Variation in ornamental traits, physiological responses of Tagetes erecta L. and T. patula L. in relation to antioxidant and metabolic profile under deficit irrigation strategies

- Two deficit irrigation strategies, DI and RDI were applied.
- Ornamental and physiological parameters were positively correlated.
- Flower yield showed statistical differences in both DI and RDI.
- Enzymatic and non-enzymatic anti-oxidant activities increased in RDI and DI compared to control.
- GC-MS profiling of essential oils of both T. erecta and T.patula flowers showed marked increase under different irrigation strategies.

The present study evaluated the effect of deficit irrigation strategies on the ornamental traits, physiological, biochemical and antiradical potential of two cultivars PNG and MGO of Tagetes erecta L.and Tagetes patula L, respectively. Deficit irrigation was applied in two ways a) plants were subjected to deficit irrigation (DI) at 50% field capacity (FC) as compared to control treatment (100% FC), b) regulated deficit irrigation (RDI) where DI was restricted to two stages of plants i.e. before initiation of floral buds and after 50% flowering. In between these two stages, non-limiting water supply was given to cultivars (100% FC).Findings of the experiments revealed that induction of secondary metabolites under DI and RDI could be taken into account for increased antioxidant activities in both the cultivars of Tagetes spp. Under second DI strategy (RDI), showed significant difference with DI at all phases. Flower yield was not significantly distinguishable compare to control treatment. Volatile principles of flowers of Tagete spp. produced under control, DI and RDI, were analyzed through GC-MS. Alpha-pinene, bicyclo heptane, limonene, p-cymene terpinolene, increased in RDI and DI compared to non-limiting water supply (control) in both Tagetes cultivars. Ocimene and n-decaldehyde content decreased under water deficit conditions as compared control.In both Tagetes species, ornamental traits like number of flowers, flower diameter and flower yield, exhibited positive correlation with photosynthetic rate (Pn), stomatal conductance (gs) and relative chlorophyll content (RCC). In contrast, negatively relation was found with SOD, CAT and electrolyte leakage.