Agro-morphological and biochemical responses of quinoa (Chenopodium quinoa Willd. var: ICBA-Q5) to organic amendments under various salinity conditions

Abstract

In the Sahara Desert, due to drought and salinity and poor soil fertility, very limited crop choice is available for the farmers to grow crops. Quinoa (Chenopodium quinoa Willd.) has shown promising under such conditions in the South of Morocco, a true representative site of Sahara Desert. Soil organic amendments have the potential to minimize negative effects of soil salinity and improve crop production. Thus, this study aimed to elucidate the impact of nine organic amendments on quinoa (var. ICBA-Q5) growth, productivity, and biochemical parameters under saline irrigation water application (4, 12, and 20 dS·m^-1). Results of the experiment indicate a significant effect of organic amendments on major agro-morphological and productivity parameters. Biomass and seed yield tends to decrease with the rise of salinity level, and organic amendments have improved productivity compared to the non-treated control. However, salinity stress alleviation was assessed by determining pigments concentration, proline content, phenolic compounds, and antioxidant activity. Therefore, the action of organic amendments varies from one level of salinity to another. Furthermore, a remarkably significant decrease in total saponin content was reached due to the application of amendments even at high saline conditions (20 dS·m^-1). The results demonstrate the possibility of enhancing the productivity of quinoa as an alternative food crop under salinity conditions by using organic amendments and improving the quality of grains (saponin reduction) during the pre-industrialization process.

Keywords: growth; organic amendment; osmotic stress; quinoa; saponin; seed yield.

Figure 1

Experimental design showing allocation of main and sub-plot treatments (A), Layout of the irrigation water distribution system in the experimental plots (B).

Figure 2

Variation of rainfall and temperature (A), wind speed (B), and relative humidity (C) during the growing period in Laayoune, Morocco.

Figure 3

Stacked area plot of daily soil salinity (ECe) dynamics during the crop growing period measured under sheep manure amendment and three irrigation water salinity levels at 0-10 cm soil depth (A). Stacked area plot of daily soil moisture dynamics during the crop growing period measured under sheep manure amendment and three irrigation water salinity levels at 0-10 cm soil depth. (B), and under three organic amendments (sheep manure, compost, and biochar) measured at irrigation water salinity of (4 dS·m-1) (C), at 0-15 cm soil depth.

Figure 4

Photosynthetic pigments content measured on fresh leaves of quinoa as affected by different irrigation water salinity and organic amendments. Chlorophyll a (Chl a), chlorophyll b (Chl b), total chlorophyll (Chl tot), and chlorophyll a to chlorophyll b ratio (Chl a/Chl b). Values represent mean ± standard deviation. Different letters indicate a significant difference between salinity levels (uppercase letters) and between organic amendments (lowercase letters) at p < 0.05 level of significance using the Tukey post-hoc test.

Figure 5

Variation of quinoa’s leaf Proline content under different salinity levels and various organic amendments. Values represent mean ± standard deviation. Different letters indicate a significant difference between salinity levels (uppercase letters) and between organic amendments (lowercase letters) at p < 0.05 level of significance using the Tukey post-hoc test.

Figure 6

Variation of seed saponin content in quinoa as affected by different irrigation water salinity levels and organic amendments. Values represent mean ± standard deviation. Different letters indicate a significant difference between salinity levels (uppercase letters) and between organic amendments (lowercase letters) at p < 0.05 level of significance using the Tukey post-hoc test.

Figure 7

Variation of quinoa phenolic content under different salinity levels and various organic amendments. Values represent mean ± standard deviation. Different letters indicate a significant difference between salinity levels (uppercase letters) and between organic amendments (lowercase letters) at p < 0.05 level of significance using the Tukey post-hoc test.

Figure 8

Pearson’s correlation matrix for the investigated parameters. Values in the matrix represent Pearson’s correlation coefficient. *, **, *** indicate the significance of the correlation coefficient at p < 0.05, 0.01, and 0.001, respectively (A). PCA-biplot projection of individuals (black points), variables (blue arrows), and supplementary qualitative variables (red arrows) on the main axis for agro-morphological and productivity traits (B), and biochemical and physiological parameters (C).