engleski

Leaf relative chlorophyll content and plant sap nitrate-nitrogen concentration as indicators for predicting nitrogen status in maize (Zea mays L.)

Nitrogen (N) management is critical in optimizing maize yield and reducing environmental pollution. Several field tests were proposed for assessment of N status in crop plants. Aim of this study was to determine adequate leaf chlorophyll content and nitrate-nitrogen (NO3-N) concentration in stem sap in order to predict maize N needs in different growth stages. Completely randomized block design experiment with three replications was conducted in north-west region of Croatia in 2008 and 2009 growing seasons on Pioneer A24 maize hybrid. At preplant 50 kg N ha-1 was applied. Treatments were four sidedressed N levels, 0, 50, 100 and 150 kg ha-1, applied at three fully expanded leaves growth stage. Dynamics of chlorophyll and NO3-N were measured by Chlorophyll content meter and Cardy twin nitrate meter, respectively, in three (V3) and seven (V7) fully expanded leaves and at silking (R1). Strong relationships between grain yield and chlorophyll content were obtained in V7 and R1 in both years (r2= 0, 78 and 0, 63 in 2008 and r2= 0, 77 and 0, 72 in 2009). In addition, strong relationship between grain yield and NO3-N concentrations was observed in 2009 (r2= 0, 82 in V7 and 0, 75 in R1). Chlorophyll meter readings above 31, 4, 58, 2 and 52, 5 in 2008 and 30, 3, 62, 0 and 60, 5 in 2009, as well as NO3-N concentration readings above 539, 961 and 704 ppm in 2008 and 515, 5, 473, 9 and 478, 3 ppm in 2009 at V3, V7 and R1, represented adequate values for achieving high yields.

maize; nitrogen status; chlorophyll content; nitrate-nitrogen concentration

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