Response of coconut seedlings to elevated CO2 and high temperature in drought and high nutrient conditions

Abstract

The interaction effect of climate change variables elevated CO₂ and elevated temperature (ET) with drought and nutrients on growth and development of coconut seedlings was studied in an open top chamber (OTC) at Central Plantation Crops Research Institute (CPCRI), Kasaragod. Seedlings were exposed to ambient (normal CO₂ and temperature), elevated CO₂ (550 and 700 ppm), ET (3 °C above ambient) and ET + elevated CO₂ (550 ppm CO₂ + 3 °C). In each OTC, a set of seedlings were subjected to drought (50% FC) and another set was maintained at 150 per cent recommended dose of fertilizer (RDF). Seedlings in elevated CO₂ treatments accumulated significantly higher biomass. It was 1.13 and 1.98 kg seedling^-1 with 550 and 700 ppm CO₂ respectively as against 1.10 in ambient treatment. It was the least in ET treatment (0.91). The stomatal conductance (gs) and transpiration (Tr) of plants grown under elevated CO₂ was reduced without affecting the photosynthesis. As a consequence, the whole plant WUE of coconut seedlings grown under elevated CO₂ was high both under control and drought condition. The WUE significantly reduced both in high temperature and drought stressed plants. Elevated CO₂ to certain extent compensated for water stress and high temperature induced reduction in growth of coconut.