Vermicompost-based amendment compensated for the reducing effect of water stress on growth and yield of quinoa by improving soil moisture characteristic

Abstract

Water scarcity has widely affected agricultural production and food security, particularly in arid regions. There is little information available on the concurrent effects of water stress and organic amendment application on the water holding capacity of soil as well as the growth and yield responses of quinoa as a drought-resistant plant. In addition, there are limited reports on the optimum levels of deficit irrigation as a promising strategy for enhancing the water use efficiency and production of quinoa plant. Therefore, the aim of this study is to investigate the moisture holding capacity of soil as well as the morphological and physiological responses of quinoa to the interactive effects of drought and organic amendment under field conditions. Three levels of water stress (full-irrigation, moderate drought, and severe drought) and four treatments of organic amendment including control (without the use of organic matter), vermicompost (20 t ha⁻¹), biochar (20 t ha⁻¹), and the composition of vermicompost and biochar (at an equal rate of 10 t ha⁻¹ each) were applied as the subsidiary factor. Result indicated that severe drought reduced the plant yield significantly (21.7%) as compared to control, whereas moderate drought showed no significant effect. Drought increased the proline content, whereas reduced all other traits including crop growth rate, 1000-seeds weight, bush height, panicle length, leaf area index, chlorophyll, proline, carotenoids, protein, and relative water content. However, the application of biochar, vermicompost, and Bvrm relative to the control treatment increased WUE by 12.3, 36.8, and 45.6%, soil moisture content by 2.0, 20.1 and 28.9%, and the quinoa yield by 1.0, 21.9, and 28.6%, respectively. There was an inverse relationship between water use efficiency and the grain yield of quinoa. The simultaneous effect of drought and biofertilizer on the quinoa grain yield (Y) was demonstrated based on soil moisture content (θ) using a linear relationship (Y = 168.5(θ) − 4.74; R² = 0.994, p < 0.01). The results also indicated that WUE was reduced linearly with increasing soil moisture content. Among different relationships, logarithmic function exhibited the best performance for predicting the yield of quinoa based on the amount of irrigation water. The findings of this study revealed the important role of soil moisture as a manageable characteristic in facing environmental stresses such as drought and achieving the sustainability of crop production.