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• Phytohormonal changes in relation to citrus rind disorder was examined postharvest. • Fruit were harvested from inside and outside canopy position of the tree. • Endogenous levels of cytokinins (CK), auxins, isomers and conjugates were analysed. • Cis -zeatin-type CK concentrations were higher in outside canopy fruit postharvest. The role of phytohormones in mitigating or enhancing the incidence of non-chilling rind physiological disorder of citrus fruit is largely unknown. Therefore, this study attempted to elucidate cytokinins (CK) and auxin changes in 'Nules Clementine' mandarin fruit rind from different canopy positions during postharvest non-chilling cold storage regarding rind breakdown disorder (RBD). Fruit from the inside canopy (IC) and outside canopy (OC) positions of citrus trees were harvested at commercial maturity from Eastern Cape (EC) and Western Cape (WC) provinces of South Africa, respectively. Endogenous levels of CK, auxins, their isomers, and conjugates were analysed using ultra-performance liquid chromatography coupled with a triple quadrupole mass spectrometer (MS/MS) equipped with an electrospray interface. Cis -zeatin-type cytokinins were significantly higher in the OC fruit than in the IC fruit from both provinces during cold storage. Whereas dihydrozeatin concentration (the most abundant CK) was significantly higher in fruit from IC (326.10 and 29.38 nmol kg−1) than in OC (65.75 and 17.72 nmol kg−1) fruit before cold storage, respectively. Fruit without rind disorder had lower CK - conjugates than fruit with the disorder. The IAA concentration was higher in the IC fruit (344.15 nmol kg−1) than in the OC fruit (194.20 nmol kg−1) from EC at week 0 while the IAA concentration of OC fruit from WC was below the limit of detection and IC fruit had 53.20 nmol kg−1 at week 0. Fruit without the disorder had more IAA concentration than fruit with RBD while indole-3-acetylaspartic acid (IAAsp) was higher in fruit with RBD than fruit without the disorder, indicating the preventive role of IAA in the incidence of the disorder. This study is the first to record the negative effect of IAAsp in RBD and revealed the crucial role and synergistic role of CK, IAA and their isomers in RBD of 'Nules Clementine' fruit. [ABSTRACT FROM AUTHOR]

Effect of canopy position on rind biochemical properties of 'Marsh' grapefruit during postharvest non-chilling cold storage was evaluated on fruit harvested from different orchard locations. Inside canopy (IC) and outside canopy (OC) fruits were harvested at commercial maturity from two commercial farms located at KwaZulu-Natal (KZN) and Limpopo (LMP), South Africa, during two seasons. Rind biochemical analyses including color indices, total phenolic concentration, and sugars were performed on harvested grapefruit after Weeks 0, 3, 6, and 9 of cold storage at 7.5 ± 0.5°C. Canopy position showed a high significant (p <.001) effect on rind biochemicals while significant (p <.05) influence of orchard locations was observed on the same parameters. Reducing sugars were more concentrated in IC fruit harvested from both orchard location than OC fruit at Weeks 0 and 3, but inverse results occurred at Weeks 6 and 9. Orchard location significantly (p <.001) influenced vitamin C (14.4, 14.2, 14.4, 14.8 g kg−1) and (12.3, 16.1, 15.9, 14.6 g kg−1) of fruit rind at Weeks 0, 3, 6, and 9 from KZN and LMP, respectively. This study revealed that canopy position can influence rind biochemical properties of 'Marsh' grapefruit during non-chilling postharvest cold storage. However, further studies are required to formulate and provide the citrus industries with adequate advice. [ABSTRACT FROM AUTHOR]

The physicochemical properties of citrus fruit play critical roles in its maturity and quality determination. Hence, this study investigated the effect of canopy position on physicochemical properties of ‘Marsh’ grapefruit across different production regions at harvest and after storage at 7.5 °C for 3, 6, and 9 weeks. The study also evaluated the use of BrimA as an adoptable internal quality and maturity parameter for ‘Marsh’ grapefruit. Fruit from inside canopy (IC) and outside canopy (OC) were harvested from KwaZulu-Natal (KZN) and Mpumalanga (MP) provinces in South Africa. Titratable acidity was determined by titration and calculation of the sugar/acid ratio (TSS/TA) was established while BrimA was derived from sugar and acid with tongue sensitivity index. Colour indices were measured using calibrated colorimeter while sugars were measured using high performance liquid chromatography (HPLC). At harvest, IC fruit from MP province were more luminous than the OC fruit while inverse results were recorded for fruit from KZN. At harvest, IC fruit had higher percentage of titratable acidity (TA) (2.73%) than OC fruit (2.40%) from MP, with opposite results from KZN. The BrimA showed a strong and positive correlation with TSS/TA (r = 0.9364). Overall, our result suggested that canopy position affect some physicochemical properties of ‘Marsh’ grapefruit. However, harvested fruit displayed a high level of maturity and quality over the period of cold storage. BrimA could potentially be used as an index of internal quality of grapefruit but further studies into the subject is required. [ABSTRACT FROM AUTHOR]

Rind biochemical concentrations and radical-scavenging activities of ‘Nules Clementine’ mandarin could play a significant role in the susceptibility of the fruit to various forms of physiological rind disorders. This study examined the effect of fruit position within tree canopy on biochemical concentrations and radical-scavenging activities of ‘Nules Clementine’ mandarin fruit rind after harvest at week 0 and after 3, 6 and 9 weeks of postharvest cold storage at 7.5 ± 0.5 °C. Biochemical concentrations and radical-scavenging activities of flavedo and albedo tissues of the rind were also examined. Fruit from inside canopy (IC) and outside canopy (OC) were harvested at commercial maturity in May 2015 and 2016 from Unifruiti and Swartvelei Farms located at Eastern Cape (EC) (33° 27′ 32″ S, 25° 34′ 79″ E) and Western Cape (WC) (19° 02′ 33.8″ S, 33° 41′ 17.24″ E) provinces of South Africa, respectively. Results showed that canopy position played a significant ( p < 0.001) role on total carotenoids, total phenolics and total flavonoids as well as rind dry matter, with OC fruit often characterised by higher biochemical concentrations than IC fruit during cold storage. The study further showed that production region influenced radical-scavenging activities and carbohydrate content of OC and IC fruit rind during cold storage. Radical-scavenging activities of OC fruit (61.2%) were higher than IC fruit (52.5%) from EC whereas radical-scavenging activities of IC fruit (67.1%) were higher than those of OC fruit (58.2%) from WC at harvest. Overall, this study revealed that fruit position within tree canopy influenced its rind biochemical concentrations and radical-scavenging activities. [ABSTRACT FROM AUTHOR]

Harvest maturity of avocado fruit is currently determined using indices such as mesocarp oil content, dry matter (DM) or moisture content (MC), both measured destructively using representative samples of a batch in an orchard. Although useful, destructive techniques are time-consuming and results reflect properties of specific produce evaluated. In this study, the feasibility of near-infrared spectroscopy (NIRS) as a rapid non-destructive method for predicting maturity parameters of individual avocado fruit was evaluated. NIRS prediction results showed that MC and DM were predicted accurately, with residual predictive deviation (RPD) of 2.00 and 2.13 respectively. However, models for predicting oil content, though promising, were not accurate, with RPD value of less than 1.0. The good prediction statistics between NIRS predicted MC and DM content demonstrated the potential of this system for non-destructive evaluation of avocado fruit maturity status. The stability and accuracy of models developed over two seasons, 2013 and 2014, to predict maturity parameters of avocado fruit demonstrated model robustness. NIRS combined with PLS models developed in this study are recommended for non-destructive evaluation of individual avocado fruit maturity status. [ABSTRACT FROM AUTHOR]