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Meng-Shiun Tsai, Tan-Cha Lee, and Pai-Tsang Chang

( Felicetti, 2003 ). The visible symptoms of sunscald in citrus fruit are irregular yellow or brown blotches on the peel ( Myhob et al., 1996 ), although there is a report that granulation may also be caused by severe heat injury sunscald ( Chikaizumi, 2000

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Shara E. Alexander and George H. Clough

A 2-year study was conducted in eastern Oregon to evaluate the effects of hooped spunbonded polypropylene rowcovers and Ca fertilization on yield and quality of drip-irrigated bell pepper (Capsicum annuum L. Grossum group) grown on black plastic mulch. The experiment was a complete factorial with four replications of two cultivars, covered and uncovered plots, and three levels of supplemental Ca fertilization at 0, 34, and 68 kg·ha-1 applied through the drip irrigation system as Ca(NO3)2. Rowcovers increased marketable yields both at the first harvest and over the season. Blossom-end rot and sunscald were reduced substantially by rowcovers; the effect was greatest during the earlier harvests. First-harvest and season total yield of fancy grade peppers increased linearly as rate of supplemental Ca increased, as did total marketable yield at the first harvest. Both yield of fruit with blossom-end rot and the percentage of fruit with blossom-end rot at the first harvest decreased as Ca rate increased. Yield of fruit affected by sunscald decreased linearly as supplemental Ca rate increased at the first harvest; overall, yield of sunscalded fruit was reduced by application of Ca at either rate.

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Vito S. Polito, Kirk D. Larson, and Katherine Pinney

Bronzing of strawberry (Fragaria ×ananassa Duchesne) fruit that is not the result of arthropod feeding or chemical spray application occurs frequently in California's central coast strawberry production region from late spring through midsummer, a period characterized by relatively high temperature, low relative humidity, and high solar irradiance. The cause of this phenomenon is not known, but in preliminary trials, intermittent, midday misting of plants and increased drip irrigation rate resulted in reduced incidence of fruit bronzing. To characterize the bronzing phenomenon and its development in strawberry fruit tissues, we conducted an anatomical and histochemical examination of bronzed fruit. Bronzed and nonbronzed fruit were sampled over a range of fruit maturities. Results show that bronzing derives from a lesion at the cortical surface early in the fruit's development. Epidermal cells become radially compressed and the cell contents coalesce into a densely staining mass. The cuticular layer becomes disrupted and discontinuous. As the fruit develops, densely staining materials, possibly phenolic precipitates, accumulate within subepidermal cells of bronzed fruit, subepidermal cell walls thicken, and intercellular spaces fill with pectic substances and other densely staining materials. Results are consistent with reports of sunscald injury from other fruit species, and raise the possibility that strawberry bronzing occurs in response to heat or solar radiation injury.

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B. Warren Roberts and Jeffrey A. Anderson

Experiments were conducted from 1989 to 1991 to compare the effectiveness of various cultural techniques in reducing solar injury (SI) and increasing yield of bell pepper (Capsicum annuum var. annuum `California Wonder') in southern Oklahoma. Treatments included black plastic mulch, white plastic mulch, straw mulch, living rye, spunbonded polypropylene used as a plant canopy shade, and bare soil. Marketable yields from plots shaded with spunbonded polypropylene rowcovers were equal to or greater than those from other treatments each year. Two out of 3 years, plots with a black plastic soil mulch had marketable yields lower than those from other treatments. SI was reduced by rowcover shade.

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Kirk D. Larson, Steven T. Koike, and Frank G. Zalom

Strawberry plants (`Commander') were grown with different polyethylene bed mulches in the 1999-2000 and 2000-2001 production seasons to determine the effect of mulch on plant growth, yield performance and incidence of Type III strawberry fruit bronzing (T3B), a fruit disorder of unknown origin. In 1999-2000, T3B incidence ranged from 1.8% to 3.7% of total yield, and use of clear, full-bed (CFB) mulch resulted in significantly less T3B incidence than either clear center-strip mulch (CS), or yellow-on-black full-bed mulch. Plant canopy vegetative growth and shoot to root dry mass ratios were greatest for CFB compared to other mulch treatments, but there was no effect of mulch treatment on yield or fruit size. Winter temperatures in 2000-2001 were colder than in 1999-2000, with reduced vegetative growth and increased T3B incidence in spring for all mulch treatments. Use of CFB mulch resulted in greater vegetative growth, greater yield, increased fruit size and reduced T3B incidence compared to CS or green full-bed mulch, but there was no difference among mulch treatments for number of T3B fruit per plot for any single fruit harvest interval. In 2000-2001, the onset of severe T3B symptoms on 7 May was preceded by a brief period of ambient temperatures >31 °C. For all treatments, peak T3B incidence occurred from late May to mid-June, a period characterized by high ambient temperatures and high irradiance conditions. Results indicate that temperature and radiation are significant factors in the development of T3B, and that increased plant vegetative growth in winter results in greater yields and a lower percentage of T3B-affected fruit, particularly in years with cold winters. Managing strawberry plantations to optimize plant growth and development in winter appears to be an effective strategy for reducing the severity of this disorder.

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Mark A. Ritenour, Sunita Kochhar, Larry E. Schrader, Tsui-Ping Hsu, and Maurice S.B. Ku

Western immunoblot analyses showed that small heat shock proteins (smHSPs) are low or undetectable in the peel of `Fuji', `Jonagold', `Criterion', `Gala', and `Delicious' apples [(Malus sylvestris (L.) Mill var. domestica (Borkh.) Mansf.] growing shaded within the tree canopy (shade apples), but are high in apples growing exposed to direct sunlight (sun apples). `Fuji', `Jonagold', and `Gala' sun apples sampled biweekly between 1 July and 21 Oct. 1997 were highest in content of smHSPs on 31 July, 13 Aug., and 10 Sept., corresponding to some of the warmest periods of the sampling period. The smHSPs started to disappear first in `Gala', the earliest maturing cultivar, and last in `Fuji', the latest maturing cultivar indicating that maturity might play a role in regulating smHSP accumulation. In sun apple fruit left on trees for 60 to 120 days beyond commercial maturity and exposed to field temperatures as low as -4 °C, a 71.7 ku (u = unified atomic mass unit) polypeptide was detected with a polyclonal antiwheat (Triticum aestivum L.) HSP70 in the peel and cortex of all five cultivars. While no smHSPs were detected in these apples, three smHSPs, as detected by antibodies against pea (Pisum sativum L.) cytosolic HSP18.1, could be induced in the same fruit 24 hours after heating to 45 °C for 4 hours. In `Fuji' shade apples heated at 40 °C, smHSP accumulation was detected after the second hour of a 4-hour heat treatment and continued to increase over the next 48 hours at 22 °C. Levels of HSP70 did not change in `Fuji' shade apples heated at 45 °C for 2, 4, or 6 hours, but smHSPs became detectable immediately after each of these heat treatments and further increased over the next 24 hours at 22 °C. Accumulation of smHSPs was maximal in the 4-hour heat treatment. After a 4-hour heat treatment at 45 °C, smHSPs increased during the next 48 hours at 22 °C and then declined by 72 hours. Using two-dimensional electrophoretic analysis, as many as 17 proteins ranging from 15 to 29 ku were found to accumulate in the peel 48 hours after a 4-hour heat treatment. Thus, apples can respond rapidly to high temperature stress, even at advanced stages of maturity, by synthesizing smHSPs, which likely play an important role in protecting cellular biochemical processes during these periods of stress.

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Juan Carlos Díaz-Pérez

incidences of fruit physiological disorders such as sunscald and blossom-end rot, causing significant loss ( Olle and Bender, 2009 ; Taylor and Locascio, 2004 ). Heat-induced flower and fruit abortion can also contribute to decreased fruit yields ( Deli and

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Kristine M. Lang, Ajay Nair, and Kenneth J. Moore

and fruit abortion ( Bosland and Votava, 2000 ; Deli and Tiessen, 1969 ) as well as increase the incidence of physiological disorders including sunscald ( Barber and Sharpe, 1971 ) and blossom-end rot (BER) ( Olle and Bender, 2009 ). Bell peppers are

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Rachelyn C. Dobson, Mary Rogers, Jennifer L.C. Moore, and Ricardo T. Bessin

, 2005 ). Culled, unmarketable peppers were counted and assessed for injury. Any incidence of sunscald and chewing insect injury was documented. The number of stink bug feeding sites on each pepper was recorded to determine damage severity. Fruit was

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Monica Ozores-Hampton, Philip A. Stansly, and Eugene McAvoy

were recorded and categorized based on the incidence of BES, zipper and catface (Zip/Catf), sunscald and yellow shoulders (SS/YS), off-shape fruit (OS), radial and concentric cracking (CRK), and gray wall as described by Gilreath et al. (2000) . After