Yoshida - 1981 - Fundamentals of Rice Crop Science

PHOTOSYNTHESIS AND RESPIRATION 207
Table 5.4. Growth and maintenance respiration of a rice crop during later period
of ripening. a
Days after Dry wt Respiration b Growth
trans- increase (g CH 2 O/plant per day) Rg/R efficiency
planting (g/plant (%) (%)
per day) R Rg Rm
96–103 1.74 1.09 0.74 0.35 68 63
104–110 1.42 1.03 0.61 0.42 59 58
111–117 0.64 0.95 0.27 0.68 29 40
118–124 0.13 0.77 0.05 0.72 7 14
a Yamaguchi (1978). b
R (total dark respiration) = R g (growth respiration) + Rm
(maintenance respiration).
where Rg and Rm represent respiration for growth and maintenance, respectively.
When the growth efficiency linked with Rg is 70% and this efficiency remains
unchanged until maturity, it is possible to estimate Rg and Rm at different stages of
panicle growth (Table 5.4). When active grain filling slows down toward maturity,
Rg decreases and Rm increases. As a consequence, the proportion of Rg to total
respiration and growth efficiency decreases.
5.2.3. Growth and maintenance respiration — physiological approach
The closer relationship of dark respiration of whole plants to photosynthesis than
to dry weight led McCree (1970) to propose a two-part model:
R = k 1 P g + cW , (5.17)
where R = 24 hours total dark respiration
for the whole plant,
W = plant dry weight,
P g = gross photosynthesis rate,
k 1 = growth respiration coefficient, and
c = maintenance respiration coefficient.
Conceptually, the k l P g term corresponds to respiratory activity associated with
growth and storage and the cW term to the cost of the maintenance.
For white clover (Trifolium repens L), the following equation was obtained:
R = 0.25 P + 0.015 W , (5.18)
where R = 24 hours total of dark respiration,
P = 12 hours total of gross photosynthesis, and
W = CO 2 equivalent of the dry weight.
Growth respiration appears to be the same for different species and is not affected
by temperature (McCree 1974). On the other hand, maintenance respiration varies
with plant species and is a temperature-dependent process ( Q 10 is about 2.2).