Effects of AVG, NAA, Ethephon, and Summer Pruning on Preharvest Drop and Fruit Quality of `McIntosh'

Abstract

Ethylene production increases dramatically during maturation and ripening of `McIntosh' apples, frequently resulting in preharvest drop and accelerated fruit softening. As harvest approaches, commercial growers must balance the need for color development with minimizing fruit softening and drop. The effects of plant growth regulators and summer pruning on this balance were evaluated in this study. Treatments were applied to trees in the Mid-Hudson in 1995 and 1996 and a subset of growth regulator treatments was applied in the Champlain Valley in 1996. NAA (naphthalene acetic acid) significantly reduced drop on only one sample date in only one of the three trials. Ethephon (2-chloroethylphosphonic acid) at 150 ppm plus 10 ppm NAA, accelerated ripening and permitted harvest before substantial drop occurred, but earlier harvest resulted in smaller fruit size. AVG (aminoethoxy vinyl glycine) at 124 gram a.i./ha, on otherwise untreated trees, significantly delayed drop compared to the controls in two of three trials and resulted in better fruit firmness out of storage. Use of ethephon on AVG-treated trees significantly enhanced red color but also accelerated drop, although drop was reduced compared to ethephon only treatment. Late summer pruning significantly accelerated red color development, drop and ripening in both years. Pruning 16 Aug. 1996 significantly accelerated drop compared to pruning 1 Aug. 1996. Combining AVG application and pruning on 16 Aug. 1996 resulted in improved color without increasing drop compared to controls.

Investigating the role of potassium and urea to control fruit drop and to improve fruit quality of “Dhakki” date palm

“…Foliar application of K 2 SO 4 results in improved lignin and cellulose formation as both polymers are needed to initiate synthesis of endogenous hormones process, and construction of plant structure as carbohydrates synthesis inhibits the formation of abscission layer hence results in reduced drop at premature stage ( Nijjar,1985; Jat and Kacha, 2014; Reetikaet al, 2018 ). Furthermore, an imbalance in ethylene and auxin level in plant tissues is known to have a cause of fruit drop ( Yuan and Carbaugh, 2007 , Yuan and Li, 2008 , Li and Yuan, 2008 , Zhu et al, 2010 ), as ethylene initiates the formation of the abscisic layer, breaking cell wall in the system resulting in fruit drop ( Stover et al, 1998 , Wood, 2011 ). Similarly, many other fruits also showed a reduction in fruit drop when different macro and micronutrients were applied, i.e.…”

“…It is also believed that fruit drop is caused due to an imbalance between auxin and ethylene level. Ethylene triggers the system for abscission layer formation, breaks down the cell walls leading to fruit drop ( Stover et al, 1998 , Wood, 2011 ). Hence, there is a need to adopt measures and approaches to reduce fruit drop, especially in date palm cultivars.…”

Multiple season-long sprays of ethephon or NAA combined with calcium chloride on ‘Honeycrisp’ apples: I. Effect on bloom and fruit quality attributes

“…Applications of ETH at 450 mg•L -1 in the month before harvest have resulted in reduced starch content, lower flesh firmness, and enhanced ethylene production of 'Gale Gala' at harvest and following storage, indicating advanced maturity (Drake et al, 2006). Application of NAA in the month prior to harvest has also been McIntosh' apples (Stover et al, 2003).…”