Effects of cutting number and nitrogen rate on quality and forage yield of field Amaranth

In order to study the effect of nitrogen rate and cutting numbers on forage quantitative and qualitative characters of field amaranth (Amaranthus hypocondriacus L.) a field experiment was conducted at Tarbiat Modares University, Iran, on 2019 growing season. Nitrogen fertilizer was applied in five rates (0, 100, 200, 300 and 400 kg.ha-1) and cutting has two strategies: single harvest (at the beginning of grain filling) and double-cutting (at the beginning of flowering and the beginning of the grain filling). Forage yield and qualitative traits (crude protein, acid detergent fiber, crude fiber and cell wall) were measured at both cutting strategy. The results showed that nitrogen rate had significant effect on quantitative traits and crude protein, and also the effect of cutting on all traits was significant except for LAI and cell wall. Cutting×nitrogen interaction was not significant for any traits, except for dry leaf/stem ratio. Mean comparison showed that 200 kg.ha-1 nitrogen treatment and single-cutting harvest had the highest dry forage yield of 27490 and 27120 kg.ha-1, respectively. Although the highest crude protein percentage was obtained in 400 kg.N.ha-1 treatment and were in same statistical group with 200 kg N.ha-1. Also two- cutting harvest with 15% crude protein was better than single-cutting harvest.