Soil Fertility Status, Nutrient Uptake and Productivity of Marigold (Tagetes erecta Linn.) as Influenced by Fertilizer Doses and Plant Growth Regulators

Aims: A field experiment was conducted to evaluate soil fertility status, nutrient uptake, growth and yield of African marigold (Tagetes erecta Linn.) as influenced by fertilizer management with or without foliar spray of plant growth promoting chemicals. Study Design: The field experiment was conducted with eight treatments, each being replicated thrice in a randomized block design (RBD). Place and Duration of Study: Instructional cum research (ICR) farm, Assam Agricultural University, Jorhat, Assam (India), between September 2013 and January 2015. Methodology: The treatments comprised of an unfertilized plot, application of 2500 kg ha-1 vermicompost at planting followed by 10 kg ha-1 each of N, P2O5 and K2O in two equal splits at the time of planting and at 30 days after planting (DAP), 2500 kg ha-1 vermicompost as mixture with fertilizer (comlizer) 10:10:10 kg ha-1 (Comlizer-1) or 30:10:30 kg ha-1 (Comlizer-2) of N, P2O5 and K2O, respectively applied in two splits (planting and at 30 DAP). Each comlizer treatment had two supplementary treatments of spraying either vermiwash solution (10% on second and third weeks and 20% solution on fourth and fifth weeks after planting) or indole butyric acid (IBA) and kinetin mixture (IBA-kinetin) solution (0.01% each on second and third weeks and 0.02% each on fourth and fifth weeks after planting), respectively. Results: The soil pH, organic carbon and available phosphorous contents after harvest of the crop were not affected by the treatments. The available nitrogen content in soil significantly increased in comlizer-2, but the available potassium content was not affected by the fertilizer doses. The NH4-N and NO3-N in soil at 15 and 45 DAP increased significantly with application of comlizer-2. Phosphorous and potassium uptake by aerial biomass of marigold at 21 and 42 days after planting significantly increased in Comlizer-2, but the effect of foliar spray was not significant. The highest fresh flower yield was produced by application of Comlizer-2 with foliar spray of vermiwash, and differed significantly to the rest of the treatments. Conclusion: Application of mineral fertilizers as mixture with vermicompost and integrated with foliar spray of growth regulators showed promising results. Further works with higher doses of nutrient and compost, frequency and intensity of foliar application of growth regulators are required to develop cost effective nutrient management practice.