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  • Author or Editor: Doyle A. Smittle x
  • Journal of the American Society for Horticultural Science x
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Abstract

Snap bean, Phaseolus vulgaris L., yield was increased by higher plant population, more frequent irrigation, and additional N applied as a topdress. Highest yields were obtained with the irrigation-fertilization program that included applications of 8 mm of water at 23 mm of pan evaporation until 1/3 foliage cover, at 15 mm of pan evaporation until 2/3 foliage cover, then at 8 mm of pan evaporation until harvest with N applications to maintain petiole NO3-N level above 1500 ppm preblossom and 1000 ppm during fruit development. Response of 30 × 8 cm and 91 × 3 cm plant spacings to irrigation and N fertilization were similar.

Pan evaporation data can be used to schedule irrigation under varied climatic conditions and maintain a low soil water tension throughout snap bean growth. The relationship of water use by snap bean to pan evaporation changes with crop development. An adjustment must be made to compensate for the changing relationship; and frequent irrigation and N fertilization must be made to snap beans produced on sandy soil under humid conditions.

Open Access

Abstract

‘Granex’ onions were stored in an air-conditioned room at 27°C, at 5° in air, 5% CO2−3% O2 or 10% CO2−3% O2, and at 1° in air or 5% CO2−3% O2. Relative humidity of storages at 5° and 1° was maintained at 70% to 85%. The quantity of marketable bulbs decreased 12% to 25% per month when stored at room temperature. Virtually all onions were marketable after 7 months of storage at 1° in 5% CO2−3% O2. More than 92% of these bulbs remained in a marketable condition after an additional 3 weeks in air at room temperature. Bulb quality of these sweet onions decreased during storage, as indicated by lower sugar concentrations and greater pungency. Bulb quality decreased most rapidly when onions were stored in air at 1° and least rapidly when onions were stored in 5% CO2−3% O2 at either 1° or 5°.

Open Access

Abstract

Experiments were conducted during 1981 and 1982 to determine the yield and quality responses of lima bean (Phaseolus lunatus L.) cultivars to air temperatures preceding harvest. Temperature conditions and cultivars that produced large lima bean plants at blossom increased seed yields. Quality parameters of seeds after separation into maturity groups by salt brine were influenced by cultivars and air temperatures. Sugar content, green color intensity, and chlorophyll content decreased as seeds matured. Sugar contents of ‘Nemagreen’, ‘Bridgeton’, and ‘Thorogreen’ were greater than ‘Kingston’ at comparable stages of maturity. Sugar content increased when air temperatures during the period of 0–7 days preceding harvest were high. Air temperatures were most closely related to sugar content of mature seeds. Chlorophyll content was closely correlated with tristimulus chlorimeter – a value. The chlorophyll contents at all maturities were reduced by high air temperatures preceding harvest. The average temperature during the period of 7–14 days before harvest had the greatest influence on the chlorophyll content. The influence of air temperatures on chlorophyll content during this period was 3 to 4 times greater for immature (25% total solids) than for mature (35% total solids) seeds, and minimum air temperatures were more closely correlated with chlorophyll contents than were maximum air temperatures. These results indicate that quality (intensity of green color) was affected more by high air temperatures than was seed yield. Chlorophyll contents were more closely related to minimum than to maximum air temperatures, indicating that the effect of high temperature would be increased in humid areas where night temperatures are high.

Open Access

Abstract

Yield of shelled lima beans was greatest when 15 mm of irrigation was applied at 38 mm of pan evaporation until 1/3 foliage cover, at 30 mm of pan evaporation until 2/3 foliage cover, then at 23 mm of pan evaporation until harvest. More frequent irrigation with smaller amounts of water per application increased uniformity of seed maturity, but reduced seed yield. Plant growth and yield were not affected by N fertilization. Grading seed in a vertical air column to remove smaller seed increased shelled lima bean yield. Yield response to seed grading was the same for all irrigation frequencies.

Open Access

`Gemini II' cucumber (Cucumis sativus L.) fruits were stored for 2, 4, or 6 days at 5 and 6C in 1989 and for 5 days at SC or 10 days at 3C in 1990. Chilling injury (CI) symptoms were rated after 2 to 4 days at 25C. Cell wall polysaccharide concentrations in the peels and in injured and noninjured portions of the peels were determined only in 1990. High CO2 and low O2 delayed the onset of CI symptoms, but did not prevent symptom development. Chilling injury symptoms increased with longer exposure to chilling temperatures. Solubilization of cell wall polysaccharides was associated with development of CI symptoms. Variations in low methoxyl pectinates accounted for 70% of the variation in CI.

Free access

Abstract

Fruits of rabbiteye blueberries (Vaccinium ashei Read cvs. Climax and Woodard) harvested by hand in 1984 and machine in 1985 were stored in air, 100% N2, and in 10%, 15%, or 20% CO2 with 5% O2. Storage of either blueberry cultivars in high-CO2 atmospheres resulted in greater percentages of marketable and firm fruit, and better sensory ratings, than did storage in air. Fruit of ‘Climax’ lost less weight, were firmer, and developed less decay after 21 or 42 days of storage than ‘Woodard’ fruit. Fruit quality characteristics of hand-harvested ‘Climax’ stored for 42 days and machine-harvested ‘Climax’ stored for 21 days in 20% CO2 with 5% O2 were similar to those of freshly harvested fruit.

Open Access

An irrigation scheduling model for turnip (Brassica rapa L.) was validated using a line-source irrigation system in a 2-year field trial. The model used a water balance, a variable root length, and a crop factor function of plant age (i). Evapotranspiration was computed daily as class A pan evaporation times a crop factor [CF(i) = 0.365 + 0.0154i-0.00011i2]. Irrigation according to the model maintained soil water tension at <25 kPa at a 30-cm depth. When rainfall amounts were less than water use, leaf yields responded quadratically to irrigation rates, from 0% to 160% of the model rate, and the highest leaf yield with the lowest water applications corresponded to the model rate. Therefore, this model could replace the “feel or see” methods commonly used for scheduling irrigation of leafy vegetables grown in the southeastern United States.

Free access

Sweetpotatoes [Ipomoea batatas (L.) Lam cv. Georgia Jet] were grown on two soil types in drainage lysimeters under controlled soil water regimes during 1982 and 1983. Water regimes consisted of irrigating the sweetpotatoes throughout growth when soil water tension at 23 cm exceeded 25, 50, or 100 kPa or by allowing a 100-kPa water stress before root enlargement, during early root enlargement, or throughout root enlargement. Water use and marketable yields were greater when sweetpotatoes were grown on a Tifton loamy sand (fine loamy, siliceous, thermic, Plinthitic Paleudult) than when grown on a Bonifay sand (loamy, siliceous, thermic, Grossarenic, Plinthitic Paleudult). Water use, marketable yield, and yield of U.S. #1 grade roots generally decreased when soil water tensions exceeded 25 kPa before irrigation, although soil water stress of 100 kPa during storage root development did not significantly affect yield. Regression equations are provided to describe the relationships of water use to plant age and to compute daily evapotranspiration: pan evaporation ratios (crop factors) for sweetpotatoes irrigated at 25, 50, and 100 kPa of soil water tension.

Free access

Cabbage (Brassica oleracea L.) was grown in drainage lysimeters under controlled soil water regimes during 3 years. Three irrigation regimes were imposed on cabbage grown on two soil types during the spring and fall growing seasons. Irrigation regimes consisted of applying water when the soil water tension at 10 cm exceeded 25, 50, or 75 kPa during crop growth. Yields and water use were highest when irrigation was applied at 25 kPa soil water tension. Regression equations are presented to describe the relationships of water use to plant age and to compute the ratios of daily evapotranspiration to pan evaporation (crop factors) for cabbage grown under the three irrigation regimes.

Free access

An irrigation scheduling model for summer squash (Cucurbita pepo L.) was developed and validated during 1986, 1987, and 1989. The model is represented by the equation: 12.7(i - 4) × 0.5ASW = Di-1 + [E(0.14 + 0.015) - P - I]i, where crop age in days is i; effective root depth is 12.7(i - 4) with a maximum of 381 mm; usable water (cubic millimeter per cubic millimeter of soil) is 0.5ASW, deficit on the previous day is Di-1; evapotranspiration is pan evaporation (E) times 0.14 + 0.015i; rainfall (in millimeters) is P; and irrigation (in millimeters) is I. The model was validated during the three years using a line-source irrigation system with irrigation depths ranging from 5% to 160% of the model rates. Nitrogen rates were 50%, 100%, and 150% of the recommended rate. Marketable fruit yields increased as the irrigation depths increased up to the model rate then decreased with greater water application depths. Marketable fruit yields increased as the N rate increased in 1987 and 1989, but yields were similar at all N rates in 1986. The shelf life of marketable fruits was not influenced by irrigation or N rates.

Free access