Genotype and genotype x environment interaction of some rice grain qualities in Tanzania Nkori J.M. Kibanda 1 and Ashura Luzi-Kihupi 2 1 Rice Breeder 2 ECARRN Coordinator

Genetic and Genotype x environment interaction cont.. Introduction Genotype x environmental interaction –Is important in plant breeding programs –When is large, testing in several (stratified) environments becomes necessary to optimize testing environments

Introduction cont.. adequately measure genetic value of a cultivar –Reports on the effect of genotype, genotype x environment interaction on rice grain qualities are available (Resurrecion, 1977, Mackill et al.1996, Unevehr et al, 1992)

Objectives This study had the following objectives: - Overall objective –Investigate the response of newly breeding rice genotypes and their interaction on the performance grain quality attributes under varying environments

Specific objectives To assess the contribution and the relative magnitudes of rice variety and variety x environment interaction on physical and biochemical traits under upland and irrigated ecosystems To estimate and assess correlations and genetic parameters of physical and biochemical grain quality attributes and determine their relative importance on rice improvement under upland and irrigated cultures

Materials and Methodology Location: TAC (Ifakara) and SUA (Morogoro) Soil and weather data were determined Rice genotypes –Collected from ARI KATRIN and SUA –Selected based on yield potential –Composed of conventional and mutants

Materials and Methodology cont.. –Genotypes: SSD1, SSD3, SSD5, M15A,Line85, Line88, TXD275, TXD220, TXD306 and Supa (control Design: RCBD; Three replications with 2m x 4m Seeding: 2-3 seeds/hill at 20cm x 20cm Agronomic practices

Materials and Methodology cont.. Data recorded: Grain size and shape, opacity - (Jennings et al. 1979, IRRI 1988) AC - Modified simplified assay procedure (Jliano et al. 1981) GC – (Campagn et al. 1973)

Statistical analysis Statistical Analysis Analysis of variance (ANOVA) Single site and combined analysis – SAS software Estimates of variances of G, E, G x E interactions (AlJibouri et al. 1958) Estimates of Genetic Coefficient of Variation (Burton 1952)

Statistical analysis cont.. Estimates of Heritability in the broad sense (Hanson et al. 1956) Estimates of Genetic Advance at 5% intensity (Johnson et al. 1955) Estimates of Phenotypic and genotypic correlation

Table 1a: Performance of rice lines/variety on physical analysis at SUA

Table 1b: Performance of rice lines/variety on biochemical analysis at SUA

Table 2a: Performance of rice lines/variety on physical analysis at TAC

Table 2b: Performance of rice varieties/lines on biochemical traits at TAC

Table 3a: Performance of rice lines/variety on physical traits combined in two locations (SUA &TAC)

Table 3b: Performance of rice lines/variety on biochemical traits combined in two locations (SUA &TAC)

Results and discussion cont.. Genotypes were significant in all the traits except for grain shape in all the locations an when data were pooled Performance of genotypes on the traits varied across environments Grains ranged from very long to medium, slender to intermediate grain shape with small opacity

Table 4: Mean squares from combined analysis of variance (ANOVA) for different physical and biochemical characters/traits at SUA and TAC

Results and discussion cont.. Location and genotype mean squares were significant on chalkiness, AC, GC and GT Genotype x Environment interactions were significant on AC, GC and AC

Table 5: Genotypic (top) and phenotypic correlations of rice grain qualities from 10 rice genotypes combined from SUA & TAC

Results and discussion cont.. Significant genotypic and phenotypic correlations were positive between AC with GC suggesting that selection for GC would simultaneously improve AC, but with significant negative correlation with GT Similar result between AC and GC have been reported (Juliano and Villareal, 1993)

Table 6: Table Variance components of grain qualities of 10 rice genotypes at SUA and TAC

Results and discussion cont.. High genetic variance were on chalkiness, GC and AC High heritability on GL, AC and GC High genetic advance on GC

Conclusion Grain qualities varied among genotypes and in varying environments Most lines tested meet most of the market and consumers’ preferences in Tanzania (Long to medium) grain size with slender to intermediate shape, intermediate AC, intermediate GT and soft GC GC had high heritability and genetic advance and had significant positive phenotypic and genotypic correlations with GL and AC suggesting that GC can be used as a reliable selection criterion for indirect improvement of AC in early generations in specific environments