Induced Mutation in Some Guar (Cyamopsis tetragonoloba) linesUsing Gamma Irradiation and Sodium Azide

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El Amin, Osman Ali Hag
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A mutagenesis study was carried on seeds of two lines of guar L18 and L14, which were bombarded with doses of 150, 300, 450 and 600 Gy gamma irradiation. Part of the irradiated seeds with the dose 300 Gy and untreated seeds were then soaked separately in 40 or 80 mM of sodium azide for 20 or 30 hours and germinated in vitro to evaluate germination per cent. Another part of the irradiated seeds with 450 and 600 Gy, were then treated separately with 20 or 40 mM of sodium azide for 10 or 20 hours. Germination of guar was not affected by gamma doses. On the other hand, treatment with sodium azide alone had a great effect on the germination of guar. The percentage of germination ranged between 13.3 and 34.7%. High effects were obtained on seeds treated with 300 Gy and sodium azide (40 and 80 mM) for either 20 or 30 hours, which recorded a range between 9.3 and 13.3%. This indicated that the combined treatment with gamma rays and sodium azide were more effective than sole treatment. Gamma irradiation doses showed no effect on survival of M1 generation, while the combined treatments caused a reduction of about 81.3%. In M2 generation, the growth of the treated plants was slower than the control and the rate of growth decreased with the increase of dose. Variable chlorophyll abnormalities were also detected. In M3 generation leaves with chlorophyll abnormalities varying between green-yellowish, variegated, yellow-whitish and totally yellow were recorded. Deformated leaves and flowers were recorded at very low rates. In line 18 a reduction and an increase in plant height were caused by different treatments. On the other hand, treatment with gamma rays and combined mutagens increased plant height in line 14. Gamma irradiation enhanced internode length in line 18. The increase in internode length over the control ranged between 37.1 and 48.6%. A similar pattern was detected for the combined treatments, except the highest dose 600 Gy/40 mM Na N3 for 20 hours. However, no definite pattern was obtained for line 14. For gamma doses, a reduction in the number of nodes/main stem ranging between 2.4 and 28.1% compared to the control was recorded in line 18. Both an increase and a decrease in number of nodes were detected at combined treatments. However, in line 14 gamma and combined treatments increased the number of nodes. In line 18, increase in fertile nodes/main stem ranging between 7.8 and 48.1% was detected at gamma doses and most of the combined doses. In line 14, gamma irradiation and the combined treatments increased the number of fertile nodes over the control by a range varying from 2.7 to 60.3%. In contrast gamma doses caused a decrease in number of branches fluctuating between 1.0 and 35.2%. Also most of the combined treatments caused a decrease in number of branches ranging between 10.5 and 52.4%. On the other hand, in line 14, an increase in number of branches, ranging between 39.1 and 117.2% was obtained in gamma doses and six of the eight combined treatments. Similarly the number of fertile branches was increased at gamma doses. In these doses the fertile branches constituted 61.8 to 93.8% of the total branches. However, half of the combined treatments had an increase in number of fertile branches, which was ranging between 14.5 and 61.3% over the control. The other half of the combined doses showed a reduction between 3.2 and 5.2% compared to the control. Similar effect of an increase and decrease in fertile branches was detected in line 14 for gamma and the combined doses. In line 18, the height to the first pod was enhanced by treatment with the combined doses as well as 600 Gy. An inverse relation was obtained in line 14, where a decrease in height to the first pod was reported in most of the treatments. Positive and negative effects were caused by the different treatments on number of pods per plant in both lines. The number of seeds/pod was reduced in both guar lines. Similarly a reduction in 100-seed weight ranging between 2.7 and 13.5% was obtained in most of the treatments in both lines. For seed yield, an increase and reduction were reported in line 18 and 14. The reduction in yield was higher in line 18 (51.4% less than the control), whereas in line 14 it was 44.3% less than the control. On the other hand, the increase of seed yield over the control was higher in line 14 (47.2%) compared to line 18 (22.9%). In line 18, most of treatments showed a reduction in number of seeds per plant. On the other hand, in line 14, most of the treatments showed an increase in number of seeds per plant. Gamma doses caused a reduction in pollen fertility in both lines of guar. Line 18 was more sensitive to gamma irradiation than line 14. The reduction in the former line was up to 38% and in the later line it was up to 18.6%. A drastic reduction in pollen fertility was caused by the combined treatments, where it was up to 61.8% in line 18 and up to 38.0% in line 14. Small pod mutants containing from 2.0 to 2.2 seeds were detected in both lines. Seed colour change was observed in both lines, varying between yellow, purple and black. However, some potential families were selected in both lines. The height to the first pod in the mutant family 8 in line 18 at the combined dose 450 Gy/20 mM/20 hours was increased over the control by 481%. Also an increase in yield in these potential mutants, ranging between 43 and 184%, was obtained. The most suitable doses that produce maximum variability were 450 Gy and 450 Gy/20 mM/20 hours in line 18 and 150 Gy and 450 Gy/40 mM/10 hours in line 14
Induced Mutation ,Guar (Cyamopsis tetragonoloba) line,Gamma Irradiation,Sodium Azide