EFFECT OF DIFFERENT IRRIGATION REGIMENS ON WATER-YIELD RELATIONSHIPS OF POTATO

Yield response to irrigation of different crops is of major importance in production planning. The study aim of the experiment was to determine the effect of different irrigation regimens on water-yield relationships of potato. The study was carried out at the experimental field of the Institute of Field and Vegetable Crops in Novi Sad in the period 2002-2003. The trial included three irrigation variants (pre-irrigation soil moisture of 60, 70 and 80% of field water capacity - FWC, or irrigation was performed when 70%, 50% and 30% of available soil water, respectively, was consumed), and the non-irrigated, control variant. The trial was established in a system of random blocks and adapted to technical specifications of the sprinkling irrigation. Water used on evapotranspiration of potato was determined by balancing the amounts of water taken up from the soil layer of 2 m depth, from natural rainfall and irrigation. To assess the effectiveness of irrigation IWUE and ETWUE coefficients were used. Effects of irrigation on potato yield were positive and highly significant. The highest yield of potato was obtained on the irrigation variant of 70% of FWC (43158 kg ha^-1). The amounts of water. used on evapotranspiration under irrigation (ET_m) and non-irrigation conditions (ET_a) ranged from 451.4 to 501.4 mm, and 373.4 to 381.2 mm, respectively. The values of IWUE and ETWUE varied from 71.4-112.5 kg ha^-1 mm-¹ and 67.0 do 91.9 kg ha^-1 mm^-1 respectively. As the highest values of yield, IWUE and ETWUE coefficients of potato were obtained on the irrigation variant of 70% of FWC that level of soil moisture represents the time when to start with irrigation if potato is grown in a soil with medium soil texture, under climatic conditions of the Vojvodina region.