Singapore - A Singapore lecturer has found a way to determine the health of plants long before they show obvious signs of wilting, a centre for biomedical life sciences said Saturday. 

Dr Liew Oi Wah, at Singapore Polytechnic, is relying on light sensors to study the wave pattern reflected from plants. 

"It will be too late for the plant if you wait until the leaves become brown and withered," The Straits Times quoted Liew as saying. 

She is able to determine the extent of minerals a plant needs depending on the light spectrum produced, the report said. 

Liew is aiming to develop a system of sensors that will help farmers detect exactly when and how much fertilizer and water their plants need. 

More than 70 per cent of the world's freshwater supply goes to agriculture, with fertilizers causing severe pollution in some countries. (dpa)