multiple regression analysis

Nitrogen is one of the important nutrient elements necessary for the production of agricultural products, but the excessive application of nitrogenous chemical fertilizers and their leaching cause environmental pollution. Crops’ cultivars with high nitrogen use efficiency is one of the environmental friendly aproaches to mitigate this problem.

To evaluate grain yield and nitrogen use efficiency in barley genotypes under low input conditions (without fertilizer application), a field experiment was conducted in research field of the agricultural faculty of Shahed University, Tehran, Iran in 2016-2017 cropping season. Thirty six barley genotypes, purified for three cropping seasons, were planted using simple alpha lattice design with two replications.

The results showed that genotypes; 106, 107, and 68 had the highest grain yield (7963, 7920 and 7900 kg ha-1, respectively), the highest nitrogen use efficiency (58.6, 58.5 and 56.9 kg.kg-1, respectively) and the highest nitrogen uptake efficiency (2, 2 and 2.25 kg.kg-1, respectively). The results of multiple regression analysis showed that the three variables of nitrogen use efficiency, nitrogen uptake efficiency, and biomass yield explained 98.2% of variation in grain yield. Principle component analysis revealed that barely genotypes divided into four groups. The first group included genotypes; 88, 119, 54, 107, and 68 for nitrogen uptake efficiency and nitrogen use efficiency, grain yield and quality. These genotypes are suitable for low input cropping systems to increase nitrogen use efficiency.

The results of this experiment indicated that further investigations are required for recommendation of barley genotypes with higher nitrogen efficiency and grain yield for low input cropping systems.