Plant physiology (Impact Factor: 6.56). 08/1949; 24(3):389-94.
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    ABSTRACT: Scots pine (Pinus sylvestris) grows some 400 km south of its current native limit at Wybunbury Moss, Cheshire, UK, on a peatland around a small floating bog (Schwingmoor). Cone and seed production of trees, which have been growing on the site for just over 100 years, were investigated over 3 years. Cones matured between September and March and seed shedding began in early April. The number of cones produced per reproductive tree ranged between 31 and 2,418, with a total average of 685 cones tree−1 y−1. A strong relationship was found between tree diameter and seed production which allowed the prediction of annual seed production. Scots pine on this peatland produced between 766,874 and 950,000 seeds ha−1 annually with a germination percentage of 64%. The predicted number of seeds reaching the central bog (maximum of 120 m from the trees) every year was c. 16,000.
    Trees 01/2012; 26:1305-1315. · 1.93 Impact Factor
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    ABSTRACT: Hoffmannseggella cinnabarina has not been found in the wild for the last 70 yr in the State of São Paulo and, therefore, wild populations of this native orchid are thought to be extinct. This investigation studied seed storage at a low temperature, in vitro germination, and seedling development of H. cinnabarina in order to establish an optimized protocol for propagation, and thus assure species conservation. Seeds of different ages were incubated on Knudson C (KC), Murashige and Skoog, and Vacin and Went media with or without 1 μM of N6-benzyladenine (BA) and exposed to either 12 or 16 h of light (30 μmolm−2s−1 at 26±2°C). Seed surface sterilization was deleterious to 3-mo-old seeds and severely reduced the viability of the 4-mo-old seeds. More mature seeds were not affected by the sterilization procedure. In general, the germination of 4-, 5-, 6-, and 7-mo-old seeds increased when BA was added to the culture medium especially under 16 h of light. Germination rates were highest with 8- and 9-mo-old seeds, and application of BA failed to enhance germination rates further. Developmental studies revealed that this cytokinin reduced seed and protocorm mortality rates; however, protocorm development was negatively affected in its presence. Seedling development was more pronounced when KC medium with 16 h of light was used. Long-term seed storage at 4°C did not provide promising results. The protocol described in this study proved to be efficient and relevant to in vitro seed germination and initial development of H. cinnabarina, and thus will contribute to conservation of this orchid species.
    In Vitro Cellular & Developmental Biology - Plant 10/2012; 48(48):500–511. · 1.14 Impact Factor
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    ABSTRACT: Laboratory experiments were conducted to determine the allelopathic potential of 17 Iranian barley cultivars in four development stages and their variations over the last 60 years of collection. Imbibed seeds and water leachates that were extracted from the barley plants at the seedling, tillering, stem elongation, and heading stages were used for the bioassays, including filter paper, neighboring barley seeds in soil, and soil mixed with dried barley residues. The experiments were conducted with the use of wild mustard (Sinapis arvensis) as the test plant. The Germination Rate Index (GRI) and emergence of S. arvensis were inhibited on both the filter paper and soil. The highest inhibitory effect was seen with the tillering stage's water leachate on filter paper. The GRI decreased in response to the increased density of barley imbibed seeds.The germination was less affected by the presence of barley seeds from the soil than those from the filter paper.The GRI of S. arvensis seeds was lower in the older than in the recently developed cultivars. Although there were some fluctuations in the GRI value with time, the germination inhibitory effect has decreased as new, higher-yielding cultivars have been released.
    Weed Biology and Management 04/2013; · 0.72 Impact Factor


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