Screening for susceptibility and tolerance to Meloidogyne incognita and M.javanica in okra cultivars in Iraq
الباحث الأول:
Basil H. Kandouh
الباحثين الآخرين:
A. E. Hasan, A. M. Abd-Alrasoul and B. S. Sipes
المجلة:
Arab Journal of Plant Protection
تاريخ النشر:
None
مختصر البحث:
Ten okra cultivars were screened for their susceptibility (resistance) and tolerance to the Root-knot nematodes Meloidogyne incognita and M. javanica in a two trial experiment under the ambient condition. Okra seedlings at 14 days old were inoculate…
Ten okra cultivars were screened for their susceptibility (resistance) and tolerance to the Root-knot nematodes Meloidogyne incognita and M. javanica in a two trial experiment under the ambient condition. Okra seedlings at 14 days old were inoculated with 3000 egg/J2 of M. incognita or M. javanica. The nematode reproduction factor Rf (Rf= final population (Pf)/initial population (Pi)) was used to determine susceptibility or resistance among cultivars, cultivars considered highly susceptible if Rf ≥ 2, susceptible where 2 > Rf ≥ 1 or resistant with Rf < 1.While reduction in plant shoot weight (ShW) over the control indicated tolerance and categorized into tolerant, moderately tolerant and intolerant where the ShW reduction at < 10%, 10-20% and >20%, respectively. Most the cultivars tested were susceptible at various levels. Although Rf of M. javanica was always higher than that of M. incognita, but the plant growth (Shoot weight) was rather highly affected by M. incognita than M. javanica. Lahluba was the only resistant to both nematode species, tolerant to M. javanica but intolerant to M. incognita (>30% ShW reduction). Taiwan Hybrid F1 was resistant/intolerant (shoot and root weight were decreased) to M. javanica and susceptible/moderately tolerant to M. incognita. Although M. incognita infected Musoliya showed high rates of egg masses (EMR) and galling (GR), it was moderately resistant and highly tolerant. Betraa was the most susceptible to both nematode species with moderate tolerance to M. javanica and intolerance to M. incognita. Clemson Spineless was susceptible/tolerant to M. incognita despite of EMR, GR and Rf high values. All the other cultivars failed in the category of susceptible/intolerant. The galling index did not always reflect the reproduction index or the rate of shoot weight reduction. Nematode reproduction Rf was reliable as susceptibility-resistance indicator as well as the extent of ShW reduction for tolerance assessment. The sever root weight reduction due to nematode infection may also indicate plant intolerance. Different levels of resistance and tolerance to nematode infection can be found among okra varieties. Selecting okra cultivars resistant and tolerant to Meloidogyne spp. is an effective approach to maintain high yield, mitigate yield costs and manage the nematode.
