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Japanese barberry (Berberis thunbergii DC.) is a widespread invasive plant that remains an important landscape shrub represented by ornamental, purple-leaved forms of the botanical variety atropurpurea. These forms differ greatly in appearance from feral plants, bringing into question whether they contribute to invasive populations or whether the invasions represent self-sustaining populations derived from the initial introduction of the species in the late 19th century. In this study we used amplified fragment length polymorphism (AFLP) markers to determine whether genetic contributions from B. t. var. atropurpurea are found within naturalized Japanese barberry populations in southern New England. Bayesian clustering of AFLP genotypes and principal coordinate analysis distinguished B. t. var. atropurpurea genotypes from 85 plants representing five invasive populations. While a single feral plant resembled B. t. var. atropurpurea phenotypically and fell within the same genetic cluster, all other naturalized plants sampled were genetically distinct from the purple-leaved genotypes. Seven plants from two different sites possessed morphology consistent with Berberis vulgaris (common barberry) or B. × ottawensis (B. thunbergii × B. vulgaris). Genetic analysis placed these plants in two clusters separate from B. thunbergii. Although the Bayesian analysis indicated some introgression of B. t. var. atropurpurea and B. vulgaris, these genotypes have had limited influence on extant feral populations of B. thunbergii. [ABSTRACT FROM AUTHOR]

Container production of nursery crops is intensive and a potential source of nitrogen release to the environment. This study was conducted to determine if trickle irrigation could be used by container nursery producers as an alternative to standard overhead irrigation to reduce nitrogen release into the environment. The effect of overhead irrigation and trickle irrigation on leachate nitrate N concentration, flow‐weighted nitrate N concentration, leachate volume, and plant growth was investigated using containerized rhododendron (Rhododendron catawbiense Michx. 'Album') supplied with a controlled‐release fertilizer and grown outdoors on top of soil‐monolith lysimeters. Leachate was collected over two growing seasons and overwinter periods, and natural precipitation was allowed as a component of the system. Precipitation accounted for 69% of the water entering the overhead‐irrigated system and 80% of the water entering the trickle‐irrigated system. Leachate from fertilized plants exceeded the USEPA limit of 10 mg L−1 at several times and reached a maximum of 26 mg L−1 with trickle irrigation. Average annual loss of nitrate N in leachate for fertilized treatments was 51.8 and 60.5 kg ha−1 for the overhead and trickle treatments, respectively. Average annual flow‐weighted concentration of nitrate N in leachate of fertilized plants was 7.2 mg L−1 for overhead irrigation and 12.7 mg L−1 for trickle irrigation. Trickle irrigation did not reduce the amount of nitrate N leached from nursery containers when compared with overhead irrigation because precipitation nullified the potential benefits of reduced leaching fractions and irrigation inputs provided under trickle irrigation. [ABSTRACT FROM AUTHOR]

Focuses on the characterization of tissue proliferation with reference to the habituated Rhododendron `montego' (Ericaceae) cultures. Propagation of a significant proportion of rhododendron; How tissue proliferation is characterized; Observation of an abnormal phenotype.

• Premise of the study: Microsatellite markers were isolated and characterized in Berberis thunbergii , an invasive and ornamental shrub in the eastern United States, to assess genetic diversity among populations and potentially identify horticultural cultivars. • Methods and Results: A total of 12 loci were identifi ed for the species. Eight of the loci were polymorphic and were screened in 24 individuals from two native (Tochigi and Ibaraki prefectures, Japan) and one invasive (Connecticut, USA) population and 21 horticultural cultivars. The number of alleles per locus ranged from three to seven, and observed heterozygosity ranged from 0.048 to 0.636. • Conclusions: These new markers will provide tools for examining genetic relatedness of B. thunbergii plants in the native and invasive range, including phylogeographic studies and assessment of rapid evolution in the invasive range. These markers may also provide tools for examining hybridization with other related species in the invasive range. [ABSTRACT FROM AUTHOR]