Agriculture Reference
In-Depth Information
Fig. 4.25.
(a) Relative growth rate of onion leaf length at 25°C as a function of leaf
water potential and of turgor pressure (redrawn from Fig. 9 of Millar
et al.
, 1971).
(b) Stomatal conductance of onion leaves at 25°C as a function of leaf water
potential and of turgor pressure (redrawn from Fig. 7 of above source).
any free water around them for up to 200 days (see Fig. 2.13e) (Stasovski and
Peterson, 1993). The bulbing habit may have evolved in the ancestors of
onions as a strategy to survive summer drought. As with other features, like
the low relative growth rate and the low-growing, upright leaves, the water
relations of the onion suggest evolution from ancestors with stress-tolerant
rather than competitive traits (Grime, 2002).
