Spring.wmf (18300 bytes) Plant Physiology (Biology 327)  - Dr. Stephen G. Saupe;  College of St. Benedict/ St. John's University;  Biology Department; Collegeville, MN  56321; (320) 363 - 2782; (320) 363 - 3202, fax;    ssaupe@csbsju.edu

Photomorphogenesis:  Effect of Light on Seedling Growth & Development

:  The purpose of this lab experience is to provide an opportunity to:

  1. observe the effect of light and dark on plant growth

    Light has a major impact on plant growth and development (photomorphogenesis).  For example, plants grown in the dark or under light exhibit a series of characteristics termed etiolation.  Etiolated plants typically are yellow, have elongated internodes (stems) with unfolded leaves and thin stems.  These features can be considered ways of conserving energy until conditions improve (e.g., light).  In addition, dark-grown eudicot seedlings have an apical hook and grass seedlings have an unopened coleoptile; these features help to protect the meristematic regions. In this exercise we will observe the effect of light on maize, sunflower and pea. 

    In each of three pots containing pre-moistened Jiffy Mix plant three seeds each of corn, bean and sunflower.  Moisten the medium, label with your name and date, cover with plastic wrap and then put one pot in the dark, one under high irradiance, and the other under low irradiance light.  After several days, sketch or photograph the seedlings and complete Table 1.  

Table 1.  Comparison of dark and light grown seedlings of maize, sunflower, and pea.  Seedlings were grown in four-inch pots in Jiffy-Mix for ______ days at room temperature.
  Dark Light (fluence:                  ) Light (fluence:                  )
Maize Sunflower Pea Maize Sunflower Pea Maize Sunflower Pea
seedling weight (g)                  
shoot length (mm)                  
root length (mm)                  
stem / coleoptile dia (mm)                  
cotyledon / leaf width (mm)                  
describe shoot tip                  
other observations





  1. Turn in on a separate sheet of paper a completed version of Table 1.
  2. Write a summary of your observations comparing the response of the three species to the three different treatments.
| Top | SGS Home | CSB/SJU Home | Biology Dept | Biol 327 Home | Disclaimer |

Last updated:  01/07/2009     � Copyright  by SG Saupe