Investigation of some growth indices of two cultivars of autumn sugar beet (Beta vulgaris L.) under the influence of planting method, different levels of nitrogen fertilizer by foliar application of zinc sulfate

Autumn planting of sugar beet has more water use efficiency and agricultural advantages than spring planting. In order to investigate the possibility of autumn planting of two sugar beet cultivars and compare their root yield, a study was conducted in the Faculty of Agriculture of Lorestan University during two cropping years (2017-2018 and 2018-2019). This study was conducted in the form of a split factorial design with three replications. The main factor has two levels and includes planting method 50-50 (P1), 25-50 (P2), and the sub-factors including two varieties of autumn sugar beet (Rosagold and Chimene) and four levels of fertilizer (F1: application of 300 kg.ha-1 nitrogen (Control), F2: application of 270 kg.ha-1 nitrogen and foliar application of zinc sulfate, F3: application of 240 kg.ha-1 nitrogen and foliar application of zinc sulfate, F4: application of 210 kg.ha-1 nitrogen and foliar application of zinc sulfate in the amount of 5 per thousand. Rosagold cultivar with F2 treatment significantly (p<0.01) increased the photosynthesis active rate. The highest amount of stomatal conductance was observed in P1 planting arrangement with Rosagold cultivar. The highest CGR (16 g.m-2.day-1) and root yield (98.70 t.ha-1) were obtained from P1 planting arrangement, Rosagold cultivar and F2 fertilizer level. According to the obtained results, it can be stated that zinc sulfate foliar application has the ability to compensate for the reduction of nitrogen consumption by 10%, without reducing the yield and quality of autumn sugar beet.