I
126
w. Schulze and E.-D. Schulze
400
(J)
100
Vl
Q)
+0 400
L
""0
>...c 300
0
.D
L
200
0
u
100
0
Arabidopsis thaliana
high light
Wild type
high N
6
18 6
low light
Wild type
high N
6
18
Dslarch
~soluble sugars
18
D
7%ADPGPPase-mulanl
high N
6
18
time [h]
B
E
PGM-mulant
high N
6
18 6
55%ADPGPPase-mutant
PGM-mutant
high N
high N
6
18
6
18
time [h]
c
low N
18
F
Fig. 6.2A-F. Contents of starch and soluble sugars in the morning (6h) and evening
(18 h) to show the turnover at high (A-C) and low light (D-F) as well as at high and
low N supply
6.4 Significance of Leaf Starch for Growth
6.4.1 Effects of Leaf Starch on Biomass Formation
The starting point of our experiments was the observation of Caspar et al.
(1986) that starchless mutants grew as rapidly as wild type in continuous
light, but died if the dark period exceeded 12 to 14h. Therefore, the
plants in this experiment were grown in a 14-h light/31O-h dark regime. We
investigated whether growth was quantitatively related to the amount of
starch moving through the starch pool, and to what extent the significance of
leaf starch for growth was influenced by light and nitrogen supply.
At high light and N supply, there was a positive linear, and near
stoichiometric, correlation between the daily amount of carbon passing
through the leaf starch pool of the different mutants and the daily increment