Amelioration of mineral nutrition, productivity, antioxidant activity and aroma profile in marigold (Tagetes minuta L.) with organic and chemical fertilization

Abstract

The marigold (Tagetes minuta) oil finds an extensive use in food, flavoring, pharmaceutical, and perfumery industry. Increasing crop productivity and oil yield of the marigold by combining organic and chemical fertilizers is a commercially viable possibility. A field experiment was conducted to study the effect of integrated nutrient management on productivity of marigold and soil fertility during 2012–2014. The treatment comprises FYM (Farmyard manure 20tha−1), VC (vermicompost 10tha−1), PM (poultry manure 5tha−1), CF (chemical fertilization 100:60:60kg N:P2O5:K2Oha−1), FYM+CF (FYM 10tha−1+50:30:30kg N:P2O5:K2Oha−1), VC+CF (VC 5tha−1+50:30:30kg N:P2O5:K2Oha−1), PM+CF (PM 2.5tha−1+50:30:30kg N:P2O5:K2Oha−1) and unfertilized control. Application of PM+CF resulted in significantly superior growth attributes and oil yield in marigold than other treatments. Chlorophyll-a and chlorophyll-b contents increased by 45 and 35%, respectively, in PM+CF treatment as compared to the control. The nitrogen fertilization and organic amendments linearly correlated with biomass and oil yield with coefficient values of R2=0.882 and 0.887, respectively. Aroma compounds of Tagetes oil represented by dihydrotagetone, (Z)-β-ocimene, (E)-ocimenone, limonene and (Z)-tagetone were unaltered and remained within the commercially acceptable range in all the treatments. N uptake was highest in CF (28%) followed by PM+CF (22%) treatment. Antioxidant activity (DPPH) was higher than the control by 14% in FYM+CF and PM+CF treatments. Similarly, Mg content was highest in PM+CF and FYM+CF, around 32% higher over the control. Soil fertility parameters viz., organic C, N, P and K showed marked improvement in all the treatments over the unfertilized soil.