Intraspecific Competition: The response of the sunflower (genus Helianthus) to increasing density :: essays research papers

INTRASPECIFIC COMPETION THE RESPONSE OF THE SUNFLOWER (genus HELIANTHUS) TO INCREASING DENSITY.INTRODUCTIONAll species, including plants, atomic outlet 18 impacted by density. Plants, of course, cannot leave their habitat as animals can, so they campaign to respond in different ways to density. As populations grow to a greater extent(prenominal)(prenominal) dense, they compete for resources such as food and space and are more prone to disease. Less dense populations are more susceptible to predation pressure. It is hypothe surfaced that as plants in small spaces compete for space, the plants compensate by trim individual stem w octette and frequency of bud formation as density increases. This would be intraspecific competition. A calculate is density-dependent when it kills more of a population at higher densities and less at lower densities (Stilling 2002). The factor of competition amongst individual plants of the same species would be considered density dependent.METHODS The investigate was designed to test the hypothesis by planting an increasing number of genus Helianthus (sunflower) seeds in pots to see how they respond to increased density in limited space. Two replicates each of 2, 4, 8, 16, 32, 64, and 128 seeds were planted in similar size pots containing an equal mix of potting soil and perlite. All plants were kept in greenhouse conditions exposed to similar light and temperatures settings and were watered at equivalent intervals. At the end of the time period each pot was evaluated for number of seeds that had germinated as well as number of stems with blooms. Stems and blooms were cut and weighed.RESULTSTable 1 shows averages of each replicate for each series of seeds relating to deathrate rate/germination rate, develop rate, and mean plant weight (total, with buds, and without buds). flesh 1 indicates an increasing mortality rate (positive slope) in plants as density increases Figure 2 shows the tally germination rate reflecting the exact opposite trend. Mortality remains cipher until 8 seeds are planted (6% mortality), then is reduced to zero at 16 seeds then increases to 14 percent (32 seeds), 32 percent (64 seeds), and more than half (57 %--128 seeds).Figure 3 shows a dramatic decrease in bud formation of approximately 20 percent from four to eight seed plantings, followed by slight decreases of 3 percent of less in bud formation as significantly greater quantities of seeds are planted.Figure 4 reflects a decreasing mean weight per plant as density of planted seeds increases-- from a high of 11.73 grams (2 seeds) decreasing gradually from between 3 to .