Evaluation of forage Amaranth (Amaranthus hypochondriacus l.) yield via comparing drought tolerance and susceptibility indices

In orther to investigate the influence of different drought stress levels on the quality and quantity yield of forage Amaranth, a set of split-plot analysis were carried out in randomized blocks design with three replicates during the 2018 and 2019 growing seasons. The main factor of this study was different irrigation levels (50, 60, 70, and 80 % of the plant available water depletion) and the sub-factor was considered to be three different forage Amaranth genotypes, including Cim, Kharkovski, and Loura. The results revealed that an increase in irrigation intervals especially in 80 % water-deficit condition, will lead to a decrement in the fresh and dry yields (62 and 50 %), a reduction of WP factor (50 %) and an increase of the dry matter and crude protein percentages regarding the control treatment. Furthermore, to specify the most significant stress indices from Principal Component analysis in different drought stress levels, Harmonic Mean was chosen as the best index to examine the tolerance of Amaranth cultivars to the drought condition. According to the 3D graph of the opted index correlation with the yields, it was concluded that while Loura presents a better yield under mild stress conditions, the Cim genotype has the highest performance under moderate and severe drought stress conditions.