Assessment of Genetic Variability & Adaptation to Climate Change in Advanced Gezira Population of Sorghum (Sorghum Bicolor (L.) Moench) Under Four Rainfed Areas in Sudan

Abstract

The study was conducted during two seasons (2004-2005) to study genetic variability in the population (GSP-1) at four rain-fed areas in Sudan namely; Gedarif University farm in 2004, at Gedarif Research Station at northern Gedarif in 2005 at Rahad rain-fed area Gedarif marginal environment in 2004 and Kasamor at Gedarif middle environment in 2005. With the objectives to study; 1) The genetic diversity on the population 2) Heritability estimates and gains from selection. One hundred and twenty S1 families were taken at random from the population developed and improved for five cycles using S1family selection, the design used was a modified (RCBD) Design with replication nested within blocks. Genetic variability, expected genetic gains from selection and broad sense heritability were estimated for each of the following traits; days to 50% flowering (day), yield (Kgh-1), leaf angle (º), 1000 grains weight (gm) and plant height (cm).
The combined analysis over environments revealed significant differences between environments, which indicated that four environments are contrasting for evaluating the genotypes. In average over environments the genotypes have shown significant differences for all traits studied, which mean that there is a wide range for selection. However G×E interaction was not significant for yield, indicating relative ranking of the genotypes remained constant and yield was stable over the four environments.
The mean was 53.3 day for days to 50% flowering, 1448 for yield Kgh-1, 28.4 º for leaf angle, 22.9 gm for 1000 grains weight and 85.9 cm for plant height. The highest expected gain from selection was given by plant height (3.1 %) and the lowest value was obtained by days to 50% flowering (0.21%). The highest heritability estimate was given by plant height, days to 50% flowering and yield (0.52-0.50) and the lowest heritability value obtained by leaf angle (0.11), this indicates the fact that plant height, days to 50 % flowering and yield Kgh-1 traits were targeted in the previous improvement of this advanced population, whereas leaf angle trait has not been targeted yet.