Effects of acid rain in germination and growth of mustard seeds

Authors Avatar

Verónica Rosinha 5IB

Effects of acid rain in germination and growth of mustard seeds

Research question

How is the germination and growth of mustard seeds affected by exposure to acid rain?


By carrying this investigation I expect that acid rain will decrease the germination and growth rate of mustard seeds. The lower the pH, the more the germination and growth will be decreased.

General background

Acid rain is caused by the presence of SO2 and NO2 in the air, which dissolve in the water forming sulphuric acid and nitric acid. It usually has a pH value of about 5; however this value can be lower. Due to the presence of acids, the acid rain causes decreased growth in plants, whose usual effects are usually poor root growth and poor leaf development. Poor root growth can result from exposure to soil of low pH, as the shape of proteins – including enzymes – are changed. Poor leaf development might result from deterioration of the cuticle by the acidic rain.

Mustard is a quick-to-mature, easy-to-grow vegetable for greens or salads. For a higher rate of growth of mustard seeds, soils with a neutral pH are required, although an alkaline pH can be tolerated “Soils with a pH neutral are desired for this crop. Nevertheless, an alkaline and slightly saline soils are tolerated” (quoted from ).  


Variables to be kept constant:           Temperature (room temperature)

                                            Species of seed

                                        Batch of seeds

                                        Initial size of seed

                                        Volume of solution

                                        Spacing of seeds

                                        Oxygen availability

Independent variable                        pH of the sulphuric acid solution (will be used as

                                        the acid rain solution)

Dependent variables                        length of root

                                        Number of leaves

                                        Colour of leaves

                                        Length of stem



  • 5 x Petri dish with lid
  • marker for labeling
  • 5 x circles of filter paper
  • 5cm³ of each of the following sulphuric acid solutions: pH 3, pH 4, pH 5, pH 6 and pH 7
  • 5 x 5cm³ syringe
  • 50 x mustard seeds (of the same size)
  • Forceps
  • Ruler measuring in mm
  • Sheet of graph paper
  • Scissors
  • pH meter
Join now!


  1. I took five Petri dishes with lids and then labeled them pH 3, pH 4, pH 5, pH 6 and pH 7.
  2. I placed a disc of filter paper in the base of each dish (they had to be slightly cut as they were too big for the Petri dish)
  3. Then, 5cm³ of sulphuric acid pH 3 was poured into the dish labeled pH 3. it was poured in a way for it to be evenly distributed.
  4. I repeated the procedure in 3. for the other solutions and respective dishes
  5. 50 similar sized seeds were ...

This is a preview of the whole essay