ارزيابي اثر همزمان كم آبياري و تنش قطع آب بر صفات فيزيولوژيكي مؤثر بر عملكرد ذرت دانه اي سينگل كراس 704

Simultaneous effect of deficit irrigation and irrigation-off on physiological traits related with yield of maize S.C 704

ﺑﻪ ﻣﻨﻈﻮر ارزﯾﺎﺑﯽ اﺛﺮ ﻫﻤﺰﻣﺎن ﮐﻢ آﺑﯿﺎري و ﺗﻨﺶ ﻗﻄﻊ آﺑﯿﺎري، ﺑﺮ ﺻﻔﺎت ﻓﯿﺰﯾﻮﻟﻮژﯾﮑﯽ ﻣﺆﺛﺮ ﺑﺮ ﻋﻤﻠﮑﺮد ذرت داﻧـﻪ اي اﯾﻦ ﺗﺤﻘﯿﻖ ﻃﯽ ﺳﺎل ﻫﺎي 1387 و 1388 ﺑﻪ ﺻﻮرت ﻓﺎﮐﺘﻮرﯾﻞ در ﻗﺎﻟﺐ ﻃﺮح ﺑﻠﻮك ﻫﺎي ﮐﺎﻣﻞ ﺗﺼﺎدﻓﯽ ﺑﺎ ﺳـﻪ ﺗﮑـﺮار در ﻣﺰرﻋﻪ ﺗﺤﻘﯿﻘﺎﺗﯽ داﻧﺸﮕﺎه آزاد اﺳﻼﻣﯽ، واﺣﺪ ﻋﻠﻮم و ﺗﺤﻘﯿﻘﺎت ﺧﻮزﺳﺘﺎن اﺟﺮا ﺷﺪ. ﻋﻮاﻣﻞ ﺗﺤﻘﯿـ ﻖ ﺷـﺎﻣﻞ ﺗـﺄﻣﯿﻦ ﻧﯿﺎز آﺑﯽ در ﺳﻪ ﺳﻄﺢ )ﺗﺄﻣﯿﻦ 100، 80 و 60 درﺻﺪ ﻧﯿﺎز آﺑﯽ ﮐﺎﻣﻞ ﮔﯿﺎه ذرت( و ﺗﯿﻤﺎر ﻗﻄﻊ آب در ﻣﺮاﺣﻞ ﻣﺨﺘﻠـﻒ رﺷﺪ در ﭘﻨﺞ ﺳﻄﺢ )ﺑﺪون ﻗﻄﻊ آب در ﻃﻮل دوره رﺷﺪ )ﺷﺎﻫﺪ( و ﯾﮏ ﺑﺎر ﻗﻄـﻊ آب در ﻣﺮﺣﻠـﻪ ﻫﺸـﺖ ﺑﺮﮔـ ﯽ، دوازده ﺑﺮﮔﯽ، ﮔﺮده اﻓﺸﺎﻧﯽ و ﺷﯿﺮي( ﺑﻮدﻧﺪ. ﺗﯿﻤﺎرﻫﺎي آزﻣﺎﯾﺶ از ﻣﺮﺣﻠﻪ ﭼﻬﺎر ﺗﺎ ﭘﻨﺞ ﺑﺮﮔﯽ ﮔﯿﺎه ﺗﺎ ده روز ﭘﯿﺶ از رﺳﯿﺪﮔﯽ ﻓﯿﺰﯾﻮﻟﻮژﯾﮑﯽ اﻋﻤﺎل ﺷﺪ. ﻧﺘﺎﯾﺞ ﺗﺤﻘﯿﻖ ﻧﺸﺎن داد ﮐﻪ ﺑﺎ اﻓﺰاﯾﺶ ﺷﺪت ﮐﻢ آﺑﯽ، درﺻﺪ ﻟﻮﻟﻪ ﺷﺪن ﺑﺮگ اﻓـﺰا ﯾﺶ ﯾﺎﻓـﺖ وﻟﯽ ﻋﻤﻠﮑﺮد داﻧﻪ، ﻣﺤﺘﻮاي ﻧﺴﺒﯽ آب ﺑﺮگ و ﻏﻠﻈﺖ ﮐﻠﺮوﻓﯿﻞ ﻫﺎي a و b ﮐﺎﻫﺶ ﯾﺎﻓﺘﻨـﺪ . ﺑﯿﺸـﺘﺮﯾﻦ درﺻـﺪ ﻟﻮﻟـﻪ اي ﺷﺪن ﺑﺮگ ﺑﺎ ﻣﯿﺎﻧﮕﯿﻦ 67 درﺻﺪ، در ﺗﯿﻤﺎر ﺗﺄﻣﯿﻦ 60 درﺻﺪ ﻧﯿﺎز آﺑﯽ ﮔﯿﺎه ﻫﻤﺰﻣﺎن ﺑﺎ ﻋﺪم آﺑﯿﺎري در ﻣﺮﺣﻠـﻪ دوازده ﺑﺮﮔﯽ ﻣﺸﺎﻫﺪه ﺷﺪ و ﮐﻤﺘﺮﯾﻦ ﻣﻘﺪار آن ﺑﺎ ﻣﯿﺎﻧﮕﯿﻦ 9 درﺻﺪ ﺑﻪ ﺗﯿﻤﺎر ﺗﺄﻣﯿﻦ 100 درﺻﺪ ﻧﯿﺎز آﺑﯽ ﮔﯿﺎه، ﺑـﺪون ﺗـﻨﺶ ﻗﻄﻊ آب در ﻃﻮل دوره رﺷﺪ اﺧﺘﺼﺎص ﯾﺎﻓﺖ. ﺑﯿﺸﺘﺮﯾﻦ ﻏﻠﻈﺖ ﮐﻠﺮوﻓﯿﻞ a و b در ﺗﯿﻤﺎر ﺗﺄﻣﯿﻦ 100 درﺻﺪ ﻧﯿﺎز آﺑـﯽ ﮔﯿﺎه و ﺑﺪون ﺗﻨﺶ ﻗﻄﻊ آب در ﻃﻮل دوره رﺷﺪ ﺑﻪ ﺗﺮﺗﯿﺐ ﺑﺎ ﻣﯿﺎﻧﮕﯿﻦ 3/1 و 1/1 ﻣﯿﻠﯽ ﮔﺮم در ﻫﺮ ﮔﺮم ﺑﺮگ ﺑﻪ دﺳﺖ آﻣﺪ. ﮐﻤﺘﺮﯾﻦ ﻏﻠﻈﺖ ﮐﻠﺮوﻓﯿﻞ ﻫﺎي a و b ﺑﻪ ﺗﯿﻤﺎر ﺗﺄﻣﯿﻦ 60 درﺻﺪ ﻧﯿﺎز آﺑﯽ ﮔﯿﺎه ﻫﻤﺰﻣﺎن ﺑﺎ ﻋﺪم آﺑﯿﺎري در ﻣﺮﺣﻠﻪ ﮔﻠﺪﻫﯽ ﺑﻪ ﺗﺮﺗﯿﺐ ﺑﺎ ﻣﯿﺎﻧﮕﯿﻦ 1/7 و 0/5 ﻣﯿﻠﯽ ﮔﺮم در ﻫﺮ ﮔﺮم ﺑﺮگ ﺗﻌﻠﻖ ﯾﺎﻓﺖ. ﺗﯿﻤﺎر ﺗﺄﻣﯿﻦ 100 درﺻﺪ ﻧﯿـﺎز آﺑـﯽ،ﺑﺪون ﺗﻨﺶ ﻗﻄﻊ آب ﻣﺮﺣﻠﻪ اي ﺑﺎ ﻣﯿﺎﻧﮕﯿﻦ 90 درﺻﺪ ﺑﯿﺸﺘﺮﯾﻦ و ﺗﯿﻤﺎر ﺗﺄﻣﯿﻦ 60 درﺻﺪ ﻧﯿﺎز آﺑـﯽ ﻫﻤﺰﻣـﺎن ﺑـﺎ ﻋـﺪم آﺑﯿﺎري در ﻣﺮﺣﻠﻪ ﮔﻠﺪﻫﯽ ﺑﺎ ﻣﯿﺎﻧﮕﯿﻦ 64 درﺻﺪ ﮐﻤﺘﺮﯾﻦ ﻣﺤﺘﻮاي ﻧﺴﺒﯽ آب ﺑﺮگ را داﺷﺘﻨﺪ. ﺑﯿﺸﺘﺮﯾﻦ ﻋﻤﻠﮑﺮد داﻧـﻪ در ﺗﯿﻤﺎر آﺑﯿﺎري ﮐﺎﻣﻞ و ﺑﺪون ﺗﻨﺶ ﻗﻄﻊ آب، ﺑﺎ ﻣﯿﺎﻧﮕﯿﻦ 7500 ﮐﯿﻠﻮﮔﺮم در ﻫﮑﺘﺎر و ﮐﻤﺘـﺮﯾﻦ ﻣﻘـﺪار آن در ﺗﯿﻤـﺎر 60 درﺻﺪ آﺑﯿﺎري ﮐﺎﻣﻞ و ﺗﻨﺶ ﻗﻄﻊ آب در ﻣﺮﺣﻠﻪ ﮔﻠ ﺪﻫﯽ ﺑﺎ ﻣﯿﺎﻧﮕﯿﻦ 490 ﮐﯿﻠﻮﮔﺮم در ﻫﮑﺘﺎر ﺑـﻪ دﺳـﺖ آﻣـﺪ. ﺑـﺮ اﺳﺎس ﻧﺘﺎﯾﺞ اﯾﻦ ﺗﺤﻘﯿﻖ و ﺑﺎ ﺗﻮﺟﻪ ﺑﻪ ﺣﺴﺎﺳﯿﺖ زﯾﺎد ﺻﻔﺎت ﻓﯿﺰﯾﻮﻟﻮژﯾﮑﯽ ﺑﺮرﺳﯽ ﺷﺪه ﻧﺴﺒﺖ ﺑـﻪ ﺗـﻨﺶ ﮐـﻢ آﺑـﯽ راﺑﻄﻪ اﯾﻦ ﺻﻔﺎت ﺑﺎ ﻋﻤﻠﮑﺮد داﻧﻪ، ﻻزم اﺳﺖ از وﻗﻮع ﺗﻨﺶ آﺑﯽ در ﻣﺮاﺣﻞ ﺣﺴﺎس رﺷﺪ ﮔﯿﺎه ﺟﻠﻮﮔﯿﺮي ﻧﻤﻮد.

Abstract In order to investigate the effects of both deficit irrigation during growth stage and irrigation-off in some growth stages on effective physiological traits, and its relation with grain yield of Maize, this research was conducted in experimental field of Research and Science Branch, Islamic Azad University of Khuzestan, during 2008 and 2009 cropping season as factorial experiment, using Randomized Complete Block Design (RCBD) with three replications. Factors in this research were consisted of three irrigation levels (100, 80, 60 percent of full irrigation) and water stress in five levels (full irrigation and irrigation-off at the 8 and 12 leaf, the tasselling and milky stages). Irrigation treatments implement at 4-5 leaf stage (seedling establishment) and continued until 10 days before physiological maturity. The results indicated that leaf rolling percentage increased as drought stress intensified, but grain yield and other leaf indices (relative water content and chlorophyll a and b concentration) were reduced. The highest leaf rolling percentage by the average of 67% obtained from 60 percent of full irrigation with irrigation-off at 12 leaf stage. Theconsisted of three irrigation levels (100, 80, 60 percent of full irrigation) and water stress in five levels (full irrigation and irrigation-off at the 8 and 12 leaf, the tasselling and milky stages). Irrigation treatments implement at 4-5 leaf stage (seedling establishment) and continued until 10 days before physiological maturity. The results indicated that leaf rolling percentage increased as drought stress intensified, but grain yield and other leaf indices (relative water content and chlorophyll a and b concentration) were reduced. The highest leaf rolling percentage by the average of 67% obtained from 60 percent of full irrigation with irrigation-off at 12 leaf stage. The lowest leaf rolling percentage belonged to full irrigation with no water stress in cropping season by the average of 9%. The highest chlorophyll a and b concentration, obtained from full irrigation with no water stress in cropping season by the average of 3.1 and 1.1 mg/g respectively. The lowest chlorophyll a and b concentration, belonged to 60 percent of full irrigation with irrigationoff at tasselling stage by the average of 1.7 and 0.5 mg/g respectively. The highest and lowest relative water content, obtained from full irrigation with no water stress in cropping season by the average of 90% and 60 percent of full irrigation with irrigation-off at tasselling stage by the average of 64% respectively. The highest and lowest grain yield belonged to full irrigation without irrigation-off stress by the average of 7500 kg/ha and 60 percent of full irrigation with irrigation-off at tasselling stage by the average of 490 kg/ha respectively. According to the results of this research and due to the extreme sensitivity of the physiological characteristics in water stress conditions, and the relationship of these traits with grain yield, it is necessary to prevent the occurrence of water stress at critical stages of plant growth.