Effect of preharvest application of azoxystrobin and cytokinin on postharvest broccoli quality

HASPERUÉ HJ; KASAMPALIS, D; TSOUVALTZIS, P; SIOMOS, A

Santa Fe

Congreso; III Congreso Argentino de Biología y Tecnología Poscosecha; 2021

Universidad Nacional del Litoral - Instituto de Tecnología de Alimentos

Due to the perishability of broccoli once harvested, there are many alternatives that have been used, especially in postharvest. In the present work, the effect of pre-harvest application of cytokinin (6-BAP) and azoxystrobin, a fungicide from the strobilurins group, on the postharvest quality of broccoli was studied. For this, 30 and 15 days prior to harvest, different groups of broccoli heads were sprayed with 6-BAP or azoxystrobin. To evaluate the potential varietal effect in the application of azoxystrobin, this treatment was carried out on 3 different varieties: Long Runner, Marathon, and Parthenon. After harvest, a set of treated and untreated samples were cleaned from leaves, and analyzed for respiration rate (RR), superficial color, weight loss (% WL), and stored for 6 days at 15 ° C. Samples were kept at -30 °C until processing for antioxidants (AOX, for DPPH and Folin-Ciocalteu methods), sugars and pigments measurements. No changes in color were observed at harvest in the samples treated with 6-BAP, although a more accentuated yellowing developed in the controls during storage, linked to high values of the L* parameter. Towards day 4 of storage, a higher RR and % WL were observed in the treated samples, although they exhibited higher levels of sugars, chlorophylls and AOX. Regarding the treatment with azoxystrobin, an increased yellowing was observed in the treated samples, in which higher values of L* were observed during storage in the three varieties studied. No differences were observed in RR or %WL in none of the varieties. Regarding the pigment content, there were differences between varieties. In Long Runner, a higher chlorophyll and carotenoid content was observed in controls at harvest, however, this difference disappeared during storage. As for the Marathon variety, a higher content of chlorophylls and carotenoids was observed in the treated samples only at harvest, while in Parthenon there were no differences between controls and treated samples. Moreover, higher AOX contents were observed in the treated samples in the Long Runner and Marathon varieties, while in Parthenon a higher AOX content was observed in the controls towards the end of the storage period. In conclusion, the preharvest application of 6-BAP had effects similar to those reported in previous studies when it was applied in postharvest, observing a delay in senescence, probably by preventing sugar loss and protecting cell membranes from oxidative damage. Contrary to what was observed in other species, in general the application of azoxystrobin in pre-harvest did not delay postharvest senescence in the broccoli varieties studied, instead, it favored the development of yellowing during storage. The effect of this compound on postharvest senescence would be species dependent.