COMPARISON OF THE ABILITY OF DIFFERENT PLANT SPECIES AND CORN HYBRIDS TO ACCESS POORLY-AVAILABLE SOIL PHOSPHORUS IN AN OXISOL OF THE CERRADO REGION, BRAZIL

摘要

The soils of the Cerrado region in Brazil have severe limitations for plant growth and crop production due to their high acidity and low natural fertility, in particular low phosphorus (P) availability. A series of experiments was carried out to make a comparative assessment of a large number of plant genotypes and identify the best adapted to these acid soils. In this paper the studies reported are related to the evaluation of a) twenty two (22) plant species and b) thirty (30) of the most recommended corn (Zea mays L.) hybrids for the Cerrado region with regard to their ability to absorb poorly-available soil phosphorus using the ~(32)P isotopic dilution technique. Two soils (Typic Dystrarox) of this region with contrasting management were employed: one soil was cultivated (and fertilized) for 20 years and another (natural) was kept under native vegetation. In the first experiment, species such as crotalaria, cowpea, soybean, stylosanthes, sunflower, peanut, millet and sorghum showed to have inefficient P uptake ability, while cotton, eucalyptus, rice, white lupin and pigeon pea were found to be highly P-efficient species. Black oat, corn, brachiaria, common bean, wheat, mucuna, tomato, triticale and barley were intermediate, In the second experiment significant differences in P uptake ability were also observed among corn hybrids in the cultivated soil. Seven genotypes were ranked as efficient, sixteen as intermedfiate and another seven as inefficient. Plant growth and P concentration of all corn hybrids grown in the natural soil with low fertility status were lower than those in the cultivated soil.