No abstract available

[en] The study involved inducing mutations in the varieties Icta-Virginia and Precozicta to obtain genotypes that mature early, are resistant or tolerant to Pyricularia oryzae and have a high yield potential. To optimize the radiation dose for each variety, seeds were irradiated with doses of 0, 150, 200, 250, 300 and 400 Gy. Six thousand seeds of each variety were irradiated with the above doses to establish the M₁ generation, in which the physiological effects and somatic mutations were observed. The M₂ generation was sown in progeny groups and as the crop developed, mutants with chlorophyll changes, morphological changes, improved yield, tolerance to Phyricularia oryzae and mutants which matured earlier than the original variety were identified and selected. In the M₃ generation, derived from the Icta-Virginia and Precozicta varieties, the genetic stability of mutants with morphological changes, chlorophyll changes, tolerance to Pyricularia oryzae (classified as 0-1 on the 0 to 9 scale of the standard rice evaluation system) and those which matured earlier (15 to 20 days) than the original variety was confirmed. (author). 7 refs, 3 tabs

[en] Two varieties of Phaseolus vulgaris (Jutiapan and San Martin) were irradiated at 0, 8, 15, 20 and 30 kR doses in a 60-cobalt gamma source, to identify mutants and 20% lethality. M₂ plants showing morphogical mutations were selected. Differences in sensitivity to irradiation of the two varieties were noted, using data and physiological effects of M₁. Selection and analysis for protein content were in M₃ as well as hereditary changes. (M.A.C.)

[en] The objective of this research in rice (Oryza sativa L.) was to induce mutations for semidwarfism, early maturity, high yield potential and tolerance to Pyricularia grisea in the rice variety Pico Negro. Seeds were treated with sodium azide and gamma rays alone and in combination at various doses. In the M₁ generation the number of chlorophyll deviations was recorded for the various treatments in order to select the optimum one, which proved to be 2.5 x 10^-3 M NaN₃ + 2.5 krad (25 Gy). In the M₂ generation, mutations were obtained for morphological and chlorophyll characters, plant height, and earliness. The stability of the mutants selected in the M₂ generation was confirmed in the M₃ generation. A total of 148 mutants were selected. (author). 5 refs, 1 fig., 3 tabs

[en] Seeds of rice variety Krispo-38 were irradiated with 0, 100, 200, 300 and 400 Gy and sown in the greenhouse. Anthers from plants of each treatment containing uninucleate pollen grains were collected and cultured on an N₆ agar medium with 5% sucrose concentration and supplemented with 3 mg/l NAA, 1 mg/l kinetin and 1 mg/l 2,4-D. The pollen grains were induced to develop calli. The proportion of anthers that produced calli varied from 0.8% for the 400 Gy treatment to 3.3% for the control. The calli were transferred to N₆ medium with 3% sucrose concentration and supplemented with 0.5 mg/l NAA and 1 mg/l kinetin. The proportion of calli that produced green plants varied from 1.9% for the 300 Gy treatment to 10.5% for the 200 Gy one. Plants developed in 2-5 weeks, 101 plants were obtained. (author). 7 refs, 1 tab

[en] Anthers of five mutant lines of rice derived from the variety ICTA VIRGINIA and five derived from the variety PRECOZICTA as well as the two parental varieties (both varieties indica) containing uninucleate pollen grains, were cultured on a N₆ agar medium with 5% sucrose concentration and supplemented with 3 mg/l NAA, 1 mg/l kinetin and 1 mg/l 2,4-D. The proportion of anthers that produced calli varied from 0% for the mutant lines 881 and 940 to 1.9% for the parental variety Precozicta. The calli were transferred to N₆ medium with 3% sucrose concentration and supplemented with 0.5 mg/l NAA and 1 mg/l kinetin and plantlets developed in 2-5 weeks. A total of 153 green plantlets were obtained. (author). 9 refs, 2 tabs

[en] Seeds of the rice variety Krispo-38 were irradiated with 0, 100, 200, 300 and 400 Gray (Gy) and sown in the greenhouse. From each treatment, others containing uninucleate pollen grains were collected and cultured on a N6 agar medium with 5% sucrose concentration and supplemented with mg/l naphthalene acetic acid (NAA), 1 mg/l kinetin and 1 mg/l 2,4 dichlorophenoxyacetic acid (2,4-D). The pollen grains were induced to develop callus. The percentage of others that produced calli varied from 0.8 for the 400-Gy treatment to 3.3% for the control. The calli were transferred to N6 medium with 3% sucrose concentration, supplemented with 0.5 mg/l NAA and 1 mg/l kinetin. The percentage of calli that produced green plants varied from 1.9 for the 300-Gy treatment to 10.5 for the 200 Gy treatment. Plants developed in 2-5 weeks after callus transplant. A total of 101 green plants was obtained

[en] The objective of this research was to induce mutations for early maturity, resistance or tolerance to blast (Pyricularia grisea), and high yield potential in the rice (O. sativa) varieties ICTA Virginia and Precozicta. Six thousand seeds of each variety were irradiated and the M₁ generation was grown. The irradiation doses for Precozicta and ICTA Virginia were 31 and 29 krad (310 and 290 Gy), respectively. One row from each plant selected in the M₁ generation was sown in the field. Mutants that possessed high yield potential, early maturity, resistance to blast, chlorophyll deficiencies, and morphological differences were identified and selected. The M₃ generation of mutants identified in the M₂ generation was sown in the field to confirm the M₂ classifications. Early maturing and blast resistant mutants were harvested. Forty eight mutant lines selected in the M₃ generation were evaluated in replicated field plots in the M₄ generation. (author). 7 refs, 3 figs, 5 tabs

[en] Fifteen mutant lines from the variety ICTA-Virginia and fifteen from the variety Precozicta were evaluated according to their agronomic characteristics under conditions of the Motagua river valley during 1992. The objective was to select genotypes showing resistance to disease caused by Pyricularia grisea. The analysis of variance did not show significative differences among ICTA-Virginia mutants. The highest yield was form MV-860, 8.17 TM/ha and the lowest 5.31 TM/ha for MV-411. Significant differences were found among mutant lines from Precozicta. The highest yields were 6.06, 5.80 and 5.52 TM/ha for MPI-1189, MPI-1664 and MPI-1346 respectively. Inoculation with Pyricularia was made spraying it over the crop. However, it was not possible the evaluation of the disease in the neck (neck blast) due to absence of the pathogen. 5 tabs.(Author)