Impacts of Elevated CO2 on Growth, Carbohydrate Assimilation and Nutrient Uptake of Elaeis guineesis Jacq Seedlings

ABSTRACT

Aims: This study was conducted to characterize the growth patterns of tenera oil palm seedlings performance (Deli AVROS) under elevated CO2, that is expected to increase in the future due to climate change. Study Design: The palms were exposed to three carbon enrichment treatments (1) ambient CO2 (400 ppm); (2) twice ambient CO2 (800 ppm), and (3) thrice ambient CO2 (1200 ppm). Randomized complete block design (RCBD) with three replications was used during the experiment using Deli AVROS seedlings. Place and Duration of Study Department of Biology, Faculty of Science Universiti Putra Malaysia from March 2017 to December 2017. Methodology: Carbon dioxide enrichment treatments started when seedlings reached three months old by exposing them to three levels of CO2, i.e., ambient CO2 (400 ppm), twice ambient CO2 (800 ppm) and thrice ambient CO2 (1,200 ppm). Growth, carbohydrate and macronutrients properties were measured at the end of the treatment period of 3 months. Results: It was found that CO2 had the greatest influence on the growth over the three months’ period of experiment. As the level of CO2 increased, from 400>800>1200 ppm, the plant height, number of frond per plant, basal diameter, leaf area per seedling, root biomass, total dry matter, net assimilation rate (NAR) and relative growth rate (RGR) was significant increased between the CO2 levels. The enhanced plant growth under elevated CO2 might be contributed by increased in production of total non-structural carbohydrate (TNC) of the palm under elevated CO2. The increased in TNC exposed to elevated CO2 was supported by increase in sucrose and starch content under these conditions. More sucrose was available than starch indicate that no feedback inhibition was occurred and the palm have enough sink strength to cope with elevated CO2. The macronutrients contents (N, P, K, Ca, Mg) also was found to be reduced under elevated CO2 treatments, indicated that growth enhancement under elevated have dilute the nutrient content in the palms. Conclusion: In conclusion, the growth of oil palm seedlings was enhanced with elevated CO2 at double and triple concentration than the ambient. It was found that the increase might be due to increase in production of total non-structural carbohydrate. The enhanced growth also increased the macronutrient demands under the elevated levels of CO2. This show in future the palm needs more fertilizers with enhanced levels of elevated CO2.