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米デンプンのα-アミラーゼによる消化特性とグリセミック・インデックス(GI)を簡易に測定するため, 近赤外分光(NIR)法による推定精度について検討した. 検量線の作成は, 部分最小2乗法による回帰分析(PLS)で行った. NIR法による推定の実用性評価は, 推定値の標準誤差を検定試料の分布範囲と比較したEI法, および予測標準誤差を検定試料の標準偏差と比較したRPD法を用いて行った. 米デンプンの消化特性は3つのパラメーターを持った非線形式で表現した. そのパラメーターは, 加熱前処理に由来する分解物の割合(パラメーターa), α-アミラーゼの作用に由来する消化物の割合(同b), 消化速度(同c)である. GIはin vitroで評価したGI(EGI)を用いた. NIR法による簡易測定は, パラメーターcおよびEGIの推定において実用性があると判断された. その精度は遺伝資源にランクをつけるような一次スクリーニングに適用できるレベルであった. このことから, NIR法による簡易測定は, 米デンプンの消化速度が遅く, GIの低いイネ品種を選抜するのに有効と考えられた. また, 推定精度の向上のためには, イネの生態型や生産地によって試料を分けることが有効なことも示唆された.

The relationships between the climbing growth and the seed production in yabumame (Amphicarpaea edgeworthii Benth.) were analyzed based on the phytomer concept. An intensively positive correlation was found between the number of subterranean cleistogamous flowers and phytomers. The plasticity of branching construction (H) was influenced by the number of phytomers, whereas the entropical plant type index (H') and the plasticity of phytomer elongation (PE) were not affected. The H' of secondary branches significantly correlated positively to the number of aerial flower pods. The PE of primary branches close to the ground significantly correlated negatively to flowers per phytomer. The numbers of aerial and subterranean phytomers were under such an allometric relationship that the number of aerial phytomers had a significant correlation with the number of penetrated subterranean phytomers (PS), a lower correlation with the number of cotyledonary subterranean phytomers (CS), and the most intense correlation with the total (PS+CS). So CS was presumed to compensate subterranean growth. The PE of primary branches close to the ground correlated negatively to the aerial-phytomer penetration percentage into soil, revealing the trade-off relationship between the emigration by climbing stem and the settlement by penetration into soil. The relationship between PS and CS and variations in H' and PE is appreciated as clues to improve the plant type and seed allocation to geocarpic seed production around the root for domestication.

Strains of yabumame (Amphicarpaea edgeworthii Benth.), an edible resource of geocarpic wild legume, were collected from various stands in Japan and grown to investigate the geographic variations in its flowering and ripening behaviors. Northern strains needed fewer days after sowing to flower. The flowering period lasted longer for northern strains, where the duration varied among strains. Significantly negative correlation existed between days after sowing to flowering and flowering duration. The average 1.000-seed weight including all strains was 22g for aerial seeds and 143g for subterranean seeds. The former was a hard seed since scratching the seed coat increased the germination percentage sharply, whereas the latter germinated at high percentage without any pretreatment. The 1, 000-seed weight did not correlate with the latitude of home habitat. Subterranean pod including 2 mature seeds, twin bean, was produced at a higher probability in the case of the strains which had a heavier 1, 000-seed weight. The degree of subterranean seed to the total of its number and weight correlated vaguely to the latitude of each strains's home habitat. The deviation of the rate among strains was wider in southern strains.

To elucidate the relationship between the seed production of yabumame (amphicarpaea edgeworthii Benth.) and the micro-envivronment of its habitat, vegetation and external leaf morphology (leaf color, leaf area, density of pubescence, and pulvinus color) were investigated for indicating indirectly the latter. In addition, the association between taxonomic groups and seed production was reviewed since leaf morphologies were criteria for the taxonomy of varieties in A.edgeworthii. A stand of each strain's home habitat was surveyed by ordination concept based upon the biological spectrum. Degree of succession (DS) was calculated from the spectrum of Raunkiaer's dormancy form. Most of the stands were kept at rather intensely disturbed states so that the DS was between 5 and 10. The percentage of rosette species was calculated in each stand from the spectrum of growth form. Among the stands, 0.15 to 0.30 of the percentage was outstanding. This percentage had a significant negative correlation with 1, 000-seed weight. The leaf morphologies were vaguely associated with vegetation and seed production. It was confirmed that distributions of strains of thinly pubescent, blackish-purple pulvinused leaves with grayish-green backs were geographically localized. Since this pattern was similar to what had been reported for A.edgeworthii var. trisperma, it appeared that the leaf traits were the criteria by which the varieties were judged. As we failed to correlate those leaf traits with seed production, it is not considered to be possible to use the differences in geocarpic seed production as their traits of the 2 varieties.

As a threshold to investigate the climbing growth relative to seed production in yabumame(Amphicarpaea edgeworthii Benth.), the plant size, branching construction, and elongation of the climbing stem were analyzed with reference to phytomer concept. Four strains with different characteristics of seed production were grown for 150 days and harvested during their flowering period. Branching development was observed up to the 4th order. The production of branches and phytomers were maximal at the secondary order in each strain. A significant difference was detected among strains in the number of main-stem phytomers and in the number of primary branches. Since the branching pattern was too complex to analyze, the plasticity of branching construction(H)and the plant-type index(H'), based on entropy, were calculated in each branch order. H was maximal at secondary branches, and H' increased as the branch order rose in each strain. A significant difference existed in H and H' of primary branches among strains, and the two significantly correlated positively. Branches were classified into "aerial" and "close to the ground." The plasticity of phytomer elongation(PE) was calculated on the basis of range among phytomer lengths and the F-value by linear prediction applied to those as serial data. The PE of primary branches close to the ground was significantly different among strains. The order of PE magnitude between aerial branches and close-to-ground branches was dissimilar among strains. The plasticity of branching construction and of phytomer elongation appeared to have different ecophysiological backgrounds, since neither H nor H' hardly correlated to PE value.

Field experiments were carried out to clarify the differences and key factors in the rate of seedling establishment among rice varieties sown on the soil surface in flooded paddy fields. The percentage of seedling establishment in flooded paddy fields with average temperatures of 17.9 and 22.7°C using 7 varieties of rice (4 Japanese, 1 Portuguese, 1 Chinese and 1 Hungarian) varied from 18 to 94% with a significant varietal difference. The main causes for lower seedling establishment rate existed in floating and seedling mortality in the younger stage. These two causes were independent of each other, and their relative importance differed among varieties. The percentage of floating seedling in cv. Arroz da Terra was relatively low compared with other varieties. No clear correlations were found between the percentage of floating seedling and the plant length, the seminal root length or the apparent weight of seedling underwater. It was presumed that the varietal difference in the percentage of floating seedling might be caused by differences in the rooting abilities into the soil up to the 2nd leaf stage.

To clarify lodging resistance of high yield examples, characters related to lodging of Shan You 63 (F1 hybrid rice) with 965 gm-2 of a brown rice weight were analyzed. There were various factors for early lodging regarding external morphological characters. The lodging index (a distance between fulcra in 5 cm) at the 4th internode from the top (N4) at maturity was more than 200. High yield of Shan You 63 was obtained under quite dangerous conditions as regards lodging. The reason for increase in the lodging index at N4 was low breaking resistance. This phenomenon could be explained by a high rate of translocation of non-structural carbohydrate (NSC) and total nitorogen (N) from the culm and leaf to ear, and an extreme decrease in dry weight per unit length of the portion lower than N4 at maturity. To consistently obtain a yield exceeding 965 gm-2 in Shan You 63, it is necessary to develop cultivation techniques to store more NSC, N and dry matter in the culm and leaf sheath and ear.

Analysis of the characteristics of grain production of 965 gm-2 obtained by Shan You 63 (F1 hybrid rice) in 1991 was carried out Absorption of nitrogen reached 21 gm-2 up to the time of heading, and a large capacity of grain yield (50, 360 spikelets per m2) was obtained. Efficiency of increase in spikelet number per m2 by absorbed nitrogen up to heading was essentially the same as in west Japan. Mean Leaf Area Index 10 days before heading became exceptionally large (10.18). A large amount of translocation of accumulated assimilation products before heading improved the percentage of ripened grain. Increase in translocation of assimilated products stored in the culm and leaf before heading may remarkably increase yield in China.