Pot experiments were conducted during 2002 and 2003 seasons to study the
effect of irrigation water with three salinity levels, 4000 6000 and 8000 ppm with two
levels of Sodium Adsorption Ratios (SAR) 6 & 12 and foliar sprays of phosphorus as
H3P04 ; at the highest level of salinity and SAR 6& 12 on plant growth ,some
physiological aspects, changes of chemical constituents of jojoba seedlings, as well
as the effect on anatomical features of jojoba leaf,
Also, the study aimed to determine the physiological mechanism of
phosphorus as foliar application in reducing salt stress effects on jojoba seedlings .
The obtained results could be summarized as follows:
Increasing salt concentration ¡n irrigation water caused marked decrease ¡n
growth parameters of both seasons, namely, stem length, number of leaves I plant,
leaf area and assimilation area as w&l as dry weight of ‘eaves ,fresh and dry weight of
stem and roots of jojoba seedlings. In contrast, fresh weight of leaves significantly
increased, ¡t mainly due to an increase in tissue water content reflected in the
¡ncreasing fresh weight: dry weight ratio which can take as a good indicator of tissue
succulence within plant.
The result also indicated that treating the seedlings which growing under 8000
ppm and SAR 6 &12 by phosphorus foliar sprays apparently tended to minimize the
adverse effect of salinity.
No visual salt damage in vegetative growth during the two seasons, where the
suniival percentage was 100% in all treated plants were observed. It seems that
jojoba seedlings able to tolerate the salt concentrations of irrigation water up to 8000
ppm &though; vegetative growth was significantly reduced under that salinity
treatment.
Regarding the effect of salinity levels in irrigation water on physiological and
chemical aspects, the obtained data showed that, leaf osmotic potential (LOP) ,Ieaf
succulence grade (LSG) , total soluble sugars and proline content increased with
increasing salinity levels, whereas, results in both seasons showed significant
reduction in chlorophyll a , b and carotene content as well as N , P , K content in the
leaves of jojoba seedlings compared with control in two seasons.
Sodium and chloride were significantly accumulated in jojoba leaves in
response to the increase in salinity levels of irrigation water. The amount of N and
C1 uptake by jojoba plants appear to be the highest under the highest salinity level
comparing with other treated salinity levels in (he two seasons.
Phosphorus application significantly increased cNorophyll a, b and carotene,
on the other hand P decreased total soluble sugars and proline content in leaves of
biaba seedlings as compared with only irrigated with satine water.
Concerning the effect of phosphorus sprays on minerals content of jojoba
leaves, results showed that P treatment results in higher leaf N, P and K content of
jojoba seedlings than their analogous without P spraying. Moreover, P application to
plants results in a signficant reduction in Na and C1 concentration ¡n leaves of jojoba