Correlation of Leaf Glucose Content with Mineral Nutrients Uptake of South African Geranium (Pelargoniumsidoides)

Abstract

The relationships between soil nutrients uptake, leaf glucose contents, and chlorophyll contents of Pelargonium sidoides was investigated. Pelargonium sidoides is a medicinal plant grown in Kenya for export. It is used in the manufacture of drugs for lung related diseases. P. sidoides plants were elected at a field site, where the soil N, P, K and Ca contents had prior been analysed. These plants were dressed with both inorganic (Calcium Ammonium Nitrate, Triple Super Phosphate, Calcium Carbonate, Potassium Nitrate) and organic fertilizers (worm leachate) of known nutrient levels. Leaf glucose contents before and after application of the mineral nutrients were measured by colorimetry. Verification of the colorimetric results was done by high performance liquid chromatography fitted with a refractive index detector (HPLC). Predictions for nutrients in soil and plant tissues were done by DRIFT FTIR. Leaf chlorophyll measurements were done by Soil Plant Analysis Development units (SPAD). The mean glucose contents before and after each nutrients application were subjected to GENSTAT statistical software for the ANOVA and t-test to find out whether there were any significant differences between the two. The results indicated that the levels of leaf glucose increased with type and uptake of certain applied fertilizers. FTIR predictions closely matched the wet chemistry data. Uptake of calcium corresponded to the highest increase of glucose while that of worm leachate had the least effect. Change in glucose levels was evident within an hour after application, suggesting the possibility of predicting nutrients uptake within a short period. Chlorophyll content was also found to increase with nutrients uptake. All plants treated with fertilizers displayed significantly higher glucose contents in comparison to the control samples. The study opened way for real time analysis of plant status and allowed for real time interventions where necessary.