Applications in sustainable production

Abstract

It is well‐known that different maize (Zea Mays L.) hybrids can utilize N‐fertilizers to different degrees. Experiments are needed to determine their N utilization manifesting itself in dry weight production and within that in grain weight. The chemical analysis of the plants can give us further information about their quality parameters. Fertilization model experiments were conducted with two maize hybrids (Pioneer 3732 and Volga) of similar yield potential in green house using large pots (40 kg dry clay lessivated brown forest soil per pot) in three experimental years (1993–95). 150 mg N kg^‐1 soil was applied in form of NH₄NO₃ or KNO₃. In addition, phosphorus and potassium fertilizers were added too. The plants were grown under two different soil water regimes (65% and 80% water holding capacity) up to full ripening (from May to the middle of September). Compared with the unfertilized control plants, the dry weight of the whole plants and grains in the fertilized treatments was 2–2.5‐fold and 3–4‐fold higher, respectively, on the three years’ average. Volga showed a more favorable response to N‐fertilization, as regards N‐forms, to NO₃‐N. The more beneficial effect of N‐fertilization on this hybrid appeared in greater grain yield production, too. The nitrogen harvest index of both hybrids amounted to about 40, 30 and 30% in the KNO₃‐, NH₄Cl‐ and unfertilized treatments, respectively. The water demand of the hybrids was different, too. Volga produced more dry weight under drier soil conditions. The N‐uptake of both hybrids was considerably higher from the NO₃‐N source than from the NH₄‐N one, and NO₃‐accumulation could be detected in the grains, in ones of Pioneer 3732 to a higher extent. This suggests that nitrate reduction could also take place in the grains. N‐accumulation in the different plant parts was also examined. The yearly variation in the tested parameters was more expressed with the unfertilized plants than with the fertilized ones.