|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; email@example.com|
Photomorphogenesis: Effect of Light on Seedling Growth & Development
Objectives: The purpose of this lab experience is to provide an opportunity to:
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: )|
|seedling weight (g)|
|shoot length (mm)|
|root length (mm)|
|stem / coleoptile dia (mm)|
|cotyledon / leaf width (mm)|
|describe shoot tip|
01/07/2009 � Copyright by SG