RESPONSE OF SALTBUSH (ATRIPLEX HALIMUS L.) PLANTS TO SALINITY AND TYPE OF GROWING MEDIUM

A pot experiment was carried out under the full sun at
Orman Botanic Garden, Hort. Res. Inst., Giza, Egypt during 2013 and
2014 seasons in order to reveal the effect of different media, namely:
pure sand, pure loam and sand + loam mixture at 1:1, 1:2 and 2:1 ratio
salinized with a homogenous salt mixture of NaCl and CaCl2 (1:1,
w/w) at 0.00, 0.75, 1.5 and 3.0% concentrations on growth and
chemical composition of the 6-months-old transplants of
Mediterranean saltbush (Atriplex halimus L.) cultivated in 40-cmdiameter
clay pots filled with a known weight of the abovenamed
media.
The results of this experiment have shown that all vegetative and
root growth measurements were significantly improved by the law and
medium levels of salinity (0.75 and 1.5%, respectively), with the
mastery of 0.75% level which gave the highest means various growth
traits except of leaf area character that reached the maximum values by
1.5% level over control and other salinity treatments in the two
seasons. However, 3.0% rate significantly reduced means of the
different vegetative and root growth parameters to the least values
compared to control in most cases of both seasons. The mixture of
sand + loam, especially at 1:2 and 2:1 ratio recorded the best
improvement in vegetative and root growth parameters over all other
media in the two seasons. The interaction between the 3 used mixtures
salinized with 0.75% of salt mixture gave the tallest plants, thickest
stems and highest No. branches and leaves/plant in both seasons, while
the heaviest fresh and dry weights of aerial parts and roots were
achieved by 0.75% salinity level for plants cultivated in either pure
sand or pure loam, or in the mixture of both at equal parts (1:1). The
content of chlorophyll a, b and carotenoids was slightly improved by
either soil salinity treatments or media contained loam granulars. On
the other side, the content of Na, Ca, Cl and free proline was
progressively increased with raising salinity level, but the opposite was
the right concerning K content, which descendingly decreased with
increasing salinity rate. The content of Na and Cl was not markedly
affect by medium type, whereas content of K, Ca and free proline was
greatly increased in the leaves of plants cultivated in pure loam or pure
sand amended with loam at any ratio. The interaction treatments have
shown variable effects, as the highest content of Na and K was mostly
achieved by the low (0.75%) and medium (1.5%) salinity treatments
under loam or sand or sand + loam media, while the highest content of
Ca, Cl and proline was scored by plants cultured in loam or sand +
loam media salinized with the high salinity rate (3.0%).
It appears from the previous results that Mediterranean saltbush
(Atriplex halimus L.) plants can grow well in the loam or sand
amended with loam media salinized with NaCl + CaCl2 salt mixture
(1:1, w/w) at low and medium concentrations.