Concentrations of some chemical components in white asparagus spears depending on the cultivar and post-harvest irrigation treatments

The effect of post-harvest irrigation and genotype on the quality components of white asparagus spears was investigated. The field experiment was conducted in 2003-2008 on a very light soil in the Bydgoszcz region. The research was based on a two-factorial split-plot design with randomly selected sub-main blocks. The first studied factor was irrigation applied as two treatments: drip irrigation and microsprinkler irrigation. Non-irrigated plants were tested as the control. The second factor considered was genotype represented by three male cultivars of the garden asparagus: ‘Gijnlim’, ‘Ramos’ and ‘Vulkan’. The irrigation started after the harvest of the spears, while the concentrations of chemical ingredients were measured in the white spears collected in the next growing period. The level of the tested components was significantly influenced by both factors studied. The average amounts of dry matter, potassium, iron and nitrates measured in the white spears were 6.37%, 268.9 mg 100 g⁻¹ f.m., 0.29 mg 100 g⁻¹ f.m. and 62.1 mg kg⁻¹ f.m., respectively. Compared to the control, both irrigation treatments considerably increased the dry matter and potassium contents. The irrigation reduced the amount of nitrates, although the microsprinkler irrigation gave better results than the drip irrigation. The highest concentrations of potassium and iron were measured in the spears of ‘Ramos’, especially in the case of drip-irrigated (potassium) and non-irrigated (iron) plants. The amount of dry matter was high in the spears of ‘Ramos’, while ‘Vulkan’ presented a low tendency to accumulate nitrates.