Genetic Variation for Phosphorus Efficiency of Common Bean in Contrasting Soil Types: II. Yield Response
- Xiaolong Yan,
- Stephen E. Beebe and
- Jonathan P. Lynch
Phosphorus deficiency is a primary constraint to common bean (Phaseolus vulgaris L.) production in the tropics. Bean genotypes differ in their P efficiency, defined as growth and yield in low P soil. The objectives of this study were to evaluate genetic variation in diverse bean germplasm for P efficiency in soil types with contrasting P chemistry and to assess possible relationships between dry matter distribution, P partitioning, and yield. Experiments were conducted at two sites in Colombia, one an Andosol in which P availability is limited by allophane and recalcitrant organic matter and the other an Ultisol in which P availability is limited by Fe and AI oxides, with three levels of P fertilization. Twelve contrasting genotypes were evaluated for yield components, harvest index, and P partitioning. Genotypes yielded differently under P stress. Andean germplasm was often higher yielding under P stress than Mesoamerican germplasm but less responsive to added P fertility. Genotypic rankings for P efficiency did not differ in the two soil types. Reproductive parameters such as harvest index, yield components, and P allocation among plant parts at maturity were not related to P efficiency. We conclude that (i) there is no evidence for specific adaptation to low P availability in volcanic or mineral soils in beans; (ii) Mesoamerican and Andean genotypes respond differently to P availability; and (iii) vegetative and reproductive responses to low P availability are not always correlated. Further studies of P acquisition mechanisms related to root traits and efficiency of P use are warranted.Please view the pdf by using the Full Text (PDF) link under 'View' to the left.
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