Effects of infection with narcissus mosaic, narcissus yellow stripe and tobacco rattle viruses on the growth and flowering of narcissus cv. 'Minister Talma'

Three plots were planted with similar-sized narcissus bulbs: healthy; infected with narcissus mosaic virus (NMV); and infected with narcissus yellow stripe + tobacco rattle virus (NYSV+TRV). No effects of infection were observed on flower number, diameter, paracorolla length or flower dry weight, but the flower stalks were shorter in the infected plants. NMV-infected plants produced slightly blemished flowers, and 74% of the NYSV + TRV-infected flowers were of poor quality. Virus infection delayed leaf growth and loss of bulb dry weight early in the season and senescence in July. NYSV+TRV-infected plants were more affected than NMV-infected plants. However, maximum leaf area was similar for all plants. The maximum plant dry weight and the final weight of the bulb were not significantly affected by infection, but small differences, which could be cumulative in successive years would not have been detected. Differences in net assimilation rate, if any, were small.