The frost hardiness of five apricot (Prunus armeniaca L.) cultivars used for drying and/or the fresh market was investigated under controlled conditions and in the orchard. The hardiness of flower buds at three different development stages, such as first white, first bloom, and full bloom, was tested at –4 °C for 1 hour and 3 hours in the laboratory. The flower buds of `Kabaasi', `Sekerpare', and `Alyanak' were hardier. The field observations obtained from the apricot orchard where the late frost occurred at night on 3 to 4 Apr. 2004 supported this result, and the temperatures at frost date varied from –2 to –9 °C.
Paul T. Austin, Errol W. Hewett, Dominique Noiton, and Julie A. Plummer
Integer values used to represent apricot (Prunus armeniaca L.) flower bud growth stages in a phenological scale were adjusted by a simple technique based on cumulative counts of bud observations. Adjusted stage values on a new continuous scale were calculated so that differences between consecutive values were proportional to the frequency with which buds were observed in each growth stage class during the entire assessment period. This meant that adjusted scale values were linearly related to bud development rate at 20 °C. The method was applied to a scale describing flower development from budbreak to petal fall for three cultivars of apricot growing under orchard conditions.
Twenty variables were recorded on 15 apricot (Prunus armeniaca L.) genotypes differing in growth habit and blossom time to detect possible associations among morphological and phonological traits. The widest range of variability observed among phenotypes was for fruit size and factors associated with adaptation to local conditions, such as blossom season and yield potential as expressed by number of buds, flowers, and fruits per length of fruiting spurs. The most important morphological traits correlated with fruit weight were tree growth habit, apical and basal diameter of fruiting spurs, and bud and leaf size. Multivariate analysis allowed tree and variable grouping, which might encompass the basic criteria for apricot breeding programs in central México.
Santiago Vilanova, Carlos Romero, Gerardo Llácer, María Luisa Badenes, and Lorenzo Burgos
This report shows the PCR-based identification of the eight known self-(in)compatibility alleles (S 1 to S 7 and S c) of apricot (Prunus armeniaca L.). Two sets of consensus primers, designed from P. armeniaca S-RNase genomic sequences and sweet cherry (P. avium L.) S-RNase-cDNAs, were used to amplify fragments containing the first and the second S-RNase intron, respectively. When the results obtained from the two PCRs were combined, all S-alleles could be distinguished. The identity of the amplified S-alleles was verified by sequencing the first intron and 135 base pairs (bp) of the second exon. The deduced amino acid sequences of these fragments showed the presence of the C1 and C2 Prunus L. S-RNase conserved regions. These results allowed us to confirm S-genotypes previously assigned by stylar ribonuclease analyses and to propose one self-(in)compatibility group (I) and one universal donor group (O) containing unique S-genotypes and self-compatible cultivars (SC). This PCR-based typing system also facilitates the identification of the S c-allele and might be a very useful tool for predicting self-compatibility in apricot breeding progenies.
S.W. Westcott III, E.I. Zehr, W.C. Newall Jr., and D.W. Cain
Prunus accessions were screened in a greenhouse for suitability as hosts for Criconemella xenoplax (Raski) Luc and Raski. All 410 accessions examined were suitable hosts for the nematode. Included in this study were 266 Prunus persica L. Batsch cultivars and cultivars representing 25 other Prunus species: P. americana Marsh., P. andersonii A. Gray, P. angustifolia Marsh., P. argentea (Lam.) Rehd., P. armeniaca L., P. besseyi L. H. Bailey, P. cerasifera Ehrh., P. cistena N.E. Hansen, P. davidiana (Carriere) Franch., P. domestica L., P. dulcis (Mill.) D. Webb, P. emarginata (Dougl. ex Hook.) Walp., P. hortulana L. H. Bailey, P. insititia L., P. kansuensis Rehd., P. maritima Marsh., P. munsoniana W. Wright & Hedr., P. pumila L., P. salicina Lindl., P. simonii Carriere, P. spinosa L., P. tenella Batsch, P. texana D. Dietr., P. tomentosa Thunb., and P. webbii (Spach) Vierh. Also, another 66 interspecific hybrids were tested. Although a few accessions seemed to exhibit an unstable form of resistance, it seems unlikely that Prunus selections that exhibit useful resistance to population increase by C. xenoplax will be found.
Twelve peach (Prunus persica) cultivars, six apricot (Prunus armeniaca) cultivars, two japanese plum (Prunus salicina) cultivars, three european plum (Prunus domestica) cultivars, four sweet cherry (Prunus avium) cultivars, and three tart cherry (Prunus cerasus) cultivars were monitored for winter damage at New Mexico State University's Sustainable Agriculture Science Center in Alcalde, NM (main site), and the Agricultural Science Center in Los Lunas, NM (minor site), in 2011. Uncharacteristically low temperatures on 1 Jan. and 3 Feb. were recorded as −7.2 and −11.3 °F, respectively, at Alcalde, and 4.8 and −13.9 °F, respectively, at Los Lunas. On 10 Jan. at Alcalde, live peach flower bud percentage varied by cultivar, ranging from 11% for Blazingstar to 25% for PF-1, and 85% to 87% for Encore and China Pearl. Apricot flower buds were hardier, with 70% survival for ‘Perfection’, 97% for ‘Sunglo’, and 99% for ‘Harglow’ on 10 Jan. By 10 Feb., almost all peach flower primordia were discolored, with no cultivar showing more than 1% survival. Based on this information, the 10% kill of flower buds for most peach cultivars occurred at temperatures equal to or slightly higher than −7.2 °F, and 90% kill occurred between −7.2 and −11.3 °F. On 10 Feb., 0% to 15% of apricot flower buds on spurs or shoots of the middle and lower canopy had survived. For vigorous shoots in the upper canopy, apricot flower buds on 1-year-old shoots had a higher blooming rate than those on spurs of 2-year-old or older wood. Flower buds of japanese plum were also severely damaged with less than 0.2% survival for ‘Santa Rosa’ and 4.8% for ‘Methley’, but european plum were relatively unaffected with over 98% flower bud survival for ‘Castleton’ and ‘NY6’, and 87% for ‘Stanley’ after −11.3 °F at Alcalde. Cherry—especially tart cherry—survived better than peach, apricot, and japanese plum after all winter freezes in 2011.
Timothy L. Creger and Frank J. Peryea
Concerns about food safety prompted a case study of the arsenic and Pb contents of tree fruits grown on lead arsenate-contaminated soil. The arsenic concentration in apricot (Prunus armeniaca L.) and `Gala' apple (Malus domestica Borkh.) fruit was positively related to concentrated HCl-extractable soil arsenic. Fruit arsenic in both species did not exceed 70 μg·kg-1 fresh weight (fw). Fruit Pb was below the limits of detection of 20 μg·kg-1 fw for apricot and 24 μg·kg-1 fw for apple. All of these concentrations are substantially below levels associated with human health risk. `Riland' apricot trees did not show arsenic phytotoxicity at soil, fruit, and leaf arsenic concentrations associated with phytotoxicity symptoms in `Goldrich' apricots. The apple trees showed no visual symptoms of arsenic phytotoxicity.
On the basis of investigating pollination habits of 45 cultivars of Mei Hua, interspecific hybridization between Mei Hua and apricot (Prunus armeniaca). David's peach (P. davidiana) as well as siberian apricot (P. sibirica) were made from 1982 to 1991. With total number of pollination flower 17,050, 168 hybrid seed and 75 hybrid seedlings were obtained. Embryo culture in vitro was used for undeveloped young hybrid embryos. Test of freezing resistance both in artificial freezing and in overwintering for the hybrid seedlings showed that there were 5 hybrids with double and nice flower to be very hardy to low temperature. They were able to tolerate as low as -35C for 30 days in open ground, and now they were planted in northwest China's Gansu province and northeast China's Liaonin province without cold injury.
Sorkel A. Kadir and Ed L. Proebsting
Differential thermal analysis (DTA) was used to measure deep supercooling in flower buds of Prunus dulcis Mill., P. armeniaca L., P. davidiana (Carr.) Franch, P. persica (L.) Batsch, three sweet cherry (P. avium L.) selections, and `Bing' cherries (P. avium L.) during Winter 1990-91 and 1991-92. Low temperatures in Dec. 1990 killed many flower buds. After the freeze, dead flower primordia continued to produce low-temperature exotherms (LTEs) at temperatures near those of living primordia for >2 weeks. In Feb. 1992, cherry buds that had been killed by cooling to -33C again produced LTEs when refrozen the next day. As buds swelled, the median LTE (LTE50) of dead buds increased relative to that of living buds, and the number of dead buds that produced LTEs decreased. LTE artifacts from dead flower priimordia must be recognized when DTA is used to estimate LTE50 of field-collected samples.
O. Pérez-Tornero, F. Ortín-Párraga, J. Egea, and L. Burgos
Apricot (Prunus armeniaca L. cv.'Helena') shoots grown on a proliferation medium containing 3% sucrose, 0.4 mg·L–1 benzyladenine (BA), and 0.04 mg·L–1 indolebutyric acid (IBA) and solidified with 0.6% agar were stored at three different temperatures in the dark for up to 24 weeks. All shoots remained viable for 24 weeks when stored at 3 °C, while at 14 °C the percentage of survival decreased quickly after 12 weeks of storage. At 7 °C, percentage of survival started to decline after 18 weeks of storage. Shoots stored at 3 °C had the highest regeneration rates and shoot lengths following transfer to standard proliferation conditions. This temperature also had a beneficial effect on shoot proliferation during the first 12 to 18 weeks of the experiment.