I screened my melon accessions. I want to categorize them in to different groups based on there resistance like highly resistant, resistant, moderately resistant, etc..
Fusarium wilt was determined as % disease plants by the following produre .In each pot, a plastic grid was placed at the bottom to prevent the soil from escaping; 20 mL of autoclaved perlite was also added to allow water drainage. After that, 100 mL of Fusarium-infested soil was added and covered with a 2 mm layer of autoclaved perlite to prevent pre-emergence damping off. each pot was seeded with 3–5 melon seeds and a second layer of autoclaved perlite was added as a cover. After emergence, one seedling was maintained per pot. The pots were placed in plastic boxes on three layers of mesh and the control treatment pots were protected from contamination from splashing irrigation water. Plants were incubated in a growth chamber at 25°C, with a 15 h photoperiod or greenhouse . Plants were irrigatedwith deionized water each day. Wilted plants were identified by observing the discoloration in the vascular systems, which was done by making horizontal sections
in the stem. The numbers of wilted plants were recorded twice a week after sowing from week 3 to week 8, and were removed. The fresh weight of the unwilted plantswas measured at the end of each assessment date.
Thank U for your attention. But I want to know the scale like
0-10% = Highly Resistant
10.01-25% = Moderately Resistant...
Like wise, I need scale.
Generally, disease symptoms are rated according to their incidence and/or their severity. Incidence is usually given as a percentage of plants (or plant parts) affected, while severity is often rated on a scale from 1 to 9 (direction depends on your perspective, I prefer 9 to represent the most severe). Larry Madden has given a good presentation on the topic in general (For soybean rust, but generally applicable. linked below).
It is important to note that for Fusarium wilt in melon, these ratings would only be meaningful in the absence of the qualitative resistance genes Fom1, Fom2, Fom3, and/or Fom1.2 (depending on which races are active in your area).
What I mean is that if you observe x% mortality in an accession, it may be more likely that a qualitative resistance gene is segregating than that the accession is "moderately resistant". Progeny testing the survivors may help determine if that is the case.
I would expect a "true" moderate resistance phenotype to be slower symptom progression and/or delayed mortality of infected plants (relative to a control) rather than a lower frequency of mortality, but I could be wrong.
Best of luck with your screening and categorization!
http://www.plantmanagementnetwork.org/infocenter/topic/soybeanrust/2006/presentations/Madden.pdf
There have been many papers are there.
http://www.fupress.net/index.php/pm/article/viewFile/2245/2166
I followed Liu et al., 1995
http://www.apsnet.org/publications/phytopathology/backissues/Documents/1995Articles/Phyto85n06_695.PDF
Plants are classified as very resistant, when the level of mortality is ranged between 0-15 %, resistant , if the percent of infested plant varied from 16-30% and considered as suaceptible when presented more than 30% diseased plant
Hi Sayeed
https://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=5&cad=rja&uact=8&ved=2ahUKEwiBpqn_9c_fAhWL2KQKHd6QDdYQFjAEegQIBxAB&url=https%3A%2F%2Fapsjournals.apsnet.org%2Fdoi%2Fpdf%2F10.1094%2FPDIS-03-13-0217-RE&usg=AOvVaw3ReUPdC7e2sRZJYk6N1oxt
Ref.2
https://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=7&cad=rja&uact=8&ved=2ahUKEwiBpqn_9c_fAhWL2KQKHd6QDdYQFjAGegQICBAC&url=http%3A%2F%2Fwww.calstrawberry.com%2FPortals%2F2%2FReports%2FResearch%2520Reports%2FAnnual%2520Production%2520Research%2520Reports%2FAnnual%2520Production%2520Research%2520Reports%25202011%2F2011-12_Chapter1_TomGordon_Vert_Fus.pdf%3Fver%3D2018-03-01-145023-270&usg=AOvVaw0m90cgLqsCvJnbKwFj_WyA
Ref.3
https://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=9&cad=rja&uact=8&ved=2ahUKEwiBpqn_9c_fAhWL2KQKHd6QDdYQFjAIegQIBBAC&url=https%3A%2F%2Fir4.rutgers.edu%2FFooduse%2FPerfData%2F1953.pdf&usg=AOvVaw2Il2a4ReKUEqRFxLaroIjD
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