The beneficial effects of growth regulators on forage yield and quality of Amaranthus caudatus under different water stress conditions

Abstract

In order to improve crop productivity, farmers should have strategies for higher quantity and quality of forage without excessive inputs, like irrigation water. In order to assess forage quality of Amaranthus caudatus in response to irrigation levels (irrigation after 70, 140 and 210 mm of evaporation from class A pan) as main plots and foliar sprays of abscisic acid (ABA; 50 μM), salicylic acid (SA; 3 g l⁻¹) and potassium sulfate (PS; 3 g l⁻¹) as subplots. A water shortage from 70 to 210 mm of evaporation decreased the stomata conductance and leaf-area index, but the crude protein concentration, dry matter digestibility, leaf/stem ratio, forage yield and total nitrogen were increased from 70 to 140 and then decreased. Using deficit irrigation for amaranth can reduce water usage without significant yield loss, so that water use efficiency remains at the relatively high levels. Leaf water potential, relative water content, leaf-area index, total chlorophyll, carotenoid, crude protein, dry matter digestibility, leaf/stem ratio and forage yield were increased by foliar sprays. Significant reduction in forage quality occurred at delayed harvest. Forage yield of potassium sulfate treated under severe stress was increased by 29% and 56% at flowering and seed set stages, respectively.

Keywords: abscisic acid, nutritional value, potassium sulfate, salicylic acid