Agriculture Reference
In-Depth Information
Nonetheless, despite all the variability in photosynthetic rate through the day
and across the growing season, there is in fact a surprisingly good correlation
between the highest photosynthetic rate on a given day and the actual carbon gain
on that day (Zots and Winter 1996; Rosati and DeJong 2003; Koyama and
Kikuzawa 2009). Zots and Winter (1996) reported a linear relationship between
daily photosynthetic gains of single leaves (
A
day
) and their maximum photosynthetic
rate on a given day,
A
(Fig.
2.9
):
max
ˆ
+
(2.3)
A kA c
=
·
day
max
A
is in fact the true photo-
synthetic capacity (
A
max
) and if
c
is zero, then the proportionality constant
k
equals
the leaf mean labor time. This relationship within days, however, does not assure
that the highest photosynthetic rate achieved by a species under ideal conditions,
its true photosynthetic capacity,
A
max
, will in turn correlate consistently with the
maximum photosynthetic rate (
where
k
and
c
are constants. Note that if the value of
max
A
) achieved on a given day. The value of the mean
labor time concept as a complement to the concept of photosynthetic capacity is
that it emphasizes the necessity of identifying the true maximum photosynthetic
rate for a species as opposed to a transient value associated with conditions over a
given time interval.
max
ˆ
A
−
relationship. The daily photosynthetic gain by a leaf (
A
day
, mmol m
−2
12 h
−1
) on a given day plotted against the maximum net photosynthetic rate of the leaf on that day
(
Fig. 2.9
The
day
max
A
here is not the true value of photosynthetic capacity (
A
max
) for the species,
but only the highest photosynthetic rate on each day of observation. (From Zots and Winter 1996)
A
). Note that
max
max
