EVALUATION OF EMBRYO RESCUE MEDIA ON GERMINATION AND PLANTLET DEVELOPMENT IN MANDARINS (Citrus reticulata)

Morocco is one of the major exporting Country or small citrus fruits. However, the varietal profile is restricted and dominated by the early clementine. For that reason, the variety diversification has become one of the main objectives of the citrus genetic improvement program. In the same sense, our study focuses on optimizing the production of good quality triploid mandarin hybrids with late maturity. The embryo rescue is the crucial step in this program. For this purpose, three culture media were tested for increasing the in vitro germination of immature embryos of four varieties of late mandarins (Nadorcott, Ortanique, Murcott Honney and a variant of Murcott (mandarin 104)). At the maturity stage, the fruits were harvested to extract the seeds. Only abnormal seeds have been cultured in three culture media, the basic medium of which is that of Murashig and Tucker (MT): (M1 at 1 mg / L GA3), (M2 at 0.5 mg / L NAA; 0.5 mg / L BAP and 0.1 mg / L Kinetin) and (M3 at 25 mg / L Adenine Sulfate). According to the culture medium, the germination rate varied from 90% (M2) to 93% (M1). Also, it fluctuated from 89% (Ortanique) to 95% (Murcott Honney). This study showed that there is a difference between varieties and between media for all parameters studied (the rate and the interval of germination, the root and aerial development, and the rate of acclimatization). Likewise, M1 remains the best for the success of embryos rescue program for mandarins. While, M3 allowed a rate of germination and a significant average number of leaves for all the varieties studied. However, this medium was not able to develop adequate roots for acclimatization. Seedlings from embryo rescue will be analyzed by flow cytometry and only triploids will be tested for varietal behavior in different citrus sites in Morocco.