Breeding for phosphorus use efficiency

Abstract

Low phosphorus availability is one of the major agricultural limitations in tropical soils. Phosphorus deficiency causes a series of effects in plants such as changes in root and shoot morphology, in plant physiology and in plant internal transport. Phosphorus deficiency also affects the use of other nutrients, resulting in reduction of crop yield potential. Among the macronutrients, phosphorus has the lowest use efficiency in plants. This low efficiency is related to the ability of soils to adsorb the applied P, making it unavailable to the crop. Phosphorus efficiency has been defined as the processes by which plants acquire, translocate, accumulate, and utilize this nutrient to better produce dry matter and/or grain under conditions of high and low supply. Nutrient use efficiency has been defined as grams of grain produced per gram of nutrient supplied to the crop. This index can be decomposed into two main components: acquisition efficiency, and internal utilization efficiency. Phosphorus acquisition efficiency has been found to be two to three times more important than phosphorus internal utilization efficiency in tropical soils. Breeding programs for phosphorus use efficiency should take into account a number of issues such as: use of appropriate screening sites, germplasm sources, experimental conditions, intensity of stress imposition, selection criteria, genetic information and evaluation methods. A general discussion of these topics are covered in this chapter.