1. Intraspecific Competition in Viola Tricolor ABSTRACT Intraspecific competition is competition between members of the same species. In this experiment intraspecific competition was tested in Viola tricolor (pansies). My hypothesis was that intraspecific competition does affect plant growth. In order for this to be true the p-value in the t-test would have to be less than 0.05. The plants were grown in different densities (3,6,10, 18) in the same size containers to test this idea. T-tests were taken and mean weights and heights were compared. When the t-tests were calculated the lowest density vs. the highest density (3 vs. 18) had a p-value of 0.049 which allowed the null hypothesis to be rejected which was that intraspecific competition did not affect plant growth. BACKGROUND [ Many factors should be considered when determining what affects plant growth. One of these factors is competition. In this study, intraspecific competition will be tested. Intraspecific competition is defined as competition between different individuals of the same species. Intraspecific competition also affects size in animals such as marine invertebrates (Marshall 2006). Plants are not territorial in the same sense that animals are territorial, but plants capture and hold onto space (Smith and Smith 2006). Plants respond to intraspecific competition through plastic responses such as growth or reallocation or mortality responses (Harper, 1977). If intraspecific competition is found to be a key factor in plant growth, then innovative growing and management techniques can be established to grow larger, healthier plants. Intraspecific competition has been tested before using different plants species, such as in the endangered northeastern bulrush (Lentz 1999) and Polygonum aviculare L. (Foderaro 1997). Both Foderaro and Lentz found that intraspecific did affect competition in the plants that they were studying. Lentz mainly tested the double factors of intraspecific competition and nutrient supply on plant growth, while Foderaro tested the triple factors of intraspecific competition, soil salinity, and temperature effects. This study focuses solely on intraspecific competition as a factor in plant growth. In this study, I hope to prove the hypothesis that intraspecific competition affects plant growth. I plan to test this by growing pansies in a controlled environment for a three-month period. Then I will take the mean of each sample density and compare those using t-tests. If the t-tests show no significant differences, then the null hypothesis cannot be denied. The null hypothesis for this study states that intraspecific competition has no effect on plant growth. OBJECTIVE Objective: To find out which type of competition has the most impact on growth: intraspecific or interspecific competition. Hypothesis: Interspecific competition is stronger than intraspecific competition. Null Hypothesis: Intraspecific competition is stronger than interspecific competition. METHODS [ RESULTS The p-value between the highest density is 0.049 which states that there is a significant difference between the largest density and the small density of pansies. The proves the null hypothesis can be rejected. [ Literature Cited Donald C.M.1951. Competition among pasture plants. I. Intraspecific competition among annual pasture plants. Australian Journal of Agricultural Research. Vol. 2. pp. 355-376. Harper, J.L. 1977. Population biology of plants. Academic Press, New York: 892. Lentz, K.A. 1999. Effects of Intraspecific Competition and Nutrient Supply on the Endangered Northeaster Bulrush, Scripus ancistrochaetus Shuyler (Cyperacaea). The American Midland Naturalist 142:47-54. Foderaro, M. A. 1997. Growth and Survival of Polygonum aviculare L. at a Brine-contaminated site in Southeastern Ohio. The American Midland Naturalist 138: 140-152. Marshall D.J. 2006. Offspring size effects mediate competitive interactions in a colonial marine invertebrates. Ecology 87: 214- 225. Smith R. L. and Smith T. M. 2006 Elements of Ecology: 6th Edition. Pearson Education Inc., San Francisco. CONCLUSIONS [Replace, move, resize, or delete graphic, as necessary.]  Plan: grow pansies in different densities (3,6,10 and 18) and then measure height and weight of each group. After they measurements are taken, the measurements will be compared (mean and t- tests). Expected Results: There will be a significant difference (p-value less than 0.05) between the low density and the high density group. Data will be calculated using a series of t-tests and mean values which will then be plugged into a data form. Methods were modeled after Lentz and Fonderaro studies. Brittany Bird, Undergrad Student, Department of Biology, Tennessee Technological University, P.O. Box 5063 Cookeville, TN 38505 My results agreed with Lentz and Fonderaro. Intraspecific competition does affect growth in the plants studied. So either adding nutrients or planting pansies farther apart would increase the size of the individual plants.