Acceleration of Callus Formation in Date Palm (Phoenix dactylifera L.) Zygotic Embryos

Abstract

This study was carried out to test the effect of water soaking of
seeds of date palm ( P. dactylifera L.) as a pre-empryo excision treatment,
on in vitro culture of zygotic empryos. The objective was optimization of
organogenic callus formation. Mature seeds of “Barakawi” and “Mishrig
Wad Laggi” date palm cultivars were used as sources of embryos.
Durations of 0- up to 9-days of seed water soaking, prior to embryo
excision and culture, were tested. Murashige and Skoog (1962) medium
was used as basal medium. The cultures responded positively to the water
soaking treatments and resulted in the organogenic responses of swelling,
germination, callus and adventitious roots formation were obtained. The
magnitude and type of response varied with cultivar and soaking duration.
All water soaking treatments increased the measured responses relative to
the control. The results showed that a 6-day soaking treatment was
optimal for all measured responses compared with the other periods of
soaking tested. Calli formation in 6-day water soaking treatment were
50% and 70% for “Barakawi” and “Mishrig Wad Laggai” ,respectively.
However, increasing the soaking duration beyond the 6-day had a marked
negative effect on morphogenic response regardless of cultivar. The best
results for all measured parameters were obtained with embryos of
“Mishrig Wad Laggi” compared with embryos excised from “Barakawi”.
It seems that soaking date palm seeds in water prior to embryo excision
play an important role, in enhancing morphogenic response and callus
formation in date palm tissue culture.