生殖器官の生産量からみたシイ林の有性生殖(林学部門)

松尾大社(京都市嵐山)の境内のシイ成熟林において, リタートラップ法で1986年～1989年の生殖器官の生産量(林分当たり)を測り, また花粉生産量は開花前の雄花序当たり花粉量を基に推定した。これらの諸量を検討し, 有性生殖についてえた主な結果は次の通りである。花粉生産量は重量(218～359kg (ha)^<-1> (yr)^<-1>)では最大クラス, 粒数(64.2～103×(10)^<12>(ha)^<-1> (yr)^<-1>)では突出して多く, しかも年次変動が小さかった。この莫大な花粉数は, しかし, 胚珠数に見合ったものであった(花粉/胚珠の数比, 4.1～8.3×(10)^5)。花粉粒は小形であるから(1.94～4.30×(10)^<-6>mg), 同化産物の花粉への流れは節約されている。開花年ごとの乾物量は1609～1803kg (ha)^<-1>で, 雄性と雌性の部分量は逆比例の関係にあった。年度ごとの乾物生産量は1237～2204kg (ha)^<-1> (yr)^<-1>の範囲で, これは種子の並作～凶作の年の値である。この生産量の多少と各部分の割合との間には, 一定の傾向はなかった。これは種子成熟に2カ年を要することに関係がある。また, 当年生と1年生の部分の生産量は等しくなる年が多かった。結実率は低いが(5.5%～10.6%), ほかの種と大略等しい。年々の種子数は結実率と並行して推移し, 総雌花数も種子生産に関係があるようだ。種子対投資の重量比は種子の並作年に3倍, 凶作年6倍で, これはほかの重力散布種子の種の値と一致した。

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In a mature stand of Shii chinkapin (Castanopsis cuspidata SCHOTTKY) at Matsuotaisya shrine, Arashiyama, Kyoto, annual production rates of reproductive organs were studied using 20 litter traps (each 50cm×50cm in mouth area) in 1986-1989,and those of pollen were estimated by multiplying the number of fallen male catkins per ha per year by the mean amount of pollen per catkin before anthesis. The main results were as follows. The pollen production rate of 218-359kg d. w. (ha)^<-1> (yr)^<-1> was one of the highest among other species, and that of 64.2-103×(10)^<12>(ha)^<-1> (yr)^<-1> was by far the largest number; moreover, these showed small year-to-year fluctuations. Such a huge number of pollen grains, however, was balanced by the number of ovules in a stand (numerical ratio of pollen grains to ovules : 4.1-8.3×(10)^5). The light pollen grains (1.94-4.30×(10)^<-6>mg d. w.) save the assimilation products invested in pollen formation. Dry matter of reproductive organs by the year of anthesis was within the range 1609-1803kg d. w. (ha)^<-1>, and those of male and female parts were inversely proportional to each other. Annual production rates were within the range 1237-2204kg d. w. (ha)^<-1> (yr)^<-1>, equivalent to values in years of average to poor seed crop. There was no relationship between the annual production rates (by weight) of male and female parts, because fruit maturation requires two growing seasons. In three years among four, the 0-and 1-yr-old parts showed equal dry weight allocation. Seedmaturing ratios or numerical ratios of mature nuts to total female flowers were small (5.5%-10.6%), being approximately equal to those of other species. The year-to-year trend in nut production (by number) parallelled those of seed-maturing ratio and the number of female flowers. Mean nut weight vs. assimilation products necessary for producing a single nut, calculated by dividing the drymatter production rate of overall parts by the number of nuts, was 1 : 3 in a year with an average seed crop, and 1 : 6 in a year with a poor crop. This seed production effort was similar to those of five other barachorous species.

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書誌情報

ja : 京都府立大學學術報告. 農學
en : The scientific reports of Kyoto Prefectural University. Agriculture

巻 43, p. 8-23, 発行日 1991-11-19

雑誌書誌ID

収録物識別子タイプ

NCID

収録物識別子

AN00062275

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収録物識別子タイプ

PISSN

収録物識別子

00757373

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