A pear rootstock trial in Israel

The pear cultivars ‘Spadona Estiva’, ‘Coscia’, ‘Beurré Superfin’ and a ‘Bartlett’ clone of South African origin (termed ‘Bartlett Sport’) were tested on 5 quince rootstock types, 5 Pyrus species and on 5 or 30 cm long interstocks of the pear cultivars ‘Bergamotte Esperen’ and ‘Spadona Estiva’ on quince MA, while ‘Dr. Jules Guyot’ was used as an interstock on ‘Bartlett’ seedlings.At the age of 10 years only ‘Spadona Estiva’ showed no signs of decline on quince rootstocks, ‘Coscia’ showed moderate decline, while the remaining cultivars had already declined severely. When the trunk circumference of ‘Beurré Superfin’ trees on the various quince clones was taken as an indicator for the degree of graft incompatibility, a negative correlation was found between this parameter and cyanogenic glycoside content in the stem bark of ungrafted quince plants belonging to the same clones. Pear interstocks on quince MA rootstocks did in some cases increase crops compared to the same quince alone, but did not prevent the decline of ‘Beurré Superfin’ and Bartlett Sport' on quince.The most vigorous and most prolific rootstock was Pyrus betulaefolia. However, with ‘Spadona Estiva’ differences in vigor between the rootstocks were only small and crops on the Israeli quince CI 7 were similar to those on Pyrus betulaefolia, but fruit size was larger on quince. Cropping of this cultivar at the age of 4 years was closely related to the intensity of flowering, whereas with ‘Coscia’ this relation was much less evident.Leaf fall in autumn and the opening of the vegetative buds of ‘Beurré Superfin’ in spring were earlier on quince than on Pyrus rootstocks.     

Replacing saline–sodic irrigation water with treated wastewater: effects on saturated hydraulic conductivity,slaking, and swelling

Irrigation with saline–sodic water imposes sodic conditions on the soil and reduces the soil’s productivity. We hypothesized that replacing saline–sodic irrigation water with lesser saline–sodic treated waste water (TWW), albeit with higher loads of organic matter and suspended solids, might help sodic soils regain their structure and hydraulic conductivity. We studied hydraulic conductivity (HC), aggregate stability and clay swelling of a soil from the Bet She’an Valley, Israel using samples taken from a non-cultivated field (control), and plots irrigated with TWW, saline–sodic Jordan River (JR) water, and moderately saline–sodic spring (SP) water. Soil samples were taken at the end of the irrigation season (autumn 2005) and at the end of the subsequent rainy season (spring 2006). In the HC and the aggregate stability determinations, for both sampling seasons, the TWW-irrigated samples gave significantly higher values than the SP- and JR-irrigated samples, but lower than the samples from the control plot. The autumn samples exhibited, generally, higher HC and lower swelling levels compared with the spring samples. Conversely, aggregate stability of the spring samples was higher than that of the autumn samples. These seasonal changes in the results of the three tests were associated with seasonal changes in the salinity and sodicity of the soils. Contributions from the Agricultural Research Organization, The Volcani Center, Bet-Dagan 50250, Israel. No. 601/2007 series.     

Reclamation of oil-induced soil hydrophobicity in the hyper-arid Evrona Nature Reserve, southern Israel

Two oil spills occurred in the Evrona Nature Reserve (southern Israel), in 1975 and 2014. This oil contamination induced highly persistent soil hydrophobicity. The objective of this study was to investigate the decrease in oil-induced soil hydrophobicity under different environmental conditions and to assess the relationship between the hydrophobicity and hydrocarbon content. A laboratory incubation experiment was conducted over 1.5 years to monitor the soil hydrophobicity and total hydrocarbon concentration under different environmental conditions. We hypothesized that the addition of water (20% or 50% saturation), nutrients, and biosurfactants can accelerate the reduction in hydrophobicity and decomposition of hydrocarbons. Water drop penetration time and molarity of ethanol droplet tests were used to assess soil hydrophobicity. In parallel, alkane composition and total petroleum hydrocarbons were evaluated to indicate oil attenuation. The addition of water, nutrients, and biosurfactants resulted in a concomitant reduction in hydrophobicity and hydrocarbon concentration of varying degrees, exhibiting enhanced degradation and hydrophobicity reduction observed in treatments to which nutrients and biosurfactants were added. At the end of the incubation, however, soil hydrophobicity in all treatments remained severe, even though total petroleum hydrocarbon removal was fairly high and reached 40%–80% in the treatments to which water with or without nutrients and/or surfactants was added.     

Gene expression in mice after high efficiency retroviral-mediated gene transfer

A retroviral expression vector (N2) containing the selectable gene, neoR, has been used to determine the optimal conditions for infecting murine hematopoietic progenitor cells at high efficiency. After infected bone marrow cells were introduced into lethally irradiated mice, the presence, stability, and expression of the vector DNA sequences were analyzed either in individual spleen foci 10 days later or in the blood, bone marrow, and spleens of mice 4 months later. When bone marrow cells were cultured in medium containing virus with titers of more than 10(6) colony-forming units per milliliter in the presence of purified murine interleukin-3, more than 85 percent of the resulting foci contained vector DNA. This proviral vector DNA was intact. Efficient expression of the neoR gene was demonstrated in most of the DNA-positive foci examined. The spleens of reconstituted animals (over a long term) contained intact "vector DNA" and the blood and bone marrow expressed the neoR gene in some animals. Thus, a retroviral vector can be used to introduce intact exogenous DNA sequences into hematopoietic stem cells with high efficiency and with substantial expression.     

An in vivo model of somatic cell gene therapy for human severe combined immunodeficiency.

Deficiency of adenosine deaminase (ADA) results in severe combined immunodeficiency (SCID), a candidate genetic disorder for somatic cell gene therapy. Peripheral blood lymphocytes from patients affected by ADA- SCID were transduced with a retroviral vector for human ADA and injected into immunodeficient mice. Long-term survival of vector-transduced human cells was demonstrated in recipient animals. Expression of vector-derived ADA restored immune functions, as indicated by the presence in reconstituted animals of human immunoglobulin and antigen-specific T cells. Retroviral vector gene transfer, therefore, is necessary and sufficient for development of specific immune functions in vivo and has therapeutic potential to correct this lethal immunodeficiency.     

Multiparametric analysis of diversity in <Emphasis Type="Italic">Botrytis cinerea</Emphasis> isolates from Israel

The necrotrophic fungus Botrytis cinerea, known as the causal agent of gray mold, is ranked second for its phytopathological global-impact. The disease is controlled by cultural means and fungicides, however, these techniques have variable effect on different fungal isolates due to the plasticity of the pathogen populations. Here we studied and characterized the genetic and virulence associated variability of B. cinerea isolates from different sources. Starting from initial survey of 31 B. cinerea isolates, collected from seven hosts in different locations of Israel, we have focused on 10 isolates that exhibited potential phytopathogenic variability. Two genetic markers (microsatellite) Bc1 and Bc7, were able to differentiate between these isolates. Our analysis demonstrates significant variability in saprophytic growth rate, necrotrophic growth rate on tomato leaves and stems, and in the incidence of infection on leaves of whole plants. Following the observation of significant correlation between saprophytic growth rate, and necrotrophic growth on leaves, we have studied normalized (by saprophytic growth) virulence. Utilization of normalized necrotrophic growth rate enabled to indicate on the presence of virulence mechanisms other than growth rate, for several isolates. Exploration of this direction illustrated variability in resistance to paraquat (associated with resistance to oxidation), which was associated with high and low superoxide dismutase (SOD) gene expression for selected isolates showing high or low paraquat resistance, respectively. Finally, we have used unsupervised learning (clustering analysis) to explore patterns in the multivariable space, which demonstrated two modes of pathogenicity in the tested B. cinerea isolates.     

Water distribution pattern in treated wastewater irrigated soils: hydrophobicity effect

The shortage of fresh water (FW) in Israel and other semiarid regions has forced farmers to significantly expand the use of treated wastewater (TWW). Recently, farmers utilizing reclaimed wastewater (TWW) reported a unique type of water distribution regime in drip-irrigated soils, as follows: (i) limited wetted area on the soil surface; and (ii) small saturated areas around and below the dripper, in TWW irrigated soil as opposed to an even, onion-like wet profile, formed under fresh water (FW) irrigation. Following this observation in the field and after conducting preliminary tests in the laboratory, we hypothesized that TWW irrigation introduces water-repellent organic constituents into the soil. Tests characterizing the water distribution showed the diameter of the saturated area on the soil surface and its water content (at a depth of 0–10 cm) was smaller with TWW than with FW irrigation. The TWW accumulated on the soil surface in small lenses and then flowed rapidly into the ground. The repellency of soils irrigated with FW and TWW was measured with the water drop penetration time test. Soils irrigated with FW were hydrophilic, whereas those irrigated with TWW exhibited hydrophobicity. Fourier transform infra-red spectroscopy (FTIR) and ¹³C-NMR analyses of organic components extracted from the soils with organic solvents indicated differences in composition only at a depth of 0–2 cm. Extracting soils with a methanol + chloroform (1:1, by volume) mixture was found to be very effective in the removal and extraction of hydrophobic aliphatic components from soils irrigated with TWW.     

Mist propagation of peach and almond × peach hybrids

Several factors contributing to the successful rooting of stem cuttings of four peach clones and one almond × peach hybrid under intermittent mist were tested. With the almond × peach cross, leaf-bud cuttings were also tested.Severe cutting back of adult peach mother trees in winter favoured rooting of the cuttings, but less severe cutting back induced maximum roots per cutting.For short periods vermiculite was found to be a suitable medium. Sand alone or mixed with vermiculite or gravel gave poor results. Gravel alone or mixed with vermiculite was intermediate. For growing the rooted cuttings for a longer period, a mixture of perlite and peat was very suitable.A period of illumination of 3 h starting at midnight with incandescent light improved rooting of peach cuttings in August and October, but not in June.With cuttings obtained from old fruit-bearing peach trees highest rooting rates were obtained in July, but best root development occurred when rooting was carried out in October. In July rooting rate of basal cuttings was much higher than that of terminal ones. Success with leaf-bud cuttings (including a small branch piece) obtained from young mother trees of the almond × peach hybrid was only achieved at the end of May or in June.Dipping the base of peach cuttings in water before rooting was of advantage with one cultivar rooted in September, but of no advantage with another cultivar rooted in June.When the base of stem cuttings was dipped for a prolonged period in IBA solutions of various concentrations, highest rooting rates were obtained with 25–50 ppm IBA for peaches and with 200 ppm for the almond × peach hybrid. The addition of Phygon XL to this solution was of some advantage for peach cuttings. The concentration inducing maximum root development was higher than that required for maximum rooting and callusing. The optimal IBA concentration for rooting of almond × peach leaf-bud cuttings was 100 ppm.Penetration of the IBA into the leaf-bud cuttings reached a maximum 45 min a after floating them on a 100 ppm solution.Transplanting cuttings which had been rooted under mist was somewhat difficult; however, high rates of survival were obtained with cuttings planted in September which had developed a good root system.     

Universality of a surface tension—contact‐angle relation for hydrophobic soils of different texture

Wettability of soil affects a wide variety of processes in soils like infiltration, percolation, preferential flow, and surface runoff. Even though efforts have been made to determine contact angles and surface tension or energy of smooth surfaces, the determination on granular materials like soil particles remains unsolved. One objective of this study was to test the consistency of contact angles (CA) measured with the newly modified and easy‐to‐apply Wilhelmy plate method by using solid particles and liquids with defined variations of surface tension. A second objective was to derive basic physical surface properties for the irregularly shaped and chemically heterogeneous soil particles. Advancing contact angles were determined by using model soils varying in texture from clay to coarse sand to check the impact of grain size on the CA measurements. Varying the solid‐surface tension with dichlorodimethlylsilane treatments provided for pure‐water wetting stages ranging from wettable to extremely hydrophobic. The surface tensions of the liquids were varied from 72 mN m^–1 to 25 mN m^–1 by using water or water‐ethanol mixtures. The surface tensions of the model soils were determined with the zero degree–contact angle method following Zisman's critical–surface tension concept. Results show that the measured CA varied continuously with the variations of the surface tension of the liquid and the solid phase, respectively. A general interpretation of the results is possible by using the concept of the Equation of State Approach.