly correlated with the number of hours of chilling. Physiological dormancy of the buds was removed after approx 2500 hours of storage at 5°C and this coincided with the beginning of increased root regeneration potential. Increased periods of chilling enhanced the rate at which growth was resumed after transfer of seedlings to environmental conditions adequate for growth. The present study indicates that fall-harvested white ash seedlings can be stored at 5° at least until May without any apparent detrimental effects on root regeneration potential or seedling condition.

Abstract

The capacity of ‘Eldorado’ pears to ripen increased dramatically after 4 weeks of exposure to 0°C and was associated with the synthesis of ethylene by pear tissue. Endogenous levels of ACC and internal ethylene were low after harvest, but increased rapidly after 4 weeks at 0°. Exposure to 0° for 4 weeks also resulted in an increase in soluble polyuronide during subsequent ripening at 20°. In contrast, after 9 months at 0°, soluble polyuronide content showed little increase when pears were transferred to 20°, and fruit failed to soften normally even though ACC content, internal ethylene concentration, ethylene evolution, and respiration remained relatively high. The content of arabinose, galactose, and rhamnose residues in cell walls decreased substantially during the ripening period after 4 weeks or longer at 0°. These cell wall neutral sugars decreased during ripening, even after 9 months of storage at 0°, while firmness and soluble polyuronide showed little change after fruit were transferred to 20°. These data indicate that the failure of pears to soften normally at 20° after prolonged storage at 0° is not related to ethylene synthesis or to changes in cell wall noncellulosic neutral sugar content, but is probably associated with mechanisms of polyuronide solubilization. Chemical name used: 1-aminocyclopropane-1-carboxylic acid (ACC).

Two mild and two pungent onion (Allium cepa L.) selections (hereafter referred to as cultitypes), W420B, W424B, MSU8155B, and Exhibition, were grown at two locations in two states (Wisconsin and Oregon) during 1994 and 1995. Onion bulbs were harvested, stored at 4 °C and sampled for antiplatelet activity, pungency, and soluble solids 10 days after harvest and every 40 days during a 210-day postharvest storage period. Significant cultitype × state and cultitype × year interactions were detected. However, these were primarily due to the change in rank of cultitypes within the mild or pungent group. Averaged over all environments, antiplatelet activity was significantly greater in 1994 compared to 1995 for all cultitypes. Significantly greater antiplatelet activity was measured for three out of four cultitypes grown in Oregon compared to Wisconsin. During postharvest storage, antiplatelet activity increased 61% and 56% across all cultitypes and across both states during 1994, and across all cultitypes in Wisconsin during 1995, respectively. Although pungency determination can be a good indicator for relative rankings of different cultitypes for antiplatelet activity, changes in pungency were not correlated with changes in antiplatelet activity during postharvest storage. Results demonstrate cultitype, environment, duration of postharvest storage and genotype × environment interactions influence pungency, soluble solids, and antiplatelet activity, which should be considered when assessing onion-induced antiplatelet activity.

Abstract

‘Bosc’ pears (Pyrus communis L.) harvested at an optimum maturity, based on flesh firmness (about 62 N), were stored either in air or 1% O₂ (plus <0.03% CO₂) at −1°C. Fruit stored in air for 1 to 3 months softened rapidly after 2 days of ripening at 20°C and reached ripeness with flesh firmness of 20 N or lower by the 9th day. Ripening was associated with a reduction in extractable juice (EJ) and an apparent increase in water soluble polyuronides (WSP). Fruit stored in air for 4 to 5 months also softened rapidly after 2 days of ripening, but flesh firmness was still between 26 and 30 N after 9 days; however, EJ and WSP of fruit did not change appreciably during 9 days of ripening. The WSP content in fruit stored in either air or 1 % O₂ increased substantially during 6 months of storage at −1°C. Increased WSP content during storage did not affect the quantity of EJ. Fruit stored at 1% O₂ showed a reduction in EJ and an increase in WSP during the 9-day ripening period, whereas, in long-term air-stored fruit, EJ did not decline while WSP was degraded. Correlation of EJ and WSP during each ripening period provided an estimation of storage life. Increased WSP after ripening might be responsible for the increase in hygroscopic binding capacity of the ripened pulp tissue.