Grain filling in two-rowed winter barley

Kernel weight depends on the rate and duration of grain filling (GF). Rate of GF presents the rate of dry matter accumulation per kernel and GF period duration from anthesis to physiological maturity. In this paper two two-rowed winter barley cultivars were used to investigate the rate and duration of GF and rate of kernel water release during the GF period. Accumulated growing-degree days (GDD) from anthesis were used as a time scale. The relation between kernel weight and accumulated GDD was presented by fitting a quadratic polynomial and the relation between kernel water content and accumulated GDD by fitting a linear equation. Depending on the cultivar and year, rate of GF ranged from 0.068 to 0.082 mg/kernel/GDD and the duration of CF from 572 to 778 GDD. Both the rate and duration of GF were influenced the most by environmental factors. Yield was positively correlated with rate of GF, while between yield and duration of GF there was no significant correlation. The phenotypic correlation between rate and duration of GF was negative. Rate of GF had positive and duration of GF negative indirect effects on yield through yield components. The positive correlations between the rate of GF and kernel weight as well as kernel weight and yield enable indirect selection for yield and a high rate of GF via breeding for a larger kernel