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Gerry Neilsen, Denise Neilsen, Shufu Dong, Peter Toivonen and Frank Peryea

Calcium application trials were undertaken in a 'Braeburn' apple (Malus ×domestica Borkh.) orchard with a history of bitter pit development at harvest. In 2000, an early season calcium chloride application strategy was compared with the unsprayed control and a late season application strategy. From 2001–03, the assessment of timing of calcium chloride sprays was extended by comparing effects of five weekly sprays applied during the growing season either early, middle, or late season. Other Ca application strategies tested included sprays of acidified calcium carbonate suspensions and soil application of calcium thiosulphate. In the first experiment, early application of calcium chloride reduced the occurrence of bitter pit at harvest and after 3 months cold air storage, despite having low harvest fruit Ca concentrations. Late sprayed fruit had a higher incidence of bitter pit. In the second experiment, the later calcium chloride was sprayed in the growing season, the higher the fruit Ca concentration at harvest. Despite this, no bitter pit was measured at harvest for 2 years for early and midseason calcium chloride spray regimes. In 2003, when Ca disorders were severe and fruit large, bitter pit was observed despite early season calcium chloride sprays. Soil calcium thiosulphate application and foliar sprays of acidified calcium carbonate suspensions failed to meaningfully augment harvest fruit Ca concentrations and affect bitter pit incidence.

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Gerry H. Neilsen, Denise Neilsen, Sung-hee Guak and Tom Forge

’ apple N and Ca concentrations ( Mills et al., 1996 ) but increased ‘Anjou’ pear fruit Ca concentrations ( Brun et al., 1985 ). It has, however, been generally concluded that deficit irrigation has limited effects on fruit mineral nutrition which, if

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Amanda J. Vance, Patrick Jones and Bernadine C. Strik

to be competitive in the market place. Calcium is often applied to fruit crops before harvest at the recommendation of some crop consultants in an effort to increase postharvest fruit quality. Fruit Ca has been found to be related to fruit firmness by

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Lee Kalcsits, Gregory van der Heijden, Michelle Reid and Katie Mullin

, increased leaf area or decreased number of fruits can negatively affect Ca levels in fruit and cause a higher amount of Ca to be distributed to leaves. Calcium sprays have been used for a number of decades to increase fruit Ca levels and reduce the incidence

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Paweł Wójcik, Anna Skorupińska and Hamide Gubbuk

the fruit, they were weighed. Fruit Ca concentration was determined in the same manner as leaf samples, using a 30-fruit sample per plot. “King” fruitlets/fruit were collected from the peripheral zone of the canopy at a height of 1.5–2.0 m above the

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Babak Madani, Marisa Wall, Amin Mirshekari, Alagie Bah and Mahmud Tengku Muda Mohamed

practical and effective approach for postharvest disease management of papaya fruit. Ca may mitigate fungal disease incidence via two ways; directly by inhibition of fungal germination and fungal cell wall degrading enzymes ( Wisniewski et al., 1995 ), and

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Renee H. Harkins, Bernadine C. Strik and David R. Bryla

, and Zn in the ripe fruit than ‘Black Diamond’ but had lower concentrations of S and B. Only fruit Ca concentration was affected by weed control and only in ‘Marion’ where levels were higher with weed mat than with hand-weeding or no weeding ( Fig. 4

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William B. Beavers, Carl E. Sams, William S. Conway and George A. Brown

Fruit from five apple (Malus domestica Borkh.) cultivars were pressure-infiltrated at 103 kPa for 6 min with a 0%, 0.73%, 1.46%, 2.91%, or 5.82% (w/v) Ca-equivalent solution of CaCl2, Ca EDTA chelate, or buffered CaCl2 solution (Stopit). The fruit were stored at 0 ± 1C for 18 weeks and then evaluated for Ca content, firmness, and injury. Fruit treated with Ca chelate had no increase in fruit Ca content and were injured at all treatment levels. No significant differences occurred in fruit Ca levels between CaCl2 and Stopit treatments across all cultivars tested. Apples treated with Stopit were firmer than apples treated with CaCl2, when averaged across cultivars. Fruit Ca levels, firmness, and incidence of injury were positively correlated with concentrations of CaCl2 and Stopit for all cultivars.

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John A. Cline and Eric J. Hanson

Individual fruit of `Delicious' apple (Malus domestica Borkh.) were exposed to low, high, or ambient relative humidity (RH) levels during different stages of fruit development to study the importance of transpiration and the xylem system in supplying Ca to fruit. The Ca content of fruit exposed to low RH was the same or higher than that of fruit exposed to high RH. Treatments imposed early or late in the season usually affected fruit Ca levels similarly. Fruit weight was not consistently affected by RH treatments. The xylem may be a significant source of fruit Ca throughout the season.

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T. Casey Barickman, Dean A. Kopsell and Carl E. Sams

, results indicated that ABA treatments were effective in the early stages of plant development but are not enough to completely combat fruit Ca deficiencies in the later stages of growth. Other additional treatments such as increasing the frequency of ABA