Development and seed production of different topinambur (Helianthus tuberosus L.) cultivars when changing the photoperiod and fertilizing

Here we reported the results of the field multifactorial experiment (2014 - 2016) related to the developmental peculiarities and seed productivity of different grades of Jerusalem artichoke on sod-medium podzolic light loamy soil. The scheme of the experiment included: the background of the mineral nutrition (factor A) - without fertilizer, the calculated dose of NPK for the yield of 40 tons of tubers with the corresponding number of leaves; sort (factor B) - early maturing Skorospelka, late-ripening Interest; the shading time (factor C) - on the 10th and 20th days after germination; duration of shading (factor D) - for 10, 20, 30 and 40 days, control is a natural light day. We revealed that under the photoperiodic influence the sort Skorospelka accelerates the development for 4-10 days, while the Interest accelerates for 43 - 52 days. Sort under the shortened photoperiod increase the content of chlorophylls and carotenoids in leaves, as well as the intensity of photosynthesis. They form ripe seeds: an average of 2.00 pieces per plant (Skorospelka) and 0.22 pieces per plant (Interest). The best way to get full seeds from the Skorospelka sort is to shade it on the 20th day after sprouting for 10 days and (more expensive) on the 10th day for 30 and 40 days against the the effective soil fertility, while the Interest sort should be shaded on 20th day after germination for 40 days when grown on a fertilized soil.