EFFECTS OF LED LIGHTING DURATION ON GROWTH AND PHYSIOLOGY OF RUBBER SEEDLINGS CLONE RRIM 600

Abstract

This research aimed to study (1) the effects of LED lighting duration on the growth and physiological characteristics of RRIM 600 rubber seedlings and (2) the relationship between growth and physiology. The experiment involved four treatments and three replications: 12 hours of natural light (no supplementary lighting) and supplementary LED lighting at night for 4, 8, and 12 hours, respectively. Data were collected on growth, including height, stem diameter, leaf number, leaf area, fresh and dry weight, as well as physiological traits such as chlorophyll content, photosynthesis, transpiration, and stomatal conductance. Data were analyzed using analysis of variance, LSD, and linear regression analysis.

The results revealed that supplementary lighting duration significantly affected the growth of rubber seedlings (p<0.05). The 12-hour supplementary lighting treatment had the highest growth values, with average stem diameter of 8.66 mm, height of 100.43 cm, and leaf area of ​​67.78 cm2. Chlorophyll content, photosynthesis, and transpiration were also significantly lower. And transpiration was not different between treatments. However, stomatal conductance was significantly related to growth. The results showed that supplementary LED lighting at night could accelerate the growth of rubber seedlings, especially the 4-hour treatment, which was suitable in terms of energy saving and growth promotion. Therefore, it is a potential approach for producing high-quality rubber seedlings to reduce the cultivation time and support commercial cultivation.