10:	Development of chlorophyll in germinating barley (Hordeum vulgare) seeds under different light regimes.

Authors:	Guralnick, Lonnie, J.(A)
Affiliations:	(A): Dept of Biology, Western Oregon University
Presenter:	Guralnick, Lonnie J., guralnl@wou.edu

Investigations of phytochrome dependent processes is sometimes limited to studying germination rates of lettuce seeds under red and far-red light regimes. In our plant physiology laboratory, students have three weeks to investigate a topic. One of the areas that students have investigated is the production of chlorphyll. In germinating seeds chlorophyll development is a light dependent response mediated through phytochrome. Students identify which light regime they will use and examine the time dependent changes of chlorophyll concentration. Students germinate barley seeds (50-100) in a flat with vermiculite under dark grown conditions. When the seedlings have reached 5-10 cm in length, the flats are transferred to different light regimes. Students have utilized red, far-red, white, and blue lights. The last flat remains in the dark. Samples were collected prior to illumination and at 1, 2, 4, 8, and 24 hours. Approximately 1 g of tissue was collected and frozen for chlorophyll analysis. The samples were ground with 10 ml of 80% acetone for 1 minute and then centrifuged at 2500 rpms (4oC) for 5 minutes. The absorbance for each was read at 645 and 663 nm and chlorophyll concentration was calculated using standard equations. The results indicated that red light was the best regime for chlorophyll development with blue light showing the next highest chlorophyll concentration. Far-red light showed some chlorophyll development while the dark grown seedlings showed very little chlorophyll development. Students then write up and discuss their results in relation to phytochrome mediated responses. Other questions arise to why the far-red light regime showed some chlorophyll development. If time permits other aspects of chlorophyll development can be studied.