Relationships of Light Intensity and Temperature with Growth and Development of Preconditioned and Shaded Ranunculus Plants under High Altitude Tropical Conditions

A study was conducted to determine how shade (0%, 40%, 80%) reduces high light intensity and temperature to optimize growth of ranunculus (Ranunculus asiaticus L.) under high altitude tropical conditions. The study was set up in a split plot design, replicated three times and repeated once. Ranunculus tuberous roots were preconditioned at 30C, 20C, 10C or 2C for two weeks and thereafter grown under the four shade levels. The relationships of sprouting with light intensity were negative and positive quadratic in seasons 1 and 2, respectively, and with soil temperature negative quadratic. The relationships of light intensity and air temperature were correspondingly negative and positive linear in seasons 1 and 2, respectively, with flowering time; negative linear with flower stem length; negative quadratic with flower buds and flower head diameter; positive and negative quadratic in seasons 1 and 2, respectively, with flower stem diameter; and positive quadratic with tuberous root fresh biomass. Thus, shade modifies light intensity and temperature that then interact to influence growth and development of ranunculus in diverse ways. Moderate seasonal temperatures and 40,000 lux light intensity, prevailing under 40% shade are ideal for best top growth of ranunculus. High air temperature and light intensity, prevailing under 0% shade in a cool season and low air temperature and light intensity, prevailing under 80% shade in a hot season are the best for growth of heavy tuberous roots of ranunculus.