Ghobad Mohamadpoor; Salim Farzaneh; Saeed khomari; Seyedeh Yalda Raeisi Sadati; Raouf Seyed Sharifi; Behrooz Esmaielpour; kianoosh Azarshab
Abstract
IntroductionQuinoa (Chenopodium quinoa Willd.) is a highly nutritious crop with a well-balanced amino acid profile, including lysine and tryptophan, making it a suitable alternative ...
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IntroductionQuinoa (Chenopodium quinoa Willd.) is a highly nutritious crop with a well-balanced amino acid profile, including lysine and tryptophan, making it a suitable alternative to rice. Given its nutritional value, expanding quinoa cultivation is crucial. However, since Iran is located in an arid and semi-arid region with high evaporation rates exceeding annual rainfall, crops frequently experience drought stress, particularly at the end of the growing season. The application of natural fertilizers such as seaweed extract and humic acid may help mitigate the effects of drought stress.Materials and MethodsThis study aimed to assess the impact of irrigation cut-off on biochemical traits of quinoa in two contrasting climates: Qasr-e-Shirin (hot) and Dalaho (cold) in Kermanshah province. The experiment was conducted as a split-plot design within a randomized complete block design (RCBD) during the 2018-2018 cropping season. The main plots included three irrigation treatments (full irrigation, irrigation cut-off at the beginning of flowering, and irrigation cut-off at the beginning of seed formation). The sub-plots consisted of five foliar spray treatments: seaweed extract at two concentrations (2.5 g l-1 and 3.57 g l-1), humic acid at two concentrations (3.75 g l-1 and 5 g l-1), and a control treatment (pure water spray). The quinoa seed used in this study was the Titicaca variety. The first foliar spray was applied when the plant height was about 20 cm, and the second foliar spray was applied 10 days later. Irrigation of plants in the control and irrigation cut-off treatments was carried out after 50% of the usable soil moisture was drained before irrigation cut-off was applied. Results and DiscussionThe results showed that irrigation cut-off significantly reduced the concentration of photosynthetic pigments (chlorophyll a, chlorophyll b and carotenoid), protein content, and relative water content in quinoa leaves compared to full irrigation. Under drought stress, proline accumulation, electrolyte leakage from cell membranes, and the activity of antioxidant enzymes (superoxide dismutase, catalase and peroxidase) increased. The results showed that the application of seaweed extract and humic acid alleviated the negative effects of irrigation cut-off. The highest levels of chlorophyll a (1.760 mg g-1), chlorophyll b (0.989 mg g-1), carotenoid (0.291 mg g-1), protein content (1.40 mg g-1), and relative water content were observed with the foliar application of 3.75 g l-1 seaweed extract. The adverse effects of drought stress were more pronounced in Qasr-e-Shirin (hot climate), particularly when irrigation was interrupted at the flowering stage. ConclusionsThe results showed that the effects of foliar application of seaweed extract and humic acid in modulating drought stress were much greater in plants that faced irrigation interruption at the beginning of the flowering period. However, foliar application of seaweed extract reduced the negative effects of drought stress more than humic acid. Overall, these findings suggest that foliar application of seaweed extract and humic acid is an effective and environmentally friendly strategy to mitigate the adverse effects of irrigation cut-off on quinoa. Quinoa production efficiency in the temperate region of Dalahu was much better than in the Qasr-e-Shirin region..
