Plant Physiology Below is a table summarizing the results of a study comparing g
ID: 212815 • Letter: P
Question
Plant Physiology
Below is a table summarizing the results of a study comparing growth and various physiological parameters in alder seedlings either inoculated with Frankia to seedlings grown in the same soil with added Nitrate fertilizer but without the N-fixing symbiont. Summarize what these results show about the growth of young alders depending on whether their main source of nitrogen is a symbiotic bacterium or nitrate already in the soil. Your answer should do more than just say that one treatment grew better than the other treatment. There is no one correct answer here, but what I’m looking for is whether you can use results from one set of measurements to explain results of other sets of measurements. For example (this is an example, not the only possibility to consider) do the results of the transpiration measurements help explain the CO2 uptake results?
Table 1. Mean plant growth and physiology in Alder seedlings grown in soil with either added symbiotic N-fixing Frankia or with added NO3-. Means of 10 plants per treatment +/- 1 std error.
Total plant biomass
-kg-
Net CO2 uptake
-mmole CO2/m2/sec-
Transpiration Rate
-mmoleH2O/m2/sec--
Leaf chlorophyll concentration
-mg/m2-
Concentration of N
In plant tissue
-mg/g-
Shoot Respiration
Rate
-mmole CO2/m2/sec-
Alder with Frankia
1.2 +/-0.2
5.1 +/- 0.1
10.3 +/- 0.4
450 +/- 11.0
40.0 +/- 0.5
1.1 +/- 0.05
Alder with
added NO3-
1.9 +/-0.3
6.3 +/- 0.05
9.8 +/- 0.5
800 +/- 15.0
45.0 +/- 0.5
0.5 +/- 0.03
Total plant biomass
-kg-
Net CO2 uptake
-mmole CO2/m2/sec-
Transpiration Rate
-mmoleH2O/m2/sec--
Leaf chlorophyll concentration
-mg/m2-
Concentration of N
In plant tissue
-mg/g-
Shoot Respiration
Rate
-mmole CO2/m2/sec-
Alder with Frankia
1.2 +/-0.2
5.1 +/- 0.1
10.3 +/- 0.4
450 +/- 11.0
40.0 +/- 0.5
1.1 +/- 0.05
Alder with
added NO3-
1.9 +/-0.3
6.3 +/- 0.05
9.8 +/- 0.5
800 +/- 15.0
45.0 +/- 0.5
0.5 +/- 0.03
Explanation / Answer
Alder plants grown with nitrogen fares better than alder plants grown with frankia in all respects.
It yields more plant biomass due to the higher growth of plants under nitrogen supply
The net CO2 uptake is higher in the plants grown with nitrogen and thsi may be due to higher photosynthesis in these plants.
The transpiration rate ins lower in the plants growing with nitrogen may be due to the lesser stomatal opening which helps in lower transpiration rates.
The higher photosysnthesis rates in plants grown with nitrogen leads to more cholorophyll concentration in the leaves.
The shoot respiration rate is lower in the plants with nitrogen leads to higher biomass production.
All the plant physiologic properties leads to better growth of plants grown with nitrogen.