Articles
Effect of synthetic auxin sprays on yield of almond trees and orchard profit
Article number
1449_18
Pages
135 – 140
Language
English
Abstract
Low yield is the main weakness of almond orchards in Chile (under 2000 kg ha‑1 vs. 2500 kg ha‑1 in California or Australia) mainly due to weather conditions that would affect pollination and fruit set.
Across the last seasons, small kernel size has been an issue for growers.
Synthetic auxin sprays have been reported to increase fruit size in different fruit species, but they have not been validated in nuts crops.
With the aim of improving seed size, a study assessing the effect of two commercial agents containing synthetic auxins (2,4-DP and NOA plus 4-CPA) in ‘Nonpareil’ almond trees was carried out.
The results were integrated, and the profit of the best treatment of each auxin was simulated under different scenarios, according to fruit density and orchard PAR interception (Photosynthetically active radiation intercepted). To normalize tree size, the fraction of PARi was expressed as m2 of PARi (fraction multiplied by allocated space). Auxin treatments were done at full bloom and shuck split, based on commercial products available in Chile: Stonegross® (2,4 DP) and Propulse® (NOA plus CPA), and compared with not sprayed trees.
Different concentrations (30 and 40 mg L-1 of NOA; 75 mg L‑1 of 2,4-DP) were evaluated as unique or double spray.
At harvest, auxin treatments significantly increased seed size and, consequently, the yield efficiency adjusted by crop load (~7 to ~8%) without affecting crop load or double seeds.
The double spray of 30 or 40 mg L-1 of NOA did not show better response than a single application of 30 mg L-1 of NOA or 75 mg L-1 of 2,4-DP at full bloom.
Finally, the spray of 30 mg L-1 of NOA or 75 mg L-1 of 2,4-DP generates a sufficient yield increase to make the application profitable, even under conditions of low crop load (250 fruits m‑2 PARi) in orchards intercepting at least 60% PAR.
Across the last seasons, small kernel size has been an issue for growers.
Synthetic auxin sprays have been reported to increase fruit size in different fruit species, but they have not been validated in nuts crops.
With the aim of improving seed size, a study assessing the effect of two commercial agents containing synthetic auxins (2,4-DP and NOA plus 4-CPA) in ‘Nonpareil’ almond trees was carried out.
The results were integrated, and the profit of the best treatment of each auxin was simulated under different scenarios, according to fruit density and orchard PAR interception (Photosynthetically active radiation intercepted). To normalize tree size, the fraction of PARi was expressed as m2 of PARi (fraction multiplied by allocated space). Auxin treatments were done at full bloom and shuck split, based on commercial products available in Chile: Stonegross® (2,4 DP) and Propulse® (NOA plus CPA), and compared with not sprayed trees.
Different concentrations (30 and 40 mg L-1 of NOA; 75 mg L‑1 of 2,4-DP) were evaluated as unique or double spray.
At harvest, auxin treatments significantly increased seed size and, consequently, the yield efficiency adjusted by crop load (~7 to ~8%) without affecting crop load or double seeds.
The double spray of 30 or 40 mg L-1 of NOA did not show better response than a single application of 30 mg L-1 of NOA or 75 mg L-1 of 2,4-DP at full bloom.
Finally, the spray of 30 mg L-1 of NOA or 75 mg L-1 of 2,4-DP generates a sufficient yield increase to make the application profitable, even under conditions of low crop load (250 fruits m‑2 PARi) in orchards intercepting at least 60% PAR.
Publication
Authors
V. Beyá-Marshall, T. Fichet
Keywords
Prunus dulcis, 2,4-dichloro phenoxy propionic acid (2,4-DP), 2-naphthyloxyacetic acid (NOA), 4-chlorophenoxyacetic acid (4-CPA), crop value, plant growth regulators
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