Co-effects of Fusarium Root Rot and Water Stress on Some of the Morphophysiological Features of Christ Thorn: s Seedlings

Christ thorn (Ziziphus spina-christi) is a forest tree species that grows wild in the arid and semiarid areas of Asia and Africa where rural populations intensively use its fruits، leaves، bark، and wood. The death of a large number of seedlings with root rot symptoms has been observed since 2008 in Kazerunand Lamer nurseries in Fars Provience of Iran. Necrosis of internal skin and crown were also detected in the infected plants. Some isolates of Fusarium oxysporum were recovered through plating the infected tissues on the PDA medium which were found to be pathogenic on the Christ thorn seedlings through Kock’s postulate. Since Christ thornis cultivated in the arid areas and damping-off of the seedlings is a common disease in these areas، the present study was conducted to study the co-effects of water stress and the pathogen on the plant seedlings. The effects of F. oxysporum infection and the levels of irrigation frequencies (every 2، 3، 5 and 8 days) was studied through using a factorial experiment that was arranged in a randomized complete block design with four replications. Some morpho-physiological features of the seedlings such as height، leaf number، leaf height، and width were measured. The results of this experiment indicated that the growth response of Christ thorn to drought stress depends on the levels of irrigation applied. Compared to the unstressed control، the interaction of F. oxysporum and water stress reduced the seedling height and leaf numbers up to more than 50%.