MSc

ABSTRACT
Gomphrena globosa L. is a charming ornamental annual plant, commonly known as globe amaranth or bachelor’s button. Gomphrena is native to tropical and sub-tropical countries including India. It belongs to the family Amaranthaceae. Colourful and globular flower heads add colour and beauty to the garden and the flowers are suitable for cut and dried floral arrangements. Gomphrena is also an excellent choice for beds, borders and rock gardens. Among the various factors responsible for high crop yield, optimum spacing coupled with supply of appropriate quantity of nutrients at appropriate time plays a vital role in enhancing the productivity and the quality of the crop. For the commercialization of this crop, there is need to standardize optimum plant spacing and fertilizer levels. In this context, the study “Spacing and nutrient management for Gomphrena globosa L.” was carried out in the Department of Floriculture and Landscaping, College of Horticulture, Vellanikkara during 2019- 2020. Objective of the study was to standardize the spacing and fertilizer requirement of Gomphrena globosa for cultivation in Kerala.
The experiment was carried out in Randomized Block Design (RBD) with eight treatments comprising two levels of spacing i.e., 30x30 cm and 45x45 cm and three levels of fertilizers viz; NPK @ 50:25:50 kg/ha, 75:50:75 kg/ha and 100:50:100 kg/ha. Observations on growth characters, yield, post-harvest parameters, nutrient status of the soil, plant nutrient content and uptake were recorded.
Among the growth characters, plant height was found significantly higher in the treatment with closer spacing of 30x30cm compared to 45x45cm spacing. Other growth characters including plant spread, number of branches per plant and dry matter production per plant showed significant improvement when grown under wider spacing (34.92 cm, 14.83, 52.53 g/plant respectively). However, dry matter production per unit area (4 t/ha) was found the highest under closer spacing. Different fertilizer doses were found to be on par with one another with respect to plant height and were superior over control. Similar trend was found in plant spread, number of branches per plant and dry matter production. There was no significant interaction effect of spacing and nutrients on growth parameters.
Early bud initiation (46.81 days) and minimum number of days to 50% flowering (50.58 days) was observed under closer spacing of 30x30cm. Wider spacing of 45x45 cm produced greater number of flowers per plant (42.64), flower yield (40.90 g/plant) and seed yield per flower (0.29 g). The flower yield per hectare was found to be highest in closer spacing (2.50 t/ha). The different nutrient doses had significant effect on flower yield (g/plant). Application of N:P2O5:K2O @ 50:25:50 kg/ha produced greater flower yield (40.41 g/plant) which was on par with N:P2O5:K2O @ 75:50:75 kg/ha (35.11 g/plant) and superior over control treatments without fertilizers. The earliest bud initiation was observed in plants applied with N:P2O5:K2O @ 50:25:50 kg/ha along with closer spacing of 30x30 cm (42.78 days). Other floral characters and post-harvest parameters were not significantly influenced by spacing and fertilizer treatments.
Nutrient content in the plants was found the highest in wider spacing (45x45 cm) and the content in the plant increased as the dose of nutrient applied increased. However, the nutrient uptake by the plants (kg/ha) was found to be the highest in plants grown under closer spacing (30x30 cm) and the uptake of the nutrients also increased with increase in fertilizer dose.
Results showed that higher dose of fertilizers (N:P2O5:K2O @ 100:50:100 kg/ha) and wider spacing (45x45 cm) promoted vegetative growth of plants. Plants spaced at 30x30 cm and fertilized with N:P2O5:K2O @ 50:25:50 kg/ha produced more flowers and higher flower yield and can be recommended for improving the growth and flowering of gomphrena plants.