SCREENING OF ONION CULTIVARS FOR RESISTANCE AND TOLERANCE TO PRATYLENCHUS PENETRANS AND MELOIDOGYNE HAPLA

Pang, W., S. L. Hafez, and P. Sundararaj. 2009. Screening of onion cultivars for resistance and tolerance to Pratylenchus penetrans and Meloidogyne hapla. Nematropica 39:47-55. Greenhouse experiments were conducted to evaluate commercially grown onion cultivars for resistance and tolerance to Pratylenchus penetrans and Meloidogyne hapla. Onion seedlings of cv. Tioga, Orizaba, Caveat, Citation, Vision, R10 Tinto, Sanfan, Sweet Sunrise, Nirvana, and Mercury were inoculated with female adults and juveniles of P. penetrans or second stage juveniles of M. hapla at four nematodes/cm3 soil, respectively. Eight weeks after inoculation plants were harvested and resistance and tolerance were evaluated based on nematode reproductive factor and the reduction in onion total plant dry weight. Cultivars Mercury, R10 Tinto, and Caveat were both tolerant and resistant to P. penetrans infection. Caveat has the best tolerance to P. penetrans. Mercury and R10 Tinto were both tolerant and resistant to M. hapla, and they were tolerant and resistant to both nematode species. Sanfan and Sweet Sunrise were susceptible to P. penetrans, whereas Tioga, Citation, and Vision were susceptible to M. hapla. No cultivar tested was susceptible to both nematode species. Cultivars with both tolerance and resistance can be used as a standard for future screening and are potential cultivars for nematode management in field production.