Ecology project: The Effect of Varying Soil pH on the Rate of Tomato Plant Transpiration by: Taylor Jones, Amy Latimer, Lisa Merritt & Shauna Steele

To measure the effect of pH on transpiration, we will use 18 tomato plants as model organisms over a two week period. Each will be planted in the same soil, left in the same location, and watered the same amount at the same time. Three tomato plants will grow in unaltered potting soil, and Three tomato plants will grow in soil at different pH levels. The pH levels are as follows: three in strongly acidic conditions, three in moderately acidic conditions, three in strongly basic conditions, three in moderately basic conditions, three will be in neutral conditions, and three will be the control plants where the pH is not changed. In order to determine the rate of transpiration the plants will be checked twice a day and the weight and pH will be taken. Along with the weight and pH data observations about the plants condition will also be noted.

Objectives:

• To explore the process of transpiration
• To practice reading pH levels
• To explore the role of stomata in water loss
• To explore how minerals and water are transported from root to shoots
• To determine how transpiration (or lack thereof) can affect ecology short and/or long term

Hypothesis:

If plants are placed in a more basic soil, then the rate of transpiration will increase due to the the tendency of stomata to open up in less acidic environments.

Null hypothesis:

Soil pH has no effect on plant transpiration.

Prediction:

We predict that tomato plants in more basic soil will lose more water in more acidic soils.

Background Information & Significance:

When conditions are too hot, we get a little sweaty. Plants “sweat” as well. They lose water through their leaves, which is similar to how we lose water through our skin. The process of plants losing water is called transpiration. Transpiration is the loss of water via evaporation from the aerial parts (or parts completely exposed to air) of a plant. It takes place when two conditions are met: stomata (guard cells) are open and the air surrounding leaves is drier than the leaves inside. The stomata are located on the bottom of the leaves of plants which open and close in order for the plant to breathe in carbon dioxide from the surrounding air. Carbon dioxide is an essential molecule that is needed for plants for photosynthesis. When stomata open, water inside the plant is lost and evaporated into the air for us to breathe thus continuing the water cycle between air, plants and humans. Stomata regulate the process of transpiration in order to avoid the plant from losing too much water.

Transpiration is also important for plants because it helps with cooling them down in conditions that may be too hot for them. Plants need to cool down in order to avoid having their metabolic functions from slowing down which could lead to slow growth and flowering (or even stopping those processes altogether).  Transpiration also helps in moving water and changing the water pressure in plant cells which in turn help move minerals and nutrients up the plant from the roots to the leaves for photosynthesis. It’s pumping action helps move these needed materials against gravity with the help of (capillary) xylem water channels, the cohesion of water molecules, and the negative pressure that is caused by the transpiration process. This process is important especially when water is evaporating from the leaves of the plant. The significance of our experiment is that it provides proof of how certain growing practices can stunt plant growth or even pollute our soils that will hurt our plants or even our ecology on a large scale. This experiment will provide information on what conditions work best for plant transpiration which relates to how much the plants will grow and how we can sustain our soil pHs so that soils do not become acidic and pollute.

Progress:

On Monday the tomato plants were planted in approximately 300 grams of Black Gold potting soils. The control and neutral plants were put aside and will be allowed to grow without treatment. The initial pH of each plant was taken as well which most plants were at a pH of between ~5.5 and 6. Six of the plants were treated with Gypsum in order to make the pH more basic and six of the plants were treated with Limestone in order to lower the pH. After taking the pH's several time with a pH meter that was purchased no matter how much limestone and gysum was added the pH did not chage. Per advise from Gwen the team decided to wait until the next day and recheck the pH's in case a. it took time for the pH's to adjust or b. the pH meter was malfunctioning. After changing the pH meter that was obtained from the chemistry lab. On Wednesday the pH's were checked again and remained basic. At that time the formulas in order to change the pH were changed to vinegar in order to raise the pH and ammonia to lower the pH. On Thursday once in the morning and once in the afternoon the first reading of weight and pH were taken. (figure 1). Reading of pH and weight will be taken in the morning and the afternoon through May 25, 2016 except for Friday's and Weekends. The tomato plants will also be watered every couple days as needed with 3 sprays on the leaves and 3 sprays in the soil. All of the plants will have the same water at the same time, checked at the same time and access to the same amount of light as well We look forward to sharing our results with you!

Second Check of Ph and weight by: Lisa Merritt Date: 5/19/2016 am check @ 9:20 am

Pot #	Ph	Weight (g)	Observations
VA #1	5.93	355	Very good condition
VA#2	5.37	316	Was coming out of dirt, a little wilty. Added more soil
VA#3	5.68	341	Very good condition
MA#1	6.64	345	Wilty leaves @ the bottom
MA#2	6.65	358	Good condition
MA#3	6.93	392	Good condition
VB#1	7.68	311	Good condition
VB#2	7.59	321	Coming out of dirt. A little wilty pressed soil down
VB#3	7.42	368	Good condition
MB#1	7.30	441	Good condition
MB#2	7.36	436	Small relative to the others but good condition.
MB#3	7.77	354	One of the bigger plants. Very good condition
N#1	7.13	367	Tiny bit wilty @ top leaves.
N#2	7.03	355	Leaning and tiny wilt @the bottom
N#3	6.81	349	Leaning and leaves outside of the pot a bit wilty
C#1	6.42	451	One dead leaf @ the bottom
C#2	6.63	359	Leaning but good
C#3	6.11	319	Best one!

Figure 1: Data table of am pH and weight recordings on 5/19/2016

Image 2: Tomato plants on their first measuring day!

Image 1: Tomato plants on their planting day!