The objective of the study was to develop irrigation modes for cucumber under drip irrigation providing the most favorable conditions for crop growth, development, and high yields in the floodplain of the Lower Don. The study included three irrigation modes: moderate, differential and increased. The research resulted in establishing that the increased irrigation mode supporting soil moisture higher than 80 % of field capacity created the most favorable conditions for growth, development and productivity of the cucumber. To maintain this irrigation mode, 19.7 water applications in average were required, and the average irrigation application was 131 m³/ha. At the increased irrigation mode, there were marked: 1) prolongation of the fruiting season by 10-15 days in comparison with moderate irrigation mode; 2) higher biometric indices for linear growth, so, the total length of creeping stem at the end of fruiting season reached to 194 cm while daily growth rate was 1.47 cm; 3) increase in the rate of crop mass growth, so, it was from 1.1 t/ha at the flowering phase to 7.12 t/ha (considering harvested fruits) at the end of fruiting season. As a result, averaged for three years of research, cucumber yield was 70.9 t/ha, that is higher by 25 t/ha than under the moderate mode and by 5.7 t/ha than under the differential one. The most effective water use was also observed under the increased irrigation mode, where water consumption coefficient was 75 m³/ha against 91 m³/ha under the moderate irrigation mode.
