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  • Author or Editor: C. R. Andersen x
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Fruit characteristics of Oriental persimmon (Diospyros kaki L.) [`Fuyu' (Expts. 1 and 2) and `Tanenashi' (Expt. 3)] were assessed as a function of five pollination treatments: 1) hand-pollination (HP) with `Gailey' pollen (G); 2) HP with `Nishimura Wase' pollen (NW); 3) HP with `Turkeytown' pollen (T) (not used for `Tanenashi'); 4) open-pollination (OP), which did not necessarily result in pollination; and 5) nonpollination (NP) where pollination was prevented by covering the flower. Final fruit set of `Fuyu' and `Tanenashi' was higher for G and NW pollen than for NP. Differences in fruit set among the remaining treatments depended on the particular experiment. For example, fruit set for OP was higher than for NP in Expts. 1 and 3 but not Expt. 2. Fruit weight and soluble solids concentration (SSC) of `Fuyu' were not affected by treatment in Expts. 1 and 2; however, in Expt. 2, fruit height and diameter of G, NW, T, or OP were larger than for NP. Seed count per fruit was inversely related to fruit development period but did not influence fruit size or SSC. Fruit height, diameter, weight, and total soluble solids of `Tanenashi' for G, NW, and OP exceeded those for NP, although rarely were seeds present.

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Abstract

Three separate factorial experiments were designed to evaluate the effect of 10 adjuvants on net CO2 assimilation rate (A), leaf conductance to water vapor (g1), and transpiration rate (E) of pecan [Carya illinoensis (Wagenh.) C. Koch] ‘Elliott’, blueberry (Vaccinium ashei Reade) ‘Chaucer’, red top photinia (Photinia × Fraseri Dress), and azalea (Rhododendron × ‘Pink Ruffles’). Single applications of Bond, Leaf Act 80A, Nu-Film-17, Ortho X-77, Penetrator 3, Plyac, Sorba Spray ZNP, Sun Spray 7E, Triton CS-7, or Triton B-1956 at recommended rates did not affect A, g1, or E compared to a water spray. The main effect of plant species was highly significant in all three studies without adjuvant-species interactions. A significant adjuvant effect on A occurred with a second application of Nu-Film-17, Plyac, and Triton B-1956. The only significant effect, when treatments were analyzed separately by species, was that A of Plyac-treated blueberry was less than the control.

Open Access

The Cohesion Tension Theory, first in 1894 introduced by Dixon and Joly is the theory most often invoked to explain water movement in a transpiring plant. The pressure chamber technique has provided the strongest indirect evidence for this theory. However, controversy remains because 1) the necessary pressure gradients in xylem vessels have never been measured directly; 2) it is uncertain how continuous water columns under great tensions could persist in a metastable state for extended periods of time, and; 3) direct pressure probe measurements on individual xylem vessels have not been indicative of the extreme negative pressures obtained with the pressure chamber. Xylem fluid is an energy-limited resource containing the lowest available carbon (energy content = 2 to 15 J/cm3) of any plant tissue. However, many species of xylophagous leafhoppers subsist entirely on this dilute food source, despite the negative pressures thought to occur in xylem vessels. Carbon limitations of leafhoppers were underscored by 1) high feeding rates; 2) an unprecedented assimilation efficiency of organic compounds (i.e., >99%); 3) ammonotelism, and; 4) synchronization of feeding to optimum host nutrient content both seasonally and diurnally. The maximum tension that can be generated by the cibarial pumping mechanism of an insect based on anatomy and biochemistry is about 0.3 to 0.6 MPa, far below the purported xylem tensions occurring during most daylight hours. By contrast, we have shown that feeding has been usually independent of xylem tensions, as measured with a pressure chamber, and instead was a function of the amide content of xylem fluid. Moreover, the calculated net energy gain of insect feeding (or that contained within insect biomass) on xylem fluid of a given composition under a given tension have also been an a paradox. Experiments will be described that provide insight into the energetics of xylem fluid extraction.

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Homalodisca coagulata (Say), a xylem-fluid feeding leafhopper, vectors diseases induced by the bacterium Xylella fastidiosa such as phony peach disease and Pierce's disease. The purpose of this study was to investigate plant factors that influence feeding. H. coagulata were confined to stems of peach [Prunus persica (L.) Batsch] and crape myrtle (Lagerstroemia indica L.). Osmolarity, amino acid and organic acid concentrations of xylem fluid were maximum during the morning for peach and declined thereafter; xylem fluid chemistry of crape myrtle followed a less distinct trend. Irrigated plants had higher concentrations of organic constituents and feeding rates were higher on these plants. Feeding rates and xylem fluid tensions, were maximum during midday; feeding did not occur at night. In separate experiments feeding rates were greatly reduced at xylem tensions >1.5 MPa.

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A fresh-market tomato trial was conducted in 2003 at two locations in Arkansas (Fayetteville and Kibler) to evaluate new and old tomato varieties of interest to home gardeners and farmers' markets. The observational trial consisted of 43 varieties, indeterminates and determinates. Heirloom tomatoes comprised a large portion of the trial due to increasing popularity. Heirlooms are unique and can be very eye-catching. There is immense variety in shape, size, and color. They can be large or small, many times the shape is irregular, and the fruits flawed (cracking, cat-facing, green shoulders). The fruit may not store or ship well; most are grown and sold locally. Some heirlooms are better than others. A few of the varieties that stood out in the trial were Costoluto Genovese, Abraham Lincoln, Dona, and Persimmon. Costoluto Genovese, a uniquely ruffled red tomato, was the highest yielding variety at the Kibler location. Fruit quality remained high even in the highest temperatures. One of the most promising was a orange variety called Persimmon, it produced large fruit and the plants provided excellent cover. Dona and Abraham Lincoln, both reds, yielded well and had good flavor. San Marzano and Arkansas 7985 were the best paste types. Arkansas varieties such as Bradley, Ozark Pink, and Arkansas Traveler 76 also did well. Brandywine varieties had low yields and lesser quality fruit. Green zebra, a green striped fruit with good flavor, yielded less due to Blossom End Rot. Cherokee Purple and Carbon were two from the purple/black category that did not do well; yields were low and the fruit cracked.

Free access

Abstract

‘Sungem’ nectarine [Prunus persica (L.) Batsch] (Fig. 1) was released to provide an early ripening nectarine for commercial markets. All nectarines released by the Univ. of Florida begin with the prefix “Sun”. ‘Sun-gem’ is expected to be successful for homeowners, consumer harvest, local markets, and commercial growers with large acreage.

Open Access

Abstract

Nine pesticides (chlorothalonil, captan, benomyl, permethrin, methomyl, parathion, carbaryl, dicofol, and S) were sprayed on peach (Prunus persica L. Batsch ‘June Gold’) to determine pesticide-induced effects on leaf conductance (gl), transpiration (E), and net CO2 assimilation rate (A). Parathion was the only material to reduce A when applied <3 times. Net CO2 assimilation rate declined by 10% to 25% for parathion-, methomyl-, chlorothalonil-, benomyl-, and captan-treated trees after 3 applications; however, gl was reduced only for the parathion and chlorothalonil treatments. The pesticide-sensitivity of peach A appears to be much less than pecan and somewhat similar to apple. Chemical names used: 2,4,5,6-tetrachloro-l,3-benzenedi-carbonitrile (chlorothalonil); 3a,4,7,7a-tetrahydro-2-[(trichloromethyl)thiol]-lH-isoin-dole-l,3(2H)-dione (captan); methyl[l-](butylamino)carbonyl]-lH-benzimidazol-2-yl]carbamate (benomyl); (3-phenoxyphenyl)methyl 3-(2,2-dichloroethenyl)-2,2-dimethylcyclopropanecarboxylate (permethrin); methyl N-[[(methylam-ino)carbonyl]oxy]ethanimidothioate(methomyl); 0,0-diethyl 0-p-nitrophenylphospho-rothioate (parathion); 1-naphthalenyl methylcarbamate (carbaryl); and 4,4′-dichloro-α-trichloro-methylbenzhydrol (dicofol).

Open Access

Abstract

The development of a high yielding, pink root-resistant [Pyrenochaeta terrestris (Hansen) Gorenz, Walker, and Larson], mild, sweet, shortday onion (Allium cepa L.) with improved shipping quality was the objective for the onion breeding program in the Texas Agricultural Experiment Station. ‘Texas Grano 1015Y’ (TG1015Y) is a very mild and sweet cultivar with those quality characteristics.

Open Access