Mohamad Al -Ahmad^(1)*, Najwa Muslmani ⁽¹⁾, Imad aldeen ALKhalaf ⁽¹⁾, and Aya kanawaty⁽¹⁾

(1) Dept. of Botany, Faculty of Science, University of Aleppo, Aleppo, Syria.

(*Corresponding author: Mohamad Al-Ahmad E-Mail: mo.alahmad93@gmail.com).

Received:27/07/ 2021          Acceptance: 9/10/ 2021

Abstract: 

Air pollution with gases is one of the biggest challenges facing the world at the present time, as it threat life in all its plant and animal forms, The research was carried out to study the response of the morphological and physiological characteristics of sunflower plants when exposed to SO₂ and NO₂ gases individually and together. The experiment was factorial, as it was carried out in a random sector manner. The first factor was the type of gas with three treatments SO₂, NO₂, SO₂ + NO₂, and the second factor was the number of days of exposure to gases, which was four treatments. Sunflower plants at the age of 4 weeks were exposed to SO₂ alone with a concentration of (0.5) ppm and SO₂ alone. NO₂ alone at a concentration of (0.5) ppm and for a mixture of the two gases together for two hours daily. The first treatment was within four days, the second was eight days, the third was 12 days, and the fourth was 16 days. At the end of the 16-day experiment, the vegetative growth indicators of sunflower plants were calculated, represented by the height of the plant, the length of the root system, the wet weight of the vegetative and root groups, and the area of plant leaves. The chlorophyll content and carotene content, soluble sugars and proline concentrations were also measured. The results showed the similarity of the effect of sulfur dioxide and nitrogen dioxide, individually and collectively, on the decrease in the chemical and biological morphological vegetative growth indicators compared with control, where the average of plant height and root length when treated with SO₂ gas ranged between (6.8-13.05) cm and (9.23-16.2) cm consecutively, A gradual significant increase with time compared with the control was observed for the vegetative and root wet weights respectively, where the values ranged between (3.83-2.33) g and (1.32-0.33) g, and the value of total chlorophyll and soluble sugars in plants treated with SO₂ gas decreased from 9.24 mg/g in control plants to 2.33 mg/g, and from 103.52 to 86.3 mg/g soluble sugars, The value of proline increased in plants treated with SO₂ gas to reach 2.76 μl/g compared with the control (0.71 μl/g), and no significant differences were recorded for the leaf area index between the different treatments and the control (15.35-12.91) cm².

Key words: sulfur dioxide, nitrogen dioxide, growth parameters, sunflower.

Full paper in Arabic: pdf