2.4.6    Predicting sugar beet emergence


The standard germination test is fair to the seed in that individual seeds have minimal stress and therefore if germination is possible it should occur.  However, sugar beet growers require information on field emergence potential and therefore tests with inbuilt stresses may be more appropriate.  Perry (1973) has shown how field stresses affect beet seed lots differentially and prior knowledge of this would be very useful for seed selection for a particular situation.


Brown (1980) suggested low temperature tests (5-7°C) as viable seeds which germinate at 20°C may not do so at lower temperatures which would be experienced in the field.  Longden, Johnson & Love (1970) developed a radiography test for laboratory emergence and Longden and Johnson (1974a) compared a radiography test with other methods, i.e. leachate conductivity, a pleated paper test (Hibbert & Woodward 1969), and growing in compost, for prediction of field emergence.


The radiograph prediction is based on x-ray photographs of seed, assessed visually into "good", "dead" and "uncertain" categories.  Filled cavities, shrivelled seed, empties and double embryos can be identified with this method.  However, not all seed classified as good will germinate, and therefore radiography tends to over-estimate laboratory germinations.  Germination in compost was predicted equally well with radiography and standard germination tests.  For field performance the leachate conductivity method was hopelessly inaccurate with pelleted seed and poor with unpelleted seed and was therefore discarded as a prediction method.  The compost test was more accurate but took three weeks and was roughly equivalent to a radiography prediction.  However, radiography does not work for pellets.  Overall the pleated paper and the standard test gave the best prediction.  It was noted that a low laboratory germination always resulted in poor field performance, but a high laboratory value could result in a high or low field result.


The method of prediction of field performance was a linear regression, e.g. Y = 0.64 X + 6.2 where Y is field emergence (%) and X is laboratory germination (%) but using a field factor is simpler.  A field factor of 72% would mean a grower could expect 72% of the laboratory germination to emerge in the field.

The field factor can be applied to this formula (Bleasdale 1963 cited by Longden & Johnson 1974a).

                                   P x 100

N                   =        ----------

                                    G x F




N                   =        no. seeds required/ha


P                   =          desired population, plants/ha


G                   =         laboratory germination %


F                   =          field factor.


However, as sugar beet establishment is variable, estimating the field factor may not always be accurate enough for practical use of the formula, but it shows that improving the field factor by preparing better seed beds will reduce the number of seeds required to produce a regular stand.



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[Introduction & Contents]     [Chapter One]     [Chapter Two]     [Chapter Three]     [Chapter Four]     [Chapter Five]     [Chapter Six]     [Chapter Seven]

[2.4]     [2.4.1]     [2.4.2]     [2.4.3]     [2.4.4]     [2.4.5]     [2.4.6]     [2.4.7]     [2.4.8]