In vitro germination of date palm somatic embryos and conversion into plants under dark culture conditions: novel protocol to reducing the time and production costs

All of previous studies germinated the somatic embryos of date palm under light while neglecting germination under darkness that mimics germination in nature under soil. Studying the effect of light and darkness on the germination of somatic embryos led to the development of a modified protocol for inducing date palm somatic embryo germination and conversion into plants. Two types of somatic embryos were obtained, individual somatic embryos with bipolar structures and cluster primary embryos that multiplied to the cluster somatic embryos. The cluster embryos produced cluster shoots up on germination, while individual embryos developed into a single plantlet. The cluster somatic embryos that germinated in the dark exhibited sustained and vigorous growth, leading to the formation of long etiolated stems with thin leaves. Germination under darkness significantly shortened the conversion period of cluster somatic embryos into plants from 20 weeks, when using light, to only 7 weeks for both germination and elongation in one stage. Moreover, the plants incubated in the dark had the greatest percentage of rooting and plant acclimatization. Taken together, these results led to the development of an efficient new and simple protocol for date palm micropropagation, which led to improved germination and growth and significantly reduced time and costs.