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  • Author or Editor: Louise Ferguson x
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The `Manzanillo' olive (Olea europaea L.) is widely grown in California, because olive processors prefer its uniform size and quality for their canned product. Although it is self-compatible, 10% of a planting should be committed to a pollinizer cultivar to promote optimal production of seeded `Manzanillo' fruit and minimal occurrence of worthless parthenocarpic “shotberries.” As fruits of pollinizer cultivars are of substantially less value and more difficult to manage within a `Manzanillo' planting, less commitment of land for pollination purposes would be desirable. Here we show that topical applications of supplemental olive pollen can be a feasible alternative to commitment of land to olive pollinizer cultivars within a `Manzanillo' planting.

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Moisture and fat content, fatty acid profile, and volatile terpenes were measured for the first time for ‘Kalehghouchi’, ‘Pete 1’, and ‘Lost Hills’ pistachios grown at two California microclimates: Lost Hills and Parlier. ‘Kalehghouchi’ had the highest moisture content, followed by ‘Pete 1’ and ‘Lost Hills’, respectively. While the moisture content of ‘Kalehghouchi’ was not significantly affected by location, it was lower for ‘Pete 1’ grown at Parlier (40.8 vs. 40.8 g/100 g) and higher for ‘Lost Hill’ grown there (48.2 vs. 45.2 g/100 g). ‘Pete 1’ grown at the Parlier site had a higher fat content compared with ‘Lost Hills’ (47.7 vs. 43.0 g/100 g). ‘Kalehghouchi’ had a lower fat content at Parlier compared with Lost Hills (42.0 vs. 44.9 g/100 g), and ‘Lost Hills’ was unaffected by location. The main fatty acid measured in the pistachio samples was oleic acid (52% to 58%), followed by linoleic (26% to 33%) and palmitic acids (11% to 13%). While oleic acid content of ‘Lost Hills’ and ‘Kalehghouchi’ was higher for pistachios grown in Parlier, no impact of location was observed for ‘Pete 1’. The fatty acid profiles of all three cultivars appeared to be more dependent on genotype and less affected by microclimate. α-pinene (95–1682 ng/kg), limonene (37–741 ng/kg), and α-terpinolene (1–368 ng/kg) were the most abundant volatiles among all the cultivars and locations. Microclimate was the primary factor in determining volatile terpenes concentration in pistachio kernels.

Open Access

Salinity’s many stresses may not kill a relatively salt-tolerant perennial in one season, but they can still deplete or modify nonstructural carbohydrate (NSC) pools. Any change to the quantity or quality of NSC reserves may have detrimental effects on phenology and reproduction, as well as yield, in tree crops. This study integrates salinity’s infringement on the energy margins of pistachio rootstock ‘UCB-1’ (an interspecific hybrid of Pistacia atlantica and P. integerrima) at senescence by measuring sugar and starch pools in wood, bark, and roots after treatment with ≈100 days of moderate to high salinity (50–100 mm NaCl and 10–20 mm CaCl2). Supported by a second experiment using sodium orthovanadate (NaOV) to block active xylem retrieval in the same hybrid pistachio rootstock, we conclude that retrieval of Na+ from xylem sap may allow for the preservation of NSC pools (particularly, starch) in mature xylem tissues by limiting the demand for carbon-based osmoticum (sugars). In contrast, younger growing tissues (bark and fine roots) were found to counteract salinity by degrading carbon-dense starch into osmotically active sugars at the expense of total NSC reserves, suggesting a physiological shift toward protection/isolation from environmentally pervasive but potentially toxic salts in these tissues.

Open Access

Trunk cross-sectional area from a population of 6192 pistachio trees was used to estimate tree growth from 1995 to 1997. The narrow-sense heritabilities of trunk cross-sectional area were near zero across multiple locations based on analyses of progenies from 20 half-sib families. However, within individual location, there were values from 0.20 to 0.56 for 1995, 1996, and 1997, respectively. Broad-sense heritability estimates were considerably higher, from 0.36 to 0.64 at multiple locations and 0.51 to 1.35 for individual locations. These results suggest that dominance and significant interaction effects, epistatic and genotype by environment, were important. Breeding strategies should emphasize selection of superior parents based on individual performance, and parents should be selected in the environment in which the progeny are intended to be used.

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A pistachio breeding program was initiated in 1989 to develop new cultivars for the California industry. The program was begun with an initial set of 1940 progeny from 78 crosses. In 1990, an additional 5470 seedlings were produced from 176 controlled crosses. Progeny were planted at Winters, Calif., Kearney Agr. Center, and a plot near Bakersfield in a randomized block design with crosses as treatments. Fifty-three, 962, and 2943 genotypes flowered in 1994, 1995, and 1996, respectively. Data on flowering, flowering date, sex, tree size as measured by trunk cross-section area, and disease status were collected on all trees in the breeding program at the three field locations. Nuts were collected and evaluated for number of nuts/tree, % splits, % blanks, wet and dry weight, kernel weight, and volume. Heritability estimates for nut characters, tree size, and Alternaria resistance were ranged from 0.30 to 0.76. Several parents were identified that apparently provide a high level of resistance to Alternaria. Relationships among various nut parameters and the relationship of tree size to flowering and parentage were also investigated and evaluated statistically. Replicated advanced selection trials will be established in 1997.

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A deformity designated as `damage by other means' (DBOM) by California pistachio processors appeared in California's San Joaquin Valley orchards in 1990. Incidence, higher during the heavy crop year of this alternate bearing cultivar, was as high as 5% of harvested yield. This represents a significant loss as DBOM nuts cannot be used for shelling stock.

In 1993 ten weekly individual cluster samples from five heavily and five lightly cropped trees demonstrated a higher incidence of DBOM on heavily cropped trees. Further the damage occurred within one month of nut set, was exclusively on subterminal, adaxial positions of the rachis, and, often did not involve the nutmeat unless the deformity was extensive enough to expose the developing nutlet causing desiccation and abscission. Microanatomical studies demonstrated a deterioration of the parenchyma cells that form the inner cell layers of the endocarp (nut shell).

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A stepwise multiple regression analysis, using payment by processors as the dependent variable (Y) and numerous physical and chemical characteristics as the independent variables (X), demonstrated that the primary factor determining `Manzanillo' olive (Olea europaea L.) value at harvest was size. Optimal crop value correlated strongly with the combined percentage of standard, medium, large, and extra-large olives; R' values were 0.93***, 0.93***, and 0.42 (ns) in 1984, 1985, and 1986, respectively. As the harvest season progressed, increased percentages of olives within these size classifications, not weight increases of individual olives within the size categories, produced the increase in value. Individual olives within size categories maintained the same weight through the harvest season, regardless of tree crop load. The best criterion for predicting optimal harvest time “is the total percentage of standard, medium, large, and extra-large olives.

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The California table olive (Olea europaea L.) industry relies exclusively on hand harvesting of its primary Manzanillo cultivar. Increased harvesting costs have intensified industry interest in identifying an abscission agent that can be used with developing mechanical harvesting technologies to increase removal rates. Table olives are harvested immature green at horticultural maturity but before physiological maturity. The goal of this research was to reevaluate the potential of ethylene-releasing compounds (ERCs) as olive-loosening agents and to screen additional candidates previously shown to accelerate citrus fruit abscission. Eleven compounds were screened at two separate table olive-growing sites (Fresno and Tehama counties) in California in September until Nov. 2006. Compounds were applied at various concentrations alone or in combination. Fruit detachment force (FDF) and percent fruit drop were measured and leaf loss assessed. Of the compounds evaluated, the ERC ethephon (2-chloroethyl phosphonic acid) and 1-aminocyclopropane-1-carboxylic acid were the most efficacious. In whole tree applications, concentrations of ethephon or 1-aminocyclopropane-1-carboxylic acid above 1000 mg·L−1 reduced FDF to less than 50% of the untreated control within 17 days, but leaf drop increased with increasing concentrations. Addition of 1-methylcyclopropene reduced efficacy of ethephon and delayed leaf drop. Monopotassium phosphate + ethephon (4% and 1000 mg·L−1, respectively) reduced FDF and leaf loss was equivalent to the ethephon alone treatment. Compounds such as methyl jasmonate, coronatine, dikegulac, MAXCEL, traumatic acid, and 5-chloro-3-methyl-4-nitro-1H-pyrazole were not efficacious.

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Springtime flail mowing of row middles for weed control in California pistachio (Pistacia vera L.) orchards blows dust into the leafless canopy if it occurs during bloom. The effect of dust on pistachio pollination and fruit set is unknown. Rachises were bagged prebloom and hand pollinated with pollen and dust mixtures at 1:0, 1:1, 1:4, 1:16, and 0:1 volume/volume ratios on five successive days. The 2016 and 2017 trials demonstrated that the inflorescences treated with a high pollen:dust ratio (0:1, 1:4, and 1:16) had significantly lower split nut rates (commercially less profitable) compared with low dust ratio tests (1:0 and 1:1). Our results also showed that dust damaged both pollen viability and stigma quality, particularly if contaminated with herbicide residues (GlyStar® Plus and Treevix®). Decreased yield was a function of decreased fruit set; increased embryo abortion, parthenocarpy, or both; and a lower split nut percentage. The GA3 content in flowers of both the pollen and dust treatments was significantly higher than that in nonpollinated flowers, suggesting dust stimulated parthenocarpy, resulting in empty nutshells, “blanks” at harvest.

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