Increament and decrement effects of nitrogen sources on in vitro shoot growth traits of Aspen (Populus tremula L. )

Document Type : Research Paper

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Abstract

    European aspen (Populus tremula L.) is an adapted species of Populus genus in Iran which is propagated by micropropagation techniques. It seems necessary to increase the efficiency of the medium by giving appropriate balance between two main different nitrogen ionic sources. Total mineral nitrogen content (TNC) of ACM medium was changed into different concentrations of 0.5, 1 and 1.5. TNC treatments were defined as: 1- control NH4+: NO3- 1:2, 2 - NO3- without ammonium ions, and 3 -  NH4+: NO3-- 1:1. Effects of mentioned treatments were determined at the end of subculture on several morphological traits such as shoot length, number of lateral shoots, leaf number, green intensity, fresh weight, and dry weight of in vitro shoots. Using half-TNC in ACM medium resulted in acceptable shoot length and the highest fresh and dry shoot weight. Increasing TNC concentration to 1.5 or decreasing to 0.5 was reflected in inhibition of shoot initiation but no statistical significant differences was observed between NH4+: NO3-- 1:1 treatment and the control. Most green intensity was recorded in 1.5 TNC of ACM medium with NH4+: NO3-- 1:1 treatment. This research showed that decreasing to half-TNC in the aspen basic media improved shoot length, as the most determinant trait of in vitro mass propagation of aspen micropropagation.

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