Development of stomatal conductance of maize under moderately hot, dry production conditions
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A field trial was conducted in Hungary, in a moderately warm, dry production area to determine the effect of single or split application of N-fertilizer on the stomatal conductance and grain yield of maize. The measurements were performed at on calcareous chernozem soil, in a strip field trial, under different weather conditions (2019 and 2020). In addition to the unfertilized control (A0) treatment, 60 (A60) and 120 kg N ha-1 (A120) applied as spring basal fertilizer were followed by two top-dressing treatments in V6 (A90) and V12 (A120) phenophases with doses of +30 and +30 kg N ha-1 , respectively. Stomatal conductance measurements were taken at V6, V12 and R1 phenological phases. It was found that stomatal conductance showed a decreasing trend with advancing phenological phases in both years, with 43.9% and 32.1% (P < 0.001; P < 0.01) decreases by the R1 phase, respectively. Application of higher doses of N fertilizer increased stomatal conductance, with the exception of the R1 phenological phase, which showed a decrease compared to the A0 treatment. The decrease in 2019 was caused by a reduction of soil moisture. Although there was sufficient water in the soil in 2020, due to the intermittent water shortages caused by but the large leaf area and rapid transpiration of the plants resulted in the stomata to close. The best fertilisation strategy was A60 and A120 kg ha-1 depending on the crop year. The study showed that the highest yield is obtained when the average stomatal conductance is around 250 mmol m-2 s -1 during the growing season.