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Karine Fouldrin, Anis Limami and Thierry Lamaze

During forcing, the witloof chicory taproot produces an etiolated bud, the chicon. The axis of this organ often is brown as a consequence of a disorder associated with a localized Ca deficiency. The effect of the main anions (NO3 -, Cl-, SO4 2) in the nutrient solution on Ca (45Ca) absorption and translocation in the chicon was investigated. Although the amount of Ca that accumulated in the chicon was not affected by nutrient solution composition, Ca (45Ca) mobility was modified. The amount of radioactivity in the chicon increased slightly when the main anion in the solution was sulfate and decreased markedly when the main anion was chloride, compared to nitrate. Calculations of the specific radioactivity of Ca reaching the chicon and in root tissue suggest that, when slowed down, Ca transport consists of a homogeneous flow in all root tissues, whereas, in other cases, Ca moves along a preferential pathway, such as the xylem vessels. Modifying the anionic composition of the nutrient solution to avoid a localized Ca deficiency is discussed.

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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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David R. Byrnes, Fekadu F. Dinssa, Stephen C. Weller and James E. Simon

as the high source thresholds per nutrient trait by Codex Alimentarius (1997) definitions: 4.2 mg/100 g Fe, 90 mg/100 g Mg, 300 mg/100 g Ca, and 4.5 mg/100 g Zn, by fresh weight basis. Previous studies have evaluated vegetable amaranth for nutrition

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

Calcium (Ca) nutrition and the balance between Ca and other plant nutrients are key factors that affect fruit quality and storability. This is especially important for fleshy crops, such as apple, pear, tomato, pepper, and potato ( White and

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Jan Bizjak, Nika Weber, Maja Mikulic-Petkovsek, Ana Slatnar, Franci Stampar, Zobayer Alam, Karl Stich, Heidi Halbwirth and Robert Veberic

and years with poor coloring conditions. Phostrade Ca (Pho Ca) is a concentrated liquid P solution containing calcium and nitrogen recommended for foliar application at the beginning of fruit formation and during fruit enlargement and maturation. P

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Steven McArtney, J.D. Obermiller and A. Green

multiple GA 4+7 sprays may not be sufficient to offset this additional cost in some years or regions. Prohexadione-calcium (P-Ca) is a gibberellin biosynthesis inhibitor that is increasingly being used in apple production systems globally to reduce

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S.W. Park and S.H. Chi

During nutrient solution culture of cucumber, paclobutrazol (PBZ) promoted the Ca uptake and accumulation of cucumber fruit, but significantly inhibited the shoot growth. In the medium and stem parts of the smaller cucumber fruits treated by PBZ, Ca uptake and accumulation were vigorous but in the blossom part did not do so. PBZ was effective in the maintenance of firmness in the smaller fruits. PBZ was an effective growth regulating chemical for Ca uptake of cucumber plant and storability of cucumber fruit. This Ca accumulated in cucumber fruit reduced loss of firmness during postharvest ripening, but led to the decrease of marketable fruit per plant, as well as productivity. To solve this problem, the direct application of Ca was conducted after anthesis. Foliar treatment of Ca on leaf area around fruit was ineffective in Ca uptake, but its direct application on fruit itself increased the concentration of Ca in fruit. The cucumber fruit that Ca was accumulated by direct application maintained the firmness longer after harvest.

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F. W. Liu

A high CO2 slow cooling CA storage procedure was developed for `McIntosh' apples (Malus domestica Borkh.). The apples were cooled from 18° to 3°C in 15 days in atmospheres containing a constant O2 at 2.5% and decreasing CO2 starting with 12% and ending at 3%. The results of several tests in a flow-through simulated CA storage system revealed that the new procedure was nearly as effective as rapid CA and was much more effective than traditional slow CA in preserving the firmness of `McIntosh' apples for up to 4 months of storage. Maintaining a constant CO2 either at 12% or 3% instead of gradually decreasing it from 12% to 3% during the slow cooling period resulted in more storage disorders or/and softer apples.

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W. Rademacher, G. Stammler and P. Creemers

Many trials have demonstrated that apple and pear trees treated with the plant growth regulator prohexadione-Ca (BAS 125 W) are less susceptible to infestation by the bacterial disease fire blight. In further investigations we have studied the effect of this compound against fungal diseases, concentrating on scab (Venturia inaequalis) in apple. Working with apple seedlings and artificial inoculation under greenhouse and field-like conditions, scab infestation could be reduced by applications of prohexadione-Ca. Whereas this effect was rather marginal if inoculations were made shortly after treatment, highly significant effects were found in the time span of ≈1 to 4 weeks after application. Preliminary results from trials conducted under orchard conditions support these findings. We assume that, similar to the situation with fire blight, changes in phenylpropanoid metabolism are mainly responsible for the reduced scab incidence. It should not be ruled out, however, that anatomical and morphological changes caused by prohexadione-Ca may also contribute to this effect.

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J.M. Spiers and J.H. Braswell

The effects of varying Al, Mn, and Ca fertilization levels on `Tifblue' and `Brightwell' rabbiteye blueberry (Vaccinium ashei Reade) plant growth, chlorosis symptoms, and leaf elemental content were studied in a sand culture experiment. Increased Al fertilization linearly decreased Ca, Mg, and Mn leaf concentrations and plant vigor. Calcium fertilization did not affect plant growth or leaf concentration of the two cultivars. Increased Mn fertilization increased Al and Mn leaf concentrations and resulted in more chlorosis symptoms. Plants fertilized with the highest rates of Al and Mn had the least amount of growth.