Script:
Intro: Soil salinization is an increasing environmental issue that can reduce agricultural productivity. As sodium
chloride (NaCl) accumulates in soil, plants become less able to absorb water, limiting growth and crop yield.
Salinity also affects transpiration, an essential process that supports water movement and nutrient transport
throughout the plant.
This investigation explores how increasing NaCl concentrations influence the rate of transpiration in Phaseolus
vulgaris (common bean plants) over a 72-hour period, using cumulative mass loss as an indicator of water loss.
Methodology:
1. Plant Growth Period
Twelve identical pots were prepared with 100 g of soil and planted with one Phaseolus vulgaris (kidney bean)
seed each. The plants were grown for 2–3 weeks and watered every 72 hours with 75 mL of distilled water.
During this period, baseline mass measurements were recorded at 0, 24, 48, and 72 hours using a digital scale.
2. Experimental Period
The plants were divided into four treatment groups, with three trials per group. Each group received 75 mL of
NaCl solution at concentrations of 0.0% (control), 0.375%, 0.75%, or 1.5%. Pot mass was measured again at 0,
24, 48, and 72 hours after treatment. Cumulative mass loss was used to estimate the rate of transpiration.
Conclusion & Evaluation:
The results supported the hypothesis that increasing NaCl concentration reduces the rate of transpiration in
Phaseolus vulgaris. Over the 72-hour period, average mass loss decreased from 0.09 g in the control group to
0.04 g at 1.5% NaCl, showing an overall negative relationship between salinity and water loss. Compared with
baseline conditions, all treatment groups also demonstrated lower transpiration rates after NaCl exposure.
These results align with biological theory, as higher salinity creates osmotic stress, reducing water uptake by the
roots and triggering partial stomatal closure, which lowers transpiration. Qualitative observations supported this
overall trend.