Nitrogen fertilization enhances growth, quality and seed production of celosia (Celosia cristata L.), marigold (Tagetes erecta L.) and zinnia (Zinnia elegans L.)

Cock’s comb (Celosia cristata L.), marigold (Tagetes erecta L.) and zinnia (Zinnia elegans Jacq.) are popular ornamentals which are extensively cultivated as annual bedding adornments. A study was carried out during 2021-2023 on celosia, marigold and zinnia to scrutinize the effects of nitrogen fertilization. Greatest plant height for celosia (66.3 cm), orange marigold (90.5 cm), yellow marigold (72.8 cm) and zinnia (75.2 cm) was recorded when plants were fertilized with NPK combination @ 30:10:10 g m-2. The least production time was recorded in celosia (21 days), (23.7 days) in zinnia with treatment combination 30 g m-2 nitrogen application, whilst marigold cultivars exhibited the least production time (79 and 101 days) in orange and yellow marigold in control @0:10:10 g m-2, respectively. The highest seed yield per plant in orange marigold (6.1 g), yellow marigold (8.1 g) and zinnia (0.9 g) was measured @ 30:10:10 g m-2 NPK application. Celosia plants showed almost similar results regarding seed yield per plant and were statistically at par. Leaf nitrogen uptake in celosia (0.6%), orange marigold (0.5%), yellow marigold (1.3%) and zinnia (0.8%) and leaf phosphorus uptake celosia (1.9%), orange marigold (0.4%), yellow marigold (0.6%) and zinnia (0.4%) were recorded highest @ 30:10:10 g m-2. Leaf potassium uptake in celosia (1.9%) and yellow marigold (0.8%) was recorded as 30:10:10, and in orange marigold (0.9%), zinnia (1.7%). In summary, NPK combination @ 30:10:10 g m-2 proved best regarding vegetative, reproductive, and flower attributes, seed yield and biochemical plant attributes in tested annual flower species/cultivars in local subtropical agro-climatic conditions.