Effect of casein hydrolysate and paclobutrazol on embryogenesis of date palm (Phoenix dactylifera L.) cv. Nersy by in vitro culture

Abstract

Results showed that fresh and dry weight of primary and embryogenic callus increased significant with increasing of casein or paclobutrazol after 16 weeks from culture. The treatments of 1000 mg.L -1 casein hydrolysate and 0.5 mg.L -1 paclobutrazol showed fewer periods to embryo formation reached 21.00 and 17.00 days, respectively. However, the control observed the longest period to somatic embryo formation which reached 61.00 days. The treatments of 1000 mg.L -1 casein hydrolysate and 1.0 mg.L -1 paclobutrazol showed the highest values 6.50 and 1.60 cm length, 0.87 and 0.80 cm diameter, 0.336 and 0.361 gm fresh weight and, 0.022 and 0.033 gm dry weight of embryo’s characteristics, respectively. In addition, two treatments of paclobutrazol (0.5 and 0.7 mg.L -1 ) showed high average number of embryos (16.33 and 16.67 embryos, respectively). In contrast, the recorded data from the control treatment gave demonstrated fewer values (4.33 embryos, 0.80 cm length, 0.13 cm diameter, 0.035 gm fresh weight and 0.005 gm dry weight) of characteristics of embryos. When the culture medium contained casein hydrolysate at 1000 mg.L -1 observed the highest percentage of germination (76%) and less period of embryo germination (15.30) days in comparison with other treatments. Moreover, the culture medium with low concentration of paclobutrazol (0.3 mg.L 1 ), showed the highest percentage of germination (75.67%) in comparison with other treatments of paclobutrazol. However, the same concentration of paclobutrazol obtained the lowest period of embryo germination (14.0 days) in comparison with the other treatments. The results also showed that the callus when cultured on MS medium supplemented with 800 or 1000 mg.L -1 casein hydrolysate demonstrated indirect adventitious shoots.