عنوان مقاله [English]
نویسنده [English]چکیده [English]
Background and objectives: Availability and uptake of mineral by explants are recognized as being important in tissue culture. The limiting factor for maximum mineral uptake and optimum growth is that minerals are not enough available to the explants. There are the inter-relationships between plant growth, mineral uptake, medium water potential, and mineral movement through the medium. Plantlets growth with increasing agar concentration in plant tissue culture medium decreased due to various potential water that creates. Despite importance of mineral uptake in vitro is an indispensable part for plantlet growth in vitro, to date, less attention has been paid to the control of mineral uptake and aspects of transporting of ions and the role of water potential in mineral diffusion in the culture medium. But, this work can be used to better understand of effects of different agar concentrations on growth and mineral availability of explants.
Materials and Methods: For explant preparation, one year mature dormant shoots were used. After proliferation, three uniform explants (approximately 20 mm in length) were subcultured on same proliferation medium with different concentrations of agar [0 (as liquid medium), 3, 5, 7, 10 and 14 g l-1] foe six weeks. The experiments were set up in a completely randomized design (CRD) with four replicates. Data were collected (growth parameters and mineral) at the end of experiment (6th weeks). After data collection statistical analysis was performed using MSTAT-C program and Means were separated according to the least significant difference (DMRT) at 0.05 level of probability and charts were drawn by Excel 2007 software.
Results: Results showed that growth parameters such as fresh weight, dry weight, water content, shoot number, shoot length, leaf number increased significantly (P=0.05) to 5 g/l agar. Chlorophyll index slightly decreased compared to control at high concentrations of agar. The highest concentrations of macro elements (N, P, K, Mg, Ca) and micro elements (Zn, Fe, Mn, Cu) were obtained in 0.11 MPa water potential and lowest concentrations of mineral in 0.98 and 1.15 MPa water potential. GF677 was a capable rootstock for N uptake. Maximum height of plants was obtained in liquid treatment and best growing conditions and proliferation in 3 and 5 treatments, respectively.
Conclusion: In this experiment, optimum agar concentration for growth and proliferation of GF677 was 3 to 5 gl-1. At concentration of 3 g the highest proliferation and best growth and proliferation conditions was obtained in 5 g than the higher agar concentrations. Of course, at 3 g concentration of agar to prevent the vitrification explants must be transferred to new media after culture and proliferation and higher concentration of 7 g/l agar for this plant is not recommended.