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The use of foliar applications of abscisic acid to reduce blossom end rot in processing tomatoes

Smith, P. A., Argerich, C. A.
Acta horticulturae 2017 no.1159 pp. 125-130
abscisic acid, biodegradability, canned vegetables, cultivars, economic sustainability, evapotranspiration, foliar application, fruit set, greenhouses, mulches, stomatal conductance, tomatoes, Argentina
Blossom end rot (BER) in susceptible varieties of processing tomatoes can cause significant losses in marketable production. When using black biodegradable mulch, varieties of processing tomatoes susceptible to BER suffer an increase in the proportion of fruit affected compared with bare soil conditions. Elongated Italian pear-type cultivars of processing tomatoes used for premium whole peeled canned tomatoes are more susceptible to BER than blocky varieties. The percentage of fruit affected by BER increased fivefold (2.7 vs. 14.5%) between a susceptible cultivar without and with biodegradable mulch. Exogenous foliar applications of abscisic acid (ABA) at concentrations of 500 mg L-1 in greenhouse tomatoes have been found to reduce the incidence of BER significantly. The objective of this study was to determine whether exogenous applications of ABA can reduce the incidence of BER in a susceptible cultivar and, if so, to determine the economic viability of its use in field-grown processing tomatoes. A trial was conducted at La Consulta, INTA Experimental Station in Mendoza, Argentina, during the seasons 2014-15 and 2015-16. Black biodegradable mulch, 22 microns thick, was used. Daily water replenishment was done by a single surface tape according to evapotranspiration tank type “A”, adjusted by local KC. A variety susceptible to BER was used, 'HM 3861' (HM CLAUSE). The experimental unit was a 5-m length of bed with five replicates in a completely randomized design. During the main fruit setting period of the crop, four night-time foliar applications of ABA were used at 5-day intervals. Four different concentrations of ABA were used: 0 (control), 100, 300 and 500 mg L-1 in the 2014-15 season and 0 (control), 500, 1000 and 2000 mg L-1 in the 2015-16 season. General production parameters including BER index were measured at harvest. Stomatal conductance was measured during the application period. These parameters were evaluated by regression tests among treatments at α=0.05. The results obtained in the field showed no statistical differences in BER or any of the variables measured between treatments in the first year. In the second year, stomatal conductance was lower with higher doses of ABA, and the effects lasted about 3 days, indicating that application intervals should not exceed 4-5 days.