The effects of boron sprays on fruit yield and fruit quality in guava (psidium guajava l.)
- Publication Type:
- Thesis
- Issue Date:
- 2005
Closed Access
| Filename | Description | Size | |||
|---|---|---|---|---|---|
| 01Front.pdf | contents and abstract | 7.25 MB | |||
| 02Whole.pdf | thesis | 62.16 MB |
Copyright Clearance Process
- Recently Added
- In Progress
- Closed Access
This item is closed access and not available.
NO FULL TEXT AVAILABLE. Access is restricted indefinitely. ----- This thesis reports on field and laboratory investigations into the effects of boron
sprayed directly onto leaves (foliar spray) on growth (yield), colour, texture and
chemical composition of common guava (Psidium guavjava L.) fruit. The key areas of
research included the use of different concentrations of boron (as boric acid) in two
different growing seasons (2002 and 2003) with different climatic conditions. Physical
parameters of fruit quality were measured such as size (diameter) and weight, and
colour and texture, as well as detailed analysis of fruit chemical composition, including
crude fibre, total soluble solids, pectin, acidity and vitamin C content. Time of fruit
deterioration was monitored to assess shelf-life, and concentrations of boron taken up
into the fruit and plant leaves were monitored for safety reasons. Finally, a panel of
fruit experts was used to assess the sensory and eating quality of fruit with or without
boron application, and a final assessment of fruit eating quality was determined.
Results from the study clearly showed that boron sprays at or near the highest
concentrations used in this study significantly improved fruit size and weight. There
was a subtle colour change in the skin towards a more green fruit, and the physical
texture of the fruit was harder with boron application. Almost all chemical analyses
demonstrated that with boron application fruit had higher acidity, vitamin C content,
total soluble solids, but crude fibre had decreased. Pectin levels in 2003 were low and
could not be accurately quantified, but in 2002 boron also increased the levels of
pectins. A significant result was that boron sprays decreased fruit deterioration over
time, and shelf life of guava could be extended from 5-7 days with no boron spray to 14-
16 days with the highest boron concentration spray. A panel of fruit experts assessed
the fruit from the highest boron sprayed trees to be overall the best fruit in taste, colour
and texture, with fruit from trees without boron application being the poorest fruit in
these aspects.
This study, therefore, for the first time investigated the role of boron in post-harvest fruit
physiology and composition in a tropical fruit, as distinct from other studies on
temperate fruits. However, the results of this study are in agreement with other studies
of boron application in temperate fruits, and the available broad literature is used to
explain the effects observed. The data provided a consistent picture as to the benefits of
boron application, in what tuned out to be very different tropical climatic conditions
over the two seasons of this study. The results are discussed in relation to the effects of
boron on tree physiology, biochemistry and fruit development; additionally economic
and orchard management implications of the research are discussed. Finally, a brief
discussion on possible negative environmental effects of boron accumulation in plants
and soil are discussed as a result of boron spraying, with a brief review of possible
human heath implications.
Please use this identifier to cite or link to this item: