Jagannathan,

The phytotron studies were terminated at a young age before reproduction started, so of course they have zero yield.  In addition, if you graph the total top weight (or other components), you will see that both soybean and maize did respond to rising CO2.  Please check things out better before you list problems on the DSSAT listserve.

As for potato, I have not done a literature review, but I would be quite surprised to see zero response to CO2 for that C-3 crop.  Jon Lizaso is checking this situation out for the potato model in DSSAT and we will get back to everyone.

Sincerely,
Ken Boote

________________________________________
From: DSSAT - Crop Models and Applications [[log in to unmask]] On Behalf Of jagan TNAU [[log in to unmask]]
Sent: Thursday, May 05, 2011 10:16 PM
To: [log in to unmask]
Subject: CO2 simulation problem in Potato

Dear all,

I am really thankfull for Kenneth Boote for his suggestion on CO2 simulation
in CO2. But with lot of experiments I am unable to get diiference for
increased CO2 level in potato using file type experiment for potato. I found
there are three experiments involving CO2 GAGR0201.MZX and GAGR0201.SBX from
Envitron study using Maize and soybean and AZMC8901.COX form FACE experiment
using Cotton.

I have run both envitron experiment but I found only 0 Kg in the results
While the FACE experiment in cotton showed the difference in yield. I don't
know why this happening in in envitron study. In fact in Soybean and Cotton
experiments the CO2 simulation option is deleted from the experiment file.

I tried using seasonal file and I found there exists some difference for
levels of CO2. In Rice and Maize the enrichment of CO2 brings good
improvement in yield upto certain levels of CO2 but the difference is only
minor in potato and trend for future is only decreasing for all the level of
CO2 starting from 430ppm (+50/decade) to 830ppm.

My review of research work showed some scientist obtained no yield increase
for increased level of CO2 in potato. Is that I have to conclude that CO2
enrichment had no influence on potato.

I resquest the suggestions of DSSAT users in this regard.

--
With regards

Dr.R.Jagannathan
Professor of Agronomy,
Department of Agronomy
Tamil Nadu Agricultural University,
Coimbatore - 641 003 India

PHONE:  Mob: +91 94438 89891

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