Tribune COMMENTS ON THE DIFFICULTY IN BREEDING BANANAS AND PLANTAINS FOR RESISTANCE TO NEMATODES

Like in many other agricultural crops, incorporation of resistance through plant breeding is an advantageous form of nematode control. The high costs of nematicide applications and the negative consequences that sometimes result from residue accumulation in the environment plus the dangers of maintaining such important crops as bananas and plantains on a reduced genetic base, should be sufficient reasons to encourage genetic improvements (Gowen, 1979). In bananas and plantains, this task has not been easy. Few attempts have been made because of the difficulty of working with a host that genetically is very complex (Simmonds, 1966; Shepherd, 1968; Rowe, 1984; Stover & Buddenhagen, 1986). The main problem in incorporating genes for nematode resistance is that many important features are bound to be altered or lost during the breeding process, such as plant size, bunch size, fruit disposition, taste, maturity, shelf life, resistance to diseases, speed of growth and others. The high cost of a breedhg program together with the many years involved have also been major obstacles. Almost al1 commercially grown bananas are similar genetically, the majority belonging to the Cavendish subgroup which are triploids, also known as M u s a A A A . Plantains AAB and ABB tend to show similar genetical variability. Al1 known Musa AAA and the majority of AAB and ABB clones are susceptible to Radopholus similis (Cobb) Thorne and Pratylenchus coffeae (Zimmermann) Filipjev & Schuurmans Stekhoven, the two nematodes of major concern in banana and plantain production in Central America and the Caribbean (Wehunt & Edwards, 1968; Stover, 1972; Roman, 1978; Tarte & Pinochet, 1981). Up to date there has been no commercial banana or plantain cultivar released specifically for resistance to these nematodes, although interesting work has been done (Rowe & Richardson, 1975; Gowen, 1976; Pinochet & Rowe, 1978; Wehunt, Hutchinson & Edwards, 1978; Pinochet & Rowe, 1979). This note deals with the complexity involved in breeding for nematode resistance in Musa species taking into account the research requirements for the Central American region.