Autumn-applied growth regulators influence leaf retention, bud hardiness, bud and flower size, and endodormancy in peach and cherry

Foliar applications of growth regulators (GR) in early autumn induced leaf retention (LR) on peach [Prunus persica (L.) Batsch.] and 'Montmorency' tart cherry (Prunus cerasus L.) trees. In 'Johnson Elberta' peach, the relative effectiveness of GRs on LR was NAA = Promalin (BA + GA4+7) > GA4+7 > GA3 > BA > control, and on leaf detachment pub force (PF) NAA > BA + GA4+7 > GA4+7 = GA3 > BA3 > BA > control. Relative GR-induced chlorophyll (CL) content in retained leaves was BA + GA4+7 > GA4+7 > GA3 > BA > control > NAA. Relative xanthophyll (XN) content of retained leaves was NAA > control > BA > GA3 = GA4+7 = BA + GA4+7. Treating only half of a peach tree with NAA did not affect LR on the untreated side. NAA decreased subsequent bud and flower size in peach. Bud hardiness was enhanced by NAA in 'Johnson Elberta' peach but not in 'Redhaven' peach or in 'Montmorency' tart cherry. NAA increased hardening on both the leafy treated (foliated) and untreated (defoliated) sides of half-treated 'Johnson Elberta' trees. Increased endodormancy duration, as measured by GA3 forcing of terminal leaf buds, was proportional to LR. Chemical names used: N-(phenylmethyl)-1H-purinamine 6-amine (BA); (1a,2 beta,4b beta,10 beta)-2,4a,7-trihydroxy-1-methyl-8-methylenegibb-3-ene-1,10-dicarboxylic acid, 1,4a-lactone (GA3, GA4+7); 1-naphthaleneacetic acid (NAA).