Effect of Nitrogen Supply and Genotypic Variation for Nitrogen Use Efficiency in Maize

Aims: Effect of nitrogen supply and genotypic variation for different traits related to nitrogen use efficiency (NUE) were studied in order to enhance the understanding of genetic basis of NUE and to find genetic materials for developing low-N tolerant maize genotypes.

Methodologies: Ten genotypes (5 open pollinated varieties and 5 hybrids) were evaluated at four N levels (0; 30; 90; 180 kg N.ha-1) in split plot randomized block design with three replications at farmer field in Tulungagung, East Java, Indonesia, from November 2011 to February 2012.

Results: The results showed that genotypes exhibiting contrasted responses to N nutrition. Nitrogen deprivation caused varied reductions of plant height, leaves area, chlorophyll content, stay green, N uptake, total dry matter, grain yield, grain number and a thousand grain weight among genotypes; but did increase days to 50% anthesis, 50% silking, anthesis-silking interval, crop recovery efficiency of applied N (REN), physiological efficiency of applied N (PEN), agronomic efficiency (AE) and NUE significantly (P = .05). Heritability estimates (h2) were high (h2 > 0.5) for most of measured traits at all N levels and ranged from -0.892 to 0.998. This indicated that it is possible to select genotypes are adapted to low N under both low and high N fertilization. High genotypic variation for grain yield was observed at all N levels, while for REN, PEN and AE were found at high-N and NUE at low-N. Reduction of N level from 180 to 90, 30 and 0 kg N.ha-1 caused reduction of 7.8%, 14.4% and 49.4% grain yields respectively. High grain yield were found in Bisi-2, Pioneer-21, NK-33, Bisma and DK-979 at high-N; and less yield reduction caused by N level reduction were found in DK-979, Madura, Bima-3, Bisma and NK-33, whilst high NUE traits were found in NK-33 and Pioneer-21.

Conclusions: NK-33, Pioneer-21, DK-979 and Bisma are expected to be as genetic materials for developing tolerant low-N varieties