• Korean Journal of Breeding Science
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• v.41 no.4
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• pp.377-384
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• 2009

Three-year-old seedlings of susceptible Pinus densiflora and resistant Pinus x rigitaeda were each inoculated with the pinewood nematode, Bursaphelenchus xylophilus, to compare disease development. Needle dehydration was evident on seedlings of P. densiflora by 20 days after inoculation, 10 days earlier than this symptom was observed on P. ${\times}$ rigitaeda. Xylem drying was more frequent in seedlings of P. densiflora than in that of P. ${\times}$ rigitaeda between 20 and 60 days after inoculation. No significant differences were found between P. densiflora and P. ${\times}$ rigitaeda for stem water content or for stem and leaf relative water content in current-year branches after nematode inoculation, but the average number of B. xylophilus recovered from stems differed significantly between the two groups. The number of B. xylophilus recovered from stems was negatively correlated with the stem water content and with stem and leaf relative water content. By the time the experiment was terminated at 60 days after inoculation, all 3 of the last group of P. densiflora seedlings had died, but 2 of the 3 remaining P. ${\times}$ rigitaeda hybrid seedlings were still alive. Additional studies are needed to further explore the specific mechanisms preventing nematode multiplication in the seedlings of resistant P. ${\times}$ rigitaeda.

• Journal of Plant Biology
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• v.19 no.3
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• pp.85-91
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• 1976

A comparison betwen the productivity of Pinus rigida which is native in the Eastern United States, and P. rigitaeda which is F1 hybrid between P. rigida and P. taeda, has been established. For each tree the diameter at breast height (D) and the height of tree (H) were measured in three years. The standard sample trees were down and then weighed each organ. From obtained data the allometric relation between $D_2H$ and dry weight of the trunk (Ws), the branches (Wb) and the leaves (Wl) of P. rigida were approxmated by $$Ws=0.0592 (D^2H)^{0.837}$$ $$Wb=0.0065 (D^2H)^{0.989}$$ $$Wl=0.0447(D^2H)^{0.690}$$ and those of P. rigitaeda were approximated by $$Ws=0.0522 (D^2H)^{0.843}$$ $$Wb=0.0037 (D^2H)^{1.117}$$ $$Wl=0.0207 (D^2H)^{0.856}$$ From the above, the standing crops of above ground of P. rigida were estimated to be as much as 16.93-34.35 ton dry matter per ha, and those of P. rigitaeda were 20.45-45.55 ton per ha. Annual net production was appraised at 8.07-9.35 ton/ha.yr in P. rigida and at 11.59-13.41 ton/ha.yr in P. rigitaeda (1.0:1.4). It is assumed that high productivity of P. rigitaeda stand compared with P. rigida resulted from an increase of the leaf amount with age. Photosynthetic ability under the saturated light of the current and theold leaves of P. rigida were respectively 2.62 and 0.66mg CO2/g. d. wt..hr and those of P. rigitaeda were 1.17 and 0.96mg CO2/g.d. wt.hr. Respiration of the current and the old leaves at $25^{\circ}C$ were 1.00 and 0.90 mg CO2/g. d. wt..hr. in P. rigida and 0.90 and 0.45mg CO2/g.d.wt.hr in P. rigitaeda. It is assumed that photosynthetic longevity of P. rigitaeda leaves was vigorously maintained longer than that of P. rigida.

• The Plant Pathology Journal
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• v.26 no.4
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• pp.299-305
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• 2010

A half-sib family of two 4-year-old seedlings of Pinus $\times$ rigitaeda was inoculated with each of 20 Pinus thunbergii isolates of Fusarium circinatum (syn. Fusarium subglutinans f. sp. pini) from two pitch canker damaged sites in Jeju Island, South Korea. Initial symptoms of needle damages were visible on most of the seedlings at 18 days after inoculation. The 20 tested isolates were not significantly different in virulence, based on lesion lengths at the site of inoculation (P = 0.217). The most virulent isolate FT-7 showed the longest lesion length. Some seedlings began to die 46 days after inoculation. All seedlings were dead by 68 days after inoculation except two seedlings inoculated with each of isolates FS-2 and FS-13, respectively. Using the FT-7, 38-year-old 11 P. $\times$ rigitaeda trees, which were survived from a seed orchard severely damaged by pitch canker, were inoculated on branches in the seed orchard in Jeju Island to assess differences in susceptibility to pitch canker. The 11 trees differed significantly (P < 0.001) in susceptibility to F. circinatum based on average lesion lengths measured 56 days after inoculation. It is possible that induced resistance contributed to their capacity to limit lesion development. The susceptibility of natural selection P. $\times$ rigitaeda trees are more likely affected by interaction with F. circinatum rather than environmental conditions.

• Journal of Ecology and Environment
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• v.32 no.2
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• pp.97-102
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• 2009

This study was carried out to evaluate litterfall dynamics in three adjacent coniferous tree plantations (larch: Larix leptolepis; red pine: Pinus densiflora; rigitaeda pine: P. rigitaeda) planted in the same year (1963), and growing under similar environmental conditions in the Sambong Exhibition Forests, Hamyang-gun, Gyeongsangnam-do. Litter was collected monthly between July 2006 and June 2008. Needle, broad leaf and total litter inputs followed a similar monthly pattern in the three coniferous plantations. The amounts of needles, flowers, and miscellaneous litter were significantly lower in the larch than in the two pine plantations, while branch litter was significantly higher in the larch than in the two pine plantations. Average total litterfall for two years was significantly higher for the pine (5,475 kg $ha^{-1}\;yr^{-1}$ for red pine and 5,290 kg $ha^{-1}\;yr^{-1}$ for rigitaeda pine) plantations than for the larch (3,953 kg $ha^{-1}\;yr^{-1}$ plantation. Needle litter comprised about 73.1% of total litterfall for the rigitaeda pine, 70.8% for the red pine and 62.9% for the larch plantations. Our results demonstrate that litterfall inputs can be affected by tree species.

• The Korean Journal of Ecology
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• v.27 no.2
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• pp.67-71
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• 2004

This study was carried out to evaluate soil carbon and nutrient storage of three adjacent coniferous plantations (Larix leptolepis, Pinus densiflora and Pinus rigitaeda) growing on a similar site with a same planting age (42-year old) in the Sambong Exhibition Forests, Hamyang-gun, Gyungsangnam-do. The soil carbon concentration among three plantations was not significantly different in 0∼10cm soil depth, but other two depths (10∼20cm and 20∼30cm) showed higher carbon concentration in P. densiflora plantation than the other two plantations. The exchangeable cation concentrations (Ca and Mg) in 0∼10cm depth were significantly lower in L. leptolepis plantation than in the other two plantations, while nitrogen and phosphorus concentrations were not significantly different among three plantations except for nitrogen at 10∼20cm depth in P. rigitaeda plantation. Soil carbon storage in 0∼20cm depth of three plantations was unaffected by the stand types. Soil nutrient storage was not significantly different at each depth except for nitrogen storage at 10∼20cm depth in P. rigitaeda plantation because of the variation of bulk density and coarse fragment. This result demonstrates that soil carbon and nutrient concentrations among the plantations on a similar soil condition can be altered significantly by tree species effects over 40 years after plantation establishment.

• Korean Journal of Breeding Science
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• v.41 no.4
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• pp.420-428
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• 2009

In this study, the variation of 20 Pinus thunbergii isolates of F. circinatum from 2 damaged sites in Jeju-Island were compared with a known Fusarium circinatum using molecular biological techniques. Two- and four-year-old seedlings of Pinus rigida${\times}$Pinus x rigitaeda and two-, three- and six-year-old seedlings of P. thunbergii were inoculated with one of the most virulent isolates, FT-7, to determine differences in susceptibility. In site 1 (FT), 13 isolates of F. circinatum were isolated from 14 individuals and in site 2 (FS), 7 isolates of F. circinatum were isolated from 9 individuals. No difference was found in the sequences of the internal transcribed spacer (ITS) region of the ribosomal RNA genes in the FS and FT isolates, and also even in the known isolate of F. circinatum, FE 1-1. However, the ITS sequences of the FS and FT isolates differed from those of a fungus, Botrytis cinerea. Two-year-old seedlings of P. rigida${\times}$P. x rigitaeda showed higher susceptibility (93.3% of mortality) than four-year-old ones. Three-year-old seedlings of P. thunbergii showed the highest susceptibility (66.7% of mortality) compared to those at other ages in the same species. We found a positive correlation between basal diameter and lesion length in the seedlings of P. rigida${\times}$P. x rigitaeda ($R^2=0.66$) and P. thunbergii (p < 0.0001), respectively. There were significant differences in susceptibility by the age of seedlings in each of P. rigida${\times}$P. x rigitaeda (p < 0.0001) and P. thunbergii (p < 0.0001) based on lesion length.

• Journal of Korea Water Resources Association
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• v.30 no.5
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• pp.503-514
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• 1997

• Journal of Korean Society of Forest Science
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• v.90 no.4
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• pp.543-547
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• 2001

An fungus gnat, Bradysia agrestis in the family Sciaridae was collected from Pinus spp. seedlings. This pest is a newly recorded insect from P. thunbergii, P. rigida, P. rigitaeda, and P. densiflora seedling. Brief morphological characters, damage symptom, host plants associated with the B. agrestis were recored. Significant variation in damaged of Pinus spp. seedling was attributed to differences between pine species(P. thunbergii : 15.4-20.0%, P. rigida : 23.1-48.8%, and P. rigitaeda : 13.8-67.5%, respectively) and sowing times(May : P. densiflora, 0%; P. rigida, 0%, July : P. densiflora, 20.0%; P. rigida, 49.4%, respectively).

• Journal of Korean Society of Forest Science
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• v.29 no.1
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• pp.102-114
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• 1976

This experiment was conducted to investigate the percentage of fertile seed in terms of crossabilities and relationships of taxonomic affinities for the ${\times}$ P. rigitaeda of interspecific hybrid, ${\times}$ P. rigida rigitaeda and ${\times}$ P. rigitaeda rigida of backcross hybrids, $F_2$ of ${\times}$ P. rigitaeda and natural hybrid of ${\times}$ P. rigitaeda within Sub-genus Diploxylon of the Genus Pinus. The possibility of establishment of hybrid seed orchard and differentia of hybrids for the purpose of extensive program of reforestation in the future have also been investigated. And, the experimental results obtained are summarized as follows: 1. On the basis of crossabilities as well as on the taxonomic affinities according to the systems of Shaw, Pilger and Duffield, it has been proven that the parental species of those hybrids are of close affinities and range of the fertile hybrid seed production rate was as high as 67-87% in the best hybrid combination (Table 6). 2. Those hybrids seemed to be most promising in the growth perfermance exhibiting 28-80% more volume growth compared to the P. rigida with the statistic significance of 1-5% level (Table 7, 8, 9). And all hybrids exhibit cold hardiness as much as P. rigida except $F_1$ hybrid of ${\times}$ P. rigitaeda and it seems to suggest that the characteristics of cold hardiness were transmitted from the P. rigida. 3. With regard to the anatomical characteristics of needle, the hypoderm is biform in most of the hybrid pines and the characteristics of resin canals are medial in all hybrid. And, the fibrovascular bundles are intermediate of both parent in all hybrid. Therefore it was found to be possible to distinguish the hybrids pines from their parents by the needle characteristics (Table 10). 4. It has been demonstrated that the hybrids pines have a phenolic substance (No. 7) of pale yellow at Rf-0.66, same as P. rigida, but no trace of phenolic substance was observed in the P. taeda. This fact will serve as an important criteria for early identification of hybridity in progeny testing (Table 11). 5. It was found to be possible to distinguish by the starch gel electrophoretic variations banding patterns and staining densities of isoperoxidase in the needles of the hybrids pines from their parents (Fig. 1).

• Journal of Korean Society of Forest Science
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• v.27 no.1
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• pp.15-21
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• 1975

According to Yoshihisa Kuroki's report that the total amount of carotenoid was more in the susceptible to pine bark beetle, than in the resistant ones, carotenoids were extracted from needle leaves of one year old seedlings of Pinus thunbergii, Pinus desiflora, Pinus rigida, Pinus koraiensis, Pinus rigitaeda and Pinus taeda which are all important pines in Korea, to find their resistant ratio to the insect. The carotenoids were analyzed and compared using the spectra of them by spectrophotometer. The results were as follows: 1. The visible absorption spectra of carotenoids in those pine trees were proved to be very similar. 2. The total amount of carotenoids in needles differed with the tree species and the contents were arranged in decreasing order P. koraiensis>P. rigida>P. thunbergii>P. rigitaeda>P. taeda, it seemed that there was corelation between the cartenoid content and the extent of harm caused by the pine bark beetles except P. koraiensis. 3. But carotenoids were contained in Robinia pseudoacacia, Castanea crenata, Chamaecyparis obtusa and Cedrus deodra leaves too. 4. The total amounts of carotenoids in these pines of 9 species were arranged in decreasing order Robinia pseudoacacia>Pinus koraiensis>Pinus rigida>Pinus thunbergii>Castanea crenata>Pinus rigitaeda>Pinus taeda>Chamaecyparis obtusa>Cedrus deodara. Therefore, it was proved that there was no correlation between carotenoid cotent and extent of resistance to the insect. 5. In the thin-layer chromatography of these carotenoids, 13 kinds of components in P. densiftora, P. koraiensis and P. rigida and 12 kinds of spots in other pines, were detected respectively, under ultra-violet fluorescent lamp $3,600{\AA}$ and $2,537{\AA}$. 6. The eighth spots from the bottom in P. densiflora, P. koraiensis and P. rigida were not found in other pines and other 4 species (Robinia pseudoacacia, Castanea crenata, Chamacyparis obtusa, Cedrus deodra). Especially the spot in P. densiflora fluoresced strong cobalt blue-fluorescence under ultra-violet fluorescent lamp $2,537{\AA}$.