The effect of physiological age, cultivar and soil pH on nutrient concentrations in asparagus : A thesis submitted to the Royal New Zealand Institute of Horticulture (Inc.) as partial fulfilment of the National Diploma in Horticulture (Honours)

Abstract

There has been a great deal of research on the field response of asparagus to various fertiliser applications, however little work has been done to evaluate how factors other than fertiliser affect the nutrient concentrations in asparagus. This project evaluated the effect of physiological age, cultivar and soil pH on nutrient concentrations in asparagus fern and spears. Sampling was carried out over a three year period. Results indicated that the physiological age of the fern had_ a large effect on the nutrient concentrations in the fern. Because concentrations in the fern were most stable eight to fourteen weeks after closeup this time was recommended for sampling fern for diagnosing nutrient disorders. As there were fewer significant differences between nutrient concentrations in the spear, sampling for nutrient diagnosis could possibly be carried out during the spear stage. However, there are no critical nutrient concentrations available for spears, making interpretation difficult. Nutrient concentration for all nutrients except nitrogen varied between cultivars, however these relative differences varied from year to year making interpretation of the results difficult. Except for calcium, boron and molybdenum soil pH had little effect on nutrient concentrations in the fern. All three trials showed variations in nutrient concentrations from year to year. This was thought to be due in part to environmental factors.