PROBLEMS AND RESULTS IN ISRAEL 397 
developmental stages where the bulbs keep their viability during 
longer periods of storage. 
Another problem arose with Atriplex halimus, an excellent 
pasture plant. After extensive research it was found that this 
plant can be propagated by seeds after proper pretreatment, but 
cuttings can be used as well. The problem here was to see if 
there is any periodicity in the rooting response of cuttings. In this 
field, too, the lesson learned was that only by physiological re- 
search can the proper methods for vegetative propagation be 
found. This can be done only through the cooperation of a lab- 
oratory of plant physiology. 
Selection of Plants 
Here, naturally, the main problem is the finding of suitable 
pasture and other economically important species for reseeding 
purposes. The greatest part of our efforts was concentrated on 
local species and arid ecotypes, which are able to withstand 
prolonged periods of drought. 
Selection of Pasture Plants (12, 13) 
In the selection of pasture plants for desert agriculture consider- 
ations other than those for moister climates have to be taken into 
account: 
(a) Grasses utilize soil moisture up to a depth of 120-150 cm. 
In some of the main wadis in the Negev, moisture penetrates 300 
to 400 cm. This deep lying moisture may be utilized if deep- 
rooting pasture shrubs are found. Such a mixed grass-shrub 
pasture would afford a more rational utilization of available soil 
moisture. 
(4) In the desert the growing seasons for most grasses coincide 
with each other and last throughout late winter and spring. This 
limited grazing season may be extended by reseeding with ever- 
green shrubs like Atriplex halimus. 
(c) Legumes in general are essential for nitrogen-deficient desert 
pastures and for providing high-protein pasture. 
Consequently, great advantage may be gained from a mixed 
pasture consisting of grasses (perennials and annuals), deep- 
