Study on the Heritabilities of Pinus densiflora S. et Z. (I)

소나무의 유전력(遺傳力)에 관(關)한 연구(硏究)(I)

Pinus densiflora S. et Z. which has the widest distribution and highest stock at present in Korea and has used as materials for fuel, house construction, furniture and many other purposes for several hundred years, is considered as one of major species of economic importance, although there are a few epidemic insect injuries and silvicultural difficulties in regeneration. However, since disorderly cutting has been conducted for long time, the valuable local stands have disappeared. Therefore immediate attempts should be taken on the gene conservation and genetic studies including heritabilities and genetic gains of desirable characters. One hundred and twently five plus trees have so far been selected from the nationwide area and kept for the purpose of seed orchard establishment and other theoretical studies. In this study, the wind pollinated seeds of grafted stocks of 13 plus trees in clone bank located in Suweon and the seeds of 4 Japanese plus trees were collected and their progenies were used for heritability study. As indicated in figure 1, thirteen plus trees are from the middle part of Korea and two experimental plantations were laid out in ]972 (1-1 stock) by the randomized block design with five replications, consisting of 10 trees line plots of each family in each replication. Tree height, root collar diameter and branch diameter at 1cm apart from the main stem were measured. The results are summarized as follows 1. The rank of height growth of each plus tree progenies by age was greatly changed under age 3 and it was affected more in poor site than good site. 2. The heritabilities of height growth were estimated to be 7.2% at age 3, negative sign at age 4, 9.4% at age 5, 13.0% at age 6, 8.1% at age 7 and abrupt increase of 63.8% at age 8. The heritabilities were generally increased with increase of age. 3. The heritabilities of root collar diameter and branch diameter (average of the three biggest branches) was 3.2% and 11.8% at age 8 respectively. 4. The genetic gain was largest at age 8 and it was 46.6% when a selection intensity, 1/500 was taken. It, therefore, seems to be reasonable that selection should not be made under age 7.

우리나라 소나무 수형목(秀型木)에 대(對)한 연령별(年齡別) 수고변화(樹高變化), 유전력(遺傳力), 및 개량효과(改良効果)를 조사(調査)하였는데 그 결과(結果)를 요약(要約)하면 다음과 같다. 1. 가계별(家系別) 수고생장(樹高生長) 순위변화(順位變化)를 조사(調査)한 결과(結果) 3년생(年生)까지는 비교적(比較的) 순위변화(順位變化)가 심(甚)하게 나타나며 입지조건(立地條件)이 불리(不利)한 곳에서는 더욱 심(甚)한 변화(變化)를 나타냈다. 2. 수고유전력(樹高遺傳力)을 연령별(年齡別)로 조사(調査)한 결과(結果) 3년생(年生)은 7.2%, 4년생(年生)은 (-)값을 보였으며, 5년생(年生)은 9.4%, 6년생(年生)은 13.0%, 7년생(年生)은 8.1%, 8년생(年生)은 63.8%로 나타나 대체적(大體的)으로 연령(年齡)의 증가(增加)에 따라 증가(增加)하는 경향(傾向)을 보였다. 3. 근원경(根元徑) 및 가지 직경(直徑)의 유전력(遺傳力)은 8년생(年生)에서 각각(各各) 3.2%, 11.8%이었다. 4. 개량효과(改良効果)를 측정(測定)한 결과(結果) 8년생(年生)에서 선발강도(選拔强度)를 1/500로 볼 때 46.6%로서 가장 높은 값을 보였으므로 7년생이하(年生以下)에서는 선발(選拔)을 실시(實施)하지 않는 것이 좋을 것으로 사료(思料)된다.