Morpho-physiological characterization and standardization of agronomic practices of quinoa (Chenopodium quinoa) for salt affected ecosystems

Abstract

• During rabi season (November–April) of 2018-19, 19 germplasm lines have been evaluated under four levels of irrigation water salinity (Best available water (BAW), 8.0, 16.0 and 24.0 dS/m) to evaluate the response of quinoa to saline water in Indian conditions. • The mean SPAD meter readings (greenness of leaves) of different germplasm ranged from 43.7 to 52.3 across the salinity environments and no significant difference was observed between control and 8 dS/m treatments. SPAD readings showed an at 16 and 24 dS/m irrigation water treatments over control and 8 dS/m treatments. • Plant height of quinoa germplasms ranged between 67.1 cm to 91.6 cm at maturity. Salinity stress of 8.0 dS/m did not influence the plant height of all the germplasm studied. However, higher levels of stress (16 and 24 dS/m), significantly reduced the plant height of all the lines. • The mean no. of branches/plant of quinoa germplasm lines varied between 15.5 (Brown quinoa) to 25.5 (EC507739). Significantly highest no. of branches/plant was recorded in the germplasm line EC507739 being on par with CE507740, 507748, L1 and L2. The increasing levels of salinity significantly reduced the no. of branches/plant over best available water (BAW). • Among the germplasm lines, EC 507740 recorded significantly maximum mean grain yield of 11.08 g/plant being on par with local accession 1 (L1), local accession 2 (L2), EC507746 and EC507748 (Table 1). • The germplasm EC 507740 also recorded maximum grain yield of 9.20 g/plant at highest levels of salinity (24 dS/m ECiw) which was 19.9 per cent higher over next highest yielder germplasm (L1) at 24 dS/m stress. • The consistent increase in irrigation water salinity significantly reduced the grain yield of quinoa lines and across the germplasm lines, the magnitude of reduction was 19.2, 34.9 and 50.2 per cent under 8.0, 16 and 24 dS/m ECiw over BAW irrigation. • The ionic partitioning of Na and K also studied in plant root, shoot and leaves of quinoa lines at flowering stage and in grains after harvesting. The Na concentration in all the plant part increased significantly with the increasing irrigation water salinity (Fig. 1). • The maximum accumulation of sodium under saline water irrigation was found in shoot of the plants followed by leaves and root, and very less quantity of sodium trans-located to the seeds. • The accumulation of sodium in shoot was much higher (1.35, 2.03 and 3.57 per cent content) as compared to other plant parts, which shows adaptive advantage to leaves by controlling Na transport from shoot to leaves. • The K content in root and grains of quinoa germplasm was decreased significantly with the increase in salinity of irrigation water from 8-24 dS/m ECiw (Fig. 1). Contrary to this, the K content in shoot and leaves increased significantly with consistent increase in ECiw from 8 to 24 dS/m. This indicated the capability of quinoa to maintain high K concentration in leaves to mitigate the adverse effect of Na by maintaining favourable K/Na ratio (Fig 2). • Micronutrient content (Zn and Fe) in grains of quinoa germplasm analysed and it was observed that the mean Zn content ranged from 39.1 to 57.9 ppm among the germplasm (Table 2). Interestingly the content of Zn significantly increased along the salinity stress in all the germplasm. • The Fe content in quinoa germplasm observed in the range of 124 to 148 ppm among the germplasm (Table 3). The Fe content in grains increased dramatically with increasing salinity stress up to 16 dS/m, then a reduction in Fe content in grains was observed at highest salinity stress of 24 dS/m ECiw in almost germplasm except EC507742 and L1 which showed increase up to 24 dS/m. However the difference between 16.0 and 24.0 dS/m ECiw treatment was non-significant. • This showed that the salinity stress did not cause any adverse effect on its grain quality in terms of Zn and Fe concentration.