The objective of the research is to determine the optimal value of plant density and the mass of planting tuber on the base of photosynthetic activity study of early potato (cultivar Latona) in the plain zones of the South Kyrgyzstan at typical sierozems. There were two factors under study: 1) mass of planting tuber: small (25–50 g), mean (50–80 g), big (80–100 g); 2) plant density: 45.4; 55.4; 65.4; 75.4 thousand tubers per hectare. The study showed that the greatest leaf area had the variants at the plant density 75.4 thousand tubers per hectare – 44.8; 46.8 and 48.2 thousand m²/ha for small, mean and big planting tubers respectively. When plant density increased up to 75.4 thousand tubers per hectare the value of photosynthetic potential enlarges by the variants up to 2731, 2954 è 3349 thousand m²•day/ha. Variants with less plant density had the greater dry mass of a plant comparing with more dense plantings. While using small tubers and plant density of 45.4 thousand tubers per hectare, the rate of tuber mass increasing was 36.42 g/(m²•day), and for 75.4 thousand tubers per hectare – 44.85 g/(m²•day). When mean and big tubers were planted the rate of tuber mass increasing also was high. Its values were 41.64–47.52 and 43.38–50.02 g/(m²•day) respectively. Average daily increasing of tuber dry mass and the total dry mass yield of early potato grew together with the increasing of planting tuber mass and plant density. The study results that optimal mass of planting tuber is 50–80 and 80–100 g at plant density of 65.4 thousand tubers per hectare.
Keywords: early potato, tuber, photosynthetic activity, photosynthesis, chlorophyll, dry weight, yield, mass of planting tuber, planting density.
