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Environmental and Genetic Variables as a factor in Phenotype

Crystal Reed and Eri Koike

In this lab, we selected four characteristics of the plants (height until the first leaf, height of tallest part of plant, amount of buds on the plant and the stem color and thickness of the stem) in order to determine what factors were influenced by genes, environmental conditions and random genetic variations.

In our first of a series of observations, we counted the amount of buds on the tallest part of the plant. We initially predicted that the environmental conditions (in our case fertilizier) would affect the number of buds.

Wild Type LL HF: 21 buds

Wild Type LL LF: 10 buds

Petite LL HF: 15 buds

Petite LL LF: 10 buds

Through these two observations, we can find that the environmental conditions, which was in our case high vs. low fertilizer, drastically influences the amount of buds on the tallest part of a plant.

Wild Type HL HF: 27 buds

Wild Type HL LF: 9 buds

Petite HL HF: 22 buds

Petite HL LF: 8 buds

Through our additional observations, we found that fertilizer has more of an impact than light and the type of seed. We found that although the standard did tend to have a slightly larger number of buds, there were other instances where the standard had less or the same as the petite. Therefore, we found that the environmental factors (specifically the fertilizer) had more of an impact on the bud phenotype than the genetic factors.

 

In our next set of observations, we decided to look at the height until the first leaf and the height of the tallest plant. We initially predicted that the type of seed (wild vs. petite) and the environment (High/low fertilizer) would influence the height of the plants.

Changes in High/Low Fertilizer in Low Light:

Wild Type LL HF: (Height until first leaf) 2 in.; (Height of tallest plant) 6.75 in.

Wild Type LL LF: 3.125 in.; 6 in.

Petite Type LL HF: 1.75 in.; 5 in.

Petite Type LL LF: .9375 (15/16) in.; 3 in.

Changes in High/Low Fertilizer in High Light:

Wild Type HL HF: .75 in.; 9.5 in.

Wild Type HL LF: .125 in.; 1.75 in.

Petite Type HL HF: .0625 in.; .1825 in.

Petite Type HL LF: .125 in.; 1.75 in.

In this observation, we found that different environmental conditions work well for the growth of different types of plants. In the wild type plants, the best condition for growth was in high light and high fertilizer. Although we predicted that would be the result for both types of seeds, we found in the petite type that in fact low light and high fertilizer helps it to grow the tallest. For the height to first leaf, we found that it is greatly affected by light but also to a lesser degree by genes.

Therefore, we can state that each plant has its own optimal conditions that it can thrive in.

 

Our next set of observations has to do with the stem color and thickness of the stems. We initially predicted that the seed type would influence the color and thickness as well as the environmental factors.

Wild Type LL HF: Light green; 3/32 in. thick

Wild Type LL LF: Light purple; 1/32 in. thick

Petite Type LL HF: Dark purple; 2/32 in. thick

Petite Type LL LF: Medium Purple; 1/32 in. thick

Wild Type HL HF: Medium Green; 3/32 in. thick

Wild Type HL LF: Dark Purple; 2/32 in.

Petite Type HL HF: Dark Green; 4/32 in.

Petite Type HL LF: Dark Purple; 1/32 in.

Through this set of observations, we found that the petite type plants tended to be darker in stem shade except when high light was applied to the wild type. So therefore, we can state that the genetics had to do more with stem color than the environmental conditions and the stem thickness was heavily influenced by the environmental factors (since the stem was thickest in the high fertilizer)

And finally, our last set of observations has to do with the number of trichomes on the petiola of the first leaf.

Wild Type LL HF: 3 petiolar trichomes

Wild Type LL LF: 6 petiolar trichomes

Petite Type LL HF: 0 petiolar trichomes

Petite Type LL LF: 0 petiolar trichomes

Wild Type HL HF: 4-6 petiolar trichomes

Wild Type HL LF: 1 petiolar trichomes

Petite Type HL HF: 0 petiolar trichomes

Petite Type HL LF: 17 petiolar trichomes

Through these set of observations, we can conclude that generally, the number of petiolar trichomes has to do with seed type (*There is one outlier to this case in the Petite Type HL LF where there were 17 trichomes.*) and that environmental factors don't have any influence on the number of trichomes.

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