Articles
USE OF PLANT BIOREGULATORS TO STIMULATE EMBRYO GROWTH AND LOOSEN FRUIT TO INCREASE SPLIT NUT YIELD OF PISTACHIO
Article number
884_71
Pages
549 – 557
Language
English
Abstract
Nut size and split nut yield are key economic factors in commercial pistachio (Pistacia vera Kerman) production.
Nut size tends to decrease as trees age and can be significantly reduced during the on-crop year.
Whereas plant bioregulators (PBRs) are powerful tools for solving production problems in the field, research developing PBR strategies for the California pistachio industry has been limited.
Gibberellic acid (GA3), 3,5,6-trichloropyridyloxyacetic acid (3,5,6-TPA) and 1-(2-chloro-4-pyridyl)-3-phenylurea (CPPU) were tested for their capacity to stimulate embryo growth and increase nut size.
Abscisic acid (ABA), methyljasmonic acid (MJA), 2-chloroethylphosphonic acid (CEPA) and 2,3,5-tri-iodobenzoic acid (TIBA) were tested for their capacity to loosen mature fruit and increase the number of fruit (nuts) harvested.
Branch studies testing multiple application times, rates, and combinations of PBRs were undertaken with the goal of increasing split nut (dry weight) yield.
Application of GA3 (170 mg L-1) during late bloom-early fruit set (20 May), CPPU (10 mg L-1) at the initiation of the period of exponential embryo growth (initiation of nut fill, INF) (10 June), and the combination of GA3 and CPPU 30 days after INF numerically, but not statistically, increased split nut (dry weight) yield per branch.
TIBA (125 mg L-1) applied 4 days before harvest was the most effective fruit-loosening treatment.
MJA (10 mg L-1) applied 14 days before harvest was nearly as effective as TIBA. Both treatments reduced adherence of fruit tissues to the seed (nut), thereby reducing shell staining.
Neither treatment caused significant leaf drop.
This is the first research testing these PBR strategies on pistachio.
Our results identify PBR concentrations and application times that numerically increase yield parameters by large percentages, as well as some that cause significant negative effects, making our data valuable to PBR researchers in all pistachio-producing countries.
Nut size tends to decrease as trees age and can be significantly reduced during the on-crop year.
Whereas plant bioregulators (PBRs) are powerful tools for solving production problems in the field, research developing PBR strategies for the California pistachio industry has been limited.
Gibberellic acid (GA3), 3,5,6-trichloropyridyloxyacetic acid (3,5,6-TPA) and 1-(2-chloro-4-pyridyl)-3-phenylurea (CPPU) were tested for their capacity to stimulate embryo growth and increase nut size.
Abscisic acid (ABA), methyljasmonic acid (MJA), 2-chloroethylphosphonic acid (CEPA) and 2,3,5-tri-iodobenzoic acid (TIBA) were tested for their capacity to loosen mature fruit and increase the number of fruit (nuts) harvested.
Branch studies testing multiple application times, rates, and combinations of PBRs were undertaken with the goal of increasing split nut (dry weight) yield.
Application of GA3 (170 mg L-1) during late bloom-early fruit set (20 May), CPPU (10 mg L-1) at the initiation of the period of exponential embryo growth (initiation of nut fill, INF) (10 June), and the combination of GA3 and CPPU 30 days after INF numerically, but not statistically, increased split nut (dry weight) yield per branch.
TIBA (125 mg L-1) applied 4 days before harvest was the most effective fruit-loosening treatment.
MJA (10 mg L-1) applied 14 days before harvest was nearly as effective as TIBA. Both treatments reduced adherence of fruit tissues to the seed (nut), thereby reducing shell staining.
Neither treatment caused significant leaf drop.
This is the first research testing these PBR strategies on pistachio.
Our results identify PBR concentrations and application times that numerically increase yield parameters by large percentages, as well as some that cause significant negative effects, making our data valuable to PBR researchers in all pistachio-producing countries.
Authors
C.J. Lovatt, Y. Zheng
Keywords
Pistacia vera ‘Kerman’, tree phenology, initiation of nut fill, harvest efficiency, fruit abscission
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