Yield and zinc content of sugar beets as affected by nitrogen source, rate of nitrogen, and zinc application

Abstract

Introduction An experiment in which fidd plots were treated with a fac­ torial combination of three nitrogen sources, three ra tes of nitro­ gen, and five ra tes of zinc was sta rted at Prosser, vVashington, in 1953. The cropping sequence on these plots included grain sor­ ghum in 1953, pota toes in 1954, and suga r beets in 1955. T h e interest in sugar beets was concerned primarily with the influence of the trea tmen ts on zinc nutriti on. A t the same time, however, it was convenient to observe the effect of nitrogen ra te and nitro­ gen source on such things as yield, suga r content, and petiole nitrate. Apparently little work has b een done to determine the zinc requirements of sugar beets. In a previous paper Boawn and Viets (1)3 published data for a number of experiments showing' levels of zinc in leaf blades, and concluded that 10 ppm. zinc in young, fully developed leaves a t mid-season is adequate for above average yields. They did not report zinc levels in oth er parts of the plant nor the total zinc requirement, Lingle and Holm ­ berg (5) have reported increased grmvth of sugar bee t.s in Yolo County of California from applica tions of zinc but did not show levels of zinc in the plant associa ted with this response. In th e present experiment it was hoped that unfertilized plants would be sufficiently low in zinc tha t a g rowth response to addition s of zinc would ·be obtained. This did not occur, and therefore th e da ta do not esta blish critica l level s for zinc in th e tissues analyzed . On th e oth er hand, since additional zinc did not increase growth, th e leve ls of zinc fo und in plants from plots which did not rece ive zinc fertili zation are sh own to be adequate. Procedure Complete details of the experimentprocedure, obj ectives, and comple te experimental results-have been given in two previ­