Chlorophyll meter readings of winter wheat cultivars and grain yield prediction

Investigation of chlorophyll meter values of 13 winter wheat cultivars suggests that readings are dependent on cultivar (genotype), growth stage and years effects. Before 2(nd) top dressing at the stage EC 31/32 the average value varied from 445 to 568, and before 3(rd) top dressing at the stage EC 45/50 it varied from 487 to 580. At the stage EC 45/50 the statistically identical values of six cultivars varied from 515 to 553, with the rest the extreme readings were 487 or 580. At the stage EC 31/32 there was no strong correlation (r = 0.134) between chlorophyll meter readings and grain yield, but there was stronger correlation between the chlorophyll meter values and grain yield (r = 0.538 sig. at the 0.01 level) at the stage EC 45/50. On the basis of results at the stage EC 45/50 only it is possible to explain 37% effect of the chlorophyll meter readings on the grain yield with quadratic or cubic regression curve.