Effect of growth regulators application on the quality maintenance of 'Brookfield' apples

Abstract

The main goal of the present study was to elucidate the effect of growth regulators at harvest and postharvest quality of 'Brookfield' apples stored under controlled atmosphere through a multivariate approach. Thus, an experiment with two steps (field and storage) was carried out. The treatments in field were applied with an output of 1,000 L ha -1 of water. The following treatments were tested: Control: only water application; AVG (aminoethoxyvinylglycine): 0.83 kg ha -1 of Retain  applied 30 days before harvest (BH); NAA (naphthalene acetic acid): 40g ha -1 of naphthalene acetic acid applied 7 days BH; Ethephon: 2.0 L ha -1 of Ethrel  applied 10 days BH; 1-MCP: 0.625µL L -1 of 1-MCP (1-methylcyclopropene): applied during postharvest (storage); LE (low ethylene): with the allocation of potassium permanganate sachets during postharvest. Fruits treated with AVG in the field showed an opposite response to the fruits with NAA. AVG application followed by another growth regulator (AVG + Ethephon and AVG + NAA) showed an advance in maturation, nearing these fruits to the control treatment, this effect is likely related to the higher ethylene production by these fruits compared to fruits with AVG alone. AVG, 1-MCP and LE kept a similar response on quality maintenance. Ethephon application prevented the negative effect of NAA at harvest, but after storage, the combined NAA + ethephon application increased the physiological disorders, reducing internal quality.

Postharvest quality of ‘Brookfield’ apple field-treated with naphthalene acetic acid alone or combined with other growth regulators

“…1a). This result demonstrates that the combination of NAA plus AVG presents a response that is completely different from the other treatments, regarding the quality maintenance during the postharvest period, in accordance to the results verified by Brackmann et al (2015a). Figure 1.…”

“…3e). Brackmann et al (2015a) found higher percentage of healthy fruit in the AVG and AVG plus NAA treatment in comparison to the control and AVG plus Ethephon.…”

“…Ethylene is a key regulator for gene expression and activity of enzymes that degrade the cell wall (Payasi et al 2009;Prasanna et al 2007). A previous study also found a lower incidence of mealiness in the AVG plus NAA treatment in comparison to AVG isolated or in combination with Ethephon (Brackmann et al 2015a).…”

“…There is a complex relationship among auxin and ethylene functions in apple fruit, which are related to gene family members and fruit developmental stages (Shin et al 2015). The NAA increases the expression of genes related to the ethylene biosynthesis (MdACS1 and MdACO1), perception (MdERS1) and cell wall degradation enzymes (MdPG1) L. M. Wendt et al (Li and Yuan 2008;Yuan and Li 2008), therefore decreasing the storage potential of the fruit (Brackmann et al 2014;Brackmann et al 2015a). The high respiration rate measured in this treatment is probably related to the higher ethylene production observed in NAA-treated fruit, since respiration rate has a close relation with the ethylene production (Both et al 2016).…”

“…Naphthalene acetic acid (NAA) is a synthetic auxin that reduces the preharvest fruit drop (Yuan and Li 2008), although it may enhance fruit softening (Li and Yuan 2008). This is due to the increase in the expression of aminocyclopropane-1-carboxylic acid (ACC) synthase genes and, consequently, to higher ethylene production (Li and Yuan 2008;Unrath et al 2009), decreasing the storage period of 'Brookfield' apple (Brackmann et al 2014;Brackmann et al 2015a). This growth regulator enhances genes expression that are related to the biosynthesis and perception of ethylene, and consequently the cell wall degrading enzymes (Li and Yuan 2008;Yuan and Li 2008).…”