The aim of the research is to investigate the influence of different irrigation rates on the yield of potato at summer planting for the conditions of chernozem soils of floodplain of the Lower Don. There were four variants of irrigation regime under study: irrigation by calculated irrigation rate for maintaining the moisture in soil layer 0–60 cm in the range of 0.8–1.0 of field capacity (FC), M; by irrigation rate increased by 20 % from calculated one, 1.2 M; by irrigation rate reduced by 20 % of calculated one, 0.8 M; by irrigation rate reduced by 40 % of calculated one, 0.6 M. Irrigation events in all the variants were conducted in the same dates. As a result of the study it was found that total duration of plant vegetation from planting to full maturity was from 67 to 79 days, while the increasing of vegetation period was observed for increased irrigation rate. The area of leaf surface reached maximal values in the variant of 1.2 M in phases of “flowering” and “cessation of foliage growth”, and was 64589 and 64976 square meters per hectare respectively. Active growth of leaf surface was provided in all the variants from the moment of budding to the moment of flowering. In this period daily increase of leaf surface per one hectare of the field changed from 3313 in the variant 0.6 M to 4457 square meters in the variant 0.8 M. In the variant 0.6 M the greatest increase of tuber mass at all phases of plant development was marked. The maximal value, 37.42 t/ha, of this indicator was at the beginning of the phase “full maturity” in the variant 1.2 M, but the difference with the control variant M was within the experimental error. The variant with irrigation rate reduced by 20 % provided the yield of potato tubers 35.23 t/ha what is by 5 % less than that of the control variant. Irrigation rate reduced by 40 % provided the significant loss of the yield by 16.66 t/ha or 45 %.
Keywords: irrigation rate, potato, summer planting, floodplain lands, area of leaf surface, yield.
