effects of two type of medium cultures, gibberellic acid and some physical factors on persian walnut (juglans regia l.) embryos germination

abstract in this experiment the effects of two type of medium cultures, gibberellic acid and dark/cold and light/warm culture conditions on mature embryos germination of a local cultivar of walnut were investigated. the mature fruits were collected at 22 weeks postanthesis and after disinfection the mature embryo along with cotyledon pieces were excised and then were cultured on mt and modified dkw medium cultures supplemented with different concentration of gibberellic acid. then, cultures were transferred on different culture conditions such as dark/cold (4±20c) and light/warm (25±20c with 16.5 h photoperiod) culture conditions. significant differences were observed between different medium cultures, gibberellic acid and physical factors. percentage of embryo germination and main shoot length was higher in modified dkw medium, dark/cold culture condition and 2 mgl-1 gibberellic acid than other treatments. the mt medium and dark/cold culture condition was very efficient for root proliferation than modified dkw medium and light/warm culture condition. in this experiment gibberellic acid have a negative effect on root growth, wherein main root length in 0 mgl-1 gibberellic acid was more than 2 mgl-1 gibberellic acid. percentage of embryos germination was higher when gibberellic acid and dark/cold treatments were simultaneously applied (%63.17 germination) as compared to those when applied separately.