1 College of Agriculture University of Al-Qadissiya

2 University of Baghdad College of Agriculture


The aim of this study is to discover the activity of extracellular enzymes (amidase , alkaline phosphatase and Arylsulphatase) in vertical and horizontal developing directions of rhizosphere (0-5 and 5-10) cm . The plot experiment is performed in college of Agriculture / Al-Qadissiya University for the spring season 2013 ,the loamy sand soil was used to cultivate Tomato (Lycopersicon Esculentum mill) and Bean (Phaseolus Vulgaris L.) plants under salinity levels (without salted the natural salinity) , 6 , 8 and 10 ds.m-1 and compost levels (0,10 ,20)T.h-1 , and their interactions randomized complete design (RCD) is used with three replicates used with L.S.D test 5% level .The laboratory experiment is performed to determine the all enzymes activity above for all treatments .

The results are summarized as :
1- Enzyme activity decreases with increasing the salinity levels for all enzymes used in this study and the salinity level 10 ds.m-1 is the lowest. The arrangement of activity values as
Alkaline Phosphatase  Amidase  Arylsulphatase
2- The enzyme activity increased with increasing the added compost level 20Ton.h-1 and its interactions with salinity levels , and it has positive role to reduce the negative effect of salinity and it increases the activity in all treatments as well as the dead plant treatments .
3- The enzymes activity varied in rhizosphere developing directions and the plants are different in the site of highest activity , the enzyme activity in horizontal rhizosphere developing direction is highest than the vertical direction .
4- The enzyme activity in Tomato rhizosphere is the higher than Bean rhizosphere in all enzymes without the alkaline phosphatase in all rhizosphere vertical and horizontal directions .