Spiroplasma citri, the causal agent of stubborn disease, was isolated from leaves and fruits of diseased citrus plants and cultured on solid and liquid C3G medium. On the basis of mode of transmission, symptomatology, shape on solid medium, staining of infected plant tissues with Dienes’ stain and phase contrast microscopy, the isolated agent was identified as Spiroplasma citri. Identifiction was ensured by ELISA and PCR techniques. A fragment (1053 bp) from the spiralin gene of S. citri was amplified by PCR using two specific primers for the spiralin gene. The nucleic acid hybridization techniques (Southern and dot blots) were used for identification of the spiroplasmal genome using non-radioactive DNA probe specific for spiralin gene region. It was carried out as an alternative sensitive method for rapid detection of the Egyption isolate of S. citri   using non-radioactive DNA probe specific for spiralin gene region.

A test survey was conducted to determine the nutritional status of apple trees grown at four highly productive orchards in south of Jordan. Leaf and soil samples were taken from each orchard, and analyzed for the concentrations of macro- and micronutrients. Soils of Al-Shoubak tend to have high pH, low organic matter and high CaCO3 contents. The results showed that soil concentrations of N, K, Fe, Mn, Zn and Cu varied widely among the orchards. No deficiency or hunger signs of N, P, K, Mn and Zn nutrients were observed at any of the localities since concentrations of leaf nutrients were generally within the sufficient range, indicating adequate lev-els of fertilization applied to the trees. The leaf analysis has shown that Cu deficien-cy is found in some apple orchards. Soils and leaf nutrient levels were generally not well correlated with one another. The only highly significant correlation was be-tween soil P and leaf N. However, positive relations were observed among leaf P and Mn, Fe and Mn, Fe and Zn, and Mn and Zn contents.

Numerical analysis of 62 morphological and histological characters extracted from the 2 previous papers (Ahmed and Mohamed, 2005, a & b) of the 7 studied taxa in the genus Tribulus led to their classification into two groups. The 1st contains 5 pentacyclic flowered taxa (T.terrestris, T. terrestris var. bicornutus, T.macropterus, T.megistopterus & T.mollis) with 2 basal vascular bundles in their small leaflets while the 2nd included 2 tetracyclic flowered taxa (T.kaiseri, T.pentandrus) with single main bundle. The resulted analysis arranged taxa of gp.I into 2 sections while that of gp.II into a third section. Tribulus besides possessing its own generic characters, also shares the Zygophylloid genera in major grounds. Therefore it is recommended to remain in tribe Tribuleae of Zygophylloideae within Zygophyllaceae and never isolated either into a family or even subfamily of its own.

The most important black table olive (Olea europaea L.) “Kalamata” cultivar, grafted onto three different vegetative olive rootstocks[Picual (Pic), Frantoio (Fra) and Koroneiki (Kor) cvs.] was evaluated with 2-year-old grafted plants grown in sand clay soil, and received concentrations of salt mixture (NaCl, Na2So4, CaCl2, MgSo4 and KCl) making 6000 and 8000 ppm with SAR 12 of salinity level, for two seasons. Morphological and chemical parameters were investigated to determine the relative salinity tolerance of these rootstocks and to define possible reasons for any observed differences in the salt tolerance. However, results indicated that differences in response to salinity among rootstocks were observed primarily in morphological traits. Increasing of salinity level in irrigation water decreased, all of scion height and its rate of increase, leaf area, number of leaves/plant and fresh & dry weight of leaves and roots. But different rootstocks can affect the degree to which these pa-rameters is reduced under salinity, where Kalamata growth on Picual and Frantoio was considerably better than on Koroneiki at 6000 and 8000 ppm treatments. In-versely in untreated grafted plants Kalamata on Kornaki exhibited the best growth vigor, comparing with Kal/Pic or Kal/Fra plants, suggesting that a decrease of scion growth in untreated grafted plants is a salt tolerance quality transmitted by tolerant rootstocks. Salinity significantly decreased leaf chlorophyll (a) and (b) content of all grafted plants, but different content among rootstocks were noted. On the contrary, proline content increased in leaves of all treated plants, however, insignificant dif-ference was noted between rootstocks, yet the interaction between the two factors show that Kalamata on Picual and on Frantoio rootstocks recorded higher values of leaf proline content than Kalamata on Koroneiki rootstock. Leaves and roots Na+ and Cl- content of treated grafted plants showed an increment but to a different de-gree, comparing with the untreated (control) plants. There were differences among the grafted plants where Kalamata grafted on Koroneiki (the least tolerant cv.) most-ly affected by saline treatment and accumulated the highest content of Na+ and Cl- in leaves comparing with Kalamata on Picual (the most tolerant cv.) or on Frantoio (the Sanaa LazArab Univ. J. Agric. Sci., 13(2), 2005400moderate tolerant cv.). Tolerant rootstocks contained more Na+ in roots than in leaves. This response become apparent as salinity increased. Leaf N, P and K con-tents decreased in Kalamata leaves as influenced by different rootstocks and increas-ing salinity in irrigation water comparing with the control. Kal/Pic and Kal/Fra plants had higher N% in leaves than Kal/Kor plants, whereas Kal/Pic accumulated K more than the other plants, while P content in leaves of all grafted plants were insig-nificant in the two seasons. Based on the overall growth parameters and chemical composition in response to salinity, Kalamata grafted on Picual exhibited the great-est salt tolerance followed by those grafted on Frantoio whereas, Kalamata on Koro-neiki showed the poorest plants pertaining salt tolerance.

In this study, three isolates of Streptomyces isolated from Egyptian soil at Giza Governorate and belonging to red series were identified based on their cultural, morphological and physiological characters. According to the key proposed by Pridham and Tresner (1974), the experimental isolates ST55, ST71 and ST86 ap-peared to be related to S. lincolnensis, S. venezuelae and S. umbrinus, respectively. In addition, random amplified polymorphic DNA (RAPD)-polymerase chain reac-tion (PCR) was used to amplify the DNA genome of the three applied isolates and an identified strain to determine their fingerprints. This was carried out using 10-decamer oligonucleotides, i.e., OP-A02, OP-D01, OP-D02, OP-D05, OP-D06, OP-D07, OP-D08, OP-D11, OP-D18 and OP-D20. The PCR amplified products were detected by electrophoresing on 1.5% agarose gel and visualized by staining in eth-idium bromide and UV trasilluminator. Results showed that the same oligonucleo-tide flanking fragments differed from one isolate to another with different sizes. Monomorphic and polymorphic fragments were amplified confirming the molecular relationships as well as the genetic diversity between the four applied strains of Streptomyces. Based on the statistical analysis of RAPD-PCR polymorphisms a de-gree of similarities ranged from 33.9 to 59.2 % was found. Furthermore, frag-ment(s), whatever absent or present, were found to be unique molecular markers and could be used for characterization of some isolates. This result supported the idea for using the RAPD-PCR technique for classification of Streptomyces isolates.

The Saudi Arabian Ministry of Agriculture experimental station at Al-Maddina Al-Monwarah region, identified very few plantations of the most productive Vitis vinifera var. maddini with the highest fruit quality. This research was designed to optimize rooting effeciency in relation to cutting length and auxin treatment. Cutting length (long vs short) showed strong impact on rooting ability. Results showed that longer cuttings produce more and longer roots than shorter ones. IBA treatments up to the 500 ppm level showed significant increase in root number, but do not have significant impact on root length. Rooted cuttings were planted in an open field for further evaluations. These findings may facilitate the clonal propagation of this val-uable vines at Al-Maddina Al-Monwarah region, grapevine growers and Horticultur-ists in Saudi Arabia .

The present work was carried out to study the population dynamics of the mealy plum aphid Hyalopterus pruni (Geoff.) and related parasitoids and predators on apricot trees, during the two successive seasons, 2003 and 2004, at Qalubia Gover-norate. The obtained data revealed that, the occurrence of H. pruni on apricot trees covered 5 months (from February to June). The mean total numbers of this aphid species per season were 1.78 (0.01-6.37) and 2.83 (0.00-10.01) individuals./leaf. The maximum numbers of H. pruni were recorded during the 2nd weeks of April, 2003 and 2004. No aphid individuals were observed during the period extended from July to September, in the two studied seasons. Four species of parasitoids; namely Aphidius matricariae Hal., Lysiphylbus sp. (1ry parasitoids) and 2 species of Alloxysta spp. (2ry parasitoids) were recorded during this study, attacking H. pruni. These parasitoid species were found during nearly three months of each season, in connection with the population density of the previous aphid species. The first para-sitoid was the highest in its numbers. The total numbers of predatory species per season were 407 and 1082 individuals, in the two studied seasons, 2003 and 2004, respectively. The maximum monthly occurrence of these predatory species was dur-ing April, 2003 (146 individuals) and April, 2004 (581 individuals), respectively. The predator Chrysoperla septempunctata L. had the highest percentages of occur-rence among other recorded predatory species (52.83 and 73.01%, respectively). In general, the parasitoid A. matricariae and the predator C. septempunctata, could be mass reared and released for controlling H. pruni on apricot trees with other availa-ble safe control methods developed in Integrated Pest Management (IPM) programs against this pest.

Laying workers expressed as Workers with Activate Ovaries (WAO) having ma-ture oocytes had been studied in colonies headed with natural mated carnica queens. The results showed that the WAO were affected by the age of the queen, where it reached 0.8, 1.3 and 2.2 % for colonies headed with queens 10, 20 and 30 month old, respectively. The worker ovaries started to activate when the reached 22. 18 and 12 days from emergence for colonies headed with caged mated queens, caged virgin queens and queenless colonies, respectively. Also, when the worker's age reached 30 days, the percentages of WAO occurrence reached 3.3, 7.3 and 14.7 % for the corre-sponding colonies status, respectively. In preparing swarm boxes, when the bee-keepers failed to introduce the queens into the nuclei until two days, one week and two weeks, the WAO recorded 1.4, 4.8 and 9.2 %, respectively. In case of queen rearing, the presence of WAO was not significant until the fifth day, and then in-creased gradually to reach an average of 4.6% in the tenth day.