the drought inducer (PEG 60000
experimental design
factorial ..five varieties by 5 drought stress levels in three replicates
Hi, Laston
There are various methods depending on your aim.
Whether you are going to just screen the sesame genotype against drought or to check Morpho-Physiological parameter.
@ Germination stage
Use different concentration of PEG-6000 (file attached) start from control 0%, 5%, 10, 15%, 20%, 25% with respect to the osmotic potential.
First of all sterilize the seed
Seeds of each genotype (sterilize) immersion in a sodium hypochlorite(.1%) solution for 5 min. Then wash the seed five times with sterilized distilled water
Germinate the seed on petri dish (150*15mm) covered the bottom with two sheets of Whatman (whatman No. 1 filter) paper that should be autoclaved.
After some days count the germination percentage= germinated seed/ total seed x100
For example, if you planted 50 sesame seeds and 35 seeds germi- nated, you would write 35/50 = 70/100 = 70%. The germination rate is 70%.
you can also fix the LD50 for your sesame genotype.
@ Seedling stage use natural water holding treatments or treatments at different :100% field capacity,75% field capacity,50%field capacity, and 25% field capacity for few weeks with respect to germination percentage.
Regards
I hope it can be useful to you.
Pravin has very nicely listed out the procedure that you can follow, just see whether you are comfortable with the number of sets with different PEG concentration.
I beg to differ. Drought means osmotic pressure and osmotic pressure means some critical identifiable volume which no one bothers to do. There is massive confusion in literature about osmotic flux, associated with cell volume fluxes, osmotic compression associated with inhibition of electron transport , dehydration associated with structural changes and other effects such as changes in dielectric due to detergency, a common contaminant of PEG an awful method that allows no discrimination of any kind. researchgate has most of my papers on this with full methodological and theoretical details. Please forget shorthand methods like field capacities. It is ridiculous to germinate 50 seeds where the counting error is of the order of 1000%. We germinate 1-2000 seeds , keep good statistics. Also remember nearly all plant people use wrong stats. Osmotic responses are non-linear, which is one of the most formidable problems in statistical inference in spline regressions. We solved the relevant math stats and computer programmes are available with us , also published.
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