Disease reactions and yield performance of peanut genotypes grown under groundnut rosette and rosette-free field environments.
Experimental field conditions were established to determine the effect of groundnut green rosette (caused by groundnut rosette virus (GRV and its satellite RNA) and groundnut rosette assistor luteovirus (GRAV)) on susceptible and resistant groundnut genotypes. Test genotypes (8) were planted in alternate rows with susceptible genotype F 452.4 in which rosette-diseased plants, infested with viruliferous aphids (Aphis craccivora), were transplanted every 1.5 m. When disease incidence was high (90-100%) but severity was moderate (measured on rating scale of 1-5) in susceptible genotypes in 1988, only 9-10% of the resistant plants of RMP 12 and RG 1 showed very mild mottle. In 1989, when incidence in susceptible plants was 100% and disease was very severe, c. 87% of the resistant plants showed symptoms but only 2-5% had severe symptoms. In the rosette environment, seed yield was 33 times higher in resistant genotypes than in susceptible ones, and yields in general were comparable in the 2 groups under rosette disease-free conditions. It is concluded that RMP 12 and RG 1 are highly resistant to GRV and its satellite but not to GRAV, which causes no leaf symptoms by itself but is essential for aphid transmission of GRV and its satellite.