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The production and consumption of nuts are increasing in the world due to strong economic returns and the nutritional value of their products. With the increasing role and importance given to nuts (i.e., walnuts, hazelnut, pistachio, pecan, almond) in a balanced and healthy diet and their benefits to human health, breeding of the nuts species has also been stepped up. Most recent fruit breeding programs have focused on scion genetic improvement. However, the use of locally adapted grafted rootstocks also enhanced the productivity and quality of tree fruit crops. Grafting is an ancient horticultural practice used in nut crops to manipulate scion phenotype and productivity and overcome biotic and abiotic stresses. There are complex rootstock breeding objectives and physiological and molecular aspects of rootstock–scion interactions in nut crops. In this review, we provide an overview of these, considering the mechanisms involved in nutrient and water uptake, regulation of phytohormones, and rootstock influences on the scion molecular processes, including long-distance gene silencing and trans-grafting. Understanding the mechanisms resulting from rootstock × scion × environmental interactions will contribute to developing new rootstocks with resilience in the face of climate change, but also of the multitude of diseases and pests. info:eu-repo/semantics/publishedVersion

Understanding the mechanisms of stress tolerance in diverse species is needed to enhance crop performance under conditions such as high salinity. Plant roots, in particular in grafted agricultural crops, can function as a boundary against external stresses in order to maintain plant fitness. However, limited information exists for salinity stress responses of woody species and their rootstocks. Pistachio (Pistacia spp.) is a tree nut crop with relatively high salinity tolerance as well as high genetic heterogeneity. In this study, we used a microscopy‐based approach to investigate the cellular and structural responses to salinity stress in the roots of two pistachio rootstocks, Pistacia integerrima (PGI) and a hybrid, P. atlantica x P. integerrima (UCB1). We analyzed root sections via fluorescence microscopy across a developmental gradient, defined by xylem development, for sodium localization and for cellular barrier differentiation via suberin deposition. Our cumulative data suggest that the salinity response in pistachio rootstock species is associated with both vacuolar sodium ion (Na+) sequestration in the root cortex and increased suberin deposition at apoplastic barriers. Furthermore, both vacuolar sequestration and suberin deposition correlate with the root developmental gradient. We observed a higher rate of Na+ vacuolar sequestration and reduced salt‐induced leaf damage in UCB1 when compared to P. integerrima. In addition, UCB1 displayed higher basal levels of suberization, in both the exodermis and endodermis, compared to P. integerrima. This difference was enhanced after salinity stress. These cellular characteristics are phenotypes that can be taken into account during screening for sodium‐mediated salinity tolerance in woody plant species.

Root injuries, heat and desiccation after transplanting are abiotic stresses that may cause transplant failure. Stress signal transduction for preventing transplant failure due to root injuries and growing in hot dry conditions was evaluated using Pistacia vera , a species highly sensitive to transplanting, as the model plant. Pistachio seedlings were primed by exposure to salt stress using 100 mM CaCl 2 100 mM KNO 3 , 50 mM CaCl 2 + 50 mM KNO 3, and three foliar applications of 2.0 mM β-aminobutyric acid (BABA) for 7 days. After removing 30% of the root length, the plants were then grown under hot dry conditions for 60 days. Significant increases were observed in the plasma membrane thermostability and proline and malondialdehyde leaf concentrations after the priming treatments. The BABA and KNO 3 treatments increased leaf H 2 O 2 content by 26% while the KNO 3 + CaCl 2 treatment increased it by 63%. Detached leaves of non-primed plants lost water more quickly than leaves of primed plants. The BABA and KNO 3 + CaCl 2 treatments were most effective at limiting water loss from detached leaves. Transplanting killed all the non-primed plants. The CaCl 2 treatment increased transplant survival by 42.9% and the KNO 3 + CaCl 2 treatment by 100%. The survival rate of BABA and KNO 3 primed plants was 57.1%. These results suggest controlled salt stress could be a simple, rapid and efficient method of for controlling transplant shock.

Citrus mechanical harvesting has been investigated since the 1960's. Even though mechanical harvesting could significantly lower production costs, the implementation by the private sector has been slow. The current harvesting technologies detach the fruits with trunk, canopy or branch vibration. For late-season sweet orange varieties which simultaneously bear mature fruit, immature fruitlets and flowers, shaker harvesting decreases the subsequent year's yield. This study, investigated the frequency response of mature fruits and immature fruitlets to determine the optimum frequency range for an efficient and selective harvest. Laboratory vibration transmission tests were conducted with 14 branches bearing 76 mature fruits and 151 immature ‘Valencia’ fruitlets. The fruit and branch response to the forced vibration was measured by several sets of five triaxial accelerometers with a dynamic signal analyser. Three frequency ranges with the highest vibration transmission values were identified for mechanical harvesting lower than 10 Hz. The first frequency range (1.5–2.5 Hz) corresponded best with the most efficient vibration transmission, involving more than 90% of fruit. The second frequency range (4.5–5 Hz) successfully discriminated between mature fruit and immature fruitlets. In this frequency range, 53.4% of mature fruit amplified the acceleration a mean value of 2.2 times, while only 7.3% of immature fruitlets amplified the acceleration with a mean value of 4.4 times. The third frequency range (7–8 Hz) had the lowest vibration transmission value. The frequency response of mature citrus fruits, and their markedly higher fruit mass, were significant factors in efficient selective mechanical harvesting.

Developing mechanical harvesting for table olives will require decreasing fruit damage during harvest and postharvest handling, transport and storage. The susceptibility to bruising and its development over time were studied in three table olive varieties, cv. ‘Manzanilla’, ‘Gordal Sevillana’ and ‘Hojiblanca’. Bruising was produced with controlled energy impacts of 56, 26, 13 mJ. A strong correlation ( r 2 = 0.77–0.90) between bruise volume and impact energy was demonstrated. Bruise susceptibility was higher in the Manzanilla variety, followed by Hojiblanca and Gordal Sevillana cultivars. Bruise time evolution was evaluated using a spectrophotometer for visible and near infrared regions. A bruise index was developed using different wavelengths, 545, 670 and 800 nm. Most darkening due to the browning process happened within 1 h, was exponential and dependent on impact energy level. The discoloration was greatest in the Manzanilla, followed by Hojiblanca and Gordal Sevillana olives.

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.

Additional index words. Ficus carica, pollination biology, postharvestThe genus Ficus includes species rangingin number from 600 to more than 1900, withmost found in the tropics or subtropics andonly a handful with fruits considered edible(reviewed in Condit, 1969). The cultivatedfig, Ficus carica L., (Moraceae), is clearly ofgreatest importance as a source of humanfood. The fig fruit has long been associatedwithhorticulture in the Mediterranean region(Zohary and Spiegel-Roy, 1975) and is con­sidered to have been"first brought into cul­tivation in southern Arabia" (Storey, 1975).Wild or "nearly wild" figs are reportedthroughout much of the Middle East andMediterranean region (De Candolle, 1886).Cultivated figs are reported to have becomeestablished across the

Heritability of flowering and leafing date of pistachio (Pistacia vera L.) were estimated based on half-sib family and parent-offspring regression analyses. Narrow sense heritabilities of flowering date ranged from 0.68 to 0.88 based on half-sib analyses and from 0.89 to 0.95 based on parent-offspring regression analyses. The narrow sense heritability of leafing date was 0.75 based on half-sib analyses and 0.60 from parent-offspring regression analysis. First leafing date was highly correlated with flowering date (r =0.59–0.78), suggesting that first leafing date could be used to select for flowering date in seedlings long before the onset off lowering.

Performance of `Kerman' pistachio (Pistacia vera L.) trees on three rootstocks (P. atlantica Desf., P. integerrima Stewart and `UCB-1', a P. atlantica × P. integerrima hybrid) was evaluated with 2-year-old trees grown in sand-tank lysimeters under combined SO42- and Cl- salinity and boron (B) stress for 6 months. Four salinity treatments were imposed by irrigating the plants with water at electrical conductivity (ECiw) of 3.5, 8.7,12, or 16 dS·m-1 each containing B at 10 mg·L-1. Growth of `Kerman' was evaluated based on increase in total leaf area, increase in trunk diameter, and total above-ground biomass production. All growth parameters decreased as salinity increased, but were not significant until ECiw exceeded 12 dS·m-1. However, growth of `Kerman' on P. atlantica and `UCB-1' was considerably better than on P. integerrima at 16 dS·m-1. The onset and severity of foliar injury differed among scions and treatments and was attributed primarily to B toxicity, rather than the effects of salinity. Concentrations of B in injured leaf tissue ranged from 1000 to 2500 mg·kg-1. Leaf injury decreased with increasing salinity, although leaf B was not significantly reduced suggesting an internal synergistic interaction between B and other mineral nutrients. However for P. vera on P. integerrima, the highest level of salinity produced the greatest injury, possibly as a combination of B plus Cl- and/or Na+ toxicity. Leaf transpiration, stomatal conductance, and chlorophyll concentration of P. vera, determined by steady-state porometry, were also reduced to a greater degree by combined salinity and B when budded on P. integerrima than on the other two rootstocks.

Pistachio nut (cv `Kerman') development was examined on light-bearing and heavy-bearing trees during the 1993 and 1994 growing seasons to characterize fruit development. The highest incidence of damage by other means (DBOM) occurred during May when fruit thinning was occurring and shells were developing. Disease, insects, and mechanical damage were eliminated as causing DBOM. Dormant spraying of calcium, manganese, and boron resulted in no significant mitigation of DBOM. However, the incidence of DBOM appeared to increase with increasing crop load. From an anatomical study it appeared that the process leading to tissue degeneration in pistachio fruit pericarp may start as early as the second week after bloom, although in some cases its onset is later. The most affected tissue is the endocarp parenchyma, whose cells become necrotic and collapse, thus causing shrinkage and fracture in the shell. In the worst cases only the mesocarp (hull) remains functional, providing thin protection for the embryo, as no shell is present in the affected areas. The degeneration may also involve the mesocarp, at times with hypertrophy. The localized curly aspect of the nuts occurs when the degeneration is not simultaneous, or equal, on the entire wall. The macroscopic degeneration ranges from dramatic to barely noticeable.

Until the 1940s, when production economics and labor shortages became pressing, olives around the world were hand harvested. Despite 60 years of research, mechanical. There are two major reasons for this. First, trees over 20 years old are too tall and poorly structured for mechanical harvesting. Second, mechanical harvesting research for table olive production has not been sufficiently focused on the final goal, processed fruit quality. For oil olives, which are physiologically mature at harvest and require less removal force, advances in both trunk shaking and picker head technology are advancing rapidly. Also, as olive oil is enjoying a renaissance around the world new orchards are being planted in the hedgerows that facilitate mechanical harvesting. For table olives however, mechanical harvesting is still in the developmental stage. The research being done now, unlike earlier work, focuses on the parallel goals of efficient fruit removal and final processed product quality. Within 10 years most olive oil orchards of suitable tree size and shape will be mechanically harvested. When table olives will be routinely harvested mechanically cannot be predicted.Las aceitunas se recogieron a mano hasta los años cuarenta, cuando la necesidad de reducir costes de producción y la escasez de mano de obra comenzaron ya a hacer inviable tal sistema. A pesar de la investigación realizada durante los últimos 60 años, la recolección mecánica no es todavía una práctica común. Hay dos razones principales para ello. La primera es que los árboles de más de 20 años de antigüedad son demasiado altos y no están adecuadamente estructurados para aplicar dichas técnicas. La segunda es que la investigación sobre la recolección mecánica para las aceitunas de mesa no se ha enfocado adecuadamente dándole el peso suficiente al objetivo final de obtener frutos elaborados de calidad. Para el caso de las aceitunas destinadas a la obtención de aceite, cuyos frutos están fisiológicamente maduros en el momento de la recolección y requieren menos fuerza para desprenderles del árbol, se han producido, sin embargo, importantes avances tanto en cuanto a los vibradores como a los sistemas de recogida. También, a medida que el aceite de oliva esta extendiéndose alrededor del mundo, las nuevas plantaciones están realizándose de manera que faciliten la recolección mecánica. Por el contrario, en el caso de las aceitunas de mesa, las técnicas de recolección mecánica están todavía en fase de desarrollo. En contraposición con los trabajos realizados con anterioridad, la investigación que se está realizando actualmente en este campo va encaminada a obtener simultáneamente los objetivos de un desprendimiento eficaz de los frutos y de la obtención de un fruto elaborado de calidad. Dentro de los próximos diez años, la mayoría de los olivares de tamaño y formas adecuadas dedicados a aceite se recolectarán mecánicamente. No obstante, no es posible aún predecir cuando las aceitunas destinadas a mesa se recogerán de la misma forma.

Summury. 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. Additional index words. supplemental pollination, parthenocarpy

Currently, 94% of California fig production is dried or otherwise processed, but there is interest in expanding fresh fig sales. Since cultivars dominating the industry were largely selected for dried fig use, the fig collection of the National Clonal Germplasm Repository (NCGR) in Winters, Calif., was screened for traits of interest in fresh fruit production. For some traits, the bearing collection of 137 accessions was screened, while for most traits, data was collected on a core group of 30 accessions. While current commercial cultivars feature flavors of honey or caramel, some NCGR accessions have bright fruity flavors, reminiscent of berries or citrus, as well as noticeable acidity. Considerable variation was observed for time of maturity. Breba (figs on previous year's wood ripe in June/July) production was markedly greater in `King' than in any other core-group genotype, with ≈3× more fruit per branch than the next most breba-productive variety and 8× higher than the commercial standards. Earliness of ripening in the large collection was most pronounced in `Yellow Neches', `Orphan', and `Santa Cruz Dark', with 3× as many ripe fruit per tree in early August as the earliest commercial standard. Several commercial standards scored among the varieties with greatest late-season production (≈200 fruit per tree ripe after mid-September), comparing favorably with `Zidi', `Panachee', and `Ischia Black', among others. The SSC at commercial ripeness ranged from 13% to 19%, and SSC at tree-ripeness averaged 30% higher than in commercially ripe fruit. Several accessions were observed to have fruit traits that might also contribute to sustained quality through market channels.

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.

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).

Pistacia integerrima (rootstock cultivar Pioneer Gold) is resistant to Verticillium dahliae, and P. atlantica (rootstock cultivar Standard Atlantica) is susceptible in the field. We developed greenhouse and laboratory assays that differentiate between the resistant and the susceptible cultivars. After injection of the stems of seedlings with conidia, the cultivars showed differential symptoms. After infusion of conidia into stems, V. dahliae colonized significantly fewer xylem vessels in the resistant than in the susceptible cultivar (...)

10 B, carbohydrate reserves, fruit tree nutrition, 15 N, Pistacia vera, uptake efficiancy Abstract. The effects of alternate bearing on recovery and loss of isotonically labeled fertilizer N and B and on the accumulation of carbohydrate and N reserves were assessed in mature 'Kerman' pistachio (Pistacia vera L.) trees. Total recovery of labeled fertilizer N applied once (in late January) was ≈ 60% greater if applied to trees entering an "off' than an "on" year, with respect to fruiting. Eleven percent more labeled B was recovered in off- than on-year trees. Five times more N (1 vs. 0.2 kg N) was lost from the tree in fruit and senescent leaflets from on- than off-year trees. In dormant trees, 144% and 22% more starch and N reserves, respectively, were present after off than on years. Thus, on-year trees were characterized by a greater reproductive demand for N and carbohydrates, reduced accumulation of C and N (i.e., storage) reserves in perennial tree parts, and reduced recovery of January-applied labeled fertilizer N than off-year trees. As B is absorbed passively, the higher transpiration that may accompany the 43% larger leaf area per tree and the probability of increased root growth probably contributes to its increased uptake during off years. The enhanced labeled N recovery in early spring by trees entering their off year preceded fruit and seed development in on-year trees. The differential tree capacity for nutrient uptake in spring may have been conditioned the previous rather than the current year. The increased uptake of labeled N by trees entering an off year (i.e., emerging from an on year) was associated with lower levels of carbohydrate and N reserves than for on-year trees that had just completed an off year. Future experimentation should assess the comparative capacity for nutrient uptake by on-and off-year trees at other stages of phenology, e.g., during seed development and postharvest. Alternate bearing-the alternation of high and low crop years—