Investigation of the effects of methyl jasmonate and salicylic acid elicitors on yield and yield components of quinoa (Chenopodium quinoa Wild.) under irrigation levels

The use of new agricultural technologies such as bio-elicitors is a valuable approach to reduce effects of drought stress. The present study investigated the prospects of enhancing yield and some physiological properties in quinoa under different levels of plant water requirement using elicitors, such as methyl jasmonate (MeJA) and salicylic acid (SA) elicitors.

The aim of this study was to evaluate comparative effect of elicitors MeJA and SA foliar application on the yield and yield component of quinoa under drought stress. This experiment was conducted during 2020-21 cropping season as split plots in a randomized complete block design with three replications at research farm of Zabol University, Iran. The main plots was irrigation regimes at three levels: 100, 75, and 50 percent of crop water requirement and sub-plots of foliar spraying in six levels including: Control (sprayed with distilled water), 70% ethanol, 0.5 mM SA, 0.5 mM MeJA, 1 mM SA and 1 mM MeJA. In this study fertile branches per plant, sterile branches per plant, panicle numbers per m2, seed numbers per panicle, 1000 seeds weight, leaf relative water content, chlorophyll index (SPAD) and seed yield were measured. Determination of irrigation cycle and crop water requirement was based on CROPWAT 8.0 software and Penman-Mantis equation. For plant coefficients used FAO default data. Irrigation planning was determined with 85% efficiency and water volume of each plot calculated using a digital water meter.

The physiological response of the plants in terms of relative water content (RWC) was improved by 100 and 75 percent of crop water requirement conditions. The relative water content of the leaves decreased significantly under the influence of drought stress, although there was no significant difference between the control treatment and the supply of 75% of the water requirement of the plant, by increasing the stress intensity to 50% of the water requirement of the plant, a decrease of 31.6% in the relative water content of the leaves was observed. Additionally, doubling the elicitors concentration increased the yield and non-yield traits. Foliar application of MeJA and SA significantly increased the seed yield and fertile branches and sterile branches per plant, panicle number per m2, seed number per panicle and chlorophyll index treats. The use of 1 mM SA gave the best response after MeJA. Despite providing 50% of the plant's water needs, plants treated with 1 mM methyl jasmonate produced 45% more fertile shoots than plants sprayed with distilled water. Drought stress increased the number of infertile shoots by 77% compared to control plants. Increasing the intensity of drought stress and decreasing water availability decreased the filling rate and ultimately the seed weight. The application of 1 mM concentration of methyl jasmonate and salicylic acid increased the chlorophyll index compared to the control. Based on the results of comparing the averages, the highest level of this trait (46.84) was observed in the concentration of 1 mM methyl jasmonate. The positive effect of methyl jasmonate on the chlorophyll concentration of leaves may be due to the increase in the number and size of chloroplasts. The results showed that the interaction of irrigation and foliar application had a significant effect on all traits except 1000 seeds weight, RWC and chlorophyll index. The highest seed yield (2929.3 kg ha-1) was obtained from 100 percent of crop water requirement (4662 m3 ha-1) with 1 mM MeJA treatment.

Our results showed that impaired water supply of quinoa with significant loss of relative water content endangers cellular health and reduced yield. In general, it can be said that, to achieve maximum yield of quinoa it is possible to use 100% of crop water requirement with 1 mM MeJA foliar application.