G. S. Nanda

A comparison of cytoplasmic and chemically-induced male sterility systems for hybrid seed production in wheat (Triticum aestivum L.)

A comparison of two male sterility systems was carried out in wheat for hybrid seed production and hybrid performance. Seventeen hybrid combinations based on Triticum timopheevi cytoplasm were compared with their genetically equivalent CHA-facilitated combinations. The same set of restorer lines was used as parents in CMS- and CHA-based hybrids to maintain genetic equivalence. In the first experiment aimed at study of female line behavior and crossed seed production, the CHA treated lines showed significantly shorter heights whereas CMS lines were similar to the control. The two systems were equally effective in sterilizing rate. The outcrossing percentage of the CMS lines was almost twice that of the CHA treated lines. Thousand-grain weight of the crossed seeds on CMS lines was greater than on the CHA treated lines and control. On average, the germination percentage of seeds on CMS lines was double that of the CHA treated lines and the percentage of effective outcrossed seeds in CMS lines was 3 times more than that from CHA treated lines. The second experiment was conducted to examine the yield performance of the hybrids derived from the two systems of male sterility. A total of 40 entries including 20 hybrids and 20 parents were evaluated in the experiment. The mean grain yield of the CMS-based hybrids was greater than that of the CHA-based hybrids,the B and R lines. All the CMS-based hybrids showed significantly higher grain yields than their better parents whereas all the CHA-based hybrids, except two,showed no significant yield increases over their better parents. Possible reasons for differences in CMS- and CHA-based hybrid performance are discussed.

Genes Lr48 and Lr49 for hypersensitive adult plant leaf rust resistance in wheat (Triticum aestivum L.)

The genetic bases of leaf rust resistance in wheat (Triticum aestivum L.) line CSP44, selected from the Australian cultivar Condor, and Indian cultivar VL404, were studied. The reaction patterns of CSP44 and VL404 against Indian races 12, 77, 77-1, 77-2, 77-3, 77-4, 77-5 and 108 were different from reaction patterns shown by near-isogenic lines with known adult plant resistance (APR) genes, viz. Lr12, Lr13, Lr22b and Lr34. Although the reaction patterns of CSP44 and VL404 were similar to the near-isogenic line Tc+Lr22a, tests of allelism indicated absence of Lr22a in both CSP44 and VL404. On the basis of genetic studies, their resistances in field tests against race 77-5, the most virulent race from the Indian sub-continent, were each ascribed to two genes. One of the two genes in each wheat was identified to be the non-hypersensitive APR gene Lr34. The second APR genes in CSP44 and VL404 gave hypersensitive reaction types and were recessive and dominant, respectively. The gene in CSP44 was designated Lr48and the gene in VL404, Lr49.

Additive genes at nine loci govern Karnal bunt resistance in a set of common wheat cultivars

The genetics of Karnal bunt (KB) resistance were studied in populations derived from crosses of four resistant stocks (HD 29, W 485, ALDAN ‘S’/IAS 58, H 567.71/ 3*PAR) and a highly susceptible cultivar, WH 542. The plant materials screened for KB response consisted of F2, BC1 and RILs from all ‘Resistant’בSusceptible’ crosses and RILs from the six possible ‘Resistant’ × ‘Resistant’ crosses as well as the parents and F1s. The screening was performed under optimal conditions for disease development with a mixture of isolates from North Western Plains of India using the widely followed syringe method of inoculation. The KB scores of the F1 from the four ‘Resistant’ × ‘Susceptible’ crosses indicated partial dominance of resistance. Genetic analysis revealed that HD 29, W485 and ALDAN ‘S’/IAS 58 each carried two resistance genes whereas 3 genes were indicated in H 567.71/3*PAR. The six ‘Resistant × Resistant’ RIL sets showed that the genes in the four resistant stocks were different and that there may be as many as nine genes governing KB resistance in the four parents.

Stability analysis over seasons and locations of multilines of wheat (Triticum aestivum L.)

SummaryThree multilines each of Kalyansona and PV 18 varieties of wheat were compared for their stability of yield and agronomic characters and disease resistance against the respective recurrent parents. The experiments were conducted for four years at nine locations.The multilines had more tillers and bolder seeds than the recurrent parents. There were, however, no differences for plant height, ear length and number of spikelets per spike.The genotypes x years x locations interaction was much more important than genotypes x years or genotypes x locations interaction as well as the main effects for genotypes. It is suggested that the number of test locations should be increased while decreasing the number of years.The stability parameters indicated that the multilines had a higher mean yield in the case of Kalyansona multilines whereas the yield of multilines of PV 18 was not significantly inferior to that of the recurrent parent. The regression coefficients were very close to unity except for KSML 3 (b=1.132). The deviations from regression were much larger for the multilines than for the recurrent parents.For rust resistance the multilines were superior over the varieties Kalyansona and PV 18.

Studies on multilines in wheat (Triticum aestivum L.).12. Breeding of a multiline variety by convergence of breeding lines

SummaryThe variation among the component lines of the KSML 3 (a multiline based on cultivar Kalyansona, spring bread wheat) was studied for agronomic characteristics. For days to earing and plant height the variation was small. This helped in imparting uniformity to the multiline. The lines had an improved tillering ability and had larger seeds. This partially explained the increased yield potential of the multiline as compared with Kalyansona.All the lines were susceptible only to one or two races of the yellow and brown rust. In no case any race was virulent against all the lines. In the field all the lines were resistant to both rusts.

Prospects of triticale as a dual purpose crop.

Eight triticale genotypes were evaluated using two currently cultivated fodder oats varieties as control The experiment comprised of 2 sets viz. grain purpose (with all the genotypes grown to maturity) and fodder plus grain purpose (all the genotypes harvested for fodder seventy days after sowing and then allowed to regenerate and set seed). The data were recorded for green fodder yield, dry matter yield, grain yield, plant height, tillers per meter, harvest index and fodder quality attributes. Distinct genetic differences were observed for most of the characters particularly number of tillers per meter in the regenerated crop after the fodder harvest. In dual purpose experiment there was a general reduction in plant height (up to 31 per cent) and a corresponding reduction in lodging tendency which is a desirable feature. The salient finding of the study was the identification of dual purpose triticale genotype like TFL-3 which gave adequate fodder yield (72% of oats) without any significant reduction in grain yield (96% of the grain purpose experiment) showing its potential as a fodder cum grain crop.