Since the plant world creates caffeine, it would seem a reasonable possibility that a plant's growth might benefit from its direct application. In 2003, biology students at Michigan State University tested this idea by adding caffeine to a consistent watering routine of field mustard (Brassica Rapa). Their results indicate that applying caffeine directly to a plant (not to be confused with applying spent coffee grounds to soil) is far from a favourable choice.
Inhibited Tissue Growth
Vascular tissue in a plant receiving caffeine develops a thin wall, which makes the plant system weak. This results in the plant's inability to organise its growth properly, detoxify oxalic acid and hydrolyze starch the way it needs to. Delivery of vital nutrients throughout the plant is inhibited by a weak vascular system, causing the plant to grow slowly and incompletely.
Caffeine stunts the overall growth of a plant and most noticeably its height. Plants fed a caffeine solution compared to those that are not are much shorter. This is due to caffeine's ability to absorb calcium, a much-needed ingredient for plant growth. In addition, plants receiving caffeine do not grow leaves as easily and do not display the prominent green colour of normal growth.
Application of caffeine affects the chloroplasts in a plant. Chloroplasts grab energy from sunlight, initiating the photosynthesis process. Spectrometer testing reveals that caffeine reduces a plant's ability to absorb light, possibly even altering what pigments the plant develops. Pigments are chemical substances located in chloroplasts that reflect light and give the plant its colour. Plants are green because they do not have a pigment that absorbs green light.