ABSTRACT
Effect of different molecular weight and concentrations of chitosan on the phenology of tomato in greenhouse conditions

Daniel Alejandro Anaya-Castro1, Adolfo Dagoberto Armenta-Bojorquez1, Julián Alberto Galaviz-Lara1, Blanca Elvira López-Valenzuela2, and Cesar Marcial Escobedo-Bonilla1*
 
The use of synthetic fertilizers is among the most expensive and pollutant supplies in agriculture. An alternative to reduce their use is through complementary products such as biostimulants like chitosan. Biostimulants represent a sustainable alternative to chemicals as they contain or help generate beneficial substances for plant growth. The present study evaluated the effect of different molecular weights of chitosan (low, medium, and high) and different doses (120, 210, and 300 mg) on the growth of tomato (Solanum lycopersicum L.) plants in greenhouse conditions. The evaluated variables were plant dry weight, foliar dry weight, root volume and root dry weight, plant height, stem diameter, and analysis of foliar nutrients. Results showed a positive effect of chitosan supplementation on plant growth and nutrient uptake, showing that both dose and molecular weight influenced growth and nutrient absorption. Treatment with low molecular weight chitosan at a dose of 300 mg increased root dry weight by 107% and plant height by 35% compared to the control, on the other hand, while high molecular weight chitosan applied at 210 mg, increasing plant dry weight by 73% and foliage dry weight by 76% compared to water control. Total plant weight is a good measure of overall plant growth and nutrient absorption. It was concluded that high molecular weight chitosan represents a good biostimulant alternative to chemical fertilizers such as urea for tomato plant cultures.
Key words: Biostimulant, chitosan, molecular weight, Solanum lycopersicum, tomato plants.
1Instituto Politécnico Nacional, Centro Interdisciplinario de Investigación para el Desarrollo Integral Regional, Guasave, Sinaloa, México.
2Universidad Autónoma de Sinaloa, Facultad de Agricultura del Valle del Fuerte, Juan José Ríos, Sinaloa, México.
*Corresponding author (cescobe@ipn.mx).
Received: 9 May 2026; Accepted: 9 August 2026, Available online: 7 September 2026.