How does far-red radiation influence the fruit set of sweet pepper?

Sijia Chen is a PhD candidate working on the effect of light spectrum on the fruit set of sweet pepper (Capsicum annuum L.), at the Horticulture and Product Physiology Department, Wageningen University (The Netherlands). She studies under the supervision of Dr. Ep Heuvelink, Professor Leo Marcelis, and Professor Remko Offringa. She found that the fruit set of sweet pepper can vary strongly under different light spectra. Far-red radiation strongly reduced the fruit set of sweet pepper grown within climate chambers. However, the underlying mechanism is unknown. Based on observations during her studies, Sijia hypothesized that the strong auxin stream from apical shoots (which causes apical dominance) may inhibit the auxin export from flowers under far-red light according to the auxin transport canalization theory. She suggested that blocked auxin export from flowers increased the sensitivity of the abscission zone to ethylene, and triggered abortion. To test this hypothesis, Sijia conducted a series of climate chamber experiments. She found that although far-red light increased fruit abortion in sweet pepper, this effect disappeared when the apices of the plants were removed. This suggested the important role of the shoot apex in mediating the effect of far-red on the fruit set of sweet pepper. However, chemically blocking the auxin basipetal stream did not restore the fruit set under the far-red condition. Thus, factors other than auxin, play a role in causing fruit abortion under far-red light. The detailed mechanism of this effect awaits further investigation.

Sijia Chen won the ISHS Young Minds Award for the best oral presentation at the International Symposium on Advances in Vertical Farming at IHC2022 in France in August 2022.

Sijia Chen, Horticulture and Product Physiology, Wageningen University, Droevendaalsesteeg 1, 6708 PB Wageningen, The Netherlandsn, e-mail: sijia.chen@wur.nl

The article is available in Chronica Horticulturae