Avocado orchard management: effects of boron and branch-girdling on special carbohydrates
2012
Tesfay, S.Z. | Bertling, I. | Bower, J.P.
Avocado contains a number of "unusual" sugars, characterised by a C7 versus the usual C6 carbon backbone. Although the role of these sugars remains unknown, there are several indications that these compounds contribute to fruit growth and development, act as 'potential inhibitors' of fruit ripening and are, hence, related to fruit quality. Therefore, possibilities to increase the size of the C7 sugar pool in avocado were explored. Firstly, two methods of boron (B) application (soil and foliar) were tested as a means to improve the leaf C7 sugar (in particular perseitol) concentration, as this element is involved in the transport of sugar alcohols. Secondly, the effect of girdling of fruit-bearing branches on the concentration of fruit sugars was examined to determine if the C7 sugar accumulates in response to this treatment in a manner similar to sucrose in C6 sugar accumulating plants. Leaf carbohydrate analysis carried out after the application of four levels of B showed that B application positively influenced leaf D-mannoheptulose levels. Girdling of individual branches during the later fruit growth period also affected fruit mesocarp sugar concentration. In conclusion, D-mannoheptulose levels can be influenced through timed fertilizer application as well as other tree manipulation practices, concomitantly improving postharvest fruit quality.
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