Scientific Reports of the National University of Life and Environmental Sciences of Ukraine

The article highlights the dynamics of the formation of the leaf surface area of root chicory plants depending on the sowing time during the growing season in the conditions of the Right-Bank Forest-Steppe of Ukraine. Phenological observations, biometric studies were carried out according to B.A. Dospekhova, V.F. Moiseichenka. The research material was the experimental field soil – limed blacksoil mid loam on loesslike loams. Root chicory plants were used as the research object. The studies were conducted on the experimental field of the Khmelyitskyi State Agricultural Experimental Station of the Institute of Feed and Agriculture of the Podillia of the NAASU during 2014-2016. It was established that in 2014 the largest average leaf surface area in the winter sowing period was 30.2 thousand m² / ha, while the photosynthetic potential was 3326 thousand m² / day. Then, as when sowing in 2015 and 2016, the leaf area was 9.0 and 17.9 thousand m² / ha, the photosynthetic potential was 1045 and 1971 thousand m² / day, respectively. Slightly lower indicators of leaf surface area were obtained from early spring sowing dates (1.04-4.04). On average, during the growing season, the largest leaf area was in 2014 and amounted to 20.5 thousand m² / ha, photosynthetic potential - 2250 thousand M2 × days / ha. According to summer sowing (1.06-4.06), the largest leaf surface area of chicory plants on average during the growing season was in 2016 - 9.1 thousand m² / ha, photosynthetic potential of 1003 thousand m² / day / ha. It was established that in chicory plants in the unfertilized area in the first and second variant, at the beginning of the growing season, the assimilation surface increased more intensively with increased soil moisture of 80 % of the total moisture capacity. Starting from the third decade of July, chicory plants in the second variant began to lag behind in growth from the plants of the first variant, which were grown at 60 % soil moisture. The use of fertilizers has the positive effect on the increase in leaf area. It should be noted that the largest leaf surface area was on fertilized varieties and with high soil moisture of 80% during the growing season in all accounting periods. This, in turn, was reflected in the level of the crop, both plants and root crops

root chicory; leaf surface area; photosynthetic potential; yield