coauthors Mr Somphanh Sakanphet, Upland Research Center; Mr Houmchitsavath Sodarak, Upland Research Center; Mr Sianouvong Savathvong, Souphanouvong University; Dr Outhai Soukkhy, Northern Agric.& Forestry College; Mr Bounkieng Souliyasak, Northern Agric., Forestry College; Mrs Khonpanh Kanyavong, Agriculture Research Center; Dr Jonathan Newby, The University of Queensland.