The South African fresh fruit industry is a significant exporter, accounting for approximately 45% of the country's agricultural exports. However, certain physiological rind disorders such as mango lentil damage and citrus rind enlargements are frequently observed, reducing the commercial value of the fruit. Factors of particular interest were harvest maturity, climate and the mineral content of the fruit.
The South African fresh fruit industry is a significant contributor to the agricultural export industry, accounting for approximately 45% of the country's agricultural exports (Department of Science and Technology, 2006). However, physiological skin abnormalities such as skin breakdown are frequently observed, reducing the commercial value of the fruit. This thesis deals with two of the important peel physiological disorders of citrus (peel) mango (lenticel damage).
Inappropriate MAP can further promote the development of scab disorders by removing the fruit from the MAP system.
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However, the degradation of chlorophyll in the peel of this fruit was only stimulated by continuous exposure of the fruit to ethylene. Goldschmidt supported the contribution of ethylene to the escalation of citrus flaveda. In longitudinal section, Ca concentration decreases from the proximal to the distal end of the fetal calyx (Chaplin and Scott, 1980).
Subsequent results confirmed that there is a relationship between the mineral composition of the fruit and the incidence of lens damage (Kruger and Fraser, 2004). Calcium is known to reduce physiological disorders by stabilizing fruit cell membranes. Clements (1964a) found that organic acids make up about 50% of the total anions in the peel.
Up to 90% of cell boron is found in the cell wall (Blevins and Lukaszewiski, 1998), and early symptoms of boron deficiency disorders include disorganization of the cell wall and middle lamella (Hu and Brown, 1994). These researchers observed that only about 2% of boron in leaves was derived directly from soil-applied fertilizers. It was further observed that the proportional increase in manganese content in the skin after good rains was significantly higher than in the pulp.
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A preliminary study of the effect of climatic conditions and fruit mineral concentration on the development of lens damage in 'Tommy Atkins'. The study also aimed to provide fruit mineral content "point" for the development of lens damage. However, compared to fruit from Bavaria, the Numbi fruit had the highest incidence of lens damage.
Similarly, Keitt's results showed that the intensity of lentil damage was significantly higher in the orchard receiving supplemental nitrogen in the form of LAN. The first aim of this study was to determine the effect of mulching and preharvest rainfall on the postharvest development of lentil damage. Tommy Atkins', conventional orchards 3B at Numbi Estates and AL5 at Bavaria Estates were studied.
In the plastic sheeting trial at Numbi Estates, the difference between fruit lens damage from the plastic sheeting treatment and the control was not statistically analyzed. This lack of evidence emphasized the importance of fruit origin rather than fruit mineral concentration in the development of lens damage. In all four treatments, the incidence of lens damage was relatively low at the beginning of the pre-rainfall evaluation period.
This author also reported that the incidence of lens damage was reduced as the soil dried. However, the nitrogen concentration of the LAN treatment with the highest lens damage was not statistically significant from other treatments. This observation suggests that the direct effect of nitrogen application of a particular form was not important for the development of lens damage and fruit nitrogen concentration.
Mean lentil damage score and percentage of pulp and skin nitrogen from five treatments in the 'Keitt' plantation at Bavaria Estates. Daily lentil damage scores for fruit from five treatments in the 'Keitt' orchard at Bavaria Estates.
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In order to investigate the possible role of nitrogen in the development of the shell, the element was applied towards the end of the season. The incidence of shell was low at the beginning of the sampling period, followed by a peak and a decline towards the end of the sampling period. With respect to fruit position within a canopy, the severity of the disorder was not affected by fruit position.
Nitrogen concentration in fruit harvested from the east side of the trees was not significantly different. In fruit from the west side, nitrogen concentration in the exocarp of oranges from trees that received Horticote® was significantly lower (P<0.05) than in LAN and control treatments. These observations seem to indicate that nitrogen concentration in the exocarp is not important in the development of the disorder.
Fruits from the eastern side of the tree were found to contain significantly lower concentrations of more mobile N, P and K than western fruits. In this study, it was noted that control fruit with a higher nitrogen concentration on the west side consistently had less manganese on this side of the tree. Severity of pit formation on the skin of fruit on the east side of the tree, influenced by nitrogen treatments and sampling dates.
Severity of pitting on fruit placed on the west side of the tree as affected by nitrogen treatments and sampling dates. Severity of pitting on fruit placed on the east and west sides of the tree as affected by nitrogen treatments. Exocarp nitrogen concentration of oranges harvested on different sampling dates from the eastern side of the tree.
Nitrogen concentration in orange exocarps collected at different sampling dates from the west side of the tree. Average nitrogen concentration on the exocarp of oranges harvested from the west and east sides of the tree. Fruit mass of oranges harvested from the eastern side of the tree at different sampling dates.
Fruit mass of oranges harvested from the west side of the tree on different sampling dates.
GENERAL DISCUSSION
Regarding mineral association with the disorder, there is insufficient evidence to support that fruit N and Mn concentrations are important for the development of the disorder. The severity of the disorders varied with the sampling date, with relatively lower incidences of lens damage and crusting stones at the beginning of the sampling period. Similarly, the incidence of crust pits was low at the beginning of the sampling period, followed by a peak and a decline towards the end of the sampling period.
Regarding the position of citrus fruits in the canopy, the position of the fruit did not affect the severity of the disorder. These authors also reported that fruit oriented toward the northwest (northern hemisphere) of the canopy was most affected by the disorder. 2005) reported a significant difference between mineral concentrations in the rind of fruit from different tree positions.
This study showed that fruits from the eastern side of the tree contained significantly lower concentrations of more mobile N, P and K than western fruits. In contrast to mobile elements, less mobile Ca, Mg, Cu, and B were found to be consistently lower in fruits on the west side than fruits on the east side of the canopy. It has been suggested that this may be a result of light- and heat-dependent transport of these less mobile elements, which caused fruits on the eastern side of the tree to contain more of these elements (Curie, 2000; Curie and Briat, 2003).
It is probably a result of the light- and heat-dependent transport of these mobile elements that fruit on the eastern side of the tree had higher concentrations of immobile elements. Furthermore, fruit position within a canopy affected the severity of pitting, with fruit located on the west side of the tree being more susceptible to pitting than fruit on the east side. 1999) maintained that symptoms of pitting occur on the parts of the shell most exposed to external factors such as radiation.
Both authors also reported that fruits oriented on the west side of the canopy were more affected by the disorder. It is probably a result of this light-dependent transport of these elements that the fruits on the eastern side of the tree had more immobile elements.
Effects of rate and frequency of fertilizer application on yield and quality of 'Valencia' oranges in Indian River. The influence of different levels of nitrogen on the quality, yield and photosynthesis of 'Fuji' apple fruits. Dry matter accumulation in citrus is not limited by the transport capacity of the pedicel.
Regents of the University of California, Department of Agriculture and Natural Resources, Oakland, CA, pp. The effect of the timing of the last seasonal nitrogen fertigation on early fruit ripeness, fruit diameter and leaf nitrogen on 'Navel' oranges. Potential use of the immobile mineral element composition of mango fruit as an indicator of susceptibility to lenticel damage.
Effect of boron sprays on boron and calcium content, fruit physiology disorder and citrus storage. Determination of ameliorative nutrient applications to improve fruit quality produced by a 'Tommy Atkins' orchard. Effects of each stage on the packing line on the incidence of lentil damage in 'Keitt' and 'Tommy Atkins' mangoes.
The effect of pre- and postharvest calcium applications on postharvest quality of 'Pinkerton' avocados. Initial characterization of the brown skin of the mango (cv. 'Kensington Pride') and the effect of post-harvest detergents. Dark-colored tissues of the epicarp of 'Encore' mandarin: interactions with hydroxyl production.
