engleski

Agronomic and dietary value of pak choy in different growing periods

Pak choy, in Croatia less known oriental leafy vegetable species, can be found on the Croatian market in the winter period as an import from other Medditerranean countries. The purpose of the investigation was to obtain information about its (cv. Hypro F1) agronomic traits and dietary value in different growing periods (two spring and a summer-autumn in the open, and a overwinter period in an unheated high tunnel) from 1998 to 2000. Field trials were laid out according to the split-plot scheme in five replications, with plant density as the main factor (16.7 and 22.2 plants/m2) and harvest dynamics as the sub-factor [(30, 37 and 44 days after planting (DAP)]. The monofactorial overwinter trial was set up so as to involve supplementary direct covering with polypropylene material (PP) and no covering, at a plant density of 16.7 plants/m2. Undesirable bolting was recorded in spring growing periods (0%, 0 to 9% and 5 to 40% at harvest 30, 37 and 44 DAP, respectively) and in the winter period (with PP covering 2 to 10%, without covering 6 to 20%). Contents of leaf petioles and blades in the rosette mass were about equal in the harvest 30 DAP in spring periods (ca 45%), and it increased as the vegetation progressed to the advantage of petioles (to 64% at 44 DAP in the summer-autumn period, to 60 % in the overwinter crop). The highest contents of total dietary fibres (0.56 to 0.79 g/100 g fresh matter) and biogenic elements (N, P, K, Ca, Mg, Fe, Mn, Zn, Cu) were recorded in the spring growing periods, as well as significantly lower concentrations of nitrates (1104 to 1187 mg/kg fresh matter). Closer spacing and supplementary direct crop PP covering had a positive effect on yields (P ≤ 0.01) and mainly no significant effect on the other traits studied.

growing periods ; plant density ; harvest dynamics ; bolting ; yield ; dietary

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