MWCC Biology I-109
Professor: Dr. Atryzek
The response of Phaseolus vulgaris to increased levels of saline solution at germination and seedling growth was investigated. Seeds were germinated in paper towels placed in plastic Ziploc bags with varying concentrations of saline solution and incubated at 25°C. At the end of 14 days the seeds were removed and observations and measurement of any root and shoot growth were taken. There was insignificant or no germination in most of the sampled beans with an unusually high germination of the 1.0% saline group.
This study was to observe the effects of increased saline (NaCl) concentrations in relation to the germination of P. vulgaris seeds. The hypothesis is that with each increase in saline concentration there will be less root development. Why do higher concentrations of saline inhibit germination? What does the higher concentrations of saline do to the P. vulgaris seed? Are seeds tolerant to higher concentrations of saline?
“All soil contains salts, many of which are essential nutrients for plants. Salinity occurs when soluble salts (usually NaCl) are elevated in soil and water. Every continent is affected by salinized soil and water; approximately 7% of the world’s land area.” (Nerissa Hannink, 2005).
“But why should we care about how a plant copes with excess salt? Once inside the cell, salt can cause ionic stresses, largely as Na+ (and Cl-) inhibit metabolic processes including protein synthesis. Na+ can rise to toxic levels in older leaves causing them to die.” (Dr. R. Munns, 2001)
Since there is salt found in the soil naturally, and higher levels will cause ionic stress; what levels are considered to inhibit growth? “Salt tolerance is defined when plants show little growth reduction at concentrations of 300mM NaCl or more. (M. Tester and R. Davenport, 2003)
“Seedlings are the most vulnerable stage in the life cycle of plants and germination determines when and where seedling growth begins.” (A. Lianes, H. Reinoso, V. Luna, 2005). “There are contradictory reports in the literature as to the relative sensitivity of germination and seedling growth to salt stresses. According to Munns, salt stress decreases growth in most plants, including halophytes.” (R. Munns, 2002) “Salinity can affect germination of seeds either by creating osmotic potential which prevent water uptake, or by toxic effects of ions on embryo viability.” (A. Lianes, H. Reinoso, V. Luna, 2005). “Shoot growth was reduced by salinity due to the inhibitory effect of salt on cell division and enlargement in the growing point. (K. Mccue and A. Hanson, 1990)
In results from M. Kaymakanova (2009) it was that show that; “Specific ionic effects were evident as different responses were obtained with different salt treatments at iso-molar concentrations. It showed that water uptake is reduced in salt-treated seeds, compared with those treated with distilled water.
80 Red Kidney BeansGloves
8 Small plastic Ziploc bagsRoom temperature incubator
1 Large plastic Ziploc bagMetric ruler
9 LabelsMarking Pen
8 Paper towels
7 Plastic transfer pipettes
Saline solution (NaCl) 0%, 0.025%, 0.05%, 0.1%, 0.5%, 2.5%, 5.0%
1. Wash hands with soap and water.
2. Put on gloves before you handle the beans.
3. Prepare one label for each of the 8 sets of seeds: DH2O (0% NaCl), 5% NaCl, 2.5% NaCl, 1.0% NaCl, 0.5% NaCl, 0.1% NaCl, 0.05% NaCl, 0.025%. 4. Place one label for each of the 8 seed sets in the upper corner of the plastic bag. 5. Take 8 paper towels (one for each seed set).
6. Place 10 seeds each into the fold of each paper towel. 7. Roll the paper towel around the beans, fold in half and put into...