4 Leaves Per Plant example essay topic

EXCITING PLANT STUDY LUPINS AIM: To investigate the effect that different concentrations of Rhizobia has on the growth rate of the Lupin, Lupinus arboreus. HYPOTHESIS: I think that as the concentration of Rhizobia increases the growth rate of the Lupin will also increase. RATIONALE: The Lupin is usually in the early to middle stages of a succession as it is able to grow in poor quality soils, because of this it helps to stabilise the soil and provides shelter for the growth of other species. Lupins have a mutualistic relationship with Rhizobia so are able to 'fix' Nitrogen. The Rhizobia bacteria is capable of converting atmospheric nitrogen, which cannot be used by plants, into nitrate or NO 3-, which can be used. The Rhizobia bacteria form in nodules on the root system of the Lupin and provide the plant with this nitrate, which aids the growth of the lupin as it is a much needed nutrient and produce amino acids which are transported to the shoot and leaves.

This is also good for neighbouring plants as excess nitrogen gets secreted into the soil and if the Lupin dies it also supplies neighbouring plants with nitrogen when it decays. VARIABLES: To Change: The variable to change is the concentration of Rhizobia in solution, this will be done at 0% (this acts as the control), 1.25%, 2.5% and 5%. To Control: Light - kept the same with all plants being in a glasshouse and subject to the same conditions. Water - each plant will be given equal amounts of water by a sprinkler system, the exact amount pending on the dryness. Heat - all plants subject to the same temperatures as all are in the same glasshouse.

Substrate - kept the same with all plants in sterilised sand. Seeds - all seeds sterilised with 25 seeds per concentration. EQUIPMENT: germination box, 120 Lupinus arboreus seeds, distilled water, commercial bleach, an oven, 4 grow boxes (ice-cream containers), 1.25%, 2.5% and 5% solutions of Rhizobia, sand, beaker, glasshouse, scales. METHOD: 1.

Keep a dairy of the steps below and significant changes to your plants 2. Collect about 120 seeds (to allow for those that don't germinate) and sterilise them as explained below 3. Place all the seeds in a small beaker 4. Dilute commercial bleach 50: 50 with water 5. Add the diluted bleach to the seeds for 5 minutes 6. Rinse the seeds in 5 washes of distilled water and on the last wash leave them soaking for 2 hours 7.

Nick the seeds and place them on moist paper in a germination box / petri dish to germinate, water daily until germinated 8. Sterilise the sand by placing it on a tray in an oven at 100^0 C over night 9. Place sterilised sand in the 4 grow boxes (one grow box per concentration) 10. Make up the 3 concentrations of Rhizobia using distilled water to dilute (the fourth solution is distilled water only) 11. Once germinated place 25 seeds in each grow box and water each box with 250 ml so that the sand is thoroughly wet 12. Place the grow boxes in a glasshouse and allow the germinated seeds to break out of their shell and sprout their cotyledons 13.

Now give 1 ml of the corresponding Rhizobia concentration to each plant in the grow boxes 14. Repeat step 12 approx. 48 hours later 15. Make sure the plants have water by setting up a sprinkler system or by manually watering them with 50 ml of water per day per box or when needed 16.

Collect the plants once they are about 10 cm tall or after about 1.5 months taking care not to get them mixed up 17. Count the number of nodules on the roots of each plant for the different concentrations 18. Count the number of leaves on each plant for each concentration 19. Find the total dry mass of all the plants for each concentration by placing the plants in separate tins depending on what concentration of Rhizobia they were given and heating in an oven at 80^0 C over night 20. Process your data, calculating means and using ANOVA and graphs where appropriate Diary of Lupins: Wed 6 Aug - Sand sterilised Mon 11 Aug - Seeds sterilised Tue 12 Aug - Seeds nicked and put in germination box Wed 13 Aug - Seeds watered Thur 14 Aug - Seeds watered Fri 15 Aug - Seeds have germinated, put in grow boxes (25 per box) and move to glasshouse Mon 18 Aug - Cotyledons out, 1 ml of their respective Rhizobia solution concentration added to each plant Wed 20 Aug - Second dose of Rhizobia solution added, again 1 ml per plant Mon 25 Aug - Plants going well, all alive, no noticeable differences between concentrations Mon 1 Sept - All plants well still no differences Fri 12 Sept - Plants going well, 2 dead ones though-1 in 0% and 1 in 1.25% Tue 7 Oct - Plants taken out and cleaned Thur 9 Oct - Number of leaves and nodules counted on each plant, plants put in oven to dry Fri 10 Oct - Dry mass recorded of each concentration RESULTS: Table 1 Concentration of Rhizobia solution added 0% 1.25% 2.5% 5% NUMBER OF NUMBER OF NUMBER OF NUMBER OF LEAVES NODULES LEAVES NODULES LEAVES NODULES LEAVES NODULES 4 0 4 11 4 0 4 2 4 0 4 10 4 0 4 5 4 0 4 12 4 4 4 6 4 0 4 8 4 0 4 4 4 0 4 9 3 0 4 7 4 0 4 9 4 4 4 0 5 0 4 10 5 11 4 10 4 0 4 10 4 2 3 0 4 0 4 6 4 1 4 3 3 0 4 11 4 1 4 3 4 0 4 10 4 3 5 0 4 0 4 8 4 0 4 7 4 0 4 7 4 5 4 3 4 0 4 9 4 0 4 0 3 0 4 6 4 0 5 0 3 0 4 9 4 5 4 2 4 0 4 2 4 0 5 12 4 0 5 9 4 3 4 0 4 0 2 6 4 1 4 2 4 0 4 7 4 3 4 0 4 0 4 10 4 3 4 0 4 0 4 8 4 0 4 0 4 0 5 10 4 0 4 1 4 0 5 9 4 4 4 0 - - - - 4 0 3 0 AVERAGES (to the nearest whole number) 4 0 4 9 4 2 4 3 Table 2 0% 1.25% 2.5% 5% Dry mass (total) 3.766 g 5.592 g 3.283 g 3.195 g Average mass per plant 0.157 g 0.233 g 0.131 g 0.128 g INTERPRETATION: From the results tables, graphs and ANOVA we found that adding Rhizobia did have an effect on the growth of the Lupin. Nodules: The Lupin plants that were infected with 1.25% Rhizobia solution concentration were found to have the most nodules (mean of 9) and 2.5% the least (mean of 2) as shown in table 1 of the results.

As shown by the graph, the trend tends to be that the addition of Rhizobia helped the number of nodules up until a concentration of 2.5% where it showed a great decrease. Our ANOVA also showed that Rhizobia concentration had a significant effect on the number of nodules as P was significantly less than 0.05 and F greater 1 (P = 0.0001, F = 56.29) as shown in the ANOVA results in appendix B. Dry mass: Like with the nodules the plants that were infected with 1.25% Rhizobia solution were found to have responded the best with the greatest dry mass (mean dry mass per plant of 0.233 g), but 5% was found to have done the most poorly with a mean dry mass per plant of 0.128 g. As shown by the graph there seems to be a lack of a definite trend but you can see that Rhizobia did substantially increase the dry mass, but only up to 2.5% where it decreased again to be worse off than with no Rhizobia (0%). ANOVA or chi-squared tests were inappropriate with this data as the individual masses of plants were not taken, as we took the total mass for each concentration and used this to find a mean individual mass. Leaves: The number of leaves did not change with different concentrations of Rhizobia solution so were not affected as the mean number of leaves for all concentrations was 4 leaves per plant. ACCURACY: There is plenty of room for improvement in this experiment as we did notice at one stage there was a problem with the sprinkling system and a small flood occurred in which cross-contamination could have affected the results.

Also when counting nodules it became difficult as there were so many clumped together, to improve this you could have 3 different people counting and comparing results, this way if they found they got different answers they could go back and recount together. More plants would also make the results more reliable as it would help eliminate errors. Also measuring the mass of each individual plant would help in analysing the data as ANOVA or chi-squared could be used to prove trends. CONCLUSION: In conclusion my hypothesis was partially correct in saying that Rhizobia would increase the growth of Lupins but incorrect in saying that greater concentrations would be more beneficial.

I found that Rhizobia only increased growth up to a point, and that it in fact decreased the growth at concentrations of 2.5% and 5%. This tells us that too much Rhizobia is actually non-beneficial to the growth of lupins even though some plants still get nodules. This could be due to errors like when the experiment flooded but if not then it shows that there is an amount of Rhizobia that is most beneficial to the growth of Lupins. This amount would be beneficial to farmers etc. so that optimal growth could be achieved.