Genetic variability, heritability and interrelationships of grain yield and its components in some selected genotypes from the wheat breeding program of Sudan

Three experiments (designated as Expt I, Expt 11 and Expt III) were conducted at the Gezira Research farm (GRF). Agricultural Research Corporation (ARC), Wad Medani, during two seasons 2006/07 and 2007/08. The objectives were to evaluate genetic variability, heritability and interrelationships among some bread wheat genotypes selected from different trials in the breeding program of the Sudan. Expt I was conducted in season 2006/07 while Expts 11 and III were grown in 2007/08. Expts I and II were conducted using 94 and 174 bread wheat genotypes, respectively, and were arranged in an augmented design with six checks and 4 blocks in Expt I and 12 blocks in Expt II. Expt III was grown using 32 genotypes selected from Expt I according to their grain yield, including three checks. Expt III was arranged in a randomized complete block design with three replications. Results indicated the existence of a wide range of genetic variability among the genotypes included in the three experiments for different studied traits. The grain yield ranged from 965 to 4019 kg/ha in Expt I from 1331 to 6258 kg/ha in Expt II and from 2306 to 3865 kg/ha in Expt III. (Wide ranges were also found in different traits. Among 25 genotypes selected according to their high grain yield in Expt I, 10, 12, 7 and 6 entries ranked among the 25 top genotypes in biomass, harvest index, number of spikes m-2 and chlorophyll content, respectively. When the 25 top yielding genotypes were considered in Expt II, 12 ranked top in biomass, three in harvest index, and 6 in number of spikes m, 2. Most of the 25 earliest genotypes in Expts I and II were not among the top yielding genotypes. High heritability in broad sense (h square b) was estimated for days to heading (96%), days to maturity (93%) and plant height (77%). Grain yield and harvest index showed moderate heritability. Low heritability was estimated for biomass, number of spikes m2, grain filing period, chlorophyll content, CTD, and spikeletes/spike. Positive significant correlations were found between grain yield and some traits such as biomass, harvest index, number of spikes m2, days to heading and maturity, and plant height. The wide range of genetic variability found in the wheat breeding program of Sudan suggests that the program have accumulated and maintained diverse genetic base that could be used for further improvement in grain yield and other related traits under the heat stress condition of Sudan