92 



p. E. WEATHERLEY 



2-5 



UJ 



< 



t- 



0. 



D 



cc 



UJ 



< 



5 



li- 1 c 



0l-5 



2-0 



< 



1-0 



0-5 



O 10 20 30 AC 50 60 

 TIME (MINUTES) 



20 



^ 1-6 



a 



3 



a 1-2 



UJ 



I 



ii-o-e 

 



< 



O-O-A 



JI»».tfO' 



Tat 6-26 



6 10 14 



WATER DEFICIT 



16 



30 



z 



UJ 

 ^201- 



8 



a 



UJ 



10 



15 20 25 30 35 

 TIME( MINUTES) 



40 45 50 



10 20 30 AO 50 60 

 TIME (MINUTES) 



70 



Fig. 4. A : Die-away curve of rate of continued uptake by a leaf on stopping transpira- 

 tion. Inset: the same data from 10 minutes onwards plotted on a different scale. The 

 form of the whole curve is an almost instantaneous drop followed by a slower die-away. 

 Cf. Figs. iD and 2B {Ribes sanguineum). B: Logarithmic plot of the die-away curve. 

 For pqr, see text. Cf Figs. lE and 2C {Pelargonium zonale). C: Relationship between 

 rate of water uptake and leaf water deficit during the progressive saturation of a leaf 

 on stopping transpiration. Data from a single leaf following two rates of transpiration. 

 Cf. Figs. iC and 2D {Ribes sanguineum). D : Curves showing the progressive saturation 

 of the inner and outer spaces of a leaf. The water contents were obtained by summating 

 the rate data given in Fig. 4B. For further explanation see text. The rate of water 

 uptake in all cases is expressed in arbitrary units based on the rate of travel of the 

 water meniscus in the potometer tube. (T= transpiration rate.) 



