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  • Author or Editor: D. W. Walker x
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Abstract

Field experimentation with sweet potatoes [Ipomoea batatas (L.) Lam.] is difficult because extraneous sources of error often require extensive replication and multiple experiments (1). These problems are compounded when cultivars of different growth habits are compared in adjacent plots. Because sweet potato plants produce extensive prostrate vines, there has been considerable controversy among researchers as to whether cultivars planted in adjacent rows compete with one another such that cultivar evaluation is compromised. This controversy was recently asserted by Bouwkamp (2), who used turning point tests and showed that the competitive effects of cultivars do not affect sweet potato yield trial results enough to justify the use of multi-row plots (2).

Open Access
Authors: and

Abstract

Sweet potato [Ipomoea batatas (L.) Lam.] cv. Travis storage roots were bedded on 8 and 27 Mar. 1985 according to standard cultural practices. The following row cover and mulch treatments were tested for their effects on early transplant production: a) bare soil (control); b) black polyethylene mulch; c) nonwoven polyester row cover; d) slitted, clear polyethylene row cover; or e) slitted, white polyethylene row cover. All row cover and mulch treatments increased soil temperature (at a 5-cm depth) relative to the bare soil. Compared to black polyethylene mulch, slitted, clear polyethylene row covers increased soil temperatures, whereas soil temperature was reduced by slitted white polyethylene. Mulch and row covers increased weight and number of large transplants as compared to bare soil. The primary effect of row covers as compared to mulch was to increase the percentage of large (>15 cm long) transplants. The use of slitted, clear polyethylene and slitted, white polyethylene row covers appeared to reduce the incidence of sclerotial blight (Scleratium rolfsii) in plant beds. Row cover and mulch treatments did not alter yield of storage roots grown from transplants produced under the various bed treatments.

Open Access

Abstract

Possible allelopathic effects of decaying sweet potato plant residue on sweet potato [Ipomoea batatas (L.) Lam.] and cowpea [Vigna unquiculata (L.) Walp.] growth were assessed. Residue treatments consisted of factorial combinations of 2 sweet potato cultivars (‘Jewel’ or ‘Centennial’), 2 plant parts (vines or storage roots), and 2 methods of tissue preparation–dried, or frozen and then dried. Ground sweet potato residues were mixed with sand [2.7% residue (w/w)] and placed in pots. Dry weights of ‘Jewel’ sweet potato plant shoots 57 days after planting were reduced 32% and 74% by vine and storage root residues, respectively, while dry weights of ‘Centennial’ sweet potato plant shoots were reduced 18% and 73%, respectively. Dried vine tissue had no apparent inhibitory effect, but vines frozen prior to drying reduced fresh and dry weights of ‘Centennial’ shoots. Dry weights of ‘Brown crowder’ cowpea plant shoots were reduced 79% and 91% by sweet potato vine and storage root residues, respectively. Nodulation of cowpeas grown in residue-amended pots was negligible compared to plants grown in pure sand. Leachate pH from pots containing sweet potato root residue was 1.4 and 2 pH units lower than that from nonamended pots with both sweet potato cultivars and cowpeas, respectively.

Open Access

Abstract

Concentration of endogenous ethylene was higher in Ag+-treated cuttings of sweet potato (Ipomoea batatas Lam.) than in the control or in cuttings subjected to 48°C for 2 minutes. When leaf tissue was dipped in 0, 125, 250, or 500 mg/liter Ag+, endogenous ethylene was increased by the 250 and 500 mg/liter treatments. When equal concentrations of NO3– were applied to cuttings as KNO3, Ca(N)O3)2, or AgNO3, only AgNO3 increased the endogenous ethylene content.

Open Access

Calcium chloride (CaCl2) enhances turgidity and quality of postharvest sour cherry, Prunus cerasus L., fruit. Mechanisms by which plasma membrane (PM) ATPase maintains the electrochemical gradient in cell turgor were studied in isolated PM vesicles isolated from tapwater-, CaCl2- and chelated amino acid-calcium-treated Montmorency sour cherry fruit. Electron microscopy and periodic-chromicphosphotungstic acid staining indicated 85-90% closed PM vesicles. Protein activity associated with the PM was four times higher in both Ca treatments than in untreated cherries. ATPase activity was insensitive to NO3 and NaN3, but inhibited by vanadate, indicating absence or low levels of tonoplast and mitochondrial ATPases. PM vesicles exhibited a pH jump in the presence of acridine orange (A493-530nm). Cherry fruit appeared to have a PM ATPase similar to that of other plant species. Generation of a positive membrane potential across the PM was dependent upon ATP.

Free access