Improving Nitrogen Use Efficiency in Forage Bermudagrass.

Among major nutrient elements, nitrogen (N) fertilization has influenced crop production the most. It is important to develop forage cultivars with higher nitrogen use efficiency (NUE) to minimize N losses, reduce environmental pollution and make crop production economically more efficient. A set of 290 diverse bermudagrass germplasms were evaluated in the Noble greenhouse. N uptake efficiency (NUpE), N utilization efficiency (NUtE) and NUE of each genotype were determined. The NUE was highly and positively correlated with dry matter yield (99%) and NUpE (90%), but was negatively correlated with NUtE (-24%). Contrasting 50 germplasms were further evaluated in greenhouse and hoop-house experiments with four N doses. N fertilization in bermudagrass germplasm did not show significant genotype x N interactions for dry weight and NUE in greenhouse and hoop-house evaluations. The genotypes with high biomass production and NUE in high N rates are also the top genotypes in low N rates. However, there were significant genotype x N interactions for crude protein (CP) and NUtE in both greenhouse ((p<0.0001 and p= 0.03) and hoop-house (p=0.03 and p<0.0001, respectively) experiments. Thus, genotypes with low CP in low N rates showed increased CP at higher N rates. Selected 15 accessions along with three adapted check cultivars were planted in replicated field experiment to verify the results t. All the 290 germplasms were also planted in Ardmore, OK filed for collecting data on different morphological and physiological characteristics. The population was also genotyped using genotyping by sequencing approach. Genome wide association analysis is in progress.