Mutagenesis is used for creating new genetic variability in cultivar improvement. Optimal mutagenic treatment is required for effective mutation induction in crop species. Therefore, radio-sensitivity of cowpea access...Mutagenesis is used for creating new genetic variability in cultivar improvement. Optimal mutagenic treatment is required for effective mutation induction in crop species. Therefore, radio-sensitivity of cowpea accessions to gamma irradiation was investigated. Seeds of eight cowpea accessions were irradiated with <sup>60</sup>Co gamma radiation doses of 100, 200, 300, 400 and 500 Gy. The seeds were sown in pots to evaluate the treatment effects on seed germination (SG), seedling survival (SS) and growth habits of M1 generation. Data were analyzed using descriptive statistics. Low rates of SG (10% - 45%) were recorded at higher doses (500 - 400 Gy) in Ife Brown (IB) and its derivatives, whereas high SG rates (74% - 94%) were observed in IT90K-284-2 across all treatments. Percentage SS was inversely related to gamma dosage. A wide range of LD<sub>50</sub> for SG (329 - 1054 Gy) and SS (149 - 620 Gy) were observed across the cowpea accessions. Low LD<sub>50</sub> scores for SG (329 - 516 Gy) and SS (149 - 357 Gy) were observed among cowpea with rough seed coat, whereas cowpea with smooth seed coat recorded higher LD<sub>50</sub> for SG (521 and 1054 Gy) and SS (449 and 620 Gy). Seed germination LD<sub>50</sub> and SS LD<sub>50</sub> were highly correlated with mean coat thickness (0.899 and 0.937) than mean seed weight (0.621 and 0.678). Gamma irradiation of cowpea seed at low dosage (100 Gy) increased the vigor of M<sub>1</sub> seedlings with respect to primary leaf area, terminal leaflet area, seedling height and plant height at six weeks. Doses of 200 Gy and above resulted in a progressive reduction in vigor of plant and seed setting of cowpea. Radio-sensitivity varied with cowpea genotype and was associated with seed testa texture, thickness and seed weight. Low gamma irradiation treatment (100 Gy) may be used to enhance seedling vigor, vegetative growth and yield of cowpea at M<sub>1</sub> generation.展开更多
Micro-tubers are important propagules in potato breeding and potato production, and they are also dormant and easily transported and therefore good targets for mutation induction in potato mutation breeding. A prerequ...Micro-tubers are important propagules in potato breeding and potato production, and they are also dormant and easily transported and therefore good targets for mutation induction in potato mutation breeding. A prerequisite for mutation breeding is to determine optimal mutation treatments. Therefore, radio-sensitivity tests of a tetraploid and a diploid potato to gamma irradiation were undertaken. Effects of different gamma sources on radio-activity were also studied. In vitro potato cuttings were gamma irradiated using a wide dose range (0, 3, 6, 9, 12, 15 and 20 Gy). The irradiated cuttings were then cultured to induce micro-tubers directly in vitro. Micro-tuber morphotypes were assessed after irradiation of cuttings using three gamma sources with emission activities of 1.8, 7.07 and 139 Gy/min. The diploid species (Solanum verrucosum) was more radio-sensitive than the tetraploid cultivar Desirée (Solanum tuberosum). Gamma dose rates had significant influences on subsequent micro-tuber production at various mutant generations. Effects included reductions in the number, size and weight of micro-tubers produced. Gamma dose was more lethal for the diploid potato genotype and micro-tubers produced were small compared to those produced by the tetraploid genotype after irradiation. Different treatments are recommended for diploid and tetraploid potato irradiation in producing large mutant micro-tuber populations. The mutant micro-tuber populations may then be screened for interesting mutations/trait for both genetics and plant breeding purposes.展开更多
文摘Mutagenesis is used for creating new genetic variability in cultivar improvement. Optimal mutagenic treatment is required for effective mutation induction in crop species. Therefore, radio-sensitivity of cowpea accessions to gamma irradiation was investigated. Seeds of eight cowpea accessions were irradiated with <sup>60</sup>Co gamma radiation doses of 100, 200, 300, 400 and 500 Gy. The seeds were sown in pots to evaluate the treatment effects on seed germination (SG), seedling survival (SS) and growth habits of M1 generation. Data were analyzed using descriptive statistics. Low rates of SG (10% - 45%) were recorded at higher doses (500 - 400 Gy) in Ife Brown (IB) and its derivatives, whereas high SG rates (74% - 94%) were observed in IT90K-284-2 across all treatments. Percentage SS was inversely related to gamma dosage. A wide range of LD<sub>50</sub> for SG (329 - 1054 Gy) and SS (149 - 620 Gy) were observed across the cowpea accessions. Low LD<sub>50</sub> scores for SG (329 - 516 Gy) and SS (149 - 357 Gy) were observed among cowpea with rough seed coat, whereas cowpea with smooth seed coat recorded higher LD<sub>50</sub> for SG (521 and 1054 Gy) and SS (449 and 620 Gy). Seed germination LD<sub>50</sub> and SS LD<sub>50</sub> were highly correlated with mean coat thickness (0.899 and 0.937) than mean seed weight (0.621 and 0.678). Gamma irradiation of cowpea seed at low dosage (100 Gy) increased the vigor of M<sub>1</sub> seedlings with respect to primary leaf area, terminal leaflet area, seedling height and plant height at six weeks. Doses of 200 Gy and above resulted in a progressive reduction in vigor of plant and seed setting of cowpea. Radio-sensitivity varied with cowpea genotype and was associated with seed testa texture, thickness and seed weight. Low gamma irradiation treatment (100 Gy) may be used to enhance seedling vigor, vegetative growth and yield of cowpea at M<sub>1</sub> generation.
文摘Micro-tubers are important propagules in potato breeding and potato production, and they are also dormant and easily transported and therefore good targets for mutation induction in potato mutation breeding. A prerequisite for mutation breeding is to determine optimal mutation treatments. Therefore, radio-sensitivity tests of a tetraploid and a diploid potato to gamma irradiation were undertaken. Effects of different gamma sources on radio-activity were also studied. In vitro potato cuttings were gamma irradiated using a wide dose range (0, 3, 6, 9, 12, 15 and 20 Gy). The irradiated cuttings were then cultured to induce micro-tubers directly in vitro. Micro-tuber morphotypes were assessed after irradiation of cuttings using three gamma sources with emission activities of 1.8, 7.07 and 139 Gy/min. The diploid species (Solanum verrucosum) was more radio-sensitive than the tetraploid cultivar Desirée (Solanum tuberosum). Gamma dose rates had significant influences on subsequent micro-tuber production at various mutant generations. Effects included reductions in the number, size and weight of micro-tubers produced. Gamma dose was more lethal for the diploid potato genotype and micro-tubers produced were small compared to those produced by the tetraploid genotype after irradiation. Different treatments are recommended for diploid and tetraploid potato irradiation in producing large mutant micro-tuber populations. The mutant micro-tuber populations may then be screened for interesting mutations/trait for both genetics and plant breeding purposes.
