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- Author or Editor: Doyle A. Smittle x
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.
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°.
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.
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.
Two lots of `Granex 33' and a `Walla Walla' lot of onions were stored in a Georgia CA facility designed to produce 1C, 70-75% RH, 3% 02, 5% CO2, 92% N2 and an air flow of 1m3/Mg onions. Subsamples of these lots were also stored in air at 1C. Three lots of `Granex 33' onions and one lot of `Texas 1015Y' onions were stored in a CA facility in Michigan under similar conditions.
About 85% of the onions were marketable after 5 months of CA in Georgia and 2 weeks shelf-life. Less than 25% of the onions stored in air at 1C were marketable after a similar storage and shelf-life period. All `Walla Walla' bulbs decayed.
Shelf-life differences occurred among the `Granex 33' lots grown in Georgia and the 1015 lots grown in Texas after 5 months of CA storage in Michigan. Two of the `Granex 33' lots stored fairly well (70-75% marketable) while the third lots stored less well (40% marketable). The Texas 1015 onions stored poorly (0-15% marketable).
`Fry' and `Granny Val' muscadine grapes (Vitis rotundifilia) were stored at 1C for two, four, and six weeks in himidified flow-through atmospheres of air, 0% CO2 - 5% O2, 5% CO2 - 5% O2, 10% CO2 - 5% O2, and 15% CO2 - 5% O2. Weight loss, grade, pH, acidity, soluble solids, sugars and sensory evaluations were made upon removal from 1C storage. Chill injury ratings were made after 0, 24, and 48 hours at 27C. `Fry' muscadine grapes had a better storage life than did `Granny Val'. High CO2 atmospheres extended the storage life of both cultivars. Severe chill injury symptoms resulted after 4 or 6 weeks of 1C storage in air. High CO2 atmospheres inhibited chill injury of both `Fry' and `Granny Val' grapes. No chill injury to either cultivar occurred after six weeks of storage in the 15% CO2 - 5% O2 atmosphere.
Six onion (Allium cepa L.) cultivars were grown during 2 years to evaluate the effects of environment on bulb quality as measured by sugar and pyruvate (pungency) concentrations. Within each year, bulb fresh weight was not affected by cultivar; however, bulb fresh weights were 36% higher in a year when most of the rain fell during maximum bulb expansion. Total bulb sugar concentration and pungency varied among cultivars and years. Pungency was higher and the sugar: pungency ratio was lower in `Texas 1015Y' and `Sweet Georgia' than in `Dessex', `Rio Bravo', 'Hybrid Yellow Granex', and `Granex 33'. Under low S nutrition, market acceptance of “sweet” onion cultivars that vary slightly in nonstructural water-soluble carbohydrates may be assessed more precisely by the sugar: pungency ratio than by sugar or pungency assessments.
An irrigation scheduling model for turnip greens (Brassica rapa L.) was developed and validated.. The irrigation scheduling model is represented by the equation: 12.7 (i-3) * 0.5 ASW = 0i-1 + Ei(0.365+0.00154i+0.00011i2) - R - I where crop age is i; effective root depth is 12.7 * (i-3) with a maximum of 300 mm; usable water (cm/cm of soil) is 0.5 ASW; deficit on the previous day is Di-1 evapotranspiration; is pan evaporation (Ei) times 0.365+0.0154i+0.00011i2; rainfall (R) and irrigation (I) are in millimeters. Yield measured as leaf weight, and quality analyzed in terms of color (Gardner XL20 cronameter L, a, b), leaf blade and blade: stem weight ratio were determined. Leaf yield and quality responses were affected by both irrigation and fertilizer rates. Yield increased quadratically as irrigation rates increased from 0 to 190% of the model rate. Maximum leaf yields were produced by irrigations at 100% of the model rate. Leaf quality parameters also tended to change quadratically with irrigation rates. Leaf yield and quality changed quadratically as nitrogen fertilizer rates increased from 80 to 120% of the median recommended N rate for Georgia.
Instrumented rainfall- and groundwater-protected irrigation shelters were used to establish relationships (daily crop factors) between pan evaporation and daily water use for several vegetables. Use of these daily crop factors (water use/pan evaporation) and pan evaporation data for scheduling irrigations are described. Snap bean (Phaseolus vulgaris L.) is used to illustrate irrigation scheduling by this method. A table of the model output with columnar headings of age, root depth, date, pan evaporation, crop factor, daily water use, cumulative water use, allowable water use, rainfall, and irrigation is presented. When irrigation was applied according to the model, soil water tension was held below 25 db at 6-inch (15-cm) soil depth. With varying irrigation rates under a line-source irrigation system, marketable pod yields were maximized at 100% of the model rate. Marketable yields of summer squash also were maximized when irrigation was applied at 100% of the model rate. Marketable yields of sweetpotato were not affected by irrigation rates ranging from 1% to 177% of the model rate.
`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.