Nocturnal low irradiance pulses improve fruit yield and lycopene concentration in tomato

GUSTAVO GERGOFF GROZEFF; MARÍA EUGENIA SENN; MATÍAS LEONEL ALEGRE; ALICIA R. CHAVEZ; CARLOS G. BARTOLI

SCIENTIA HORTICULTURAE

ELSEVIER SCIENCE BV

Lugar: Amsterdam; Año: 2016 vol. 203 p. 47 - 52

0304-4238

Light is one of the most important factors modulating processes and sequences in plants life, like fruitripening and the concentrations of water and lipid soluble antioxidants. The aim of this work was toevaluate the most effective frequency of low irradiance light pulses (LP) during the night and to analyzeits effect on plant and fruit growth, as well as on modifications of concentrations of soluble sugar, aminoacids, antioxidants and organic acids. LP of 15 min each were applied over the plants in a temperaturecontrolled greenhouse after fruit set till they turned to mature red, with a frequency of 2 and 4 h. LPinduced no changes in the typical maturation indexes such as soluble solid, total acidity, pH or firmness;meanwhile there was an 18% increase in fruit yield when plants were exposed to 15 min LP every 2 hduring the night. Furthermore, by analyzing the tomato cluster receiving this LP treatment separately, thebiomass of the fruit was found to have increased by 28% compared with the same cluster in control plants.In coincidence with this, fruit treated with a frequency of 2 and 4 h LP showed an increase in lycopeneconcentration, concomitantly with a rise in the proportion of red mature fruit harvested from the wholeplant. On the other hand, there was a drop in the concentration of soluble sugars and free amino acids,possibly conducing to a decrease in water soluble antioxidants (ascorbic acid and glutathione) and citricand malic acids concentration. Overall, these results showed that nocturnal LP treatments improved fruityield in tomato plants with higher amounts of lycopene, which indicate earlier fruit ripening.