Gibberellins Stimulate Lateral Branch Development in Young Sweet Cherry Trees in the Orchard

Figures & data

TABLE 1 Effects of Cytokinin and/or Gibberellic Acid Applications to Scoring Cuts on Lateral Shoot Number, Mean Length, and Vertical Distribution in Fourth-Leaf ‘Skeena’/Mazzard Sweet Cherry Trees (Experiment 1, 2006, Quincy, WA)

	Lateral shoots		Lateral shoots in leader branch section(% of total lateral shoots) ^w
Treatment (mg•L^−1) ^z ^, ^y	No./100 cm leader length	Mean length (cm)	1	2	3	4	5	6–7
Control ^x	5.1d	77a	92a	0d	0b	6a	2b	0a
ProVide (GA4+7, 5,000)	18.0b	49c	66b	19a	9a	4a	2b	0a
Maxcel (BA, 5,000)	21.9a	43c	49b	13ab	13a	14a	10a	0a
Promalin [GA4+7 (5,000) + BA (5,000)]	18.4ab	49c	53b	18a	11a	9a	4ab	5a
Prestige (CPPU, 500)	11.5c	62b	66b	7c	7a	11a	9ab	0a
CPPU (500) + GA4+7 (5,000)	19.9ab	49c	59b	15ab	8a	10a	7ab	0a
Thidiazuron (TDZ, 1,000)	11.4c	68ab	58b	10bc	17a	10a	5ab	0a
TDZ (1,000) + GA4+7 (5,000)	19.9ab	49c	60b	16a	11a	9a	3ab	0a
^zApplied by hand with a small paintbrush to 1-year-old vertical, unpruned central-leader branches at green-tip (April 6, 2006). All treatments supplemented with 0.1% v/v Regulaid surfactant.
^yMean separation in columns by Waller-Duncan Bayesian k-ratio test following significant F-test (p ≤ 0.05). All interaction terms significant (p ≤ 0.05).
^xScored every 30 cm; scoring cuts treated with Regulaid only (0.1% v/v).
^wMean leader branch length 141 cm. Leader branch sections ∼30 cm in length; 1 = terminal 30-cm section. Sections 6–7 (basal) may have been less than 30 cm.

TABLE 2 Effects of Various Gibberellic Acid Isomer/Formulation Applications to Half-Scoring Cuts on Lateral Shoot Number and Vertical Distribution in Second-Leaf ‘Skeena’/G.6 Sweet Cherry Trees (Experiment 2, 2007, Quincy, WA)

	Lateral shoots	Lateral shoots in leader branch section (% of total lateral shoots) ^w
Treatment (mg•L^−1) ^z ^, ^y	No./100 cm leader length	1	2	3	4	5	6
Control (untreated)	11.8	84	11	3	2	0	0
PG (1,000)	13.5	70	3	3	9	13	1
PG (2,500)	21.8	53	21	17	9	0	0
PG (5,000)	16.4	60	20	10	7	2	1
NG (1,000)	13.4	76	9	9	1	4	2
NG (2,500)	16.9	72	6	7	9	4	1
NG (5,000)	25.3	55	21	14	7	4	0
PV (1,000)	19.4	60	15	15	9	1	0
PV (2,500)	19.0	53	21	12	9	5	0
PV (5,000)	20.7	57	14	11	10	6	1
Regression significance ^x
Linear
PG	*	**	*	NS	*	NS	NS
NG	****	**	NS	*	NS	NS	NS
PV	**	**	*	*	*	NS	NS
Quadratic
PG	*	*	NS	NS	**	NS	NS
NG	NS	NS	NS	NS	NS	NS	NS
PV	*	**	*	*	NS	NS	NS
^zApplied by hand with a small paintbrush to 1-year-old vertical, unpruned central-leader branches at advanced green-tip (April 4, 2007). All treatments supplemented with 0.1% v/v Regulaid surfactant.
^yPG = ProGibb 40 (Valent BioSciences); NG = Novagib 10L (Fine Americas); PV = ProVide 10SG (Valent Biosciences).
^xSignificance of linear and quadratic regression effects on active ingredient concentration determined by radiating regression analysis. NS—not significant; *p ≤ 0.05; **p ≤ 0.01; ***p ≤ 0.001; ****p ≤ 0.0001.
^wMean leader branch length 137 cm. Leader branch sections ∼30 cm in length; 1 = terminal 30-cm section. Section 6 (basal) may have been less than 30 cm.

TABLE 3 Effects of Surfactants and Nicking Cuts on Gibberellic Acid Isomer/Formulation Stimulation of Lateral Shoot Number and Vertical Distribution in Third-Leaf ‘Skeena’/G.6 Sweet Cherry Trees (Experiment 3, 2008, Quincy, WA)

	Lateral shoots	Lateral shoots in leader branch section (% of total lateral shoots) ^x
Treatment (mg•L^−1) ^z ^, ^y	No./100 cm leader length	1	2	3	4	5–6
Control (untreated)	9.0e	97a	0d	1b	1bc	0a
NG (5,000) + Regulaid (0.1% v/v) banded every 30 cm	11.4de	82bc	4bcd	4ab	3abc	7a
NG (5,000) + Regulaid (0.1% v/v) painted on nicking cuts every 30 cm	19.1a	62d	13a	10a	9a	6a
PV (5,000) + Regulaid (0.1% v/v) banded every 30 cm	10.6de	89b	3cd	2b	0c	6a
PV (5,000) + Regulaid (0.1% v/v) painted on nicking cuts every 30 cm	13.0cd	73bcd	14a	4ab	7ab	2a
NG (2,500) + Pentra-bark (2.0% v/v) banded every 30 cm	14.5bc	78bcd	9ab	4ab	4abc	4a
NG (5,000) + Pentra-bark (2.0% v/v) banded every 30 cm	14.2bc	77bcd	11ab	3ab	6ab	3a
PV (2,500) + Pentra-bark (2.0% v/v) banded every 30 cm	14.4bc	70cd	10abc	8ab	5abc	7a
PV (5,000) + Pentra-bark (2.0% v/v) banded every 30 cm	16.6ab	72cd	16a	5ab	4abc	4a
^zApplied by hand with a small paintbrush to 1-year-old vertical, unpruned central-leader branches at advanced green-tip (April 10, 2008). NG = Novagib 10L (Fine Americas); PV = ProVide 10SG (Valent Biosciences).
^yMean separation in columns by Waller-Duncan Bayesian k-ratio test following significant F-test (p ≤ 0.05).
^xMean leader branch length 160 cm. Leader branch sections ∼30 cm in length; 1 = terminal 30-cm section. Section 6 (basal) may have been less than 30 cm.

TABLE 4 Effects of Pentra-Bark Surfactant Application to Scoring Cuts on 1-Year-Old Branches on Lateral Shoot Number and Vertical Distribution in Third-Leaf ‘Skeena’/G.6 Sweet Cherry Trees (Experiment 4, 2008, Quincy, WA)

	Lateral shoots	Lateral shoots in leader branch section (% of total lateral shoots) ^x
Treatment (mg•L^−1) ^z ^, ^y	No./100 cm leader length	1	2	3	4	5	6
Control (unscored, untreated)	10.4a	82a	0a	0a	10a	6a	2a
Pentra-bark (2% v/v) on scoring cuts	10.1a	87a	0a	5a	6a	2a	0a
^zApplied by hand with a small paintbrush to 1-year-old vertical, unpruned central-leader shoots at green-tip (April 10, 2008).
^yMean separation in columns by F-test (p ≤ 0.05).
^xMean leader branch length 161 cm. Leader branch sections ∼30 cm in length; 1 = terminal 30-cm section. Section 6 (basal) may have been less than 30 cm.

TABLE 5 Effects of Gibberellic Acid (GA) Applications to Scoring Cuts on 1-Year-Old Branches or GA Combined with Supplemental Surfactant and Applied to Unscored 1-Year-Old Branches on Lateral Shoot Number and Vertical Distribution in Third-Leaf ‘Selah’/Mazzard Sweet Cherry Trees (Experiment 5, 2009, East Wenatchee, WA)

	Lateral shoots	Lateral shoots in leader branch section (% of total lateral shoots) ^x
Treatment (mg•L^−1) ^z ^, ^y	No./100 cm leader length	1	2	3	4	5	6
Control (untreated)	2.9b	100a	0b	0b	0a	0a	0a
PV (5,000) + Regulaid (0.1% v/v) painted on scoring cut every 30 cm	15.0a	47c	24a	15a	6a	6a	2a
PV (5,000) + Pentra-bark (3% v/v) banded every 30 cm	5.4b	97ab	0b	0b	0a	3a	0a
PV (5,000) + Pentra-bark (6% v/v) banded every 30 cm	8.1b	74b	4b	15a	6a	0a	1a
PV (5,000) + Pentra-bark (9% v/v) banded every 30 cm	14.7a	55c	24a	10ab	7a	4a	0a
^zApplied by hand with a small paintbrush to 1-year-old vertical, unpruned central-leader shoots at green-tip (April 6, 2009). PV = ProVide 10SG (Valent Biosciences).
^yMean separation in columns by Waller-Duncan Bayesian k-ratio test following significant F-test (p ≤ 0.05).
^xMean leader branch length 166 cm. Leader branch sections ∼30 cm in length; 1 = terminal 30-cm section. Section 6 (basal) may have been less than 30 cm.