Full Length Research Paper

Allelopathic potentials of residues of 6 brassica species on johnsongrass [Sorghum halepense (L.) Pers.]

Ilhan Uremis¹*, Mehmet Arslan², Ahmet Uludag³ and Mustafa Kemal Sangun⁴

¹Mustafa Kemal University, Faculty of Agriculture, Department of Plant Protection, Hatay/Turkey.

²Mustafa Kemal University, Faculty of Agriculture, Department of Field Crops, Hatay/Turkey.

³Bornova Plant Protection Research Institute, Izmir/Turkey.

⁴Mustafa Kemal University, Faculty of Science, Department of Chemistry, Hatay/Turkey.

*Corresponding author. E-mail: iuremis@yahoo.com.

Tel.:+90(326)245 5845. Fax:+90 (326) 245 5832.

Accepted 19 May, 2009

   Abstract

Johnsongrass (Sorghum halepense (L.) Pers.) is a troublesome weed species of many crops in Turkey as well as worldwide. Allelopathic potential of residues of some brassica species, which are round white radish (Raphanus sativus L.), garden radish (R. sativus L.), black radish (R. sativus L. var. niger), little radish (R. sativus L. var. radicula, turnip (Brassica campestris L. subsp. rapa) and rapeseed (Brassica napus L. oleifera DC.) on johnsongrass were investigated under both laboratory and field conditions. All species suppressed johnsongrass in field and laboratory conditions. The lowest suppression was from garden radish, which has already been used to control johnsongrass by few farmers in Turkey. It is concluded that the plants studied can be used to control johnsongrass. Higher amount of isothiocyanates (isothiocyanate benzyl, Isothiocyanate allyl) in black radish extract and lower amount of isothiocyanates at garden radish extract were determined. Parallel results for johnsongrass suppression and amount of isothiocyanates show that allelopathy play roles in johnsongrass suppression by brassica species.

Key words: Johnsongrass, round white radish, garden radish, black radish, little radish, turnip, rapeseed, Brassicaceae.