اثرات ﺳﻄﻮح ﻣﺨﺘﻠﻒ آب، ﺷﻮري و ﮐﻮد ﻧﯿﺘﺮوژن ﺑﺮ ﺷﺎﺧﺺﻫﺎي رﺷﺪ و ﮐﺎرآﯾﯽ ﻣﺼﺮف آب اﺳﻔﻨﺎج

ﮐﻤﺒﻮد آب، ﺷﻮري و ﮐﻤﺒﻮد ﻧﯿﺘﺮوژن ﻣﻬﻢﺗﺮﯾﻦ ﻋﻮاﻣﻞ ﻣﺤﺪود ﮐﻨﻨﺪه ﺗﻮﻟﯿﺪ ﮔﯿﺎه در ﻣﻨﺎﻃﻖ ﺧﺸﮏ و ﻧﯿﻤﻪﺧﺸﮏ ﻫﺴﺘﻨﺪ. ﺑﺎ اﯾﻦ ﺣﺎل، آﺑﯿﺎري ﺑﯿﺶ از ﺣﺪ ﻣﺼﺮف ﺑﯿﺶ از ﺣﺪ ﮐﻮد ﻧﯿﺘﺮوژن ﻧﯿﺰ ﻣﯽﺗﻮاﻧﺪ رﺷﺪ و ﻋﻤﻠﮑﺮد ﻣﺤﺼﻮﻻت زراﻋﯽ را ﻣﺤﺪود ﮐﻨﺪ. اﯾﻦ ﭘﮋوﻫﺶ ﺑﺎ ﻫﺪف ارزﯾﺎﺑﯽ اﺛﺮات ﺷﻮري آب آﺑﯿﺎري در ﺗﻌﺎﻣﻞ ﺑﺎ ﺳﻄﻮح ﻣﺨﺘﻠﻒ ﻧﯿﺎز آب آﺑﯿﺎري و ﻧﯿﺘﺮوژن ﺑﺮ ﺻﻔﺎت رﺷﺪ ﮔﯿﺎه و ﮐﺎرآﯾﯽ ﻣﺼﺮف آب اﺳﻔﻨﺎج اﻧﺠﺎم ﺷﺪ. ﺗﺮﮐﯿﺒﯽ از ﭘﻨﺞ ﺳﻄﺢ ﺷـﻮري )ﯾـﮏ، ﭼﻬـﺎر، ﻔﺖ، ﻧﻪ و 11 دﺳﯽزﯾﻤﻨﺲ ﺑﺮ ﻣﺘﺮ( ﺑﺎ ﺳﻪ ﺳﻄﺢ ﻧﯿﺎز آب آﺑﯿﺎري )100 ،75 و 125 درﺻﺪ( و ﭼﻬﺎر ﺳﻄﺢ ﻧﯿﺘﺮوژن از ﻣﻨﺒﻊ اوره ﺑﺎ ﺧﻠﻮص 46 درﺻـﺪ )ﺻـﻔﺮ 150 ،100 و 200 ﻣﯿﻠﯽﮔﺮم ﺑﺮ ﮐﯿﻠﻮﮔﺮم ﺧﺎك( ﺗﺤﺖ ﺷﺮاﯾﻂ ﮐﻨﺘﺮلﺷﺪه ﮔﻠﺨﺎﻧﻪاي و در ﺳﻪ ﺗﮑﺮار ﺑﻪﻋﻨﻮان ﻓﺎﮐﺘﻮرﻫﺎي ﻣﻮرد ﻣﻄﺎﻟﻌﻪ در ﻧﻈﺮ ﮔﺮﻓﺘـﻪ ﺷـﺪﻧﺪ . ﻧﺘﺎﯾﺞ ﻧﺸﺎن داد ﮐﻪ ﺷﻮري آب در ﺗﺮﮐﯿﺐ ﺑﺎ ﮐﻤﺒﻮد آب و ﻧﯿﺘﺮوژن ﺳﺒﺐ ﮐﺎﻫﺶ ﻣﻌﻨﯽداري در ﺳﻄﺢ ﭘﻨﺞ درﺻﺪ رﺷﺪ ﮔﯿﺎه ﺷﺪ. ﻋﻤﻠﮑـﺮد در ﺗﯿﻤﺎرﻫـﺎي 75 125 درﺻﺪ ﻧﯿﺎز آب آﺑﯿﺎري ﺑﻪﺗﺮﺗﯿﺐ 22/7 و 10/8 درﺻﺪ ﮐﻢﺗﺮ از ﺗﯿﻤﺎر 100 درﺻﺪ ﻧﯿﺎز آب آﺑﯿﺎري ﺑﻮد. ﺷﻮري در ﺗﯿﻤﺎر 75 و 100 درﺻﺪ ﻧﯿﺎز آب آﺑﯿـﺎري ﺑﺎﻋﺚ ﮐﺎﻫﺶ ﻣﻌﻨﯽدار ﺷﺎﺧﺺ ﺳﻄﺢ ﺑﺮگ ﮔﺮدﯾﺪ. ﺑﻪﻃﻮريﮐﻪ، ﺗﯿﻤﺎر 75 درﺻﺪ ﻧﯿﺎز آب آﺑﯿﺎري ﻫﻤﺮاه ﺑﺎ ﺳﻄﺢ ﺷﻮري 11 دﺳﯽزﯾﻤﻨﺲ ﺑﺮ ﻣﺘـﺮ، 46 درﺻـﺪ ﺷﺎﺧﺺ ﺳﻄﺢ ﺑﺮگ را ﻧﺴﺒﺖ ﺑﻪ ﺗﯿﻤﺎر ﺷﺎﻫﺪ ﮐﺎﻫﺶ داد. ﺑﺎ ﮐﺎرﺑﺮد ﮐﻮد در ﺳﻄﺢ ﺑﻬﯿﻨﻪ 150 ﻣﯿﻠﯽﮔﺮم ﻧﯿﺘﺮوژن ﺑﺮ ﮐﯿﻠﻮﮔﺮم ﺧﺎك، رﺷﺪ ﮔﯿـﺎه و ﻋﻤﻠﮑـﺮد آن ﺑﺮاي ﻫﻤﻪ ﺳﻄﻮح ﺷﻮري اﻓﺰاﯾﺶ ﻣﻌﻨﯽداري ﻧﺸﺎن داد. ﮐﺎرآﯾﯽ ﻣﺼﺮف آب در ﺗﻤﺎم ﺗﯿﻤﺎرﻫﺎ در ﻣﻘﺎدﯾﺮ ﺷﻮري ﭼﻬﺎر و ﻫﻔﺖ دﺳﯽزﯾﻤـﻨﺲ ﺑـﺮ ﻣﺘـﺮ اﻓـﺰاﯾﺶ ﯾﺎﻓﺖ، ﺳﭙﺲ ﺑﻪﻃﻮر ﻗﺎﺑﻞ ﺗﻮﺟﻬﯽ ﺑﺎ اﻓﺰاﯾﺶ ﺷﻮري ﺑﺮاي ﮐﻞ ﺗﯿﻤﺎرﻫﺎي ﻧﯿﺎز آب آﺑﯿﺎري و ﺳﻄﻮح ﻧﯿﺘﺮوژن ﮐﺎﻫﺶ داﺷﺖ. ﻫﻢﭼﻨﯿﻦ، ﺗﯿﻤﺎر 125 درﺻﺪ ﺑﺎﻋﺚ ﮐﺎﻫﺶ ﺑﯿﺶﺗﺮ در ﮐﺎرآﯾﯽ ﻣﺼﺮف آب در ﻣﻘﺎﯾﺴﻪ ﺑﺎ ﺗﯿﻤﺎرﻫﺎي 75 و 100 درﺻﺪ ﻧﯿﺎز آب آﺑﯿﺎري ﺑﺮاي ﮐﻞ ﺳﻄﻮح ﺷﻮري ﺷﺪ. در ﻧﻬﺎﯾﺖ ﺑﻬﺘﺮﯾﻦ ﺗﯿﻤﺎر از ﻧﻈﺮ ﮐﺎرآﯾﯽ ﻣﺼﺮف آب در ﺗﯿﻤﺎر 75 درﺻﺪ ﻧﯿﺎز آب آﺑﯿﺎري در ﺳﻄﻮح ﻣﺘﻮﺳﻂ ﺷﻮري )4 و 7 دﺳﯽزﯾﻤﻨﺲ ﺑﺮ ﻣﺘﺮ( ﻣﺸﺎﻫﺪه ﮔﺮدﯾﺪ.

The aim of this study was to evaluate the effects of salinity of irrigation water in interaction with different levels of irrigation water and nitrogen requirements on growth characteristics and water use efficiency of spinach. A combination of five salinity levels (1, 4, 7, 9 and 11 dS/m) with three levels of water requirement including (75, 100 and 125% of irrigation water requirement) and four levels of nitrogen from the source of urea with a purity of 46% (0, 100, 150 and 200 mg/kg soil) under controlled greenhouse conditions in three repetitions were considered as the studied factors. The results showed that salinity in combination with water stress and nitrogen deficiency caused a significant reduction in plant growth. Yield in treatments 75 and 125% of water requirement was 22.7 and 10.8% less than 100% of water requirement, respectively. Salinity in the treatment of 75 and 100% water requirement had a significant effect on leaf area index; such that the treatment of 75% of water requirement with the salinity level 11 ds/m decreased the leaf area index 46% tward control treatment. By increasing the application of fertilizer at the optimal level of 150 mg N/kg soil, plant growth and yield for all salinity levels showed a significant increase. Water use efficiency increased in W1, W2 and W3 treatments at salinity levels 4, 7 and 4-7 ds/m, then decreased significantly with increasing salinity for all treatments of water requirement and nitrogen levels. Also, 125% treatment caused a further reduction in water use efficiency compared to 75% and 100% water requirement treatments for all salinity levels. Finally, the best treatment in terms of water use efficiency was observed in the treatment of 75% of water requirement at moderate salinity levels (4- 7 dS/m).