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At least 883 records · Page 49Linked to original sources
PubMed2002

[Analysis of natural regeneration barriers of Pinus sylvestris var. mongolica plantation on sandy land].

By employing comparison analysis, and field experiment of watering and soil-covering before overwintering for seedlings, the barriers of natural regeneration for Mongolian pine plantations on sandy soil were identified. The experimental area was divided into 3 parts according to the state of natural regeneration. Crown closure, litter, understory coverage, and site condition were the factors which affect natural regeneration. Water deficit, but not low temperature during overwintering, is the key factor that limits survival for 1-2 years old seedlings in plantation area. The water deficit is due to higher air temperature, less accumulated snow, higher soil evaporation, higher plant transpiration in plantation area than in the area in which Mongolian pine is naturally distributed. Based on the above research, it is necessary to take effective artificial measures to promote its natural regeneration so as to guarantee its successful development. The following measures are recommended: 1) covering the 1-2 years old seedlings with soil before wintering, 2) irrigating seedlings before wintering, 3) suitable forest harvest, e.g., belt clear-cutting, or patch cutting, 4) planting the pine with broadleaf species, 5) protecting forest stands from livestock grazing, seed collecting and litter gathering.

Desert Climate↗
PubMed1994

Gene expression of nitrite reductase in Scots pine (Pinus sylvestris L.) as affected by light and nitrate.

A partial cDNA clone (PSnir) encoding the C-terminal region of nitrite reductase was isolated from a lambda gt11 library of the gymnosperm Pimus sylvestris (L.). Nucleotide sequence analysis showed that PSnir contains a reading frame encoding 105 amino acid residues. The amino acid sequence revealed a homology to NiR of 63-68% to dicotyledoneous and of 57-59% to monocotyledoneous species. The protein region implicated to be involved in binding of the prosthetic group is highly conserved between the NiR of the gymnosperm and of angiosperms. In all organs (cotyledonary whorls, hypocotyls, roots) the pattern of NiR gene expression in response to nitrate and light is the same at the level of transcript accumulation and at the enzyme level. This suggests that regulation of NiR gene expression in the Scots pine seedling is predominantly at the level of transcript accumulation. The highest NiR appearance was observed in roots and hypocotyls. In the cotyledonary whorls only small amounts of NiR were found. In roots and hypocotyls the accumulation of NiR mRNA and the appearance of NiR protein is mainly controlled by nitrate, whereas the regulation of NiR gene expression in the whorls is strongly affected by light and the inducive effect of nitrate is only weak.

Amino Acid Sequence↗
PubMed1979

Inheritance of isozyme variation and heterozygosity in Pinus ponderosa.

Techniques are presented to detect 23 isozyme loci in the long-lived perennial plant, ponderosa pine. Meiotically derived megagametophyte from seeds is used to examine directly the segregation of allelic variants. Approximately seven seeds were initially examined for 12 enzymes from each of 47 trees from ten stands throughout the northern Rocky Mountain region. Additional seeds were also examined from selected families to confirm the inheritance of observed electrophoretic variants at 13 polymorphic loci and to estimate linkage relationship. Significant norandom segregation was consistently detected for three pairs of loci: ADH-1:AAT-2, ADH-1:PGI-1, and LAP-2:6PG-1. Preliminary estimates of population parameters reveal a relatively high average heterozygosity (H = 0.123). This is partitioned into a high amont of genetic variation within local stands, with only approximately 12% of the total heterozygosity resulting from genic difference between stands.

Gene Frequency↗