- Author: Brooke Jacobs
A search of Web of Science revealed a few new publications on drought stress and salt tolerance in Pistachio. I copied the citations, abstracts, and a link to the articles below. If you are working on a UC network with library access clicking on the "url" will enable you to download the full article.
Drought stress
H. Abbaspour, S. Saeidi-Sar, H. Afshari and M. A. Abdel-Wahhab. 2012. Tolerance of Mycorrhiza infected Pistachio (Pistacia vera L.) seedling to drought stress under glasshouse conditions. Journal of Plant Physiology. 169. 7. 704-709.
url: http://www.sciencedirect.com/science/article/pii/S0176161712000879
The influence of Glomus etunicatum colonization on plant growth and drought tolerance of 3-month-old Pistacia vera seedlings in potted culture was studied in two different water treatments. The arbuscular mycorrhiza (AM) inoculation and plant growth (including plant shoot and root weight, leaf area, and total chlorophyll) were higher for well-watered than for water-stressed plants. The growth of AM-treated seedlings was higher than non-AM-treatment regardless of water status. P. K, Zn and Cu contents in AM-treated shoots were greater than those in non-AM shoots under well-watered conditions and drought stress. N and Ca content were higher under drought stress, while AM symbiosis did not affect the Mg content. The contents of soluble sugars, proteins, flavonoid and proline were higher in mycorrhizal than non-mycorrhizal-treated plants under the whole water regime. AM colonization increased the activities of peroxidase enzyme in treatments, but did not affect the catalase activity in shoots and roots under well-watered conditions and drought stress. We conclude that AM colonization improved the drought tolerance of P. vera seedlings by increasing the accumulation of osmotic adjustment compounds, nutritional and antioxidant enzyme activity. It appears that AM formation enhanced the drought tolerance of pistachio plants, which increased host biomass and plant growth. (C) 2012 Elsevier GmbH. All rights reserved.
V. Bagheri, M. H. Shamshiri, H. Shirani and H. R. Roosta. 2012. Nutrient Uptake and Distribution in Mycorrhizal Pistachio Seedlings under Drought Stress. Journal of Agricultural Science and Technology. 14. 1591-1604.
url: http://www.sid.ir/En/VEWSSID/J_pdf/8482012S14.pdf
This study was conducted to determine the effects of arbuscular mycorrhizal fungi (Glomus mosseae and Glomus intraradices) symbiosis on mineral uptake of two pistachio cultivars (Pistacia vera cv. Qazvini and Pistacia vera cv. Badami-Riz-Zarand) grown in the greenhouse under different drought stress levels. Drought stress (DS) reduced the mycorrhizal colonization in both cultivars as well as nutrient uptake. The mycorrhizal plants had higher P, K, Zn and Mn concentrations than non-mycorrhizal plants regardless of soil moisture conditions while Cu and Fe concentrations were unchanged. Distribution of elements was affected by AMF treatments where all except P were accumulated more in leaves than in roots. Contrastingly, under drought conditions, the absorbed elements tended to remain in root tissue. In the case of P and Mn uptake, Qazvini was superior in comparison with Badami. In conclusion, it is suggested that AMF inoculation improves drought tolerance of pistachio cultivars at least in part through the enhanced uptake of slowly diffusing mineral ions such as PO42- and Zn2+. Moreover, arbuscular mycorrhizal (AM) colonization provides better osmotic adjustment which can be correlated with K+ accumulation in top portions of inoculated plants. Results of this study also emphasized that 'Qazvini' cultivar may be more tolerant to drought than 'Badami'.
Salt tolerance
N. Bastam, B. Baninasab and C. Ghobadi. 2013. Improving salt tolerance by exogenous application of salicylic acid in seedlings of pistachio. Plant Growth Regulation. 69. 3. 275-284.
url: http://link.springer.com/article/10.1007/s10725-012-9770-7
Salicylic acid (SA) is a common, plant-produced signal molecule that is responsible for inducing tolerance to a number of biotic and abiotic stresses. An experiment was therefore conducted to test whether the application of SA at various concentrations (0, 0.10, 0.50, or 1.00 mM) as a foliar spray would protect pistachio (Pistacia vera L.) seedlings subjected to salt stress (0, 30, 60, or 90 mM NaCl). SA improved growth rate of pistachio seedlings under salt stress and increased relative leaf chlorophyll content, relative water content, chlorophyll fluorescence ratio, and photosynthetic capacity as compared with the control at the end of salt stress. SA ameliorated the salt stress injuries by inhibiting increases in proline content and leaf electrolyte leakage. It appeared the best ameliorative remedies of SA obtained when pistachio seedlings were sprayed at 0.50 and 1.00 mM.
H. Benhassaini, A. Fetati, A. K. Hocine and M. Belkhodja. 2012. Effect of salt stress on growth and accumulation of proline and soluble sugars on plantlets of Pistacia atlantica Desf. subsp atlantica used as rootstocks. Biotechnologie Agronomie Societe Et Environnement. 16. 2. 159-165.
The effect of salt stress on several physiological and biochemical parameters of Pistacia atlantica Desf. subsp. atlantica plantlets was studied under controlled conditions in a climatic room. The plants were grown in pots and irrigated with a Hoagland nutrient solution during 120 days. Then, the plantlets were treated for 10 days with 100, 200, and 400 meq.l(-1) NaCl + CaCl2, added to the Hoagland nutrient solution. The applied salts caused stress on the young Pistacia plantlets by reducing the growth of roots and shoots. The amount of free proline in leaves increased significantly with salinity under all treatments, to reach a maximum rate at the highest salinity concentration (400 meq.l(-1)) for all the plantlets. On the other hand, a significant difference in relative water content (RWC) was noted under the effect of 400 meq.l(-1) of NaCl + CaCl2. The plantlets stressed at 100 meq.l(-1) did not exhibit any influence of the salt on RWC, but their accumulation of sugars was much higher than at 200 meq.l(-1). At 400 meq.l(-1) the plantlets also accumulated a high content of soluble sugars, and after seven days of stress, their accumulation rose with the increasing salt concentration. The content of proline and soluble sugars in P. atlantica subsp. atlantica rootstock was very high, indicating that P. atlantica subsp. atlantica can be used as rootstock for Pistacia vera as it is more tolerant to salinity.
Chill requirements
O. Elloumi, M. Ghrab, H. Kessentini and M. Ben Mimoun. 2013. Chilling accumulation effects on performance of pistachio trees cv. Mateur in dry and warm area climate. Scientia Horticulturae. 159. 80-87.
url: http://www.sciencedirect.com/science/article/pii/S0304423813002215
Pistachios (Pistacia vera L.) are widely grown in the arid rainfed areas of Tunisia. However, pistachio production is still low with important variation between years. This study investigated the responses of pistachio trees to variable winter chilling and annual precipitation. It was carried out in an experimental orchard of Mateur, the most important Tunisian cultivar in central Tunisia (34 degrees 94'11 '', 10 degrees 60'82 '') for a period of twelve years from 1997 to 2008. Yield correlated poorly with precipitation (varying on the range of 80-300 mm/year during the 12 years) and showed a moderate alternate bearing index of 0.63. However, flowering and nut yield of pistachio trees was a function of chill accumulation computed as chilling hours (CH), chill units (CU) or chilling portions (CP) depending on using Crossa-Raynaud, Utah or Dynamic models, respectively. For Mateur cultivar, the threshold chilling accumulation appeared to be 206 CH, 539 CU or 36 CP depending on the model used. Under this level, pistachio production was clearly affected. Warm winters with low chilling caused erratic floral bud break, delayed flowering, sparse foliage and decreased yield. With inadequate winter chilling, chemical treatments with hydrogen cyanamide (Dormex) at 2 and 4% increased floral bud break, advanced flowering period and improved vegetative growth of pistachio trees in comparison to the untreated control. As a conclusion, better prediction of chill accumulation must be achieved in the warm production region of Tunisia. To that effect, the Dynamic model showed the lowest coefficient of variation compared to the chilling hours and Utah models and seemed to better reflect what is happening on the field under our warm winter regions. (C) 2013 Elsevier B.V. All rights reserved.
- Author: Carlos H Crisosto
To maximize pomegranate quality fruit should be picked when fully ripe because they do not ripen off the tree. Pomegranate should be carefully maintained in cold storage after harvest because fruit are susceptible to chilling injury (CI). CI following exposure to temperatures below 5°C (41°F) during storage and transport for longer than 4 weeks is a major cause of deterioration during marketing. The incidence and severity of CI depends upon storage temperature, duration and cultivar (Photo 1). The minimum safe storage temperature is 5°C (41°F) for up to 8 weeks, if decay is not a problem. For longer storage, the temperature should be at 7oC (450F) to avoid chilling injury, but decay (Botrytis cinerea) and weight loss may become a limitation. A postharvest application of the fungicide Fludioxonil (Scholar) is approved for use on pomegranates with a 5ppm maximum residue limit to control decay development and prolong storage (Photo 2). However, pomegranates must be dipped in the fungicide solution because the botrytis spores are usually in the calyx area of the fruit, which are not adequately covered by postharvest spraying during packaging. After dipping surface moisture must be removed with a fan to eliminate free moisture on the fruit when stored in a box or bin. Under these storage conditions, pomegranates should be cooled to 70C (450F) as soon as possible after harvest and fungicide application. Fruit should be kept at 70C (450F) with relative humidity between 90-95% during storage and transportation to attain a postharvest-life longer than 8 weeks, depending on the cultivar.
Author Information
Carlos H. Crisosto
Pomologist and Specialist, Plant Sciences Department, University of California Davis
Director of the Fruit & Nut Research & Information Center
References
- Elyatem, S. M. and A. A. Kader. 1984. Post-harvest physiology and storage behavior of pomegranate fruits. Scientia Horticulturae 24:287-298.
- Kader, A. A., A. Chordas, and S. Elyatem. 1984. Responses of pomegranates to ethylene treatment and storage temperature. California Agriculture 38(7 & 8):14-15.
- Palou, L., C.H. Crisosto, and D. Garner. 2007. Combination of postharvest antifungal chemical treatments and controlled atmosphere storage to control gray mold and improve storability of ‘Wonderful’ pomegranates. Postharvest Biology and Technology 43: 133-142.
- Hummer K.E., Pomper, K.W., Postman, J.D., Graham, C.J., Stover, E., Mercure, E.W., Aradhya, M., Crisosto, C.H., Ferguson, L., Thompson, M.M., Byers, P., and F. Zee.2012. Emerging Fruit Crops. Chapter 4, pp.97-147. In: (M. L. Badenes and D.H. Byrne, eds.) Fruit Breeding. Springer, NY, NY. 875 pp.
- Author: Brooke Jacobs
All of the new additions to the FNRIC website, fruitsandnuts.ucdavis.edu, would not be possible without the hard work of our expert reviewers. With over 115,000 visits per year our website is an important source of information and outreach to the public in California. To meet high quality standards established by UC Agriculture and Natural Resources and UC Davis the FNRIC requires a minimum of two expert reviewers per crop before new information is posted online.
We would like to acknowledge the contribution of our reviewers who span a wide range of backgrounds from growers, commodity groups, extension specialists, UC faculty, and farm advisors. We sincerely appreciate your willingness to take time out of your busy schedules to provide critical feedback and suggestions on all our new website content.
Expert reviewers:
Ted DeJong, Professor, Dept. of Plant Sciences at UCD
Vito Polito, Professor, Dept. of Plant Sciences at UCD
Chuck Leslie, Specialist in the UC Davis Walnut Breeding Program
Scott Johnson, UCCE Specialist Emeritus
Maxwell Norton, Merced and Mariposa County Farm Advisor
Louise Ferguson, UCCE Specialist
Janine Hasey, Sutter and Yuba County Farm Advisor
Joe Grant, San Joaquin County Farm Advisor
Steve Sibbett, Farm Advisor Emeritus
Bruce Lampinen, UCCE Specialist
Chuck Ingels, Sacramento County Farm Advisor
Craig Ledbetter, USDA ARS
Maria Badenes, Faculty at the Instituto Valenciano de Investigaciones Agrarias
Jeff Moersfelder, USDA ARS Germplasm Repository
Carolyn DeBuse, USDA ARS Germplasm Repository
John Preece, USDA ARS Germplasm Repository Director
Wes Hackett, Professor Emeritus and walnut consultant
Paul Mesple, fig grower with Mesple Farms and the California Fig Board
Brian Blain, pecan grower with Blain Farms and the California Pecan Growers Association
Bob McClain, California Pear Advisory Board
Kitren Glozer, Project Scientist, Dept. of Plant Sciences at UCD
Tom Gradziel, Professor, Dept. of Plant Sciences at UCD
- Author: Brooke Jacobs
We searched Web of Science for new almond (Prunus dulcis) orchard management research published in 2013. Below is a list of some new publications we found spanning a wide range of topics including global warming emissions, weed management, cold tolerance, irrigation, drought tolerance, and pollination. If you access this blog from a UC or ANR office you can click on the “url” listed to view the full paper.
University of California affiliated research on emissions from almond orchards
D. L. Schellenberg, M. M. Alsina, S. Muhammad, C. M. Stockert, M. W. Wolff, B. L. Sanden, P. H. Brown and D. R. Smart. 2012. Yield-scaled global warming potential from N2O emissions and CH4 oxidation for almond (Prunus dulcis) irrigated with nitrogen fertilizers on arid land. Agriculture Ecosystems & Environment. 155:7-15
Abstract: The optimum yield-scaled global warming potential (GWP) of perennial crops on arid land requires effective strategies for irrigation and fertilization. In 2009-2010, N2O emissions and CH4 oxidation were measured from an almond [Prunus dulcis (Mill.) D.A. Webb] production system irrigated with nitrogen (N) fertilizers. Individual plots were selected within a randomized complete block design with fertilizer treatments of urea ammonium nitrate (UAN) and calcium ammonium nitrate (CAN). Event-related N2O emissions from irrigation and fertilization were determined for seasonal periods of post-harvest, winter, spring and summer. Peak N2O emissions in summer occurred within 24h after fertilization, and were significantly greater from UAN compared to CAN (p<0.001). Cumulative N2O emissions from UAN were on average higher than CAN though not significantly different. Air temperature, water-filled pore space (WFPS), soil ammonium (NH4+) and soil nitrate (NO3-) showed significant positive correlation with N2O emissions and significant negative correlation was found for the number of days after fertilization (DAF). The percentage of N2O loss from N fertilizer inputs was 0.23% for CAN and 0.35% for UAN while CH4 oxidation offset 6.0-9.3% of N2O emissions. Total kernel yield was not significantly different between fertilizer treatments. Yield-scaled GWP for almond from CAN (60.9 kg CO(2)eq Mg-1) and UAN (91.9 kg CO(2)eq Mg-1) represent the first report of this metric for a perennial crop. These results outline effective irrigation and fertilization strategies to optimize yield-scaled GWP for almond on arid land. (C) 2012 Elsevier B.V. All rights reserved.
Pollination
R. G. Danka, L. I. De Guzman, T. E. Rinderer, H. A. Sylvester, C. M. Wagener, A. L. Bourgeois, J. W. Harris and J. D. Villa. 2012. Functionality of Varroa-Resistant Honey Bees (Hymenoptera: Apidae) When Used in Migratory Beekeeping for Crop Pollination. Journal of Economic Entomology. 105. 2. 313-321.
url: http://www.bioone.org/doi/pdf/10.1603/EC11286
Abstract: Two types of honey bees, Apis mellifera L. (Hymenoptera: Apidae), bred for resistance to Varroa destructor Anderson & Trueman were evaluated for performance when used in migratory crop pollination. Colonies of Russian honey bees (RHB) and outcrossed bees with Varroa-sensitive hygiene (VSH) were managed without miticide treatments and compared with colonies of Italian honey bees that served as controls. Control colonies were managed as groups which either were treated twice each year against V. destructor (CT) or kept untreated (CU). Totals of 240 and 247 colonies were established initially for trials in 2008 and 2009, respectively. RHB and VSH colonies generally had adult and brood populations similar to those of the standard CT group regarding pollination requirements. For pollination of almonds [Prunus dulcis (Mill.) D. A. Webb] in February, percentages of colonies meeting the required six or more frames of adult bees were 57% (VSH), 56% (CT), 39% (RHB), and 34% (CU). RHB are known to have small colonies in early spring, but this can be overcome with appropriate feeding. For later pollination requirements in May to July, 94-100% of colonies in the four groups met pollination size requirements for apples (Malus domestica Borkh.), cranberries (Vaccinium macrocarpon Aiton), and lowbush blueberries (Vaccinium angustifolium Aiton). Infestations with V. destructor usually were lowest in CT colonies and tended to be lower in VSH colonies than in RHB and CU colonies. This study demonstrates that bees with the VSH trait and pure RHB offer alternatives for beekeepers to use for commercial crop pollination while reducing reliance on miticides. The high frequency of queen loss (only approximately one fourth of original queens survived each year) suggests that frequent requeening is necessary to maintain desired genetics.
S. Bayazit, B. Imrak and O. Caliskan. 2012. Determination of Pollen Production and Quality attributes of some Almond Cultivars (Prunus dulcis) and Selected Wild Almond (Amygdalus orientalis) Genotypes. International Journal of Agriculture and Biology. 14. 3. 425-429.
Abstract: This study was carried out to establish pollen production, viability and germination ratios for five almond genotypes of Amygdalus orientalis Mill. (Orientalis 5, Orientalis 6, Orientalis 7, Orientalis 9 & Orientalis 10) and four cultivars of Prunus dulcis Mill., (Nonpareil, Texas, Ferragnes & Ferraduel). For determination of pollen viability of selected almond genotypes, 2.3.5 Triphenyltetrazolium chloride and Fluorescent diacetat tests were made. Pollen germination ratios in vitro conditions were determined with petri dishes methods. For A. orientalis genotypes, pollen viability ratios according to the TTC test were found to be 61.80% and 72.88% in 2006 and 2007, respectively whereas the same ratios according to the FDA test carried out in 2006 and 2007 were 63.44% and 57.50%, respectively. The number of anthers in one flower, the number of pollen in one anther and the number of pollen in one flower were found higher in cultivars, whereas these traits turned out to be lower in A. orientalis genotypes. 'Orientalis 6' was notable pollen viability, the number of anthers in one flower, the number of pollen in one anther and the number of pollen in one flower, while the highest pollen germination percentage was recovered from 'Orientalis 9' had in 2006 and from 'Orientalis 5' in 2007. Morphological homogeneity (%) was found to be high in all orientalis types both experimental years. The results obtained with A. orientalis genotypes proved that they could well be employed as pollinizer for hybrid improving work to be made with almond cultivars. (C) 2012 Friends Science Publishers
Cold tolerance
P. M. Barros, N. Goncalves, N. J. M. Saibo and M. M. Oliveira. 2012. Functional characterization of two almond C-repeat-binding factors involved in cold response. Tree Physiology. 32. 9. 1113-1128.
url: http://treephys.oxfordjournals.org/content/32/9/1113.short
Abstract: Low temperature plays a crucial role in seasonal development of woody plants and may directly impact crop production, more particularly in temperate fruit trees. Given its high genetic variability and adaptability to different climatic conditions, almond (Prunus dulcis Mill.) is an interesting model to understand the mechanisms regulating low temperature sensing in fruit trees. In this paper, we report the cloning and characterization of two genes (PdCBF1 and PdCBF2) belonging to the C-repeat-binding factor (CBF) family of transcription factors. Southern blotting analysis showed that this family is composed of at least five members. In almond shoots propagated in vitro, transcription of these genes was rapidly induced by low temperature, suggesting an involvement in cold acclimation. Transactivation assays showed that PdCBF1 and PdCBF2 could bind to dehydration responsive element/C-repeat containing sequences, as activators of gene expression. In addition, induction of both PdCBFs by cold was higher towards the end of the day, which agreed with the expression pattern of PdDehydrin1, a predicted CBF target gene. Furthermore, PdCBF1 and PdCBF2 were also transiently induced by abscisic acid and drought treatments. Considering the bin mapping analysis that correlated PdCBFs and PdDHN1 (respectively in linkage groups 5 and 7) with two different quantitative trait locicontrolling blooming time, it is relevant to perform further association studies that may validate their effect on this trait.
Water stress and irrigation
G. Egea, M. M. Gonzalez-Real, A. Baille, P. A. Nortes, M. R. Conesa and I. Ruiz-Salleres. 2012. Effects of water stress on irradiance acclimation of leaf traits in almond trees. Tree Physiology. 32. 4. 450-463.
url: http://treephys.oxfordjournals.org/content/32/4/450.short
Abstract: Photosynthetic acclimation to highly variable local irradiance within the tree crown plays a primary role in determining tree carbon uptake. This study explores the plasticity of leaf structural and physiological traits in response to the interactive effects of ontogeny, water stress and irradiance in adult almond trees that have been subjected to three water regimes (full irrigation, deficit irrigation and rain-fed) for a 3-year period (2006-08) in a semiarid climate. Leaf structural (dry mass per unit area, N and chlorophyll content) and photosynthetic (maximum net CO2 assimilation, A(max), maximum stomatal conductance, g(s,max), and mesophyll conductance, g(m)) traits and stem-to-leaf hydraulic conductance (Ks-l) were determined throughout the 2008 growing season in leaves of outer south-facing (S-leaves) and inner northwest-facing (NW-leaves) shoots. Leaf plasticity was quantified by means of an exposure adjustment coefficient (epsilon = 1-X-NW/X-S) for each trait (X) of S- and NW-leaves. Photosynthetic traits and Ks-l exhibited higher irradiance-elicited plasticity (higher epsilon) than structural traits in all treatments, with the highest and lowest plasticity being observed in the fully irrigated and rain-fed trees, respectively. Our results suggest that water stress modulates the irradiance-elicited plasticity of almond leaves through changes in crown architecture. Such changes lead to a more even distribution of within-crown irradiance, and hence of the photosynthetic capacity, as water stress intensifies. Ontogeny drove seasonal changes only in the epsilon of area- and mass-based N content and mass-based chlorophyll content, while no leaf age-dependent effect was observed on epsilon as regards the physiological traits. Our results also indicate that the irradiance-elicited plasticity of A(max) is mainly driven by changes in leaf dry mass per unit area, in g(m) and, most likely, in the partitioning of the leaf N content.
P. Puerto, R. Domingo, R. Torres, A. Perez-Pastor and M. Garcia-Riquelme. 2013. Remote management of deficit irrigation in almond trees based on maximum daily trunk shrinkage. Water relations and yield. Agricultural Water Management. 126. 33-45.
url: http://www.sciencedirect.com/science/article/pii/S0378377413001108
Abstract: This study assesses the usefulness of the remote scheduling of regulated deficit irrigation (RDI) in almond based on the maximum daily trunk shrinkage signal intensity (SIMDS). The 2-year experiment was carried out in SE Spain on 12-year-old almond trees (Prunus dulcis (Mill.) D.A. Webb cv. Guara). Four irrigation treatments were established to evaluate soil-plant water status, yield and water productivity: (i) control treatment (CTL), irrigated to satisfy the maximum crop water requirements (ETc), (ii) RDI1 and (iii) RDI2, both established to maintain different target thresholds of SIMDS according to the phenological stage and (iv) farmer treatment (FRM), irrigated by the grower according to his own experience. In 2009 and 2010 strategies 1.3-2.2-1.6 (SIMDS target threshold for each tree development stages II-III, IV and V, respectively) and 1.6-2.8-1.6 were applied in RDI1, respectively, and strategies 1.0-2.8-1.3 and 1.0-3.2-1.0 in RDI2. A supervisory control and data acquisition platform (SCADA) was created to monitor and remotely manage the irrigation scheduling. The obtained results indicate that SIMDS is a suitable parameter for irrigation scheduling throughout the growing season. The greater or lesser accuracy of fit of the measured SIMDS values to the thresholds depended on the phenological stage and the target stress intensity. SIMDS threshold values higher than 2.8, which involve midday stem water potential (Psi(stem)) values lower than -1.9 MPa, were not suitable for almond irrigation management under our growing conditions. SIMDS-based RDI strategies were able to generate moderate to severe water stress in almond trees, which resulted in seasonal water savings around 50%. RDI strategies proved to be more cost-effective than full irrigation and farmer deficit irrigation treatment given the high price of irrigation water. (c) 2013 Elsevier B.V. All rights reserved.
Propagation
M. A. Mir, K. M. Bhat, Z. A. Rather, F. A. Peer, A. H. Pandit and G. Hussain. 2012. In vitro propagation of almond (Prunus dulcis) cv. Merced. Indian Journal of Agricultural Sciences. 82. 4. 312-317.
url: http://epubs.icar.org.in/ojs-2.3.1-2/index.php/IJAgS/article/view/16632
Abstract: Forced and unforced shoot tips were surface sterilized with different sterilant regimes and incubated under normal culture room conditions. Surface sterilization of explants with mercuric chloride 0.1% (w/v) for 10 min. was found effective in improving culture asepsis (51.66%) and explant survival (55.00%). Higher values for both these parameters were recorded with forced explants in comparison to unforced ones. Main effect of growth regulators and media was significant on explant establishment which was maximum (66.66%) on 1/2 MS media containing BAP + IBA (0.50+0.01 mg/l). Callusing at the base of initiating cultures was minimum (24.58%) with BAP+IBA (0.25+0.01 mg/l). Microshoots from the established cultures were subcultured on the MS media supplemented with BAP and NAA alone or in combination for axillary shoot proliferation. Maximum proliferated cultures (86.66%) with maximum shoot number/explant (15.61) and proliferation grade (4.00) was obtained with BAP+NAA (0.40+0.01 mg/l). BAP was found superior to NAA during axillary shoot proliferation. Microshoots (10-15 nun) from proliferated cultures were subcultured in root induction medium (MS medium supplemented with IBA) and incubated under darkness for 10 days at 24 +/- 1 degrees C and then transferred to root development medium (hormone-free MS medium) and incubated under normal culture room conditions. Highest rooting of microshoots (93.33%) with maximum root number/shoot (5.90) and root length (43.00 mm) was obtained with IBA (1.0 mg/l).
H. Yildirim, H. Akdemir, V. Suzerer, Y. Ozden and A. Onay. 2013. In vitro micrografting of the almond cultivars "Texas", "Ferrastar" and "Nonpareil". Biotechnology & Biotechnological Equipment. 27. 1. 3493-3501
url: http://www.diagnosisnet.com/bbeq/article/78f44933-e095-3484-e93c-1f8416224992
Abstract: A successful micrografting technique for the almond cultivars (cvs) "Texas", "Ferrastar" and "Nonpareil" was developed using in vitro germinated seedlings as rootstocks and axenic shoot cultures established from mature tree sources as microscions. In vitro germinated seedlings, which developed 14 days after culturing in the modified Murashige and Skoog (MS) medium, were decapitated and used as rootstock. Shoot culture initiation from three almond cvs ("Texas", "Ferrastar" and "Nonpareil') was successfully achieved by culturing mature shoot tips from forced nodal buds, about 4-6 mm, on a modified MS medium containing I mg.L-1 benzyl adenin (BA). Slit micrografting on epicotyl and on hypocotyls were equally successful (83.3 % to 100 %). Grafting success was dependent on the rootstock type and lenght of the scion. Grafting success varied between 83.33 % and 100 % depending on the cultivar, when the scion contained I, 2, and 3 nodes. When almond scions, about 1.5 cm long, were micrografted on germinated seedling and cultured on proliferation medium (PM), the mean shoot length was 19.84 mm, 16.50 mm, 26.93 mm for the cvs "Texas", "Ferrastar" and "Nonpareil" respectively Micro grafts could be easily cultured on a hormone-free semi-solid MS medium and were potted out after 4 to 6 weeks of culture growth. Rooted micrografted plantlets were successfully acclimatized and transferred to potting mix with 100 % survival. Although low percentages of variation were obtained in tested cvs (3.70 %, 6.25 % and 10.2 % in "Texas", "Ferrastar" and "Nonpareil'), molecular analysis showed that the developed micrografting technique produces genetically stable plantlets, at least up to 6 months of sub-culturing in cvs "Ferrastar" and "Nonpareil". The described micrografting technique could be used for rejuvenation of shoot explants of mature elite almond cultivars and it also has potential use in the commercial production of other almond cultivars. Biotechnol. & Biotechnol. Eq. 2013, 27(1), 3493-3501
Weed management
A. Shrestha, M. Moretti and N. Mourad. 2012. Evaluation of Thermal Implements and Organic Herbicides for Weed Control in a Nonbearing Almond (Prunus dulcis) Orchard. Weed Technology. 26. 1. 110-116
url: http://www.wssajournals.org/doi/abs/10.1614/WT-D-11-00083.1
Abstract: Sustainable weed management strategies are needed for organic orchard systems. A study was conducted in an almond orchard in Fresno, CA from 2009 to 2011. Treatment comparisons included steam, flame, and broad applications of either lemongrass oil or D-limonene. An untreated control was also included. The experimental design was a randomized complete block with four replications. Weekly evaluations on percent weed control were taken and weed biomass was sampled 4 to 8 wk after treatment (WAT). Weed control and biomass differed between seasons but, in general, steam and flame provided as much as 95% control 1 WAT. However, the effects lasted only 3 to 4 wk as new weeds emerged or the treated weeds overcame the suppressive effects of the thermal treatments. Weed biomass was 95% lower in the steam-and flame-treated plots compared with the untreated plots in summer. Both steam and flame were more effective on certain erect-growing broad-leaved weed species than on prostrate-growing weeds and grasses. Lemongrass oil provided very little weed control. However, D-limonene provided up to 95% weed control 1 WAT and in one experiment 53% control was observed up to 5 WAT. This herbicide also resulted in lower weed biomass than the untreated and the thermal-treated plots. Monthly applications of steam or flame or applications of D-limonene every 5 to 6 wk may have to be made to adequately suppress weeds in organic almond orchards. Cost estimates of propane use were $41 to 56 ha(-1) and $26 ha(-1) for the steam and flame treatments, respectively. The cost of D-limonene was estimated as $275 ha(-1). To optimize weed control and costs, these tools may need to be used in combination rather than by themselves.
Kernel quality
R. Sanchez-Perez, G. Arrazola, M. L. Martin, N. Grane and F. Dicenta. 2012. Influence of the pollinizer in the amygdalin content of almonds. Scientia Horticulturae. 139. 62-65.
url: http://www.sciencedirect.com/science/article/pii/S0304423812001033
Abstract: Bitter kernel taste in almonds is a monogenic trait, being bitter recessive. Bitterness depends on the content of the cyanogenic glucoside amygdalin, whose concentration can be more than 1000 times higher in bitter kernels than in sweet ones. Although previous studies showed that the bitter taste of almonds was not influenced by the pollinizer, nothing is known about the influence of the pollinizer on the amygdalin content of the kernel. In order to study the possible effect of the pollinizer on the content of amygdalin, we analyzed seeds from four cultivars: Del Cid (SkSk: sweet), Marcona (Sksk: sweet), Garrigues (Sksk: slightly bitter) and S3067 (sksk: bitter), which were crossed with four different pollinizers: Ramillete (SkSk: sweet), Atocha (Sksk: sweet), S3065 (Sksk: slightly bitter) and S3067. Results showed that when a sweet pollinizer was involved, the content of amygdalin could be reduced by up to 21%, compared to the bitter x bitter crosses. (C) 2012 Elsevier B.V. All rights reserved.
Self-incompatibility in the Rosaceae family
J. Wu, C. Gu, M. A. Khan, J. Y. Wu, Y. B. Gao, C. L. Wang, S. S. Korban and S. L. Zhang. 2013. Molecular Determinants and Mechanisms of Gametophytic Self-Incompatibility in Fruit Trees of Rosaceae. Critical Reviews in Plant Sciences. 32. 1. 53-68.
url: http://www.tandfonline.com/doi/abs/10.1080/07352689.2012.715986#.UqixvfRDt8E
Abstract: Self-incompatibility is an important genetic mechanism that prevents inbreeding and promotes genetic polymorphism and heterosis in flowering plants. Many fruit species in the Rosaceae, including apple, pear, plum, apricot, sweet cherry, Japanese apricot, and almond, exhibit typical gametophytic self-incompatibility (GSI) controlled by an apparently single multi-allelic locus. This locus encodes at least two components from both the pollen and the pistil, and controls recognition of self- and non-self pollen. Recently, the GSI system has been investigated at the molecular and cellular levels in Rosaceae, and findings have provided some important insights as to how these two genes interact within pollen tubes that lead to specific inhibition of germination and/or growth of self-pollen tubes. In this review, molecular features of S-determinants of both pistil and pollen, identification of S-alleles, mechanisms of self- incompatibility break-down, and evolution of S-alleles are presented. Moreover, hypothetical signal transduction models in a self-incompatible system in Rosaceae are proposed based on recent findings that indicate that several signal factors are involved in GSI responses.
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- Posted by: Brooke Jacobs
- Author: Carlos H Crisosto
During this season, I have been asked several times about the proper storage conditions for ‘Fuyu’ persimmons. ‘Fuyu’ persimmons completely lose their astringency before harvest and can be consumed, contrary to ‘Hachiya’, while they are still firm. In general, harvest time is determined according to the fruit color and size. The best method of harvesting is to clip the fruit with small clippers (orange clippers) from the tree, leaving the calyx attached to the fruit. It is also possible to snap the fruit from the tree but this practice is not recommended as it may injure the fruit and adjoining shoot. During harvesting and packaging fruit must be handled carefully to avoid bruising, which is likely to result in marking which becomes visible as the fruit ripens. Penicillium, Botrytis and Cladosporium fungi may infect ‘Fuyu’ persimmons during storage, especially, if the skin has been damaged during postharvest handling.
Fuyu’ persimmons are very sensitive to chilling injury which is expressed by fast fruit softening, flesh browning, translucency (jelly-like consistency) during and after storage. These symptoms appear more severe after 2-4 days at 68oF (20oC) following storage. Chilling injury is more rapid and severe at 41oF (5oC), especially, combined with ethylene exposure. Studies led by Dr. Kader in our department demonstrated that exposure to 1 and 10 ppm ethylene at 68oF (20oC) resulted in accelerated softening to less than 4 pounds (limit for marketability) after 6 and 2 days, respectively. Exposure to 1 and 10 ppm ethylene at 41oF (5oC) will induce fruit firmness below 4 pounds (soft) after 15 and 8 days, respectively. Therefore, the use of 1-MCP, ethylene removal and/or exclusion during packaging and storage at 32oF (0oC) operations is strongly recommended for maintaining quality and extending ‘Fuyu’ persimmons storage life potential.