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The accumulation of 1-aminocyclopropane-l-carboxylate (ACC), which is a precursor for ethylene production, in plant roots exposed to salinity stress can be detrimental to plant growth. The objectives of this study were to determine whether inoculating roots with bacteria containing deaminase enzymes that break down ACC (ACC-deaminase) could improve plant tolerance to salinity in perennial ryegrass (Lolium perenne) and to examine growth and physiological factors, as well as nutrition status of plants affected by the ACC-deaminase bacteria inoculation under salinity stress. Plants of perennial ryegrass (cv. Pangea) were inoculated with either Burkholderia phytofirmans PsJN or Burkholderia gladioli RU1 and irrigated with either fresh water (control) or a 250 mM NaCI solution to induce salinity stress. The bacterium-inoculated plants had less ACC content in shoots and roots under both nonstressed and salinity conditions. Salinity stress inhibited root and shoot growth, but the bacterium-inoculated plants exhibited higher visual turf quality (TQ), tiller number, root biomass, shoot biomass, leaf water content, and photochemical efficiency, as well as lower cellular electrolyte leakage (EL) under salinity stress. Plants inoculated with bacteria had lower sodium content and higher potassium to sodium ratios in shoots under salinity stress. Shoot and root nitrogen content and shoot potassium content increased, whereas shoot and root calcium, magnesium, iron, and aluminum content all decreased due to bacterial inoculation under salinity treatment. ACC-deaminase bacteria inoculation of roots was effective in improving salinity tolerance of perennial ryegrass and could be incorporated into turfgrass maintenance programs in salt-affected soils. [ABSTRACT FROM AUTHOR]

In order to protect the forest resources of Cedrela odorata L., currently threatened, it was considered necessary to establish a protocol for its cryopreservation. Research was conducted using shoots and seeds. Vitrification techniques were evaluated with shoots, using various solutions and rapid freezing in liquid nitrogen (LN). Initially the best results were obtained using incubation for 5 min in PVS3 solution before freezing, survival being 61% after 3 weeks of culture on Murashige and Skoog (MS) medium with 1.0 mg.l-1 BAP and 0.1 mg.l-1 GA3. Moreover, by incubating the apices in 0.3 M sucrose solution for 5 min prior to freezing, the survival rate reached 86% after 2 weeks of culture on MS medium with 1.0 mg.l-1 BAP, 0.1 mg.l-1 GA3 and 0.01 mg.l-1 IAA. When incubation in the solution of 0.3 M sucrose was used and recovery MS medium with 1 mg.l-1 KIN, 0.5 mg.l-1 GA3 and 100 mg.l-1 activated charcoal, the appearance of the surviving shoots improved significantly. For cryopreservation of cedar seeds, the methodology of dehydration and rapid freezing in liquid nitrogen (LN) was evaluated. Seeds with moisture content between 7.9% and 5.5% were placed in 5 ml polypropylene vials and these were directly immersed in NL. The effect of the storage period in NL (1 h, 24 h, 7 days, 1 month, 3 months and 6 months) on seed germination was evaluated. There were no statistical differences in ability of seeds to germinate after storage during different periods. [ABSTRACT FROM AUTHOR]

Cold resistance of interspecific intra- and inter-section Ribes hybrids and their blossom tolerance to spring frost was investigated. Cold resistance was evaluated from shoot damage. Cold resistant R. nigrum varieties were not damaged whereas R. americanum was strongly (3 points in 5 point scale) damaged. R. nigrum and R. americanum F2-F3 hybrids were also cold resistant, however R. americanum and R. nigrum hybrids were less resistant to cold. R. americanum had higher blossom tolerance to spring frost. The difference is greatest when frost damage is estimated at the level 1 meter from ground. R. nigrum had 16.8 % damaged blossoms and R. americanum had only 1.3 % damaged blossoms. Despite of the direction of hybridization R. nigrum and R. americanum hybrid blossoms were sensitive to spring frost. Severe frost in 2007 strongly damaged their blossoms (about 4 points). The damage from the moderate frost in 2008 depended on the genotype and ranged from weak to moderate and high (0.5-3 points). Interspecific hybrids of R. nigrum varieties and wild Ribes species of Eucoreosma section were cold resistant and their blossoms were rather tolerant to spring frost. R. nigrum and R. petraeum are cold resistant and their hybrids were only slightly damaged during winter. The damage of blossoms varied from 0.6 to 2.6 points. The blossom tolerance to spring frost depended on R. nigrum varieties used in hybridization. R. nigrum and R. uvacrispa hybrids were slightly or moderately damaged, so were their blossoms, however, blossom damage was not related to damage of shoots, since most damaged bushes still had slightly damaged blossoms. [ABSTRACT FROM AUTHOR]

Pecan (Carya illinoinensis) seedling rootstocks require several years of growth in the nursery before they are large enough to graft. In this experiment, first-year pecan seedlings were fertigated with varying amounts of calcium nitrate in an attempt to stimulate growth rates. Pecan seedlings were fertigated every 2 weeks from May through October for a total of 10 applications. Total amounts of nitrogen (N) applied by fertigation were 0, 4, 10, 20, and 40 g of N per seedling. Leaf samples were taken after the fourth and tenth fertigations, and leaf elemental concentration was affected by fertigation rates. Seedling height and caliper were measured monthly. Seedling caliper continued to increase throughout the experiment, whereas height increase stopped in September. Seedling height and caliper were unaffected by N fertigation except for the N rate of 40 g, which suppressed seedling growth. These results suggest that the N needs of the seedlings were met by a preplant application of 50 lb/acre N applied as 10N-4.4P-8.3K. [ABSTRACT FROM AUTHOR]