Where water is the major constraint to onion cultivation, deficit irrigation combined with ethylene will not have a negative effect on the storage qualities of onion

Premature sprouting is a major cause of onion bulb losses during storage. High dry matter con-tent (DMC) is linked to longer storage and continuous ethylene supplementation has previously been shown to suppress sprout growth in stored onion bulbs. However, the combined effect of pre-harvest deficit irrigation and ethylene during cold storage on the storage qualities of onion bulbs is not known. Two onion cultivars ('Red Baron' and 'Sherpa' for year 1 and 'Sherpa' for year 2) were grown under glasshouse over two years and subjected to two irrigation treatments. The control plants (FI) were subjected to 100% replenishment of the evapotranspiration (ET) and the test plants (DI) were subjected to 50% of the FI ET, from bulb initiation to harvest. ET and soils moisture content were measured gravimetrically and using soil moisture sensors, respectively. Bulbs were harvest at full maturity (100% fall-down), cured in the glasshouse for six weeks and subjected to continuous ethylene supplementation (10 ?L L-1) or air during storage. Samples were collected after curing and then bi-weekly during storage.No difference in DMC was found between DI and FI cured bulbs. After 20 weeks of storage, no difference in DMC was found between DI and FI bulbs stored under ethylene. While the mean DMC for bulbs stored in air was 17% higher in the FI compared to DI bulbs. Sprout emergence did not differ between DI and FI bulbs, and ethylene delayed sprout emergence by two and four weeks for year 1 and 2 when compared to bulbs stored in air. Furthermore, ethylene suppressed sprout length by a quarter when compared to bulbs stored in air. Taken together, these results showed that in places where water is the major constraint to onion cultivation, deficit irrigation combined with ethylene will not have a negative effect on the storage qualities of onion bulbs.SourcesEffect of deficit irrigation and continuous ethylene supplementation on the quality of cold stored onion bulbsIkenna Ohanenye1, Carmen Alamar Gavidia1, Andrew Thompson2, Leon Terry11 Cranfield University, Plant Science Laboratory, School of Water, Energy and Environment (SWEE), Vincent Building (52A) Cranfield University, MK43 0AL Bedfordshire, United Kingdom2 Cranfield University, Cranfield Soil and Agrifood Institute, School of Water, Energy and Environment (SWEE), Vincent Building (52A) Cranfield University, MK43 0AL Bedfordshire, United KingdomCorresponding author: i.c.ohanenye@cranfield.ac.uk11th International FRUTIC Symposium, Berlin, 7 - 9th February 2018Picture,?Restrain equipment to apply ethylene to onions