1. a Department of Agronomy , University of Natal , P.O. Box 375, Pietermaritzburg , 3200 , Republic of South Africa
2. b Cedara College , Private Bag X9059, Pietermaritzburg , 3200 , Republic of South Africa
3. c Grain Crops Research Institute, Summer Grain Sub-Centre , Private Bag X9059, Pietermaritzburg , 3200 , Republic of South Africa