I would like to obtain your suggestions for the nutrient application in a greenhouse experiment with Cinchona (Rubiaceae), subjected to mycorrhizae, N, P, N+P and control treatments.
There is plenty of information on nutrient application for mycorrhizae greenhouse experiments but each case seems to be very specific to soil/medium conditions and species, so I am not entirely sure what would be the best for our experiment. I am planning to apply a Hoaglands solution (with nitrate and some ammonium, 200 ppm N, 235 ppm K and 31 ppm P). Plants are very small (1-1.5 cm), in about 1.3 kg of substrate (3 parts sand and 1 part soil) in bags with a volume of about 1000 cm3. 1. Should the Hoaglands solution be applied at full, ½ or ¼ strength and how many ml at a time per week? 2. We have a ratio of NO3/NH4 of 12. Should we just go for nitrate as the N source? 3. What would be a reasonable minimum concentration of N and P to apply to the no-N, no-P and control plants so that they will survive the 2 year experiment? 4. Since we need an N-free Ca source, we will use CaCl2 instead of Ca(NO3)2 but this way will end up with 280 ppm Cl in the full strength solution. Is this a problem? There is not much sodium in the substrate. Would somebody be able to help me with this? Thanks a lot! Heinke Jäger Ecology and Evolutionary Biology Brown University
