Germination in three R/FR light environments (El Verde)



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Experiments were conducted in the Tabonuco forest at Luquillo Experimental Forest to determine the germination success of a number of species in different light environments. Species tested included: Byrsonima spicata, Calophyllum brasiliense, Carapa sp., Choven venosa, Guarea guidonia, Manilkara bidentata, Ochroma pyramidale and an unidentified species known locally as Jobo. Seeds were collected as they fell and placed on moist towling in horticulture trays at four sites. Seeds were kept moist and germination was recorded daily for 81 days and three times weekly for an additional 75 days. Light environments included a site exposed to full sun (FS) and sites with 55%, 75% and 80% cover. Instantaneous light measurements were made with a Licor 1800 spectroradiometer to determine the Red (660 nm) to Far-red (730 nm) ratio (R/FR) (Lee, 1987). Analysis of light data indicated that the four sites chosen provided three significantly different R/FR ratio environments, and that germination of some species was affected by the light environment (Smith, H. & Whitelam, G.C. 1990). Three species failed to germinate in any of the four light environments.

Table 1. Red/Far-red ratio & Percent Germination of five species in four sites.

site  %cover R/FR Calophyllum Manilkara Ochroma Carapa Jobo
1 55 0.53 21% 46% 10% 40% 3%
2 80 0.20 16% 48% 14% 16% 8%
3 FS 1.2 4% 16% 12% 0 0
4 75 0.20 3% 32% 16% 16% 3%

Date Range: 
1995-02-28 00:00:00 to 1995-07-22 00:00:00

Publication Date: 

2011-04-05 00:00:00



Additional Project roles: 

Name: Eda Melendez-Colom Role: Data Manager
Name: Elizabeth Hammond Role: Associated Researcher
Name: Bruce Haines (In Memorium) Role: Associated Researcher


Four sites were selected to represent a range of vegetation cover from open light to shaded conditions. Frames were placed in the sites to support horticulture trays 18 inches above the forest floor. Seeds were collected as they fell from individual trees and placed in the horticultural trays which were lined with absorbent material. The trays were covered with screen to prevent predation, and the seeds were kept moist. Germination was recorded daily for 81 days and three times weekly thereafter for 75 days. Light measurements were made with a Li-1800 spectroradiometer (LI-COR, Inc. Lincoln, Nebraska, USA) placed on the surface of the frame supporting the horticulture trays containing the seeds. The Licors internal microprocessor calculated the Red to Far-red ratio.


<p>Li-1800 spectroradiometer (LI-COR, Inc. Lincoln, Nebraska, USA)</p>

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