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  • Author or Editor: Doyle A. Smittle x
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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).

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`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.

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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.

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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.

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Abstract

Nitrogen did not influence the severity of leafspots (Cercospora cruenta and C. canescens) or rust (Uromyces phaseoli var. vigna), but these foliage disease were more severe on southernpea plants grown in disk-harrowed treatments than in treatments deep-turned with a moldboard plow. Three applications of chlorothalonil reduced the severity of Cercospora leafspots and rust, but did not effectively control the diseases in all tests. Foliage diseases were less severe on ‘White Acre’ than on ‘Purpose Hull Pinkeye’ southernpea. ‘White Acre’ produced the most foliage in disk-harrowed treatments, and ‘Purple Hull Pinkeye’ was superior in deepturned treatments.

Open Access

Abstract

Dry onions of the Granex type were undercut during harvest operations using both oscillating and rotating bar undercutters. Analyses on cleanliness, damage, and disturbance revealed that operating the rotobar with a rotational speed of 540 rpm, a depth of 25 mm below the soil surface, and a forward speed of 6.4 km·hr−1 ensured the most favorable results of the operating speeds, depths, and forward speeds evaluated. Depth of operation was the most important single factor.

Open Access

Abstract

‘Granex 33’ and ‘Sweet Georgia’ onions (Allium cepa L.) at various stages of maturity were harvested by hand and with a prototype mechanical harvester in 1985 and 1986. Bulbs were evaluated for storage losses and bulb quality. Storage losses of both hand-harvested and machine-harvested bulbs were generally similar and increased with increased maturity. Bulb pungency was not affected by harvesting methods and was least for bulbs harvested when 6% of the tops were down. Total sugar concentration of hand-harvested onions, cured with intact tops, was greater than that of machine-harvested onions, when harvested before any of the tops were down, but sugar concentrations at later maturities were similar. Onions that were harvested when < 13% of the tops were down showed greater dry weight in hand-harvested than machine-harvested bulbs.

Open Access

Responses of sweet potato (Ipomoea batatas (L>) Lam) to irrigation rates were evaluated under line-source irrigation systems on Tifton loamy sand soil in Georgia and on a Bude silt loam soil in Mississippi. Total water (rainfall plus irrigation) rates ranged from about 55% to 160% of pan evaporation (Epan). Marketable yields increased with irrigation rate until total water was about 75% of Epan then decreased rapidly with greater irrigation rates. Sweet potato yields were more sensitive to excessive water rates when grown on a silt loam than on a sandy loam soil. Storage loss and quality of cooked 'Jewel' sweet potato roots also increased as the irrigation rate increased until total water was 75% to 95% of Epan then decreased rapidly at water rates of 135 to 160% of Epan.

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A line-source irrigation design was used to provide continuously increasing amounts of irrigation at each application to sweetpotato [Ipomoea batatas (L.) Lam]. Marketable yields increased with applied irrigation amounts until a total water application of 76% of pan evaporation (Epan) was reached and then decreased rapidly with applied irrigation amounts. Weight loss and decay of roots during storage showed quadratic responses to irrigation amounts and were minimal at the irrigation level of maximum yields. Contents of dextrins and maltose increased with irrigation amounts. Glucose content was maximum at a total water amount of 94% Epan and fructose content decreased with increased amounts of irrigation. Sensory ratings for appearance, flavor, texture, and preference, and objective color measurements of cooked flesh also reached their highest values near the irrigation amount of maximum yield.

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The effect of irrigation scheduling method (variable crop factor, 1; constant crop factor, 2; empirical, 3), soil water tension (25, 50, 75kPa SWT), tillage (disc arrow, DA, moldboard plow, MP) and planting dates (PD) on total irrigation (TI), number of irrigations (NI), useful (UR) and lost rainfall (LR) was studied using a Pascal program that simulated water budgets of 720 crops of snap bean over 10 years. NI and TI were significantly (p<0.01) lower with met.1. Met.3 had the lowest LR and highest UR, but did not allow the complete calculation of the water balance. TI was significantly higher at 25kPa. MP tillage requested fewer NI and less TI, had lower LR and higher UR. Early PD requested fewer NI and TI, and had higher LR. Hence, when water supply was not limiting and weather data were available, a combination of Met.1, MP at any PD provided a continuous supply of water to the crop while controlling water deficit.

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