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.