Improving In Vitro Somatic Embryos Production of Medjool and Khalas Date Palm Cultivars via Modification of Ammonium and Potassium Nitrate

Abstract

Date palm is one of the most economically powerful fruit tree grown in Egypt. Although Egypt tops the list of date's product in the world. Egyptian date palm industry suffers from many constraints. Low-quality varieties and limited conventional propagation methods are the main obstacles. Extension of date palm plantations in various areas of Egypt and replanting trees to compensate loss due to diseases or human factors are reduced expected to lack adequate planting materials. The knowledge of the interplay between some fundamental medium parameters allows not only the optimization of the micropropagation system but also gives models to investigate and rationalize the process of induction and development of somatic embryogenesis itself. In vitro growth and development of produced embryos and plantlets has been improved by using of full MS salt strength. MS medium modification of some nutrients concentrations, i.e. NH4NO3(1237.5 mg/l) which recorded (13.20 and 9.60 embryos/explant for Medjool and Khalas respectively) at the end of three subculture. KNO3 which gave a higher score of mature somatic embryos (14.40 and 10.00 embryo/culture for Medjool and Khalas respectively) was obtained with 1425 mg/l KNO3 after three subcultures as compared to those obtained from any other treatment combination. The morphological response of somatic embryos production is controlled by some internal factors that fall under the influence of the genetic make-up of the plant and specialized for each genotype that is responsible for the production of somatic embryos (Medjool and Khalas cultivars). The genetic make-up is a decisive factor during somatic embryos production. There are differences between the two cultivars named, Medjool and Khalas. The produced somatic embryos at germination stage were transferred from the two experiments namely ammonium nitrate and potassium nitrate to multiplication and rooting stages for more in vitro growth for 12 weeks at three re-cultures. Individual shoots were cultured on modified MS basal medium in addition to IBA (1.0 mg/l), sucrose (30 g/l) and solidified with phyto-agar (8.0 g/l) for more in vitro growth and development. In vitro plantlets were transferred to acclimatization stage in plastic pots 5*18 cm diameter containing peatmoss, perlite and washed sand at equal volume. In vitro date palm plantlets produced from rooting stage grow well in the greenhouse during acclimatization stage without morphological abnormality. The growth and development of Medjool cultivar were better than Khalas during in vitro culture and ex vitro acclimatization.