Abstract
Abstract: The objective of this work was to evaluate macronutrient uptake and export by transgenic corn hybrids under medium and high fertilization levels. For each fertilization level, a randomized complete block design was carried out in the summer crop season, under no-tillage and supplementary irrigation, with four cultivars and four replicates. Plants were sampled throughout the entire cycle and separated into leaves, stalk, husk, cob, and grains for the determination of dry matter mass and accumulation of macronutrients in the different growth stages. Under the high fertilization level, a greater dry matter mass and nutrient uptake were observed, but grain yield was similar to that under the medium fertilization level. The uptake of N, P, Ca, Mg, and S occurs until later in the cycle of the transgenic cultivars, which also showed lower concentrations of P, K, and S in grains, when compared to older hybrids. The differential behavior of the evaluated cultivars under different fertilization levels indicates the need of updating and improving nutritional management and fertilizer recommendations for the corn crop.
Highlights
Knowledge of nutrient uptake and export rates throughout the corn (Zea mays L.) cycle is necessary to determine fertilization level and timing, as well as the minimum quantity required to maintain soil fertility (Duarte et al, 2003; Von Pinho et al, 2009)
The total dry matter yield (TDM) of the plant shoot differed according to the fertilization investment level in the V5, R2, and R6 stages, with increased TDM in the high investment environment
In the V5 stage, TDM was 977.0 kg ha-1 with high investment and 837.0 kg ha-1 with medium investment; in R2, 16,766 and 14,371, respectively; and in R6, 27,095 and 24,159 kg ha-1. These TDM values exceeded the range from 10,950 to 18,650 kg ha-1 obtained in previous studies with conventional corn in Brazil (Coelho & França, 1995; Duarte et al, 2003), being close to the values from 21,649 to 24,707 kg ha-1 reported more recently by Bender et al (2013) for transgenic crops in the USA
Summary
Knowledge of nutrient uptake and export rates throughout the corn (Zea mays L.) cycle is necessary to determine fertilization level and timing, as well as the minimum quantity required to maintain soil fertility (Duarte et al, 2003; Von Pinho et al, 2009). Most of the information available in official fertilizer recommendation tables (Raij et al, 1997; Alves et al, 1999; Sousa & Lobato, 2004) is not updated considering the higher productivity levels of the current cropping systems, which involve crop diversification and no-tillage. These updates are long overdue since crop nutritional requirements differ according to yield and cultivars (Von Pinho et al, 2009; Bender et al, 2013). Transgenic corn hybrids have shown increased productive potential (Freitas et al, 2013; Padilha et al, 2015)
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