Phosphorus acquisition and internal utilization efficiency in tropical maize genotypes

Abstract

-The objective of this work was to determine the relative importance of phosphorus acquisition efficiency (PAE -plant P uptake per soil available P), and phosphorus internal utilization efficiency (PUTIL -grain yield per P uptake) in the P use efficiency (PUE -grain yield per soil available P), on 28 tropical maize genotypes evaluated at three low P and two high P environments. PAE was almost two times more important than PUTIL to explain the variability observed in PUE, at low P environments, and three times more important at high P environments. These results indicate that maize breeding programs, to increase PUE in these environments, should use selection index with higher weights for PAE than for PUTIL. The correlation between these two traits showed no significance at low or at high P environments, which indicates that selection in one of these traits would not affect the other. The main component of PUTIL was P quotient of utilization (grain yield per grain P) and not the P harvest index (grain P per P uptake). Selection to reduce grain P concentration should increase the quotient of utilization and consequently increase PUTIL.Index terms: Zea mays, mineral nutrition, phosphorus acquisition, phosphorus use efficiency, plant breeding, quotient of utilization. Eficiência de aquisição e utilização interna de fósforo em genótipos tropicais de milhoResumo -O objetivo deste trabalho foi determinar a importância relativa da eficiência de aquisição (EAP -P absorvido por unidade de P no solo) e de utilização interna de fósforo (EUIP -produção de grãos por unidade de P absorvido), sobre a eficiência de uso desse nutriente (EUP -produção de grãos por unidade de P no solo), em 28 genótipos tropicais de milho, avaliados em três ambientes com baixa e dois com alta disponibilidade de P. A eficiência de aquisição de P foi quase duas vezes mais importante que a EUIP, na variabilidade observada em EUP, nos ambientes com baixa disponibilidade de P, e três vezes mais importante naqueles com alta disponibilidade. Programas de melhoramento de milho devem utilizar índices de seleção com peso maior para EAP do que para EUIP, para aumento na EUP. A correlação entre EAP e EUIP não foi significativa em nenhum dos níveis de P. A seleção numa dessas características, portanto, não deve afetar a outra. O principal componente da EUIP foi o quociente de utilização (produção de grãos por unidade de P nos grãos), e não o índice de colheita de P (P nos grãos por unidade de P absorvido). A seleção para reduzir a concentração de P nos grãos deve aumentar o quociente de utilização e conseqüentemente aumentar a EUIP.Termos para indexação: Zea mays, nutrição mineral, aquisição de fósforo, eficiência de uso de fósforo, melhoramento de plantas, quociente de utilização.

Tropical maize selection indexes genotypes for efficiency in use of nutrients: phosphorus

“…Similar results were found by Parentoni & Souza Júnior (2008) in which, according to these authors, upon using selection indexes in maize aiming to increase PUE, higher weights must be given to the PUEb.…”

Species Level Phosphorus Acquisiti on and Internal Utilization Efficiency and Their Relation With Bottom - Up and Top - Down Factors

“…Correlation was not found between PAE and PUTIL, indicating that these variables are independent. Correlation between nitrogen acquisition and nitrogen internal utilization efficiency has also been not found in wheat, triticale and maize (Anderson, 1985 andParentoni &Junior-Souza, 2008 In the present study, the lack of correlation between P acquisition and P utilization efficiency indicates that the selection of one of these should not affect the other, which would facilitate simultaneous selection of these traits, in the set of environmental studies. The main selection criteria for P internal utilization efficiency should be toward reducing the seed P concentration (inverse of the quotient of utilization) and in this case a negative weight should be used in the selection of species for ecosystem stability.…”

Duplicate and Conquer: Multiple Homologs ofPHOSPHORUS-STARVATION TOLERANCE1Enhance Phosphorus Acquisition and Sorghum Performance on Low-Phosphorus Soils

“…According to Parentoni and Souza Junior (2008), P acquisition efficiency in maize was more important than P internal utilization efficiency to explain the total variation for P use efficiency in a tropical soil. This was also the case for the SAPst phenotyped in a tropical soil in Brazil, where P availability to roots is reduced due to the high P fixation to clay minerals in the soil.…”

“…Tolerance to P deficiency in plants can be achieved by mechanisms underlying both P acquisition and P internal utilization efficiency (Parentoni and Souza Junior, 2008). One of the major mechanisms that plants have evolved to overcome low-P availability is to maximize the ability of the roots to acquire and absorb P from the soil.…”