SOIL TYPE, SOIL WATER REGIME AND GROWTH 319 



Table 5 



Least significant differences (LSD) and standard errors (s.e.), determined from analyses 

 of variance of the experiment as a whole, for certain of the indices of performances 



presented in Table 4. 



(Jarvis, M. S., 1963). In order to obtain estimates of the amounts of effective 

 SMT experienced by the seedhngs, the areas beneath the dr)dng-out curves 

 in Fig. I were summed up to a SMT of 0-5 atm. It was assumed that any 

 short-term drying-out of the soil, which occurred above the SMT at which 

 growth ceased, would have no additional effects. Some evidence for this, 

 for other species, is provided by Jarvis, M. S. (1963). The total number of 

 'atmosphere-days', experienced by the plants in the different treatments, 

 up to 0-5 atm SMT, are given in Table 6. 



Table 6 



The amount of drying-out, represented as number and percentage atmosphere-days 

 (for explanation, see text) occurring in the various soils and treatments 



The second part of the table contains, for each treatment, the number 

 of 'atmosphere-days' expressed as a percentage of the total theoretical 

 number of 'atnaosphere-days' possible if the SMTs had remained at 

 0-5 atm throughout. 



The relation between RGR and 'percentage atmosphere-days' is pre- 

 sented graphically in Fig. 3 . 



