Compensative growth mechanisms in lettuce plants after partial defoliation

Fánor Casierra-Posada1*, Valentina Zapata-Casierra2, and Stefannie Tatiana Baker-Rodríguez2
Leaf area loss is a frequent problem in crops, and it can be caused by biotic or abiotic factors. Reduced leaf area can produce alterations in plants, affecting their metabolism, growth, and yield. The leaf area in lettuce plants (Lactuca sativa L.) is often affected by herbivores such as slugs. The effects of partial defoliation on the growth of lettuce plants were evaluated under greenhouse conditions in Tunja, Colombia. Some plants had half of their leaves removed, while others were left intact as a control. The variables normally used in the basic analysis of plant growth were evaluated. There was non significant difference between the two treatments; however, lettuce plants showed a remarkable ability to reduce the negative effect caused by partial defoliation, and they managed to maintain a balance in the root to shoot ratio, leaf area ratio, specific leaf area, leaf weight ratio, DM partitioning, and harvestable DM. Partial defoliation decreased the absolute growth rate by 17.8% and the relative growth rate by 13.8%. Additionally, the chlorophyll content index and the number of leaves increased by 16.0% and 15.4%, respectively, in plants subjected to partial defoliation compared with the control plants. These results indicate the regeneration capacity of the plants after partial defoliation.
Keywords: Biomass, chlorophyll, growth, herbivores, slugs.
1Universidad Pedagógica y Tecnológica de Colombia, Facultad de Ciencias Agropecuarias, Avenida Central del Norte 39-115, Tunja, Colombia.
*Corresponding author (fanor.casierra@uptc.edu.co).
2Universidad Pedagógica y Tecnológica de Colombia, Facultad de Ciencias, Avenida Central del Norte 39-115, Tunja, Colombia.