ﻣﺪل ﺳﺎزي ﺟﻮاﻧﻪزﻧﯽ ﺑﺬرﻫﺎي زوال ﯾﺎﻓﺘﻪ ﮐﻠﺰا در ﺷﺮاﯾﻂ ﺗﻨﺶ ﺧﺸﮑﯽ و ﺷﻮري

Modeling the germination of deteriorated seeds of Brassica napus under salinity and drought stress conditions

ﭼﮑﯿﺪه آزﻣﺎﯾﺸﯽ ﺑﻪ ﺻﻮرت اﺳﭙﻠﯿﺖ ﭘﻼت در ﻗﺎﻟﺐ ﻃﺮح ﭘﺎﯾﻪ ﮐﺎﻣﻼ ﺗﺼﺎدﻓﯽ ﺑﺎ ﺳﻪ ﺗﮑﺮار در دﻣﺎي 25 درﺟﻪ ﺳﺎﻧﺘﯽﮔﺮاد اﻧﺠﺎم ﺷﺪ. ﺗﯿﻤﺎرﻫﺎ ﺷﺎﻣﻞ ﭼﻬﺎر ﺳﻄﺢ ﭘﯿﺮي ﺗﺴﺮﯾﻊ ﺷﺪه )ﺻﻔﺮ، 1، 2 و 3 روز در 42 درﺟﻪ ﺳﺎﻧﺘﯽ ﮔﺮاد( ﮐﻪ در ﻫﺮ ﯾﮏ از ﺳﻄﻮح ﭘﯿﺮي ﻫﻔﺖ ﺳﻄﺢ ﺗﻨﺶ ﺷﻮري )ﺻﻔﺮ، 50، 100، 150، 200، 250 و 300 ﻣﯿﻠﯽ ﻣﻮﻻر؛ ﻧﻤﮏ ﮐﻠﺮﯾﺪﺳﺪﯾﻢ( و ﭼﻬﺎر ﺳﻄﺢ ﺗﻨﺶ ﺧﺸﮑﯽ )ﺻﻔﺮ، 0/25،- 0/50-و 0/75- ﻣﮕﺎﭘﺎﺳﮑﺎ؛ل ﭘﻠﯽ اﺗﯿﻠﻦ ﮔﻠﯿﮑﻮل 8000( ﺑﻮدﻧﺪ. ﻃﺒﻖ ﻧﺘﺎﯾﺞ اﻓﺰاﯾﺶ زﻣﺎن ﭘﯿﺮي و در ﻫﺮ ﺳﻄﺢ ﭘﯿﺮي ﺑﺎ اﻓﺰاﯾﺶ ﺗﻨﺶ ﺧﺸﮑﯽ و ﺷﻮري ﺻﻔﺎت درﺻﺪ و ﺳﺮﻋﺖ ﺟﻮاﻧﻪ زﻧﯽ ﺑﻪ ﻃﻮر ﻣﻌﻨﯽ دار ﮐﺎﻫﺶ ﯾﺎﻓﺘﻨﺪ. اﻓﺰاﯾﺶ زﻣﺎن ﭘﯿﺮي ﺗﺎ ﺳﻪ روز ﺑﺎﻋﺚ اﻓﺰاﯾﺶ 2/1 و 1/4 ﺑﺮاﺑﺮي ﺑﻪ ﺗﺮﺗﯿﺐ ﺛﺎﺑﺖ ﻫﯿﺪروﺗﺎﯾﻢ و ﻫﺎﻟﻮﺗﺎﯾﻢ ﺷﺪ. ﻫﻤﭽﻨﯿﻦ آﺳﺘﺎﻧﻪ ﺗﺤﻤﻞ ﺑﻪ ﺧﺸﮑﯽ 81/7 درﺻﺪ )از 1/17- ﺑﻪ 0/21- ﻣﮕﺎﭘﺎﺳﮑﺎل( اﻓﺰاﯾﺶ و ﺷﻮري 84/6 درﺻﺪ )از 326/7 ﺑﻪ 50/2 ﻣﯿﻠﯽ ﻣﻮﻻر( ﮐﺎﻫﺶ ﯾﺎﻓﺖ. ﻣﻘﺪار ﺗﻨﻈﯿﻢ اﺳﻤﺰي در ﺑﺬر زوال ﯾﺎﻓﺘﻪ ﮐﻠﺰا ﺑﻪ ﻣﺪت ﺳﻪ روز 4/42 ﺑﺮاﺑﺮ )از 19/9 ﺑﻪ 4/50 درﺻﺪ( ﮐﺎﻫﺶ ﯾﺎﻓﺖ ﮐﻪ دﻟﯿﻞ آن را ﻣﯽ ﺗﻮان ﺑﻪ آﺳﯿﺐ ﻏﺸﺎء ﺑﺬر و در ﻧﻬﺎﯾﺖ ﮐﺎﻫﺶ ﺗﻮاﻧﺎﯾﯽ ﺑﺬر ﺑﺮاي اﯾﺠﺎد ﻓﺸﺎر ﺗﻮرﮔﺮ و ﺗﻨﻈﯿﻢ اﺳﻤﺰي ﻧﺴﺒﺖ داد. در ﻣﺠﻤﻮع، ﻫﺮ دو ﻣﺪل ﻫﯿﺪروﺗﺎﯾﻢ و ﻫﺎﻟﻮﺗﺎﯾﻢ ﺑﻪ ﺧﻮﺑﯽ ﻗﺎدر ﺑﻪ ﺷﺒﯿﻪ ﺳﺎزي ﺟﻮاﻧﻪ زﻧﯽ ﺑﺬرﻫﺎي زوال ﯾﺎﻓﺘﻪ ﮐﻠﺰا ﻣﯽ ﺑﺎﺷﻨﺪ.

An experiment was conducted in a split-plot arrangement based on a completely randomized design with three replications at 25 °C. Treatments were included four levels of accelerated aging time (0, 1, 2 and 3 days at 42 °C) which at each of the following seven levels of salt stress (0, 50, 100, 150, 200, 250 and 300 Mm; NaCl) and four levels of drought stress (0, –0.25, –0.50 and –0.75 MPa; PEG8000). According to the results, the germination percentage (GP) and germination rate (GR) were significantly decreased by increasing aging time and at each level of aging with increasing drought and salinity stress. Increasing aging time up to 3 days, increased the hydrotime and halotime constant by 2.1 and 1.4 folds, respectively. Also, the tolerance threshold value increased by 81.7% (from –1.17 to –0.21 MPa) and decreased by 84.6% (from 326.7 to 50.2 mM) when drought and salinity stresses were applied, respectively. The amount of osmotic adjustment in the deteriorated seed of Brassica napus at 3 days of seed aging decreased 4.42-folds (from 19.9 to 4.50%) which could be due to membrane damage of the seed and finally a reduction in the seed ability to maintain turgor pressure and osmotic adjustment. Overall, both hydrotime and halotime models are capable to simulate the germination of deteriorated seeds of Brassica napus