Search Results

You are looking at 1 - 10 of 12 items for

  • Author or Editor: D.J. Collins x
Clear All Modify Search

Abstract

Plants of sweet potato (Ipomoea batatas (L.) Lam) were exposed prior to harvest to 1 week of warm-dry, warm-flooded, cold-dry or cold-flooded soil conditions. Roots harvested from the warm-flooded soil showed more rotting during curing than roots from the other treatments, and rotting continued during storage. Roots harvested from the cold-flooded soil rotted to a lesser extent during curing but rotted rapidly during storage. Roots harvested from the cold-dry soil showed no rotting during curing; however after 52 days of storage, the number of roots with rot increased sharply. Root respiration rates from cold-flooded, cold-dry, and warm-flooded soils were not significantly different, but those rates were much higher than the rate in roots from warm-dry soil. ‘Jewel’ had a lower respiration rate than NC 317. The cold treatments stimulated sprouting of sweet potato roots during storage. ‘Caromex’ showed the highest sprouting followed by ‘Jewel’, NC 317, and ‘Centennial’.

Open Access

Abstract

Harvested roots of 2 cultivars of sweet potato [Ipomoea batatas (L.) Lam.] were submerged in water to simulate flooding damage and changes in the concentrations of carbon dioxide, oxygen, and nitrogen were followed in the internal gas atmospheres. The internal gas was almost exclusively CO2, 72 hours after submergence.

Open Access

Organoleptic evaluations of shrink film-wrapped and nonwrapped musk-melon (Cucumis melo L. var. reticulates cv.. TAM Uvalde) fruit were conducted to determine changes in flavor and taste during refrigerated storage. Ripe green and yellow `TAM Uvalde' muskmelons, shrink film-wrapped in 12.7-μm high-density polyethylene film, were compared to nonwrapped melons during 21 days of storage at 4C and 90% to 95% RH. After 21 days of storage, both yellow and green shrink-wrapped melons had better appearance, less surface mold, and less vein tract browning than nonwrapped melons. However, the flavor and taste of shrink-wrapped fruit were significantly inferior to those of nonwrapped melons. Green-wrapped melons were rated poorer in taste and flavor than yellow-wrapped and nonwrapped melons after 14 days of storage. These results indicate that shrink-wrapping may enhance undesirable flavor changes in muskmelon during storage.

Free access

Abstract

Two mist systems, one in a mature orchard and the other in a young hedgerow, delayed bloom 15 days for ‘Bartlett’ and 8 days for ‘Bosc’ pear (Pyrus communis L.), while a low pressure sprinkler system delayed bloom for 14 days for ‘Bartlett’ and 8 days for ‘Bosc’ in 1976. Bloom delay generally increased fruit set and seed content of the fruit. Return bloom was greatly reduced in the mature orchard ‘Bartlett’ mist and ‘Bosc’ sprinkler plots in 1976 and, in turn, cropping was reduced the following year on these plots. Yield during treatment years was generally lower in the delayed areas. Fruit growth rates were accelerated in the bloom-delayed trees, but total fruit volume was less than the non-delayed fruit. Leaf nitrogen levels were reduced in all bud delayed treatments. Pear psylla oviposition was delayed in the mist system. Fire blight, caused by Erwinia amylovora (Burr.) Winslow et al., absent in 1975, was found in the misted ‘Bosc’ and in the sprinkled plots of both cultivars in 1976.

Open Access

Abstract

Mature orchard misting and sprinkling and young hedgerow misting for bloom delay of pear (Pyrus communis L.) reduced fruit sizes of ‘Bartlett’ 6% and of ‘Bosc’ 12%. Harvest maturity, indicated by fruit pressure testing, was delayed 0 to 6 days for ‘Bartlett’ and 2 to 7 days for ‘Bosc’. The effect of bloom delay on fruit size and maturity was greater on ‘Bosc’ than ‘Bartlett’. Bloom delay had a greater effect on fruit sizing at harvest (3.5 days for every 6 days of bloom delay) than on harvest maturity (1 day for every 6 days delay). Soluble solids, not affected in pears from the mature plots, were slightly lower in the misted hedgerow. Titratable acids were not influenced by bloom delay.

Open Access

A random sample of 6000 individuals from a recombinant Solanum phureja - S. stentomum hybrid population and 250 individuals of Solanum phureja were twice inoculated with potato virus Y (PVY) strain “o” using the air brush technique. Symptomless seedlings were field transplanted for further evaluation and 1508 seedlings were judged to be resistant to PVY (33%). At harvest, a mild selection pressure for tuber appearance was applied and 602 clones were selected.

Selected clones were re-evaluated for PVY resistance in the greenhouse: twice inoculated with PVY, tested by ELISA (Enzyme-linked immunosorbent assay), graft-inoculated with tobacco PVY infected scions, and subjected to a second ELISA test. To assess immunity to infection by PVY, the ELISA negative clones were bioassayed using tobacco cv. “Burley 21” as a plant indicator. We identified 224 PVY immune clones (4.8%).

Simultaneously, the first year PVY selected clones were twice inoculated with U.S. common strain of potato virus X (PVX). Clones free of PVX symptoms were tested by ELISA. Negative clones were re-inoculated with PVX and symptomless clones were re-tested by ELISA. To assess immunity to infection by PVX, negative clones were bioassayed using Gomphrena globosa as a plant indicator. We identified 7 immune (1.3%); 4 highly resistant and 4 resistant clones. Eight clones showed high levels of resistance to both PVY and PVX (high resistance to immunity).

Free access

Combinations of solarized soil (SBS), bare soil control (BS), black plastic mulched soil (BM), row cover (RC), fungicide (chlorothalonil) and biological treatments (Bacillus cereus) were evaluated. SBS vs. BS treatments were main plots, mulch and row covers splitplots and foliage treatments split-splitplots. Application of either foliar treatment was superior to BS. Using a 1/2 rate of fungicide on plants from solarized soil treatments showed equal or comparable reduction of the disease when compared to tomatoes grown in BS with high rates of the fungicide. Combined treatments of solarized + BM, BM with or without RC and low rate of fungicide or biological agent, were the most effective when compared to BS + fungicide, indicating that integration of plasticulture and biological strategies can reduce early blight below the levels of commercial fungicide applied to tomatoes grown on BS.

Free access

In 1995 a study was conducted in split-split-plot design to determine the effect of single, double, and equilateral planting configurations with a single and double recommended rate of fertilizer (NPK), would have on the yield of four sweetpotato cultivars. TU-1892, Jewel, TU-82-155, and Georgia Jet were planted on a raised shaped bed 2 ft wide. Fertilizer was banded in the center of the bed and plants were then placed 6 inches away on both sides of this band for the double and equilateral configurations and on one side for the single configuration. Plants were spaced 12 inches apart within rows and the rate of fertilizer used for both single and double rows was the recommended rate for single rows. All plots were side dressed with an additional 80 lbs/acre of K at the time of flowering. Marketable yield data showed that by doubling the recommended rate of fertilizer yield increased for all cultivars which ranged from 26%-41% for single, 35%-88% for double, and 64%-104% for equilateral configurations, respectively. The results also indicated that net returns for TU-1892 was 217%, Jewel 136%, TU-82-155 203%, and Georgia-Jet 171%, for double and equilateral configurations, respectively, when the rate of fertilizer was doubled.

Free access

Agriplastic black mulch (BM), row cover (spunbonded) plus black mulch (RBM) and solarized soil treatments plus black mulch (SBM). row cover plus black mulch on solarized soil (RSBM) and row cover plus solar&d soil (RSBS) increased Floradade tomato yield from 56 to 285%. number of tomatoes and plant height compared to the non-solarized bare soil (BS). When comparing increased growth response (IGR) of the plants grown in the solarized soil with no row cover agriplastic treatments, there was no significant differences among them. When comparing the IGR parameters of tomato plants grown under SBS, BM, and RBS there were no significant differences among them. Spunbonded row cover treatments increased IGR of tomatoes over all treatments without row cover. A significant increase in plant growth promoting rhizobacteria (PGPR) was observed in the rhizosphere soil of Floradade tomatoes grown in solarized soil alone and in those other agriplastic treatments compared to bare soil. There appear to be no differences in PGPR population among SBS and all agriplastic treatments.

Free access

In 1994, a study was conducted in split-plot design to determine the effect single- and double-row plantings would have on the yield of five sweetpotato cultivars. `TU-1892', `Carver', `Jewel', `TU-82-155', and `Georgia Jet' were planted on a raised shaped bed 2 feet wide. All recommended fertilizers were banded in the center of the bed and plants then were placed 6 inches away on both sides of this band for the double rows; single rows consisted of plants placed only on one side of the fertilizer band. Plants were spaced 12 inches apart within rows, and the rate of fertilizer used for single and double rows was the recommended rate for single rows. All plots were sidedressed with an additional 80 lbs/acre of K at the time of flowering. Marketable yield data showed that double-row planting of `Jewel', `TU-82-155', and `TU-1892' resulted in 36%, 38%, and 33% significant increase in yield, respectively, compared to single-row plantings. Double-row planting also significantly increased the yield of U.S. no. 1 `TU-82-155', `Jewel', and `Carver' sweetpotatoes by 40%, 43%, and 19%, respectively. All cultivars used in the study showed a significant increase in canners yield when planted in double vs. single rows. The results also indicated that `TU-1892', `Jewel', and `TU-82-155' may be more efficient in fertilizer use because higher yields were obtained in double-row plantings at the single-row fertilizer rates without the additional application of fertilizers.

Free access