پاسخ ذرت به تنش شوري با استفاده از مدل هاي جذب آب در فصول مختلف

Maize Response to Salinity Stress Using Water Uptake Models in Different Seasons

اﯾﻦ ﺗﺤﻘﯿﻖ ﺑﻪﻣﻨﻈﻮر ﺑﺮرﺳﯽ ﺑﺮﻫﻤﮑﻨﺶ ﺗﻨﺶ ﺷﻮري و ﺗﻘﺎﺿﺎي ﺗﺒﺨﯿﺮ ﺑﺮ ﺟﺬب آب ﺗﻮﺳﻂ ﮔﯿﺎه ذرت اﻧﺠﺎم ﺷﺪ. آزﻣﺎﯾﺶﻫﺎ در دو ﻓﺼﻞ ﺑﻬﺎر و ﭘﺎﯾﯿﺰ در ﮔﻠﺨﺎﻧﻪ ﺑﻪﺻﻮرت ﻃﺮح ﮐﺎﻣﻼً ﺗﺼﺎدﻓﯽ ﺑﺎ 4 ﺗﮑﺮار در ﺳﺎل 1396 اﻧﺠﺎم ﺷﺪﻧﺪ. ﺟﺬب آب ذرت ﺑﻪﺻﻮرت روزاﻧﻪ ﺗﺤﺖ ﻣﮑﺶ 100 ﺳﺎﻧﺘﯽﻣﺘﺮ در ﺳﻄﻮح ﺷﻮري 6/33 ،3/36 ،1/7 ،0 و 8/35 دﺳﯽزﯾﻤﻨﺲ ﺑﺮ ﻣﺘﺮ اﻧﺪازهﮔﯿﺮي ﺷﺪ. ﻗﺎﺑﻠﯿﺖ ﻫﺪاﯾﺖ اﻟﮑﺘﺮﯾﮑﯽ در ﮔﻠﺪانﻫﺎ ﺑﻌﺪ از ﺷﺮوع اﻋﻤﺎل ﺗﯿﻤﺎر ﺛﺎﺑﺖ ﻧﮕﻪ داﺷﺘﻪ ﺷﺪ. ﺣﺪ آﺳﺘﺎﻧﻪ ﺷﻮري ﺑﺮ اﺳﺎس ﺷﻮري آب آﺑﯿﺎري ﺑﺮاي ﻓﺼﻞ ﺑﻬﺎر 0/52 و ﺑﺮاي ﻓﺼﻞ ﭘﺎﯾﯿﺰ 1/48 دﺳﯽزﯾﻤﻨﺲ ﺑﺪﺳﺖ آﻣﺪ ﮐﻪ ﻧﺸﺎندﻫﻨﺪه ﺣﺴﺎﺳﯿﺖ ﺑﯿﺸﺘﺮ ذرت ﺑﻪ ﺗﻨﺶ ﺷﻮري ﺗﺤﺖ ﺷﺮاﯾﻂ ﺗﻘﺎﺿﺎي ﺗﺒﺨﯿﺮ ﺑﺎﻻ ﻧﺴﺒﺖ ﺑﻪ ﺗﻘﺎﺿﺎي ﺗﺒﺨﯿﺮ ﭘﺎﯾﯿﻦ ﻣﯽﺑﺎﺷﺪ. ﺗﻨﺶ ﺷﻮري اﻋﻤﺎلﺷﺪه ﺑﻪﻃﻮر ﻣﻌﻨﯽدار ﺟﺬب آب و ﻋﻤﻠﮑﺮد ﮔﯿﺎه را در ﻫﺮ دو ﻓﺼﻞ ﺑﻬﺎر و ﭘﺎﯾﯿﺰ ﺗﺤﺖ ﺗﺄﺛﯿﺮ ﻗﺮار داد. ﻣﻘﺎدﯾﺮ ﻋﻤﻠﮑﺮد و ﺟﺬب آب ﺑﺮآورد ﺷﺪه ﺑﺎ اﺳﺘﻔﺎده از ﺗﻮاﺑﻊ ﮐﺎﻫﺶ ﻧﺸﺎن داد ﮐﻪ ﻣﺪل ﻧﻤﺎﯾﯽ وﻧﮕﻨﻮﺧﺘﻦ-ﻫﺎﻓﻤﻦ دﻗﺖ ﺑﺎﻻﺗﺮي از ﻣﺪل ﺧﻄﯽ ﻣﺎس-ﻫﺎﻓﻤﻦ ﺑﺮاي ﻋﻤﻠﮑﺮد داﺷﺖ درﺣﺎﻟﯽﮐﻪ ﺻﺤﺖ ﻣﺪل ﺧﻄﯽ ﺑﯿﺶﺗﺮ از ﻣﺪل ﻧﻤﺎﯾﯽ ﺑﺮاي ﺟﺬب آب ﺑﻪوﯾﮋه در ﻓﺼﻞ ﭘﺎﯾﯿﺰ ﺑﻮد. ﺑﻪﻃﻮر ﮐﻠﯽ ﻧﺘﯿﺠﻪ ﮔﺮﻓﺘﻪ ﺷﺪ، ﭘﺎﺳﺦ ﮔﯿﺎه ﺑﻪ ﺗﻨﺶ ﺷﻮري در ﺷﺮاﯾﻂ ﺗﻘﺎﺿﺎي ﺗﺒﺨﯿﺮ ﻣﺘﻔﺎوت ﯾﮑﺴﺎن ﻧﯿﺴﺖ.

This study was performed to investigate the effect of salinity stress and evaporative demand on water uptake by maize (Zea Mays L.). For two seasons, greenhouse experiments were conducted in pots in a completely randomized design with 4 replicates in 2017. Water uptake by maize was measured daily under constant matric suction of 100 cm at different salinity levels (0, 1.7, 3.36, 6.33 and 8.35 dS/m). The electrical conductivity in pots was kept constant after the treatment initiations. The salinity threshold level was determined to be 0.52 for spring season and 1.48 dS/m for autumn season based on salinity of irrigation water which implies more sensivity of maize to salinity stress under high evaporative demand as compared to low evaporative demand conditions. The imposed salinity stress significantly affected water uptake and yield in both spring and autumn seasons. The estimated yield and water uptake values using reduction functions indicated that the exponential model of van Genuchten-Hoffman had more accuracy than the linear model of Maas-Hoffman for yield, while the accuracy of linear model was more than the exponential model for water uptake, especially in autumn season. It is concluded that the plant response to salinity stress is not the same under different evaporative demand conditions.