Agriculture Reference
In-Depth Information
80
70
60
50
40
30
20
10
0
0
4
8
12
16
20
24
28
Days from leaf length 10 mm
Figure 7.3
Curves representing the 'normal growth' of 'Crab C'
leaves and internodes during mid-summer 1957 on a common scale
of days from the time when the leaf reaches a length of 10 mm. Bars
across the curves indicate the growth stages of 25%,50% and 75%
of final size. From Hancock and Barlow (1960). Reproduced with
permission.
which would contain them. Their leaf areas can therefore be calculated as
length
×
breadth
×
a factor which, in different studies, has been found to
range from
). There is
therefore a considerable increase in total leaf area well after the cessation of
shoot growth and the production of new leaves. This was also illustrated by
Abbott (
.
to
.
(cf. references reviewed by Jackson,
) found that the rate of increase in
leaf length during the most rapid period of leaf expansion was positively linked
to temperature, but final length was not. Barritt
et al.
(
). Hancock and Barlow (
) and others found
little or no effect of position in the canopy on individual leaf area but Jackson
and Palmer (
) found increased area per shoot leaf with increasing imposed
shade. These apparently conflicting results may reflect the counteracting ef-
fects of reduction in the potential for leaf growth and increase in the leaf area
per unit weight. Leaf expansion is checked by water stress and by nutrient
