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Abstract -112:’ - SUMi.-1ARY The present investigation was carried out to study the mutagenic effects of is -ray: and EMS, as single treatments, on M1 germination, plant height, number of tillers per plant, number of sterile spikelets per s~ke, spike length, and number of spikelets per spike on two durum wheat varieties i.e. Gerardo vz, stork1s’ .and two barley varieties G •.121 and Bonus. Plant height, nuiDber of tillers per plant, number of spikelets per spike, spike length, number of kernels per spike and chlorophyll mutations were studied, in iot” generation in one durum ”, wheat variety Gerarda vz and one barley variety Giza 121 Seeds of each variet? were -irradiated with different doses i.e. 10, 20, 30, 40, 50 and 60 fr or treated with solutions of different concentrations (0.2%, 0.4%, 0.6%,’ 0.8% and 1.0%) of EMS. The results obtained are summarized as follows: 1- Effects on M1 germination: A- Durum wheat: The p entage of M1- seed germination was found to be decreased about linearly with increasing the d-ray dosage or EMS concentrations. Almost complete seed lethality was obtained with the ~-ray dose 50 kr and with the - - ,--- --- -_ ... - --~ ----- -1])’ - EMS concentration, 0.3% in both durum wheat varieties. B- Barley complete seed lethality was not obtained with any )-ray dose in the two barley· varieties where complete seed lethali~ was found with EMS concentration O.~%. II- Effect on M1 generation: A- Durum wheat Reduction in plant height, spike length, number of spike lets per spike and fertility were found with two mutagens in both two varieties increasing in number of tillers per plant was obtained with ~ -ray. in Gerardo vz and stork’s’. B- Barley Reduction in plant height, number of tillers per plant fertility, Spike length and number of spikelets per spike were obtained in the two barley varieties with gamma-ray doses and EMS concentrations. These reduction were about linearly with increasing the gamma-ray! d~sages or EMS concentrations. -114- III- Effects on M2 generation 1- Plant height A- Durum wheat High significant decrease was obtained in plant height at all radiation doses. Greated heritability value is estimated at lower dose, while the lowest- heritabili~y value was observed at the dose 40 Kr. EMS treatment caused decreased in plant height. Greater heritability value was found at 0.4 EMS concentration, while the lowest value was found at 0.6%. B- Barley The plant height was decreased proportionally as ~-ray doses increased. Highest value of genetic variances ·.a.obtained at )).-ray dose of 30 KJJ. And it were aiuddenly decreased at the~-ray doses higher than 30 Kr. Lower coefficient of genetic variance and heritability values wereQStimated at gamma-rays dose of 60 Kr. The mean of plant height was decreased as EMe concenttration increased. The values of both phenotypic and genotypic variances were higher after all EMS treatments and were greater than that after )(-ray • ’!,. ..• ._--- - ._---._--- -115’ - 2- Effects on number of tillers per plant: A- Durum wheat The greatest heritability value was estimated with the highest ~-ray’ of 40 kr, and it is moderate at EMS concentration of 0.2% and 0.4%, lower value was found at 0.6% concentration. B- Barley The mean value of tillers per plant, phenotypic and genotypic variances were proportionally increased as d-ray. increased. EMS caused an increased in the mean number of tillers per plants. phenotypic and genotypic variances were increased as EMS concentration increased. 3- Effect on spike length: A- Durum wheat Either ~-ray or EMS resulted in reduction in the length of the mean spike. EMS doses were more effective than ’I-ray’, while the mean genetic variances after lI”-ray.· averaged high than the average of genetic variation of the EMS concentrations. Boo: Ba-rley Rada1at1on and chemical mutagens resulted in reduction in the spike length-GaMma-ray doses were more effective than ~-’~--~--~EMS·concentration.- Phenotypic and genotypic variances-·were----·~--- .. increased as ’If -ray doses increased, lower her! tabili ty -------_. --. __ ., -- -------._-- ---- .._--- ..,116_ value was estimated was larger at EMC concentration as it was compared with this ~-ray doses. 4- Effects on number of kernels per spike The lower means were obtained under 40 Kr and 30 Kr doses and the heritability estimates for the number of kernels per spike increased as ~ -ray doses increased. Highly significant differences between all treatments and the control were obtained. The mean value decreased gradually as the concentration of EMS was increased. Highest genetic changes was found with 0.4% of EMC concentration. B- Barley Radiation treatments had little effect on the means number of kernels, highest genetic va~iance and heritability were obtained with 40 Kr. Chemical mutagens produced high genetic variation than that produced by )(-ray .• 5- Effects of number of spikelets per spike: A- Durum wheat Decreasing of the number of spikelets per spike were obtained after the higher doses of ~-ray • Lower doses 10 kr and 20 kr and 20 had greater effects OB genetic changes than the highest doses. Phenotypic variances were greater after chemical treatments than that after ~-ray treatments. --------_ .. -----”.- .._- -_ ..._- .__.. --- _117 _ B- Barley Lower doses had slight effect on the number of spikelet per spike while the highest dose of ~ -ray:. produced significant reduction. Genetic variance was larger at 30 Kr dose. Lower genetic variance was estimated at higher dose of ~-ray (60 Kr). High estimates for phenotypic and genotypic variances were obtained after EMS treatments. 6- Effect on mutation rate A- Durum wheat The two mutagens, ’l5-ray” doses and EMS concentration induced chlorophyll mutation. The percentage of M 2 families segregation for chlorophyll on the average were . 4.6% while after E}.·l”Streatments the percentage was 3.39. B- Barley The EMS is mostly efficient in inducing the chlorophyll mutation than ’t -ray. The chlorophyll mutation was increased as the ~-ray doses or EMS concentration increased. |