engleski

Improvement of zinc nutrition of seed maize in the Eastern Croatia

Zinc deficiency has been observed at the early growth stage of seed-maize crops grown on neutral to slightly alkaline calcareous soil of the Eastern Croatia. Sensitivity to zinc deficiency was induced by weather conditions (cold and wet period promoting retardation of maize growth and development of typical chlorosis) and by genotype (normal status of one parent and stress status of remaining parent of maize hybrid under identical field conditions). By the our previous investigation, in the aerial part of maize with developed symptoms of zinc deficiency, either satisfied or low Zn concentrations and excess of iron and aluminum were found. Maize chlorosis were in close connection with the higher soil pH and the lower extractable Zn status. 16 field trials were conducted in four replications during three growing seasons. Different treatments of fertilization included also zinc (13 kg Zn ha-1 in ZnSO4 form) incorporation by the tillage interventions immediately prior to sowing of seed-maize, while standard fertilization was used as a control. Response of the mother parent to zinc application depended on numerous factors including degree of weather favorability (factor: growing season) and soil/plant characteristics (soil type and genetic properties of mother parent of seed-maize). Significant influences of Zn fertilization (mean 10% increase of yield) were found in 8 trials. Very high differences of grain yields of seed-corn were found among the control treatments of these field trials: from 2.02 t /ha to 6.13 t /ha. Our opinion is that they were influenced considerably more by degree of homozygotity of the mother parent than by soil characteristics. Regarding this, grain yields of pure inbred lines are considerably lower in comparison with those of modified inbred lines and especially single-crosses. Ten maize inbred lines (parental components of seed-maize) were grown on Djakovo slightly alkaline and drained gleysol (the soil A) in the growing season 1995 and on Osijek neutral eutric cambisol (the soil B) in the growing season 1996. The trials were established in four replications. Two rows of each genotype were treated with the solution of zinc sulfate (0.75% ZnSO4.7H2O), while remaining two were a control. The first treatment of spraying was at the beginning of June and the second treatment following ten days. Maize genotypes response to foliar spraying with 0.75% ZnSO4.7H2O solution was less expressed in the first year of testing: average grain yields were similar (2890 kg/ha and 2992 kg/ha, for control and spraying, respectively) while only two genotypes responded by yield increases (17% and 13% higher yields by the Os84-49 and by the Os84-24, respectively). However, in the second year of testing average grain yields were 4078 kg/ha (control) and 4418 kg/ha (spraying): by five genotypes (Os84-24, Os84-49, Os84-28, Os64-9 and Os86-39) grain yields increased from 11% to 18% as affected by ZnSO4.7H2O application. Zinc nutrition improvement of seed-maize is possible to overcome by adequate fertilization but determination of plant available zinc could be included in routine soil test procedure. Also, additional direction is avoidance of growing of susceptible maize genotypes to Zn deficiency under low zinc conditions.

seed; maize; zinc; nutrition

nije evidentirano