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  • Author or Editor: M. L. Meyer x
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Kiwifruit (Actinidia deliciosa) is a functionally dioecious plant where fruit size is dependent on number of seeds set. Pollen fertility was estimated in 1990 and 1991 by percentage stainability and percentage germinability in vitro. Profiles of the isozymes AAT, GPI and PGM were used to assess if any large differences in pollen fertility could be attributed to genotypic variation. Based on these three isozymes, eight different genotypes were discovered. Although significant differences were found among vines within orchards and among orchards, all vines can be considered good pollenizers (stainability > 87%). A positive correlation was found in 1991 between percentage stainability and percentage germination.

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Abstract

Inflorescence slices of tall bearded iris (Iris sp.) regenerated callus in vitro on a modified Murashige-Skoog high salt medium supplemented with 2.5 mg/liter napthaleneacetic acid (NAA) and 0.5 mg/liter kinetin. Callus pieces transferred to light initiated plantlets at their periphery and produced fuU-sized, true-to-type flowering plants when transplanted to soil.

Open Access

The toxic bait, Adios, was tested with the use of a trap crop in a field experiment at the Univ. of Nebraska during Summer 1998. The insecticide contains the secondary plant metabolites known as cucurbitacins that are highly attractive to the striped and spotted cucumber beetles, Acalymma vittatum and Diabrotica undecimuncata howardi, respectively. These beetles serve as the vector of the bacterial pathogen, Erwinia tracheiphila, which causes severe wilting and eventual death of susceptible cucurbits. The objective of the study was to determine whether treatments of Adios, when applied to a flowering trap crop of resistant squash plants, would lure the cucumber beetles away from the susceptible cucumber plants and reduce bacterial wilt. The study compared the effectiveness of a sprayed trap crop, the direct application of Adios to the cucumber plants and no treatment in a randomized complete-block design. A greater number of beetles were attracted to the sprayed and untreated cucumbers compared to the cucumbers surrounded by the treated trap plants. However, significant numbers of dead beetles were found near the sprayed cucumber plants. Untreated plants showed more feeding damage, diminished fruit quality, and an earlier observation date of wilt symptoms as compared to the other treatments. The treated trap plants and the direct application of Adios were effective in delaying infection in cucumbers compared to the untreated plants in the experimental plots. This treatment may be useful to home gardeners.

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Concentrations of aroma precursor compounds in ‘Riesling’ wine grapes (Vitis vinifera) are reported to correlate with fruit zone cluster exposure, although optimal cultural influences with respect to exposure timing and canopy assessment methods have not been established. To determine the impact of cluster exposure on concentrations of potential aroma compounds, correlations between light exposure metrics during the growing season and relative concentrations of eight representative aroma compounds at harvest were determined. The aroma compounds were carbon-13 (C13) norisoprenoids [1,1,6-trimethyl-1,2-dihydronaphthalene (TDN), β-damascenone, and vitispirane], monoterpenes (linalool oxide, α-terpineol), and phenolics (4-vinylguaiacol, vanillin and eugenol). Cluster exposure was determined using metrics of varying spatial precision [percent interior cluster (PIC), cluster exposure layer (CEL), ln(CEL), cluster exposure flux availability (CEFA), and the percent ambient photosynthetic photon flux (PPF)] at two sites and two phenological stages (fruit set and veraison) in two consecutive seasons (2008 and 2009). Pairwise combinations of cluster exposure metrics and compounds resulted in 360 permutations, of which 22 were significant. Response data suggested that none of the compounds studied respond to variable cluster exposure levels below 20% of ambient sunlight (CEFA < 0.2), and that low cluster exposure may be particularly effective in minimizing C13 norisoprenoid concentrations at harvest. Yield components were also tested but found to have lower R 2 values compared with cluster exposure metrics. Active canopy management, in which vine vigor and fruit exposure are independently controlled, is likely to be more effective in influencing potential aroma compounds than selectively harvesting for naturally occurring variation in cluster exposure. In comparing the relative predictive strength among metrics, CEFA ≅ ln(CEL) > CEL > PIC ≅ percent PPF, suggesting that cluster exposure metrics with greater spatial sensitivity are more effective for establishing light response curves.

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The influence of three irrigation treatments on flowering, yield, tree growth, root distribution, and leaf analysis of mature `Hass' avocado (Persea americana Mill.) was investigated over a six year period (1987-1992). Three irrigation treatments; 60, 80, and 100% of evapotranspiration (ETc) were applied using low-volume spray emitters. The differential irrigation treatments were maintained year round. Irrigation treatments did not affect the timing or intensity of bloom. Yield data from years 2-6 show a significant irrigation effect on cumulative weight and total number of fruit per tree. Trees receiving 100% ETc had higher yield/tree. This increased yield was due both to increased fruit numbers and individual fruit weight per tree. Tree growth was also significantly impacted by the irrigation treatments. Trees receiving 100% ETc exhibited the greatest amount of vegetative growth over the study. Yield efficiency (Kg fruit/m3 canopy) was not influenced by irrigation treatment. Irrigation treatment did not significantly influence nutrient analysis taken in the fall of each year.

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Mustard seed meals of indian mustard [InM (Brassica juncea)] and yellow mustard [YeM (Sinapis alba)], alone and combined, were tested for effects on tomato (Solanum lycopersicum) plants and for suppression of southern root-knot nematode [RKN (Meloidogyne incognita)] and weed populations. In the greenhouse, with all seed meal treatments applied at 0.25% total w/w soil, low tomato plant stands (up to 60% dying/dead) resulted from amendment with 3 YeM:1 InM, 1 YeM:1 InM, and YeM, applied right before transplant. Compared with untreated controls, low numbers of RKN eggs per gram root were consistently recorded from amendment with 3 YeM:1 InM. In a 2012 field study, incorporation of 1 YeM:1 InM (1700 lb/acre) resulted in lower tomato root biomass than fertilizer application (504 lb/acre), YeM or InM (each 1700 lb/acre). All treatments were applied with added fertilizer to achieve 100–102 lb/acre nitrogen, 7.4 lb/acre phosphorus, 74.7 lb/acre potassium, 6.0 lb/acre sulfur, and 1.0 lb/acre boron. The lowest numbers of RKN eggs per gram root (harvest 2012) were collected from plots amended with InM (1700 lb/acre), YeM (850 lb/acre), and 3 YeM:1 InM (1700 lb/acre), but the numbers were not significantly different from fertilizer only (504 lb/acre) controls. Highest and lowest tomato yields (numbers of fruit) in 2012 were recorded from YeM (850 lb/acre) and 3 YeM:1 InM (1700 lb/acre) amendments, respectively. In 2013, there were no significant differences among treatments in eggs per gram root or in tomato yields. No mustard seed meal treatment affected weed populations. At the tested rates, YeM seed meal showed potential for use in tomato beds but results were inconsistent between years.

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A traditional dairy-based frozen dessert (ice cream) was developed with three levels of sweetpotato (Ipomoea batatas) puree [20%, 30%, and 40% (by weight)] to determine the impact of sweetpotato content on product functionality, nutritional content, and sensory characteristics. Increased sweetpotato puree resulted in increased orange color, flavor intensity, and sweetpotato flavor, but 40% puree proved difficult to incorporate into the mixture. Additionally, nondairy frozen desserts containing 30% sweetpotato puree were compared with a milk-based control in which all ingredients were the same except that milk was replaced with soy (Glycine max) and almond (Prunus dulcis) milk. Consumer acceptability tests were conducted with panelists at Mississippi State University (n = 101) and in Pontotoc, MS (n = 43). Panelists in Pontotoc rated the overall acceptability of all three frozen desserts the same, but they preferred the appearance of the milk-based frozen dessert over that of soy- and almond-based milk alternatives. According to the panelists at Mississippi State, the milk-based frozen dessert had greater overall acceptability and aroma than the almond-based dessert and a preferential texture and appearance compared with the soy- and almond-based desserts. Milk-, soy-, and almond-based frozen desserts were rated as “slightly liked” or better by 92%, 80%, and 69% of the panelists, respectively.

Open Access

Anthracnose, caused by the fungal pathogen Colletotrichum cereale Manns sensu lato Crouch, Clarke & Hillman, can be a damaging disease on many cool-season turfgrasses; however, it has not been reported as an aggressive pathogen on fine fescue species (Festuca spp.). Symptoms and signs associated with anthracnose disease were observed in fine fescues on the Rutgers University Plant Science Research and Extension Farm in Adelphia, NJ, in Jun 2014. The objectives of this study were to identify the causal agent, determine if the isolate of C. cereale (FF1A) obtained from symptomatic Chewings fescue (Festuca rubra L. ssp. commutata Gaudin) plants was pathogenic to Chewings fescue and hard fescue (F. brevipila Tracey) turfs, and whether cultivars and accessions collected from Europe varied in disease susceptibility. Pathogenicity of this fine fescue isolate was evaluated using four Chewings fescue and four hard fescue cultivars or accessions in a growth chamber. Disease symptoms were first observed at 5 days post-inoculation, and evaluations continued to 17 days post-inoculation. Infection was confirmed by morphological evaluations, re-isolation from symptomatic tissues, and real-time polymerase chain reaction (PCR). Three noncommercial accessions (two Chewings fescues and one hard fescue) were very susceptible to the fine fescue C. cereale FF1A isolate, whereas ‘Sword’ and ‘Beacon’ hard fescues exhibited low susceptibility. In addition, an isolate of C. cereale (HF217CS) from annual bluegrass [Poa annua L. f. reptans (Hausskn) T. Koyama] was included, and our data demonstrated that this isolate was also able to infect Chewings fescue and hard fescue. This study confirmed that C. cereale can be a damaging pathogen of fine fescues, and that breeding for resistance to anthracnose should be considered when developing new cultivars.

Open Access

Avocado (Persea americana) is a subtropical tree prized for its large and nutritious fruit. Although native to Mesoamerica, avocado is now grown in tropical and subtropical regions around the world, and consumer demand for avocado continues to grow at a considerable rate. Despite the appeal of avocado, its genetic improvement has been slow owing to substantial land and labor requirements combined with the fact that young trees do not produce fruit for several years and a pollination system that makes it difficult to produce genetic crosses. Molecular markers promise to accelerate the rate of breeding progress, especially for simple traits of high heritability. One of the distinguishing features of the avocado fruit is the presence of a number of compounds that have been linked to human health. As a prelude to the use of molecular markers for the improvement of nutritional traits, this article reports estimates of the heritability of carotenoids, β-sitosterol, and α-tocopherol content (the most biologically active form of vitamin E) in ripe avocado fruit. Each of these three compounds has been linked to beneficial health outcomes, and each is shown to have a sufficiently high heritability to predict successful marker-assisted selection.

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