Spectrum and Frequency of Mutations Induced by Gamma Radiations in Three Varieties of Nigerian Sesame (Sesamum indicum L.)

Insufficient genetic variability is one of the major problems of plant breeding programmes, especially in sesame. Gamma radiation has been reported to be very effective in creating genetic variability in plants. Three varieties of Nigerian sesame were assessed for spectrum and frequency of mutation induced by Gamma radiations in M1 and M2 generations. The varieties (NCRIBEN-04E, NCRIBEN-01M and NCRIBEN-03L) were treated with four different doses of gamma rays (250, 350, 450 and 550 Gy). The treated and untreated seeds (control) were sown in planting bags (under field condition) to raise M1 plants. Four treatments: V1D5, V2D3, V3D2 and V3D4 (from M1 plants) were selected and bulked to obtain M2 populations. The results of M1 revealed four mutant fruit traits: multicarpellate capsule, multiple capsule per leaf axil, indehiscent capsule and terminal capsules. The highest frequencies of the traits in M1 generation were 2.50×10-2, 9.17×10-2, 1.67×10-2and3.33×10-2 respectively. The highest branching (7) was from NCRIBEN-01M, while the least (2) was from NCRIBEN-04E. The M2 plants were grouped into eight M2 lines. The dose range (250-550 Gy) was proved to be effective in inducing viable mutations in sesame

PRELIMINARY STUDIES ON EFFECTS OF GAMMA RAY ON SEED RETENTION INDICES OF THREE NIGERIAN SESAME (SESAMUM INDICUM L.) VARIETIES

In an attempt to improve sesame for reduction of seed loss due to shattering of capsule at harvest, the seeds of three varieties of sesame (NCRIBEN-04E, NCRIBEN-01M and NCRIBEN-03L) were treated with five different doses (0, 250, 350, 450 and 550 Gy) of gamma irradiation; 0 Gy being the control. All the treatments including the controls, were grown and monitored till maturity. The seed retention power of the treatments were assessed. From the results, the treatment due to 550 Gy had highest score (6) for both NCRIBEN-04E and NCRIBEN-01M and was categorized as non-shattering (NSH) type. All other treatments were categorized as shattering (SHA) type. Similarly all the treatments from NCRIBEN-03L were categorized as SHA with treatment due to 250 Gy having highest score (5). The three varieties showed positive correlations between the seed/capsule in upright (U) and seed/capsule in inverted (I) position but NCRIBEN-01M was not significant (r = 0.650). The NCRIBEN-04E showed negative correlation between U and length of suture (L) and I and L (r = -0.570 and -0.358 respectively). This result has shown that the dose 550 Gy seems to be promising in generating mutants with high resistance to capsule shattering in sesame. There is need to advance these mutants to M2 and M3 generations to ascertain this seed retention capacity