Search Results

You are looking at 11 - 20 of 32 items for

  • Author or Editor: Louise Ferguson x
Clear All Modify Search

Four pistachio rootstocks, Pistacia atlantica, P. integerrima, and two selections of the same interspecific hybridization, P. atlantica, P. atlantica × P. integerrima (A.K.A. PGII and UCB #1) budded with P.vera, P. vera cv. Kerman females have been evaluated since 1989 in three locations in California's central San Joaquin Valley. Thus far, Atlantica is the most cold tolerant, followed by the interspecific hybrids and Integerrima. Integerrima and UCB no. 1 have produced significantly more clusters and nuts per tree, but all rootstocks have produced the same numbers of nuts per cluster. Trees on no.1 and Integerrima rootstocks also have produced significantly more kilograms of nuts per trunk cross sectional area than Atlantica and PGII. UCB #1 and Integerrima also are significantly more tolerant of the soilborne fungus Verticillium dahl. All rootstocks are equally infected with three species vesicular–arbuscular mycorrhizzae. Two seasons of irrigation with water up to 8.00 dS·m–2, have not affected rootstock performance or yield. UCB #1, Integerrima, and PGII all require supplemental boron, zinc, and copper nutrition for good production. Thus far, Integerrima is the best rootstock for soils with verticillium infestations unless winter temperatures are frequently below freezing. UCB #1 is the best rootstock for locations with cold winters.

Free access

The uptake and distribution of foliar and soil applied boron has been followed in a seven year old pistachio orchard by utilizing 10B isotope dilution techniques and ICP-MS determination. In conjunction with these uptake studies, in-vivo and in-vitro measurements of pollination and fruit set have been used to determine the role of boron in flowering and fruit set.

Foliar applications of boron (1, 2.5 and 5 kg/400 l) resulted in improved fruit set when compared to control trees receiving no supplemental B even when tissue B levels in these control trees appeared adequate (>60 μg/g dwt). Results indicate that B applied to male trees in the late dormant phase (february) is effective in enhancing in-vitro pollen germination by as much as 50%. Movement of B into flower buds and fruit clusters was verified using 10B techniques thus demonstrating the potential usefulness of this technique in correcting incipient B deficiency. A possible role of B in the flowering and fruiting process is discussed.

Free access

Spring freeze is among the problems threatening pecan bloom and production. Pecan tree height and structure make them difficult to protect from spring freezes. Some cultivars can compensate because the secondary buds can produce healthy flowers if the primary buds freeze. The mechanism that precipitates secondary budbreak is unknown. Our results show a correlation between successful secondary budbreak and 1-year-old shoot carbohydrate levels. ‘Kanza’ and ‘Pawnee’, with the higher secondary budburst, also had higher carbohydrate levels than ‘Maramec’. This suggests higher carbohydrate levels in the bud-bearing 1-year-old shoots promote successful secondary bud burst after spring freeze destruction of the primary buds.

Open Access

A genomic DNA library enriched for dinucleotide (CT)n and (CA)n and trinucleotide (CTT)n microsatellite motifs has been developed from `Kerman' pistachio (Pistacia vera L.). The enrichment method based on magnetic or biotin capture of repetitive sequences from restricted genomic DNA revealed an abundance of simple sequence repeats (SSRs) in the pistachio genome which were used for marker development. After an enrichment protocol, about 64% of the clones contained (CT)n repeats while 59% contained (CA)n for CT and CA enriched libraries, respectively. In the (CT)n enriched library, compound sequences were 45% while for (CA)n it was 13.5%. In both dinucleotide enriched libraries, about 80% of the clones having microsatellites have a repeat length in the range of 10 to 30 units. A library enriched for trinucleotide (CTT)n contained <19% of the clones with (CTT)n repeats. Of the clones that contained microsatellites, 62% had sufficient flanking sequence for primer design. An initial set of 25 pairs of primers was designed, out of which 14 pairs amplified cleanly and produced an easily interpretable PCR product in the commercially important American, Iranian, Turkish, and Syrian pistachio cultivars. The efficient DNA extraction method developed for pistachio kernels and shells (roasted and nonroasted) yielded DNA of sufficient quality to use PCR to create DNA fingerprints. In total, 46 alleles were identified by 14 primer pairs and a dendrogram was constructed on the basis of that information. The SSR markers distinguished most of the tested cultivars from their unique DNA fingerprint. An UPGMA cluster analysis placed most of the Iranian samples in one group while the Syrian samples were the most diverse and did not constitute a single distinct group. The maximum number of cultivar specific markers were found in `Kerman'(4), the current industry standard in the United States, and the Syrian cultivar Jalab (5). The technique of using extracted DNA from pistachio kernal or shell coupled with the appropriate marker system developed here, can be used for analyses and measurement of trueness to type.

Free access

Abstract

Several experimental procedures were used to evaluate the influence of solar radiation on insect infestations in Calimyrna and Adriatic variety figs (Ficus carica L.). Direct sunlight eliminated infesting insects and prevented further infestation of ripe figs drying on the ground for at least 10 days. Placement in the shade resulted in 12% insect infestation in figs within 3 days. Figs that fell naturally into sunlighted areas contained almost no insects, whereas 31% of figs that fell into dense shade were infested. While ripening figs were still attached to trees, the level of insect infestation was 50% higher on the shady north side than the sunny south side. The insect pests most frequently encountered in these experiments were nitidulid beetles and their larvae. Disease incidence was not affected by degree of exposure. We propose that cultural techniques to maximize exposure of ripening and drying figs to solar radiation could be developed as important pest management tools.

Open Access

The effect of two fruit maturity stages on the quality attributes of four fresh fig cultivars was examined, including consumer acceptance and antioxidant capacity. Fig quality attributes such as weight, soluble solids concentration (SSC), titratable acidity (TA), SSC:TA, firmness, antioxidant capacity, and consumer acceptance varied by cultivar. Fig cultivars harvested at the advanced maturity stage (“tree ripe”) had lower TA and firmness but higher weight, SSC, and SSC:TA than figs harvested at “commercial maturity.” Fig maturity did not affect antioxidant capacity, but tree ripe figs had higher consumer acceptance than commercial maturity figs. SSC was more highly correlated with consumer acceptance than TA or SSC:TA, but other factors may also be important in controlling this relationship. Cultivars with high SSC and firmness, at a maturity stage high enough to tolerate harvesting and postharvest handling, should be selected to develop the fresh fig industry. Because fig firmness is a concern, changes to packaging should be evaluated to protect the flavor of advanced maturity figs during postharvest handling.

Free access

Most fig (Ficus carica) cultivars have potentially two crops; fruit from the first crop are called brebas. This crop is commercially important in some Mediterranean area cultivars. The second or main crop, called figs, is the commercially important crop for most fig cultivars. Due to labor cost increases, harvest of the breba crop, with its low production and lower quality fruit, has become economically unviable in some cultivars. Unharvested brebas are potential sites for fungal pathogens and they attract insects. Spring ethephon applications of 250 to 500 ppm applied before full leaf expansion, when the largest fruit are about 1.5 to 2 cm in diameter reduced the breba crop load (≈92%) without adverse side effects. The use of early fall ethephon applications of 500 ppm also resulted in breba crop load reductions (≈30%), but with significantly lower efficacy than spring treatments. These fall and/or spring ethephon treatments did not affect the percentage of vegetative budbreak, breba weight, breba soluble solids concentration, fig crop load, fig weight, or ethephon residues. Thus, early spring ethephon application at 300 ppm (0.22–0.36 kg·ha−1), when breba fruit and leaves are just starting to develop and figs are not present, was a safe, effective and inexpensive way (about $16 per hectare) to reduce the breba crop. Currently, ethephon is included in the federal IR-4 program, and residue studies are ongoing as a protocol for future registration.

Full access

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.

Full access

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