282 



K. KREEB 



ia 22 



MAY 1958 



JUNE 



Fig. 7. Yearly curves of hydrature (refractometer values) in alfalfa plots with different 



irrigations. After Kreeb, 1961. 



are able to endure drought to a certain extent we find a less rapid diminution 

 of the production. This can be seen from the following table (3). 



Much affected by lack of water are horse beans, turnips, potatoes and 

 lettuce. Their yield decreases by approximately 30-50%, if the average 



100 



80 



V 



■> 



E 60 



AO 



V 



M 20 



>- 



12 13 IA 15 16 17 18 



Average refractometer value in % 



Fig. 8. Curve of decreasing yield with increasing average refractometer value. After 



Kreeb, 1961. 



