276 K. KREEB 



Table i 



Maximum osmotic values, number of irrigations and yield of cabbage, potatoes and 



tomatoes. After Lobov, 195 1 



Number of 

 Maximum irrigations at 

 W 4 replications 

 8 5,3,5,5 



10 3, 2, 4, 3 



12 I, I, I, I 



value itself. Hydrature of plants seems to be a very important condition for 

 plant production especially in arid countries and dry years, if not the most 

 important one, besides other factors such as nutrition, temperature, light, 

 diseases, etc. 



Bauman (1955) in Canada worked with irrigation experiments using 

 alfalfa, wheat, barley, oats, sugar beet and potatoes. He found that time of 

 irrigation can be better determined by hydrature of plants than by soil 

 moisture measurement (Bouyoucos-block, tensio meter). Yield and average 

 osmotic value showed a close relationship (Table 2). Generally it can be 



Table 2 



Average osmotic value in atm {W) and yield of various crops (after Bauman, from 



Walter, 1956; see also Walter, 1961) 



