ObjectivesIt is important to understand the root response to local N and P supply among genotypic differences to help breeding nitrogen (N) and phosphorus (P) efficient maize cultivars as nutrient distribution in soils is heterogeneous naturally.

MethodsA split-root solution culture system was set up to evaluate root response to local N- and P-supplementation in three maize hybrids.

ResultsThe root responses of the three genotypes showed different to local N or P supplement. Compared to NE15, JD20 and ZN99 were more sensitive to local N supply. Root length of JD20 and ZN99 in rich N side increased by 79% and 50% respectively, comparing with no N side, especially in the part with lateral root diameter≥0.12 mm. Similar response was not shown as significant in NE15 root as the other two genotypes. After P supplement treatment, however, the root dry weight and axial root length of NE15 were increased by 38% and 24% respectively in +P side compared to the no P supply, while the lateral root length of ZN99 was increased by 35% in +P side. The majority of root length increase of JD20 and ZN99 were found in root diameter greater than 0.12 mm part in rich N side, while NE15 genotype increased its root length mostly with root diameter between 0.12 to 0.24 mm in +P side. In ZN99 samples, the fine roots with diameter ≤ 0.12 mm were increased most significantly in +P side. Not only different responses to single nitrogen and phosphorus supplement by maize genotypes, but also interaction between genotypes and nutrient supplement were found. In JD20, the lateral roots (especially those with diameter>0.12 mm) were more responsive to local N than local P supply. While NE15 showed more root dry weight gain affected by local P than local N supply.

ConclusionThe different response of heterogeneous N or P supply from different maize genotypes provides information how to use local N and P supply efficiently to increase maize production.