Experimental site and initial soil status:
A field experiment was conducted at the Soil science division of Bangladesh Agricultural Research Institute, Gazipur during Rabi season in 2019-2020. The study area was under the agro-ecological zone “Madhupur Tract” (AEZ-28). Initial soil samples were collected from a depth of 0-15 cm and analyzed prior to application of different fertilizers are presented.
Treatments and fertilizers: The design of the experiment was randomized complete block design (RCBD) with 5 treatment combinations having three replications for each as foliage and seed production. Treatments combinations were built up by using three levels of zinc (0, 2, 4 kg ha-1) and three levels of boron (0, 1, 2 kg ha-1). A basal application was made with 5 t ha-1 cowdung, 83 kg ha-1 N, 26 kg ha-1 P, 55 kg ha-1 K and 13 kg ha-1 S in each plot to support normal plant growth. The entire amount of cowdung, P from TSP, K from MOP, S from gypsum and half of N from urea were applied during final land preparation. Rest of the N from urea was top dressed after 35 days of sowing.
Experimental work: The seeds were rubbed and soaked in water for 24 hours to enhance germination. Before sowing the seeds were treated with Bavistin at 2 g kg-1 and sown it at 30 cm apart rows continuously by hand at 25 kg ha-1. The unit plot size was 1.5 m × 2 m and seeds of coriander (BARI Coriander-1) were sown at 28 November, 2019. The soils of all plots were kept moist to confirm sufficient moisture with addition of light water for quick germination. Irrigation was given according to need throughout the period to keep the soil moist. Necessary intercultural operations were done throughout the cropping season for proper growth and development of the plant. For foliage production, Green plants are harvested before bolting at 07 January, 2020.10 plants were selected randomly from each plot for recording data on plant height, number of leaves plant-1, foliage yield etc. On the other hand, plants cultivated for seed yield were harvested at 7 March, 2020 when 50% seeds turn brown color. Five plants were selected randomly from each plot for recording data on plant height, number of umbell plant-1, number of umbellate plant-1 etc. Seeds were dried in an oven at 70°C for 72 hours and the dried samples were then finely ground in a grinder for laboratory analysis. After harvest, the soil from each plot was thoroughly mixed and approximately 100 g soil was sampled for laboratory analysis.
Chemical analysis: For initial soil analysis, soil pH was measured by a combined glass calomel electrode (Jackson, 1958). Organic carbon determination was done by wet oxidation method (Walkley and Black, 1934). Total N was determined by modified Kjeldahl method. Elements K, Ca and Mg were determined by NH4OAC extractable method and Cu, Fe, Mn and Zn were determined by DTPA extraction method followed by AAS reading. Boron was determined by CaCl2 extraction method. Phosphorus was determined by Bray and Kurtz method while S by turbidimetric method with BaCl2. Total soluble solids content (TSS) was determined at 20°C with a refractometer and reported as Brix. Vitamin C was determined by classical titration method using 2, 6- dichlorophenol indophenols solution and express as 100 mg g-1 of fresh weight (Miller, 1998). Total carotenoids (μg 100 g-1) was measured by spectrophotometer (T-40, PG Instrument Ltd.UK) at 451?m (Alasalvar et al., 2005).
Zn and B uptake: Zn and B uptake were determined separately by the following formula:
Nutrient uptake (kg ha-1) = Nutrient % × Dry weight (kg ha-1) /100