How can I use R software to calculate LT50 for freezing stress in plant?

Question

[yazdanpanah.parisa]

I'm a beginner in the R program and I plan to calculate the lethal temperature (LT50) to study the effects of freezing stress. Is there anyone who can help me about their package and scripts?

Answer 1

[Michael]

This depends on the data you have, however let's assume you have the following setting:

• You observed 100 plants in temperature range 30 to -30 degrees. For each plant, you record the temperature at which the plant died (Not sure if that is easy or not).
• Then you simply run function quantile(plant.death.temp) or median, given plant.death.temp is the vector of temperatures for each plant; the 50% quantile should be your LT50.

[yazdanpanah.parisa]

Thank you for your fast answer. My samples are pomegranate stems that collected in four months during one year. For per month, stem samples from 15 genotypes were treated with six temperatures (5, 0, -5, -10, -15, -20) with three replicates and then electrolyte leakage were recorded before and after autoclaving. In papers, there is a formula REL=a/(1+eb(x-c))+d for calculating LT50, but I want use R. I desperately thought of seeking your assistance, and I will greatly appreciate it. Thank you for helping me in advance.

[Michael]

I am sorry, I am no expert with this topic and I don't quite get what a,b,c,d,e, and x mean in your equation, also this is not exactly bioinformatics, but I will ask around. There might be people doing these kinds of experiments in the sea lice centre too.

However, if you have all the values for your variables already, you can simply copy the equation above into R and use it as a calculator.

Answer 2

[yazdanpanah.parisa]

Thank you for your fast answer. My samples are pomegranate stems that collected in four months during one year. For per month, stem samples from 15 genotypes were treated with six temperatures (5, 0, -5, -10, -15, -20) with three replicates and then electrolyte leakage were recorded before and after autoclaving. In papers, there is a formula REL=a/(1+eb(x-c))+d for calculating LT50, but I want use R. I desperately thought of seeking your assistance, and I will greatly appreciate it. Thank you for helping me in advance.