Allelopathy is the compound released by the plants (example: blady grass) to the environtment and where another plants is living and could obstruct or extinguish to another plants.  The purpose of research were to figure out the effect of allelopathy  from the blady grass toward the species of acacia seedlings, to figure out the weakest affected seedling species by blady grass allelopathy, and to figure out interaction between concentration of  extracted blady grass and seedling tree species.  The research was designed based on factorial in a complete random design.  Factor I was the seedlings, consisted of acacia, mangium, and acacia alba, while factor II was concentration of extracted blady grass allelopathy, consisted of non extracted allelopathy, extracted allelopathy 25%, extracted allelopathy 50%, extracted allelopathy 75%, and extracted allelopathy 100%. Every treatment was repeated 5 times. The number of the seedlings for each experimental unit was two seeding. The observed variables  were height, diameter of the stem, number of leaves, and living percentage of the seedlings.  This observation data was tested by Bartlett test to find the variance homogenity.  Then it was analyzed by using variance analysis, and tested by least significant difference (LSD).  The calculation were done at 5% significant level.  The result of this research showed that allelopathy of blady grass were significan to the growth of acacia, mangium and acacia alba seedlings. Based on the LSD at 5% was known that the concentrate of blady grass allelopathy had strongest negative effect to the growth seedlings was 100%.  Seedling that was the most resistant to the allelopathy of blady grass is mangium seedling.  It was known from the analysis of variance test there was an interaction between the seedling and the concentration of blady grass allelopathy that effect the height, leaves number, living percentage ofseedlings.  Key words : allelopathy, blady grass, and acacia

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The low quality of student learning outcomes is influenced by the strategy delivered by the teacher that is not appropriate so that it has a major impact on student learning outcomes that are not optimal. For this reason, it is important that there is a breakthrough in the form of a strategy implemented by a teacher. The objectives of this research are; 1) To find out the learning outcomes of class XI students before and after the implementation of the Explicit Instruction Learning Model in the 2-dimensional subjects of the Multimedia Department at SMKN 2 Padang Panjang, 2) To determine the effect of the implementation of the Explicit Instruction Learning Model on student learning outcomes. The research method uses a quantitative approach. The data analysis technique used in this research is a quantitative research technique. By converting the scores into scores and using a t-test (paired sample test). The results in this study are explicit instructional learning strategies have a significant effect on student learning outcomes in class XI in the 2 Dimensional Subject of the Multimedia Department of SMKN 2 Padang Panjang. The application of the learning model with the explicit instruction strategy in the 2 Dimensional Subject of the Multimedia Department in the experimental class went well.