2017 ASHS Annual Conference

Blossom-end rot (BER) is a calcium (Ca²⁺) deficiency disorder characterized by dry, sunken, brown and/or black spots to the distal-end of tomato fruit and can result in significant crop loss. The effects of two irrigation levels [50% and 100% evapotranspiration (ET)] along with two levels of Ca²⁺ (0 and 100 ppm) on BER development between a resistant (BGV7900; Solanum lycopersicum cerasiforme) and a susceptible (BGV7936; Solanum lycopersicum lycopersicum) tomato accessions were evaluated in the greenhouse following randomized complete block design. Physiological differences between those two accessions were also compared. The BER-resistant accession did not display any symptoms of BER under Ca²⁺ and irrigation treatments. In contrast, all fruits of the susceptible accession were affected by BER irrespective of irrigation levels. Application of Ca²⁺ reduced BER incidence in the susceptible accession by 5%-11%. Stomatal conductance and leaf temperature did not differ between the accessions but varied with irrigation levels. Stomatal conductance decreased and leaf temperature increased with lower level of irrigation especially during the early stages after the commencement of the irrigation treatments, suggesting that the differences in these responses were mainly associated with water availability. Plant height and shoot dry weight were higher and chlorophyll content was lower in the BER-susceptible accession, only under well irrigated conditions. Fruit growth rate of the susceptible accession was higher than that of the resistant accession irrespective of treatments. Our data indicate that certain plant growth characteristics and fruit growth rate differ between resistant and susceptible accessions. Whether differences in plant characteristics and fruit growth rate between the two accessions can influence fruit Ca²⁺ availability and therefore BER development, requires further investigation.