, 1973 , 1975 ), “bitter pit” ( Eijsinga et al., 1973 ), and “pepper spot” ( Stolk and Maaswinkel, 1977 ) are different names that have been used in the literature to describe what is likely the same physiological disorder of peppers. This disorder
James C. Fulton and Mark E. Uchanski
Yosef Al Shoffe and Christopher B. Watkins
Manipulation of storage temperature for horticultural crops is an important approach for reducing physiological disorders and maintaining quality ( Jackman et al., 1988 ; Lurie, 2002 ; Wang, 1993 ). Temperature manipulation involves using optimum
Bradley J. Rickard, David R. Rudell, and Christopher B. Watkins
innovations that are both revenue-enhancing and cost-reducing. The empirical example that motivates our work is the use of biomarkers to manage postharvest physiological disorders in long-term controlled atmosphere (CA) apple storage. Such disorders are
Juan Pablo Zoffoli, Valentina Sanguedolce, Paulina Naranjo, and Carolina Contreras
‘Granny Smith’ is the most common green apple cultivar in the world. However, it is highly susceptible to physiological disorders such as superficial scald and bitter pit ( Mitcham et al., 1996 ). These disorders reduce the effective storage time
Jinwook Lee, In-Kyu Kang, Jacqueline F. Nock, and Christopher B. Watkins
., 2007 ; DeLong et al., 2004 ; Larrigaudière et al., 2008 ; Jung and Lee, 2009 ; Watkins et al., 2000 ). Treatment with 1-MCP can reduce the development of certain physiological disorders, such as senescent breakdown ( DeLong et al., 2004 ; Jung and
X. Fan and J.P. Mattheis
Whole carrots (Daucus carota L.) and midrib tissues of iceberg lettuce (Lactuca sativa L.) were treated with 42 μmol·m-3 MCP, then exposed to ethylene. Exposure to 42 μmol·m-3 ethylene at 10 °C increased isocoumarin content ≈40-fold in both peel and pulp of nontreated carrots within 4 days, but treatment with MCP for 4 hours at 20 °C before exposure to ethylene prevented isocoumarin accumulation. Ethylene-induced acidity loss and respiration rate increase in carrots were also prevented by MCP treatment. Ethylene treatment (126 μmol·m-3) of lettuce at 6 °C had induced russet spotting >5% to 10% of the midrib tissue by day 3 and 30% to 35% by day 9, while pretreatment with MCP for 4 hours at 6 °C prevented development of russet spotting. The results indicate that ethylene-induced physiological disorders and quality loss in carrots and iceberg lettuce can be prevented by MCP treatment prior to exposure to ethylene. Chemical name used: 1-methylcyclopropene (MCP).
Joseph P. Albano, William B. Miller, and Mary C. Halbrooks
A specific physiological disorder, bronze speckle (J.P.A.'s nomenclature), was consistently induced in `First Lady' and `Voyager' marigold with Fe-DTPA concentrations greater than 0.018 mm Fe-DTPA (1 ppm) applied to a soilless medium. The disorder was characterized by specific symptomology distinguished visually by speckled patterns of chlorosis and necrosis, and downward curling and cupping of leaves. The percentage of total leaf dry weight affected with symptoms generally increased with increasing Fe-DTPA treatments. Symptomatic leaf tissue had a greater Fe concentration than corresponding asymptomatic leaf tissue. Leaf Mn concentrations in symptomatic and asymptomatic tissue were similar. In `First Lady', older leaf tissue accumulated more total Fe and was associated with more severe symptoms than younger tissue. Media leachate Fe concentrations increased over 6 weeks and were larger at greater Fe-DTPA treatments. Adjustment of nutrient solution pH to 4.0, 5.25, or 6.5 did not alter media pH, nor did it prevent disorder symptoms. Application of Fe-DTPA containing nutrient solution to a soilless medium resulted in leachate Fe levels 3 times greater than for FeSO4 treatments. Chemical names used: ferric diethylenetriaminepentaacetic acid, monosodium salt (Fe-DTPA).
Gary R. Bachman and Mary C. Halbrooks
The role of Fe DTPA (Diethylenetriaminepentaacetic acid) in the occurrence of a specific physiological disorder affecting the leaves of cutting geranium was investigated. Industry reports indicate that affected leaves have excessively high concentrations of Fe and sometimes Mn. Symptoms of the disorder first affect maturing leaves, and may in severe cases affect immature leaves. Symptoms progress from marginal/interveinal chlorosis and necrosis, to affect whole leaf necrosis. Rooted cuttings were grown in a soil-less peat based media, with Fe DTPA concentrations of 1, 5, 15, and 20 ppm. Iron and manganese leaf concentrations were significantly higher in symptom than in non-symptom tissue and increased as Fe DTPA treatment level increased. As Fe DTPA treatment level increased there was a significant increase in dry weight of symptom tissue and a decrease in non-symptom tissue dry weight. Plants grown in media amended with dolomite (pH> 5.8) had similar degrees of symptom occurrence compared to plants grown in unamended media (pH ≈ 5.4).
Sylvie Jenni, Pierre Dutilleul, Stephen Yamasaki, and Nicolas Tremblay
In order to investigate their relationships with brown bead, a data set composed of 48 variables characterizing the developmental rate, climate, and nutrients in the soil and in the tissues of heads of broccoli (Brassica oleracea L., Italica group) was collected from 328 plots (41 experimental fields over 3 year× 4 N fertilization level× 2 blocks). The four N treatments were 85-0-0, 85-54-0, 85-54-54, and 85-54-108, the first number indicating the N level (kg·ha-1) applied before planting; the second, N level applied 5 weeks after planting; and the last, N level applied 7 weeks after planting. Broccoli plants were either direct-seeded (26 experimental fields) or transplanted (15 experimental fields). Whether direct-seeded or transplanted, fast-developing broccoli plants showed a lower incidence of brown bead. More particularly, heads of transplanted broccoli plants experiencing warmer temperatures had a lower brown bead incidence and severity. A regular supply of water decreased the incidence and severity of the physiological disorder in both direct-seeded and transplanted broccoli plants. Low levels of Ca and high levels of Mg and K in mature broccoli head tissues were associated with a higher incidence of brown bead. Multiple-regression models were developed to predict the percentage of broccoli heads with brown bead for direct-seeded plants (R 2 = 0.76; n = 104), and for transplanted plants (R 2 = 0.69; n = 44). For direct-seeded broccoli, solar radiation between the button stage (head diameter of 2.5 cm) and maturity (head diameter of 10 cm), as well as soil and tissue Mg content, were among the first variables to enter the regression models. In general, more solar radiation and less precipitation translated into more heads showing brown bead symptoms. For transplanted broccoli plants, the minimum temperature from the button stage to maturity was a key variable in the prediction of the percentage of heads with brown bead and the corresponding index of severity.
Katsumi Ohyama, Yoshitaka Omura, and Toyoki Kozai
Providing continuous light (24-h photoperiod) at a relatively low photosynthetic photon flux (PPF) is one possible way to reduce both initial and operational costs for lighting and cooling during transplant production with an artificial light. However, physiological disorders (i.e., chlorosis and necrosis) are often observed in several species under continuous light with a constant temperature. The objective of this study was to find an effective air-temperature regime under the continuous light to avoid such physiological disorders, and simultaneously enhance floral development, using tomato [Lycopersicon esculentum Mill.] as a model. The seedlings with fully expanded cotyledons were grown for 15 d at a PPF of 150 μmol·m–2·s–1, a relative humidity of 70%, and a CO2 concentration of about 380 μmol·mol–1 (atmospheric standard). Leaf chlorosis was observed when the air temperature was constant regardless of average air temperature (16, 22,or 28 °C). Neither leaf chlorosis nor necrosis was observed when the air temperatures were alternated [periods of high (28 °C) and low (16 °C) air temperatures of 16/8, 12/12, and 8/16 h·d–1]. Faster floral development was observed in the seedlings grown at lower average air temperatures. These results indicated that physiological disorders of tomato seedlings grown under continuous light could be avoided, and at the same time floral development could be enhanced, by lowering the average air temperature through modification of the periods of high and low air temperatures.