We compared peculiarities of the production process of the older and modern(created 80 years after) sorts of winter rye. It is determined that the specific coenotic productivity of a modern sort is 60.6% higher.This increase is due to higher number of productive sprouts per unit area and higher sprout weight. The coenosis of modern sorts is highly resistant to lodging. The modern sort has a 33.5% higher leaf surface index and a 17.7% higher share of the leaves in the upper tier, differing in their erectile orientation in space. As for the content of total chlorophyll in the dry matter of leaves and vagina, the modern sort is inferior to the older by 30.2%during theearing period, and by 17.5%during the milky-wax ripeness period.As for the content of total chlorophyll in the sowing area, the compared sorts were practically the same, but the ratio between chlorophyll a and c was noticeably different. As for the chlorophyll content in stems, in dry matter and in the area of sowing, the modern sort is inferior by1.5 times and more to the older in both observation terms. The sorts differed in the biomass accumulation and its distribution between the parts during the vegetation period. To establish the ear productivity, the older sort used only the current photosynthesis products.In conditions of an unfavorable growth year, the modern sort used previously accumulated by leaves and re-utilized assimilates. The actual and potential productivity of an ear in a modern sort is higher by 77.4 and 68.0%, respectively, but the degree of its vegetative mass supply is lower by 48.6%.Only due to the higher, by 77.4%, utilization of the mass of the sprout, the modern sort binds a greater number of grains in the ear with a higherseparate mass.Since the sharp increase in the ear productivity potential was not accompanied by the same growth of the sprout vegetative mass, the modern sort, in unfavorable conditions for growth, has tensions in the relation system between the sprout vegetative mass and pouring grain. This may be the reason of the unstable achievedyield level.
