Environmental stresses such as erratic and insufficient rainfall, extreme temperatures,salinity, alkalinity, aluminium toxicity, acidity, stoniness and others limit yield and productivity of many cultivated crop plants.

Plants growing in saline soils face two problems, high salt concentrations in the soil solution (i.e., high osmotic pressure and correspondingly low soil water potential) and high concentrations of potentially toxic ions such as Cl- and Na+.  

Salt tolerance is a polygenic trait, its expression is affected by various genetic,developmental and physiological interactions within and between the plant, and interaction with the environments.

Salinity tolerance in okra at seedling stage was governed by both additive and non additive genetic effects.

Okra can tolerate 60 mM NaCl, if it increase more than 60mM germination percentage, root length and shoot length will be affected in early stage.   

It is sensitive to frost and extremely low temperatures.

For normal growth and development a temperature between 24°C and 28°C is preferred. At 24°C the first flower bud may appear in the third leaf axil while at 28°C it may appear in sixth leaf axil.

For faster plant growth still higher temperature helps though it delays the fruiting. But at higher temperatures beyond 40°–42°C, flowers may desiccate and drop, causing yield losses

For seed germination optimum soil moisture and a temperature between 25°C and 35°C is needed with fastest germination observed at 35°C. Beyond this range the germination will be delayed and weak seeds may not even germinate

Low precipitation.

Low relative Humidity.

High light intensity with with hot dry condition during seed ripening

Increasing difference between day & night temperature can reduce the seed yield considerably  

High night temperature favours in plant height.

High day temperature delay in flower development.

Medium day temperature and high R.H favours flower bud initiation.

Long day light produces only vegetative phase for nine months.

Low temperature and low light intensity reduce the pollen burst .

Hard seededness affect the seed germination
Very high temperature during pod development stage influence the hard seededness
To improve seed germination , soak the seed with GA3 or thiourea at 50-100 ppm for 24 hours at 25 oC before sowing the seeds.

Remedies of overcoming hard seeds  
Treat with H2S04 for 2-3 min.
Soaking the seeds in a water bath at 45°C for 1.5h improves germination