ﺮرﺳﯽ ﺗﺎﺛﯿﺮ ﮔﯿﺎه ﭘﻮﺷﺸﯽ و زﻣﺎن ﮐﺎﺷﺖ آن ﺑﺮ ﺟﻤﻌﯿﺖ ﻋﻠﻒﻫﺎيﻫﺮز و ﻋﻤﻠﮑﺮد ذرت در دو ﻧﻈﺎم ﮐﻢ ﺧﺎكورزي و ﻣﺮﺳﻮم

The Effect of Cover Crops and Time of Sowing on Weed Population and Corn Yield in Two Minimum and Conventional Tillage Systems

ﺑﻪ ﻣﻨﻈﻮر ﺑﺮرﺳﯽ ﺗﺎﺛﯿﺮ ﮔﯿﺎه ﭘﻮﺷﺸﯽ و زﻣﺎن ﮐﺎﺷﺖ آن ﺑﺮ ﺟﻤﻌﯿﺖ ﻋﻠﻒﻫﺎيﻫﺮز و ﻋﻤﻠﮑﺮد ذرت در دو ﻧﻈﺎم ﮐﻢ ﺧﺎكورزي و ﻣﺮﺳﻮم، آزﻣﺎﯾﺸﯽ ﺑﺎ ﮐﺸﺖ ﻣﺎﺷﮏ ﮔﻞ ﺧﻮﺷﻪاي، ﺷﺒﺪر اﯾﺮاﻧﯽ، ﭼﺎودار و ﺷﺎﻫﺪ )ﺑﺪون ﮔﯿﺎه ﭘﻮﺷﺸﯽ، ﺑﺪون وﺟﯿﻦ ﻋﻠﻒﻫﺮز( در ﺳﻪ ﺗﺎرﯾﺦ ﮐﺎﺷﺖ )1 ﻣﻬﺮ، 15 ﻣﻬﺮ و 30 ﻣﻬﺮ( ﺑﺎ ﮐﺸﺖ ذرت رﻗﻢ زودرس )108( در ﺷﺮاﯾﻂ ﮐﻢ ﺧﺎكورزي )در ﺳﺎل1392-1393( و ﮐﺸﺖ ذرت رﻗﻢ دﯾﺮرس )704( در ﺷﺮاﯾﻂ ﺧﺎكورزي ﻣﺮﺳﻮم )در ﺳﺎل 1394-1393( در ﻣﻮﺳﺴﻪ ﺗﺤﻘﯿﻘﺎت اﺻﻼح و ﺗﻬﯿﻪ ﻧﻬﺎل و ﺑﺬر ﮐﺮج اﻧﺠﺎم ﮔﺮﻓﺖ. ﻧﺘﺎﯾﺞ ﻧﺸﺎن داد در ﻫﺮ دو ﺳﺎل در اوﻟﯿﻦ ﺗﺎرﯾﺦ ﮐﺎﺷﺖ، ﮔﯿﺎﻫﺎن ﭘﻮﺷﺸﯽ ﺑﺎ ﺗﻮﻟﯿﺪ زﯾﺴﺖ ﺗﻮده ﺑﯿﺸﺘﺮ، ﺟﺬب ﻧﯿﺘﺮوژن، ﺗﻮﻟﯿﺪ ﺑﻘﺎﯾﺎ و در ﻧﺘﯿﺠﻪ ﺗﻮﻟﯿﺪ ﻣﻮاد آﻟﯽ ﺑﯿﺸﺘﺮ و اﻓﺰاﯾﺶ ﺣﺎﺻﻠﺨﯿﺰي ﺧﺎك ﭘﺲ از اﻧﺠﺎم ﺧﺎﮐﻮرزي، ﻣﻮﺟﺐ ﺑﻬﺒﻮد ﺷﺮاﯾﻂ در ﺟﻬﺖ رﺷﺪ ﮔﯿﺎه ذرت و ﻋﻠﻒﻫﺎيﻫﺮز ﺷﺪه وﻟﯽ در ﺗﺎرﯾﺦ ﮐﺎﺷﺖﻫﺎي دوم و ﺳﻮم اﺣﺘﻤﺎﻻ ﻣﺤﺪودﯾﺖ ﻣﯿﺰان ﻧﯿﺘﺮوژن ﺧﺎك ﻣﻮﺟﺐ ﮐﺎﻫﺶ ﻋﻤﻠﮑﺮد و اﺟﺰاي ﻋﻤﻠﮑﺮد ذرت و رﺷﺪ ﻋﻠﻒﻫﺎيﻫﺮز ﮔﺮدﯾﺪ. در ﺷﺮاﯾﻂ ﮐﻢ ﺧﺎكورزي ﭼﺎودار )34 درﺻﺪ( و در ﺧﺎﮐﻮرزي ﻣﺮﺳﻮم، ﻫﺮ ﺳﻪ ﮔﯿﺎه ﭘﻮﺷﺸﯽ )ﺑﻪ ﻃﻮر ﻣﯿﺎﻧﮕﯿﻦ 53 درﺻﺪ( ﻣﻮﺟﺐ ﮐﺎﻫﺶ زﯾﺴﺖ ﺗﻮده ﻋﻠﻒﻫﺎيﻫﺮز ﮔﺮدﯾﺪﻧﺪ. ﺑﻄﻮر ﮐﻠﯽ ﺑﯿﻦ دو ﺳﯿﺴﺘﻢ ﺧﺎﮐﻮرزي، درﺻﺪ ﮐﺮﺑﻦ آﻟﯽ در ﮐﻢ ﺧﺎكورزي ﺑﯿﺸﺘﺮ از ﺧﺎكورزي ﻣﺮﺳﻮم ﺑﻮد. از ﻧﻈﺮ ﻧﯿﺘﺮوژن ﺟﺬب ﺷﺪه در ﻫﺮ دو ﻧﻮع ﺧﺎﮐﻮرزي اﻧﺠﺎم ﺷﺪه ﺑﯿﺸﺘﺮﯾﻦ ﻣﯿﺰان ﻣﺮﺑﻮط ﺑﻪ ﺗﯿﻤﺎر ﭼﺎودار ﺑﻮد. ﻋﻤﻠﮑﺮد داﻧﻪ ذرت رﻗﻢ زودرس ذرت در ﺗﯿﻤﺎر ﻣﺮﺑﻮط ﺑﻪ ﭼﺎودار )5/304 ﺗﻦ ﺑﺮ ﻫﮑﺘﺎر( در ﮐﻢ ﺧﺎكورزي و ﻋﻤﻠﮑﺮد داﻧﻪ رﻗﻢ دﯾﺮرس ذرت در ﺗﯿﻤﺎر ﺷﺒﺪر اﯾﺮاﻧﯽ )9/298 ﺗﻦ ﺑﺮ ﻫﮑﺘﺎر( در ﺧﺎكورزي ﻣﺮﺳﻮم ﺑﯿﺸﺘﺮ ﺑﻮد.

In order to study the effect of cover crops and sowing time on weed population and corn yield in minimum an conventional tillage systems, an experiment was conducted in the Seed and Plant Improvement Research Institute, Karaj, using Vicia villosa (V), Trifolium resupinatum (T) and Secale cereale (S) as cover crops, plus control (no cover crops, allowing weeds to grow). The cover crops were planted at three different dates of September 23rd, October 7th and October 27thin a corn field. In the first year (2013-2014) early ripening corn (Var. 108) was planted under minimum tillage. In the second year (2014-2015) late ripening corn (Var. 704) was planted under conventional tillage. Results indicated that the first cover plant sowing time was favorable in both years. This was mostly due to nitrogen availability of the soil which resulted in higher grain yield and better weed growth. Under minimum tillage, S reduced weed biomass by 34%. Under conventional tillage system, all the cover crops reduced weed biomass by 53%. Generally, percentage of organic carbon was higher in minimum tillage than in conventional system. S showed highest nitrogen uptake among the three cover crops in both tillage systems. In minimum tillage, the highest corn yield was under S cover crop with 5.304 t/ha. In conventional tillage, the highest corn yield was under T cover crop with 9.298 t/ha.