A prediction model to determine the cross-pollination ability of Citrus spp.
Loading...
Date
1995
Authors
Journal Title
Journal ISSN
Volume Title
Publisher
Abstract
Due to a greater emphasis having been placed on seedlessness by citrus consumers,
a need developed in the southern African citrus industry to avoid unwanted cross-pollination
and hence seediness. There was a paucity of knowledge upon which to
base sound decisions in order to ensure optimal orchard layout to achieve the
objective of the production of seedless or "commercially seedless" fruit. In vitro
pollen viability of all locally available citrus cultivars/selections was determined and
pollen of cultivars with strong and weak pollination potential were used for in vivo
pollen tube growth and seed content studies of 'Nules Clementine' mandarin and
'Delta Valencia' orange. Data from the in vitro assays were rated and categorized
into 'pollen germination potential categories', while the relationship between these
categories and seed content of 'Nules Clementine' was determined by regression
analysis. The development of the 'pollen germination potential categories' provides
an additional facet to the evaluation and development of new citrus cultivars,
providing a means to determine the pollination potential at an early stage of that
cultivar's development. Citrus cultivars with a pollen germination percentage
exceeding 2 % are likely to set too many seeds for the export of 'Nules Clementine'
mandarins according to South African export requirements. In addition to the two
previously known pollen sterile cultivars, viz. 'Navel' orange and 'Satsuma'
mandarin, 'Star Ruby' grapefruit and 'Delta Valencia' orange have been identified
in this study as pollen sterile cultivars that can be used as buffers to avoid cross-pollination
between two pollen fertile cultivars. Furthermore, 'Delta Valencia' is also
ovule sterile. An initial model is presented whereby the seed content of cross-pollinated
'Nules Clementine' fruit can be predicted (r2 = 0.9192) by determining the
in vitro pollen viability of the cross-pollinating cultivar/selection and be calculated
as follows: 2.619 x pollen germination category of compatible cultivars - 2.449.
Description
Thesis (M.Sc.Agric.)-University of Natal, Pietermaritzburg, 1995.
Keywords
Citrus--Pollen., Citrus--Pollination., Citrus--Varieties., Citrus--Seeds., Citrus fruits., Theses--Horticultural science.