Productivity of spring wheat and its relation to elements of yield structure in years differ by meteorological conditions

The result of seven years of research conducted on 322 collectible varieties of spring wheat in conditions of Kirov region shows the influence of meteorological conditions on the elements of productivity in the individual phases of the growing season. There was close positive correlation between yield and amount of precipitations during active plant growth - phase of elongation - earing (r = 0.87). The limits of variation of yield (148 - 500 g/m2) and its structural elements are determined; the regularities of variability of the traits in years favourable and unfavourable by heat and humidity. Within deteriorating conditions and a decrease in the average level of productivity a coefficient of intervarietal variation was increased significantly by 22 to 40 %. Unstability is shown of the values of pair correlations between productivity and its structural elements and accordingly the change in contribution of individual traits into yield depending on change of the limiting environmental factors. With a decrease in the total level of productivity its association with length of growing season and productivity of the main spike was intensified. In a comfortable growth conditions correlation between productivity and productive tillering and mass of 1000 grains was increased. Correlation of productivity with plant height was consistently high regardless of the year conditions. According to the results of the multiple regressions analysis the most informative traits were identified: plant height, the duration of the period from germination to ear emergence, length of growing season, length of spike, mass of grain per ear. Recommendations are given for selection that will improve the efficiency of breeding for environmental stability of the most limited traits