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Jalil Dejampour, Islam Majidi, Solmaz Khosravi, Sevil Farhadi, and Atena Shadmehr

great importance. The HS314 rootstock is a hybrid between almond and peach ( Prunus amygdalus × P. persica ), which is well adapted to drought conditions ( Dejampour et al., 2005 ). This rootstock that has been bred in Sahand Horticultural Research

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Pere Arús, Carmen Olarte, Miguel Romero, and Francisco Vargas

Ten isozyme genes were studied after analyzing the variability of eight enzyme systems—glucose phosphate isomerase (GPI), phosphoglucomutase (PGM), aspartate aminotransferase (AAT), leucine aminopeptidase (LAP), 6-phosphogluconate dehydrogenase (6PGD), isocitrate dehydrogenase (IDH), shikimate dehydrogenase (SDH), and aconitase (ACO)—in the progeny of five crosses among almond [Prunus amygdalus Batsch, syn. P. dulcis (Miller) D. A. Webb] cultivars. Six of these loci were found to be located in two linkage groups, one containing four loci (Pgm-2, Gpi-2, Aat-2, and Lap-1) and two more in the other (Idh-2 and Aat-1). Genetic configurations of pairs of loci specific to segregating F1 progeny of crosses between heterozygous parents were found in our data, for which we derived the estimate of the recombination fraction and its variance. Linkage data for the gene pairs that could be estimated in various crosses were used to obtain a joint estimation of the recombination fraction.

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José Manuel Alonso and Rafael Socias i Company

Pollen tube growth after selfing was studied in four almond (Prunus amygdalus Batsch) families derived from crosses between self-compatible `Tuono' and self-incompatible `Ferragnès' and `Ferralise' in both directions, in order to ascertain the phenotypic expressions of the different genotypes. A differential expression of self-compatibility was observed in the seedlings of the different families. The genetic self-compatible offspring of `Ferralise' showed a lower percentage of pistils with pollen tubes at the style base and a lower number of pollen tubes at the pistil base after self-pollination than those observed in the self-compatible offspring of `Ferragnès'. This low level of self-compatibility expression observed in some `Ferralise' seedlings may be due to the inbreeding present in `Ferralise'. As a consequence, caution must be taken in almond breeding to avoid the increase of inbreeding by the utilization of related parents and to diversify the sources of self-compatibility, at present mostly limited to `Tuono.'

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Bridget M. Lamp, Joseph H. Connell, Roger A. Duncan, Mario Viveros, and Vito S. Polito

Scanning electron microscopy was used to examine almond [Prunus dulcis (Mill.) D.A. Webb (syn. Prunus amygdalus Batsch, Amygdalus communis L.)] flower bud development for three cultivars (Nonpareil, Carmel, and Butte) from four California locations (which span the range of almond production in California) for 2 years, and for `Nonpareil' in a single location for a third year. The objectives were to document timing of floral developmental events and to better understand the extent of variation that exists within and among cultivars, locations, and years. Results indicated that the time of floral initiation relative to hull split varied among cultivars. Median time for floral initiation in `Nonpareil' was more than 3 weeks after the onset of hull split. For `Butte' and `Carmel', median time of floral initiation preceded the onset of hull split. Extensive variation in the timing of bud development events within a cultivar was apparent. Timing of developmental events varied among locations, but no patterns emerged consistent with the north to south range which spanned 4°15' latitude and 520 km. Among years, development occurred earliest in 1997, a relatively warm year, and was delayed in 1998 and 1999, relatively cool years. Results indicate an earlier onset of floral initiation than reported in the classical literature on the subject.

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J.M. Alonso, J.M. Ansón, M.T. Espiau, and R. Socias i Company

Almond (Prunus amygdalus Batsch.) blooming date is determined by the temperatures during the dormancy period, from the onset of endodormancy to just before blooming. In this work we have developed a model, based on several years data, to estimate the mean transition date from endodormancy to ecodormancy in 44 almond cultivars covering the whole range of almond bloom, through the significance of correlation coefficients between the temperatures occurring during dormancy and the date of full bloom. The estimation of this date for each cultivar has allowed the calculation of its chill and heat requirements. It was found that most cultivars have chilling requirements between 400 and 600 chill units, whereas the span of heat requirements was wider, from 5500 to 9300 growing degree hours Celsius. Some cultivars show high chilling requirements and low heat requirements whereas others show opposite requirements. These differences confirm the wide almond adaptability to different climatic conditions and offer the possibility of being utilized in breeding programs. The good fit shown by the application of this model in the prediction of bloom time may sustain its application in chilling and heat requirement estimation in other fruit species if blooming dates and climatic data for several years are available.

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D.E. Kester, T.M. Gradziel, and W.C. Micke

Six cross-incompatibility groups, which contain most of commercially important California almond cultivars [Prunus dulcis (Mill.) D.A. Webb, syn. Prunus amygdalus Batch], and their self-incompatibility (S) allele genotypes are identified. Incompatibility groups include `Mission' (SaSb), `Nonpareil' (ScSd), and the four groups resulting from the `Mission' × `Nonpareil' cross: (SaSc), (SaSd), (SbSc), and (SbSd), as represented by `Thompson', `Carmel', `Merced' and `Monterey', respectively. All seedlings from the `Mission' × `Nonpareil' cross were compatible with both parents, a result indicating that these two cultivars have no alleles in common. Crossing studies support a full-sib relationship for these progeny groups and the origin of both parents from common germplasm. Cultivars in these six groups account for ≈ 93% of present California production, a result demonstrating a limited genetic base for this vegetatively propagated tree crop.

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Joseph H. Connell

Almond, [Prunus dulcis (synonym Prunus amygdalus)] planted on approximately 595,000 acres (240,797 ha), is California's largest acreage tree crop. California's Central Valley accounts for nearly 100% of the U.S. domestic production of almonds. Integrated pest management (IPM) programs that integrate cultural practices and pest and disease monitoring with selective controls have improved plant protection in almond. Methods of orchard floor management and their effects must also be taken into account. Minimizing dust reduces mites while harvesting earlier and the destruction of overwintering refugia are cultural practices that reduce worm damage. Improved methods for field sampling and monitoring have reduced the need for pesticide applications while improving timing and effectiveness of needed crop protection sprays. Selective controls have further reduced the impact on nontarget species. Augmentative parasite releases have also helped manage navel orangeworm (Ameylois transitella). Effective use of new selective fungicides will require precise application timing and greater knowledge of diseases and resistance management. A better understanding of disease life cycles leading to improved monitoring of the fungal diseases, shothole (Wilsonomyces carpophilus), almond scab (Cladosporium carpophilum), and anthracnose (Colletotrichum acutatum) have reduced fungicide applications. Future challenges include the potential loss of effective pest control products, the need to continually develop improved utilization strategies, and maintaining economic sustainability.

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Joseph H. Connell

California almonds [Prunus dulcis, (Mill.) D.A. Webb, syn. Prunus amygdalus Batsch] are self-incompatible requiring cross-pollination to produce a commercial crop. Within seven known pollen groups, they also display cross-incompatibility. Coincidence of bloom between compatible cultivars is essential for cross-pollination. Since almonds are pollinated primarily by honeybees [Apis mellifera L.], arranging pollinizers in close proximity to one another promotes maximum pollen transfer. Almonds are frequently subject to inclement weather during their February bloom period. Strong honeybee colonies are better able to forage during marginal weather conditions than are weak colonies. Honeybee management can encourage pollen foraging and placement of colonies can affect flight activity and ultimately nut-set. Weather permitting vigorous honeybee flight activity is the most important factor for setting a good crop. Temperature also affects anther dehiscence, pollen germination, and pollen tube growth. The sooner an almond flower is cross-pollinated after opening, the greater the chance of fertilization and nut-set. Optimizing all of these pollination factors is therefore essential to achieve maximum production in almond orchards.

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Dale E. Kester, Warren C. Micke, and Mario Viveros

`Jeffries', a mutant of `Nonpareil' almond [Prunus dulcis (Mill.) D.A. Webb], showed “unilateral incompatibility” in that its pollen failed to fertilize cultivars in the `Carmel' (CIG-V), `Monterey' (CIG-VI), and `Sonora' (CIG-VII) pollen cross-incompatibility groups (CIGs), as well as specific cultivars (`Butte', `Grace', and `Valenta') whose CIG group is unknown. `Jeffries' is not self-compatible, but produced good set when pollinated by 12 almond cultivars representing the entire range of CIGs involving `Nonpareil' parentage, as well as the parent `Nonpareil'. It was concluded that the `Jeffries' mutant—both gametophyte and sporophyte—expressed a loss of a single S allele of the `Nonpareil' genotype.

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Adnan Nurhan Yildirim, Fatma Akinci-Yildirim, Mehmet Polat, Bekir Şan, and Yılmaz Sesli

almond ( Prunus amygdalus L.) varieties selected from Tokat province and Eagean region of Turkey Journal of Medicinal Plants Research 5 4907 4911 Bolarinwa, I.F. Orfila, C. Morgan, M.R.A. 2014 Amygdalin content of seeds, kernels and food products