Resistance to the rice nematodes Heterodera sacchari, Meloidogyne graminicola and M. incognita in Oryza glaberrima and O. glaberrima X O. sativa interspecific hybrids
Plowright, R.A.; Coyne, D.L.; Nash, P.; Jones, M.P.
Nematology 1(7-8): 745-751
ISSN/ISBN: 1388-5545 DOI: 10.1163/156854199508775
Rice species Oryza glaberrima and O. sativa and interspecific hybrids produced at the West African Rice Development Association in Cote d'Ivoire, were screened for resistance to Heterodera sacchari, Meloidogyne graminicola and M. incognita R2. H. sacchari screening was done in field and pot experiments in Cote d'Ivoire. Non-indigenous species were screened in glasshouse tests in the UK. All O. glaberrima genotypes were resistant to H. sacchari from Cote d'Ivoire and Ghana, M. graminicola from the Philippines and M. incognita R2. In pot tests, the number of females which developed on these genotypes was zero for H. sacchari and < 3 for both species of Meloidogyne. Within lines of O. sativa, variation in female numbers (P ltoreq 0.05) was observed, but all were susceptible both to H. sacchari and to M. graminicola. However, six cultivars and lines of O. sativa were less susceptible (P ltoreq 0.05) to M. incognita R2 than the check cultivar IDSA 6. Of 14 progeny from O. sativa cv. WAB56-104 X O. glaberrima line CG14, two WAB450-I-B-P-105 and WAB450-I-B-P-160, were resistant to H. sacchari from Cote d'Ivoire. These lines and two others were also less susceptible (P ltoreq 0.01) to M. graminicola than the O. sativa parent. The susceptibility of some of the progeny to both H. sacchari and M. graminicola and M. incognita was the same as that of the O. sativa parent. Of ten further progeny, screened against H. sacchari from Ghana, WAB450-25-1-10 was resistant. The expression of resistance in the interspecific progeny suggests that resistance to H. sacchari is qualitative, whilst that to Meloidogyne graminicola is quantitative. Resistance to M. incognita R2 was found in O. glaberrima, O. sativa and in one hybrid progeny. None of the species or progeny was resistant to Pratylenchus zeae and there were no significant differences in field population densities of P. zeae, Mesocriconema onoensis or Helicotylenchus dihystera.