ارزيابي تنش سرب بر مراحل رشد دانهال و استقرار برموداگرس (Cynodon dactylon)

Evaluation of lead stress on growth of seedlings and establishment of Bermudagrass

ﺳﺮب ﻋﻤﻮﻣﯽ ﺗﺮﯾﻦ ﻋﻨﺼﺮ ﺳﻨﮕﯿﻦ آﻟﻮده ﮐﻨﻨﺪه ﻣﺤﯿﻂ زﯾﺴﺖ اﺳﺖ. در اﯾﻦ ﺗﺤﻘﯿﻖ، ﺑﻪ ﻣﻨﻈﻮر ﺗﺎﺛﯿﺮ ﺗﻨﺶ ﺳﺮب در ﻣﺮاﺣﻞ ﻣﺨﺘﻠﻒ رﺷﺪي ﭼﻤﻦ ﺑﺮﻣﻮداﮔﺮس، ﻏﻠﻈﺖ ﻫﺎي ﻣﺨﺘﻠﻒ ﺳﺮب در ﻣﺮﺣﻠﻪ ﺟﻮاﻧﻪ زﻧﯽ ﺑﻪ اﯾﻦ ﮔﯿﺎه اﻋﻤﺎل ﺷﺪ و در اداﻣﻪ ﻣﺮاﺣﻞ رﺷﺪ، ﭼﮕﻮﻧﮕﯽ ﺗﺎﺛﯿﺮ ﻓﻠﺰ ﺳﺮب ﺑﺮ ﺻﻔﺎت ﻣﻮرﻓﻮﻟﻮژي ﮔﯿﺎه ارزﯾﺎﺑﯽ ﺷﺪ. ﻏﻠﻈﺖ ﻫﺎي اﻋﻤﺎل ﺷﺪه در ﻣﺮﺣﻠﻪ ﺟﻮاﻧﻪ زﻧﯽ ﺑﺎ اﺳﺘﻔﺎده از ﻣﺤﻠﻮل ﻧﯿﺘﺮات ﺳﺮب ﺷﺎﻣﻞ ﺻﻔﺮ، 20، 40، 80، 100، 150 و 300 ﻣﯿﻠﯽ ﮔﺮم در ﻟﯿﺘﺮ ﺑﻮد و ﺳﭙﺲ ﺷﺎﺧﺺ ﻫﺎي ﺟﻮاﻧﻪ زﻧﯽ ﺑﺬر ارزﯾﺎﺑﯽ ﺷﺪ. ﭘﺲ از ﺳﺎزﮔﺎري ﮔﯿﺎﻫﭽﻪ ﻫﺎ ﺑﻪ ﻣﺤﯿﻂ ﺧﺎﮐﯽ ﺑﻪ ﻣﻨﻈﻮر ارزﯾﺎﺑﯽ ﺗﻮان ﭘﺎﻻﯾﻨﺪﮔﯽ و ﺳﺎﯾﺮ ﺻﻔﺎت رﺷﺪي ﺑﺎ ﻏﻠﻈﺖ 800 ﻣﯿﻠﯽ ﮔﺮم در ﻟﯿﺘﺮ ﻧﯿﺘﺮات ﺳﺮب آﺑﯿﺎري ﺷﺪﻧﺪ. ﻧﺘﺎﯾﺞ ﻧﺸﺎن داد ﮐﻪ ﺗﻨﺶ ﺳﺮب در ﻣﺮﺣﻠﻪ ﺟﻮاﻧﻪ زﻧﯽ از ﻏﻠﻈﺖ 300-20 ﻣﯿﻠﯽ ﮔﺮم در ﻟﯿﺘﺮ ﺑﺎﻋﺚ ﮐﺎﻫﺶ ﺷﺪﯾﺪ ﺟﻮاﻧﻪ زﻧﯽ و ﺑﻨﯿﻪ ﺑﺬر و از ﻏﻠﻈﺖ 300-40 ﻣﯿﻠﯽ ﮔﺮم در ﻟﯿﺘﺮ ﺑﺎﻋﺚ ﮐﺎﻫﺶ ﻃﻮل ﺳﺎﻗﻪﭼﻪ و رﯾﺸﻪﭼﻪ ﻧﺴﺒﺖ ﺑﻪ ﺷﺎﻫﺪ ﺷﺪ. ﺗﻨﺶ ﺳﺮب در ﻣﺮاﺣﻞ اوﻟﯿﻪ رﺷﺪ ﺑﺮﻣﻮداﮔﺮس روي ﺑﺮﺧﯽ ﺻﻔﺎت ﻣﺮﺣﻠﻪ اﺳﺘﻘﺮار ﺗﺎﺛﯿﺮﮔﺬار ﺑﻮد، ﺑﻪ ﮔﻮﻧﻪ اي ﮐﻪ در ﻣﺮاﺣﻞ ﺑﻌﺪي رﺷﺪ ﮔﯿﺎﻫﺎن ﺑﺮگ ﻫﺎي ﮐﻮﺗﺎه ﺗﺮ ﺑﺎ ﻋﺮض ﺑﯿﺸﺘﺮ (ﺑﻪﺗﺮﺗﯿﺐ 0/7 ﺑﺮاﺑﺮ ﮐﻤﺘﺮ و 1/6 ﺑﺮاﺑﺮ ﺑﯿﺸﺘﺮ ﻧﺴﺒﺖ ﺑﻪ ﺷﺎﻫﺪ) و دﺳﺘﮏﻫﺎي ﻃﻮﯾﻞ ﺗﺮ ﺑﺎ ﺗﻌﺪاد ﺑﯿﺸﺘﺮ (ﺑﻪﺗﺮﺗﯿﺐ 2 ﺑﺮاﺑﺮ و 3/8 ﺑﺮاﺑﺮ ﺑﯿﺸﺘﺮ ﻧﺴﺒﺖ ﺑﻪ ﺷﺎﻫﺪ) ﺗﻮﻟﯿﺪ ﮐﺮدﻧﺪ. ﺑﺮﻣﻮداﮔﺮس در ﻣﺮاﺣﻞ اوﻟﯿﻪ رﺷﺪ ﻧﺴﺒﺖ ﺑﻪ ﺣﻀﻮر ﻏﻠﻈﺖ ﻫﺎي ﺳﺮب ﺣﺴﺎس ﺑﻮد؛ در ﺣﺎﻟﯽ ﮐﻪ ﭘﺲ اﺳﺘﻘﺮار ﮔﯿﺎه ﺗﻮاﻧﺴﺖ ﺑﺎ ﺑﺮﺧﯽ ﺳﺎز و ﮐﺎرﻫﺎ از ﺟﻤﻠﻪ ﺗﻮﺳﻌﻪ دﺳﺘﮏ اﺳﺘﻘﺮار در ﻣﻘﺎﺑﻞ ﺗﻨﺶ ﺳﺮب ﺗﺤﻤﻞ ﻧﺸﺎن دﻫﺪ.

Pb is the most commonly heavy metal pollution in the environment. Various concentrations of lead in the germination stage were applied to the plant in order to effect of Lead stress in different growth stages of bermudagrass and continued growth stages, effect of Pb were evaluated on plant morphological traits. Concentrations of lead nitrate solution at 0, 20, 40, 80, 100, 150 and 300 mg L -1 applied on germination stage, and germination indicators such as the percentage of seed germination, root and shoot length of seedling and etc were evaluated. After plant adaptation to the terrestrial environment were irrigated with a concentration of 800 ppm of lead nitrate to evaluate the accumulation potential and other developmental traits. The results showed that Pb stress at 20-300 mg L-1 concentrations inhibited germination and seed vigor and reduced shoot and root length at 40-300 mg L-1 concentrations compared with control. Lead stress in the early stages of bermuda grass growth stage was effected on some traits of establishment stage so, plant produced shorter and wider leaves (0.7 less and 1.6 more respectively), longer stolon and more stolon number compared with control in later growth stages. Bermuda grass was sensitive to concentrations of lead in early stage of growth and germination. Seedling growth was limited but after the plants have been established, they could resistance a number of mechanisms such as the development of stolons to lead stress.