メヒシバと陸稲の競争に関する研究 : 第1報両種の生育特性の差異について

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The purpose of this studies is to analyze the mechanisms of competition between large crab-grass (Digitaria adscendens Henr.) and upland rice, with special reference to the process of matter production by plants growing under competitive stress. An experiment was conducted to study the difference in growth characteristics of the two species in mono-culture and in mixture. The experiment involved treatments in which the rice and weed plants were grown in isolated state ( 1×1 m spacing), in pure culture (10×10cm spacing) and in mixed culture (10×10cm). Results obtained are as follows; 1) At seedling stages stem length of upland rice was larger than large crab-grass, but since about 50 days after the sowing large crab-grass had larger stem length in all the plots. Plant height of upland rice was higher than large crab-grass throughout the experiment except in mixed culture. Numbers of main stem leaves, tillers and heads were greater in large crab-grass throughout the experiment in almost all the plots. 2) At seedling stages, the amounts of dry weight and leaf area of large crab-grass were very small as compared with upland rice in all the plots. However, large crab-grass surpassed upland rice in leaf area and in dry weight since about 40 days and 50 days after the sowing respectively, owing to its higher relative growth rate (RGR) and relative leaf growth rate (RLGR). The difference of these characteristics between the two species was found to increase with time. 3) During the early and middle stages of growth, the ratios of dry weight of each organ to total dry weight were similar for the two species. The head weight ratio of upland rice became higher gradually since the heading stage, and the ratio found in isolated culture and in mono-culture were about 35% at the maturity stage. The head weight ratio of large crab-grass at the maturity stage, on the contrary, was very small (about 10%), while the stem dry weight amounted to 65〜75% of the total dry weight. 4) The superiority in dry matter production of large crab-grass over upland rice was due mostly to the difference in RGR in earlier growth stages. Growth analysis showed that leaf area ratio (LAR) was the main cause of the difference in RGR, while the difference in net assimilation rate between the two species was relatively small. Analysis of LAR into leaf weight ratio (LWR) and specific leaf area (SLA) indicated that the SLA values were much larger in large crab-grass than upland rice in all the plots during the early and middle stages, causing the interspecific difference in LAR.
日本雑草学会の論文
1978-08-25

メヒシバと陸稲の競争に関する研究 : 第1報両種の生育特性の差異について

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メヒシバと陸稲の競争に関する研究 : 第1報 両種の生育特性の差異について

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メヒシバと陸稲の競争に関する研究 : 第1報両種の生育特性の差異について