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

GERGOFF GROZEFF, GUSTAVO ESTEBAN; ALEGRE, MATÍAS LEONEL; SENN, MARÍA EUGENIA; CHAVES, ALICIA RAQUEL; BARTOLI, CARLOS GUILLERMO

SCIENTIA HORTICULTURAE

ELSEVIER SCIENCE BV

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

0304-4238

Light is one of the most important factors modulatingprocesses and sequences in plants life, like fruit ripening and the concentrationsof water and lipid soluble antioxidants. The aim of this workwas to evaluate the most effective frequency of low irradiance light pulses(LP) during the night and to analyze its effect on plant and fruit growth, aswell as on modifications of concentrations of soluble sugar, amino acids,antioxidants and organic acids. LP of 15 min each were applied over the plantsin a temperature controlled greenhouse after fruit set till they turned tomature red, with a frequency of 2 and 4 h. LP induced no changes in the typicalmaturation indexes such as soluble solid, total acidity, pH or firmness;meanwhile there was an 18 % increase in fruit yield when plants were exposed to15 min LP every 2 h during the night. Furthermore, by analyzing the tomatocluster receiving this LP treatment separately, the biomass 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 afrequency of 2 and 4 h LP showed an increase in lycopene concentration,concomitantly with a rise in the proportion of red mature fruit harvested fromthe whole plant. On the other hand,  there was a drop in the concentration ofsoluble sugars and free amino acids, possibly conducing to a decrease in watersoluble antioxidants (ascorbic acid and glutathione) and citric and malic acidsconcentration. Overall, these results showed that nocturnal LP treatmentsimproved fruit yield in tomato plants with higher amounts of lycopene, whichindicate earlier fruit ripening.