Maximizing Zygopetalum maculatum orchid yield through calcium nutrition: Unveiling calcium content and dynamics across different plant parts at different growth stages of the orchid

Abstract

This study explores the pivotal yet often overlooked role of calcium (Ca) in Zygopetalum maculatum orchid cultivation. Six different treatments, featuring graded doses of Ca (ranging from 0 to 100 mg Ca L−1 nutrient solution), were used to assess the impact of Ca on growth, development, and physiological responses of the orchids. Notably, the Ca untreated control treatment (Ca0) exhibited a rapid decline in potting media pH (became acidic in reaction with time), whereas under Ca100 treatment potting media pH declined slowly and remained near neutral. Dehydrogenase activity in the potting media significantly increased under Ca100 treatment. Significant improvements in vegetative growth parameters, like, bulb length, bulb width, and leaf characteristics, were evident under Ca100 treatment compared to the Ca0 treatment. The economic yield, measured by the number of flower spikes and various floral attributes (i.e. number of florets per spike, spike length, florets size), displayed a remarkable enhancement under Ca100 treatment. The Ca100 treatment produced 100 % more number of flower spikes as compared to Ca0 treatment. The number of new shoot initiation, and overall flower biomass also substantially increased under Ca100 treatment. Ca content analysis in different plant parts revealed presence of elevated Ca concentrations in leaves, back bulbs, new bulbs, and roots under Ca100 treatment. The Ca content in back bulbs and roots decreased after flowering phase of the orchid, but the Ca levels in leaves and new bulbs remained statistically similar during both pre and post-flowering phases.These findings underscore the positive influence of Ca application on Zygopetalum maculatum orchids for enhancing its vegetative growth and economic yield. The study contributes valuable insights into Ca dynamics in different plant parts of the orchid, and recommends a 100 mg L−1 Ca application at 7-day intervals for improving Zygopetalum maculatum cultivation practices.