Categorization and Identification of Brassica Genotypes for Phosphorus Utilization Efficiency

Development and introduction of new cultivars with higher phosphorus use efficiency (PUE) is utmost important to uphold crop yields on low-P soils. Categorization of existing germplasm based on growth performance under P-deficiency is necessary for any program aiming to enhance PUE. Ten Brassica genotypes (Rainbow, Oscar, R-75/1, R-100/6, R-125/12, Surhan-2012, R-125/17, Con-I, Con-II, and Con-III) were categorized for dry matter (DM) production and PUE in a hydroponic study by growing at two P levels (i.e., deficient, 20 mu M Pi and adequate, 200 mu M Pi). Genotypes varied significantly for plant growth and biomass related attributes under both P levels. Genotypes Oscar and Con-III produced maximum DM and accumulated more P under deficiency stress and thus proved to be efficient, while genotypes R-75/1 and R-125/17 demonstrated lower values of these indices and were therefore, in-efficient. Four methods were compared using different parameters/indices to categorize genotypes at both P levels. Some genotypes (i.e., Oscar, R-75/1, R-125/17, Con-I) maintained their status regarding P-efficiency when categorized by different methods, while other revealed variable results in response to adequate and/or deficient P level. Categorization of genotypes into four groups based on population means only, had a very narrow range between responsive and non-responsive or efficient and in-efficient genotypes. Therefore, this system may not be more helpful for screening germplasm on a large scale. Conversely, the categorization of genotypes into three classes and their distribution into nine groups was the most excellent approach to distinguish minor differences among genotypes. Moreover, root DM, shoot DM, root-shoot ratio, total P uptake, and PUE were important parameters taken into consideration while categorizing Brassica genotypes for P-efficiency. (C) 2020 Friends Science Publishers