Abstract
Rice (Oriza sativa L.) cultivar IAC-1246 seeds were treated with 10, 15, 20 and 30 Krads of gamma-rays and sodium azide (SA) concentrations of 0.5, 1.0 and 5.0 mM to study their efficiency in inducing chlorophyll mutations. Combined treatments incremented the damages when compared to single treatments, especially for seedling height and M 1 panicles fertility. Treatments with SA showed a higher frequency of chlorophyll mutations than the gamma-ray treatments, both in single and combined treatments. The gamma-ray spectrum was different for the various types of mutations, whether in individual or combined treatments. The SA efficiency was higher than that of gamma - rays at 1.0 and 5.0 mM concentrations and lower at 0.5 mM. On average, the additive effect of the mutagenic combinations was more evident than the frequencies of the mutations.
Highlights
The presence of genetic variability is necessary for crop improvement
For the sodium azide treatment, seeds were treated with 250 ml of freshly prepared 0.5, 1.0 and 5.0 mM of SA solution for 8 hours with continuous shaking at room temperature (25o C + 2)
Single treatments tended to be more efficient with the increase in dosage or concentration, but they decreased after reaching a maximum level
Summary
The presence of genetic variability is necessary for crop improvement. The variability available to the breeder comes from spontaneous or artificially induced mutations.Plant breeding involves procedures which increase genetic variation, select desirable genotypes, evaluate selected genotypes, and multiply and release new cultivars.In mutation breeding, the enhancement of the genetic variation is made through the influence of mutagens. The presence of genetic variability is necessary for crop improvement. The variability available to the breeder comes from spontaneous or artificially induced mutations. Plant breeding involves procedures which increase genetic variation, select desirable genotypes, evaluate selected genotypes, and multiply and release new cultivars. The enhancement of the genetic variation is made through the influence of mutagens. Several traits have been subjected to mutation breeding: yield, lodging resistance, disease resistance, maturity, culm length, etc. These facts were evaluated by Fehr (1987) who reported that artificial mutation can be a practical mean to achieve genetic improvement in crop species
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