the effect of plant density on extinction coefficient and radiation use efficiency in modern and old wheat (triticum aestivum l.) genotypes

to achieve optimal yield and high production in wheat, need to adapt the plant's vegetative and reproductive growth stages to environmental conditions and increase use efficiency of production factors by desirable density. in order to study the effect of plant density on extinction coefficient and radiation use in modern and old wheat (triticum aestivum l.) genotypes, an experiment was conducted on the agricultural research farm located in gorgan city using three density levels (150, 262 and 375 plant per meter square) and three wheat- genotypes (falat, tajan, n-81-18) during 2007-2008. the experiment was conducted with factorial arrangement based on randomized complete block design, with 4 replications. results showed that the highest amount of lai and dm was obtained in n-81-18 line and 375 plant in meter square, also plant density and genotype was not effect on the extinction coefficient, but just plant density effects on radiation use efficiency. in such a way that the highest amount of radiation use efficiency is for n-81-18 line in 375 plant in meter square.