Variability of spike harvest index in wheat (Triticum aestivum L.)

Grain spike index indicate wheat productivity and can be used as criterion in wheat selection in the wheat breeding program. Aim of this investigation is study of variability of grain spike index in wheat cultivars grown under different environmental condition. Ten genetically divergent winter wheat cultivars were included in two year investigation in field experiment in randomized block design in three replications. The seeds of varieties were sown at the distance of 0.10 m in rows of 1.0 m length with the distance of 0.2 m. For analysis of grain spike index determined in proportion of grain mass spike-1/mass of spike, 60 plants in full maturity stage (20 plants per replication) were used. On the base of analysis of variance by using MSTAT C (5.0 version) and computed F-test values, differences among cultivars according to value of grain mass spike-1, mass of spike and also, spike harvest index were established. In the first year the highest spike harvest index was 0.82 (Fortuna) and the lowest 0.76 in Ljubičevka, with average for all varieties 0.79, while in the second year the highest spike index was 0.83 in Somborka, and the lowest 0.77 in Ljubičevka, with average value 0.80. The different values of spike harvest index indicate response of genotypes to environmental factors as well as interaction of genotype/environment.