Impact of early growth traits on further genotypic performance during the vegetative growth of maize (Zea mays L.) in response to phosphorus (P) availability.

The aim of this study is to analyze the effects of early growth behaviors under conditions of P deficiency on further performances at the end of the vegetative phase of different Zea mays L. genotypes. The effects of soil P availability on biomass and P allocation during early growth and its effects on further performances were investigated on six maize genotypes which were chosen for their growth and development traits in response to P availability. Plants were grown under two contrasting P supplies and collected at 393 degreesC d and 780 degreesCd after emergence. Shoot and root growth, root:shoot allometric indicators and efficiencies related to P uptake and utilization, carbon (C) assimilation and allocation were determined. The results showed that the behavior of the six-leave-stage plants was a determining indicator of plant performance at the pre-anthesis phase. Total dry weight of the different maize genotypes ranged from 8.3 to 19.2 g/plant under low P supply at 780 degreesC d. At 393 degreesC d, extreme genotypes in growth were shown to have contrasting root: shoot ratios under high P supply (0.38 and 0.2) but similar ones under low P supply (0.5). We concluded that early investment in root or shoot growth in response to P availability determined the P and C partitioning at later stages. Through the screening of several maize genotypes, this study provided a quantitative analysis of plant growth and development to better understand the impact of early architectural tradeoffs and feedback effects on plant development under P deficiency.