Morphological and physiological impacts of cement kiln particle on Ziziphus spina-christi L

Today, a lot of information about the negative effects of cement kiln particle on vegetation exists, but so far the impact of this pollutant on species are poorly investigated. Ziziphus spina-christi L. is present in a wide range of semi-arid areas and has high ecological value and widespread use in folkloric medicine. In this study, the effect of particle depot of Behbahan cement factory on morphological and physiological characteristics of Christ's thorn jujube trees at 0.5, 2, 5 and 7 kilometers northwest of the factory during growing season was evaluated. The results showed that with decreasing distance from the factory from five km the amount of particle depot on the leaves was significantly increased and the amount of leaf area reduced but no changes in leaf dry weight was observed. The frequency of stomata diminished due to cement particle depot in both sides, but this change in adaxial surface was greater than abaxial surface. Content of leaves chlorophyll a and carotenoids also decreased, but there was no significant change in the content of chlorophyll b. Leaf initiation rate of the trees also was not affected by cement depot. The longitudinal growth of the branches of the plant facing to the factory decreased from five km of factory. The results showed that Behbahan cement factoy with current production rate (one million tons of cement per year) causes limitations in photosynthesis and activities of the shoot apical meristem in the trees.