Phenotypic variability of bread wheat genotypes for nitrogen harvest index

Abstract

Gorjanovic B., M. Brdar-Jokanovic, and M. Kraljevic-Balalic (2011): Phenotypic variability of bread wheat genotypes for nitrogen harvest index-Genetika, Vol 43, No. 2, 419 -426. Nitrogen harvest index (grain nitrogen content over total nitrogen content ratio) is a measure of the efficiency of nitrogen translocation from the vegetative portions of the plant to the grain. It can be recommended as a selection criterion for nitrogen use efficiency improvement. The aim of this study was to investigate nitrogen harvest index in twelve bread wheat genotypes at three nitrogen levels and to classify genotypes according to their phenotypic similarity for the examined trait. The results of factorial ANOVA showed that nitrogen harvest index was influenced mostly by the year x genotype interaction, year of investigation and genotype; and to the lowest extent by the applied nitrogen rate. Increasing nitrogen doses did not lead to the increased nitrogen harvest index. The calculated nitrogen harvest index values were the highest for wheat growing season 2004/05, and the smallest for the season 2006/07. The highest nitrogen harvest indices were calculated for cultivars Pobeda at the N-0 rate and Zlatka at the N-100 rate (0.93), and the lowest for cultivar Tamaro at the N-0 rate (0.63). Analyzing the constructed dendogram, cultivars Pobeda and Renan at all three levels of nitrogen supply can be singled out as the genotypes with the highest, and cultivar Tamaro as the variety with the lowest harvest index value. The results of this study may be used in developing new high-yielding bread wheat cultivars with improved nitrogen use efficiency. Growing such cultivars would provide the savings in mineral fertilizers and minimize their possible harmful effect on environment.