Rast in pridelek sladke koruze v odvisnosti od organskih in mineralnih dušikovih gnojil, odmerkov dušika in oskrbe z vodo

Sweet maize is an underutilized vegetable in European temperate areas, and its consumption is increasing. For better understanding of cultivation practices, this pot experiment aimed to determine the eff­ects of diff­erent water regimes and nitrogen (N) rates calculated from N target values. N rates of 0 (control), 0.6 and 2 g N pot$^{-1}$ were applied as organic by-products pumpkin cake and pig manure digestate, and mineral fertilizers CAN 27 and ENTEC®26. Treatments of water supply were based on measured soil matric potentials of 2.8 pF (drought stress), 2.6 pF (optimal water) and 2.4 pF (overwatered). In comparison to mineral fertilizers, pumpkin cake proved to be equal in eff­ectiveness in plant height (155.8 cm), cob (85.8 g), green (124.9 g) and leaf mass per plant (44.2 g), or even better in root (72.3 g) and broom mass per plant (3.0 g). Yield parameters, cob mass (70.1 g), its length (6.3 cm) and diameter (2.0 cm), as well as the residual mineral N (59 mg N kg$^{-1}$) significantly increased at the highest N rate. Significantly lower values of the evaluated morphological parameters and photosynthetic rates (at brooming and harvesting) were associated with drought stress. The matric tension of 2.6 pF was established as an appropriate water regime for sweet maize growth.Sladka koruza je v evropskih območjih z zmernim podnebjem premalo pridelovana zelenjadnica, njena poraba pa narašča. Za boljše razumevanje načinov oskrbe sladke koruze, je namen lončnega poskusa ovrednotiti vpliv različnih vodnih režimov in odmerkov dušika (N) izračunanih iz ciljnih vrednosti. N v odmerkih 0 (kontrola), 0,6 in 2 g N lonec$^{-1}$ je bil dodan v obliki organskih ostankov – bučne pogače in digestat iz prašičje gnojevke, ter mineralnih gnojil – CAN 27 in ENTEC®26. Obravnavanja oskrbe z vodo so temeljila na izmerjenih talnih matričnih potencialih: 2,8 pF (sušni stres), 2,6 pF (optimalna preskrbljenost z vodo) in 2,4 pF (prekomerna oskrbljenost tal z vodo). V primerjavi z mineralnimi gnojili, so se bučne pogače izkazale za enako učinkovite glede na izmerjeno višino rastlin (155,8 cm), maso storža (85,8 g), zeleno maso (124,9 g) in maso listov na rastlino (44,2 g), oziroma celo kot boljše gnojilo glede na izmerjeno maso korenin (72,3 g) in metlic na rastlino (3,0 g). Parametri pridelka, kot masa (70,1 g), dolžina (6,3 cm) in premer storža (2,0 cm), kakor tudi ostanki mineralnega dušika (59 mg N kg$^{-1}$ ) so bili značilno višji pri gnojenju z najvišjim odmerkom N. Statistično nižje vrednosti vrednotenih morfoloških in parametrov fotosintetske aktivnosti (merjeno ob metličenju in spravilu) so bile povezane s sušnim stresom. Matrični potencial 2,6 pF se je izkazal kot najustreznejši za rast sladke koruze