344 



B. ORCHARD 



1-5 



CM 

 E lO 



a> 



OS 



B. 

 .Watered 



Expl. I. 1958 



Tc. 



Started 



I 1 . L_ 



Expt. 2. 1959 



B. 

 Watered 



C Started 



I . ' 1 — ,_ 



05 



Expt. 3. I960 



025 



B.Walered 

 i 



Julv 



Aug 



Sept 



July I Aug I Sept Oct I Nov I Dec 



Fig. I. Total dry weight of plants. Circles -treatment A, squares -treatment B (BH) 

 (open squares treatment BL), triangles -treatment C. A-frequent watering, B -inter- 

 mittent drought, C-continuous drought, as detailed in Table i. Vertical lines, least 



significant differences (P<o-05). 



RESULTS 



The results of Exp. 3 are given as means of the two nitrogen levels. The 

 nitrogen residues from the previous experiment had no important inter- 

 action with water regime, although they increased the dry weight and 

 leaf area of the plants significantly they had no effect on the relative growth 

 rates in the experimental period. 



Effects of treatments have been expressed as percent of the value for the 

 A plots. 



Dry Matter Production 



Dry matter production was significantly affected by drought in only one 

 of the three experiments; in 1959, treatment B (Fig. i) decreased the yield 

 by 38% after 23 days without watering. The corresponding treatment C 

 caused a similar decrease but the relative response was smaller (10%). The 

 increase in dry weight during the second moist period of treatment B 

 was only sHghtly greater than with treatment A, and the difference in dry 

 matter yield between A and B persisted for over 9 weeks. 



The 1958 B plots gave no sign of a drought effect but the decreased dry 

 weight of the C plants at the final harvest was almost significant. This was 



