Dynamics of Growth and Nitrogen Capture in Winter Oilseed Rape Hybrid and Line Cultivars under Contrasting N Supply

Yangyang Zhang,Jianwei Lu,Tao Ren,Li Wang,Piaopiao Lu

doi:10.3390/agronomy10081183

Abstract

Cultivation of winter oilseed rape hybrids has been introduced as a promising solution to improve the nitrogen use efficiency (NUE) and to reduce the large N balance surpluses in this crop. To achieve a better understanding of the underlying physiological mechanisms, field experiments were conducted over two years to investigate the dynamics of growth and N capture in an oilseed rape hybrid and its parental lines under both low (0 kg ha−1) and high (180 kg ha−1) N supply. The results showed that the dynamic trajectories of crop growth and N capture could be accurately characterized by logistic equation using growing degree days as the independent variable. At both N rates, the oilseed rape hybrid outperformed the parental lines in seed yield and aboveground biomass accumulation, which was more closely associated with the longer duration (td) of the rapid growth period (RGP), than with the higher maximum growth rate (vm). N uptake was the main factor driving genotypic variation in seed yield, with an increasing importance of N utilization efficiency at high N supply. The hybrid had significantly higher N uptake than the parental lines at both low and high N supply, because of larger vm for N accumulation during the RGP, which may present a scope for genetically improving NUE in oilseed rape. High N application enhanced crop biomass production and N accumulation, as a result of prolonged td and larger vm during the RGP. The initiation of RGP for N accumulation occurred after overwinter period, which could not be accelerated by high N supply, suggesting rational distribution of N fertilizer with reduced basal dose. However, larger amounts in spring would be beneficial for a better synchronization to crop N demand with lower environmental risks.

Highlights

Winter oilseed rape (Brassica napus) is a species in the Brassica genus characterized with high nitrogen (N) demand [1,2]
The results revealed that the simulated values matched reasonably well with the measured values estimation of logistic model in the simulation of crop aboveground dynamics showed that the R2 in both crop aboveground biomass (Figure 1a) and N accumulation (Figure 1b)
The results in the presents suggest that the logistic model using GDD as the independent variable could be extended to characterize the dynamics of aboveground biomass and N accumulation in winter oilseed rape cultivars under contrasting N supply

Summary

Introduction

Winter oilseed rape (Brassica napus) is a species in the Brassica genus characterized with high nitrogen (N) demand [1,2]. With the use of modern cultivars and increase of N fertilizer input, there has been substantial improvement in oilseed rape production during the last few decades [5,6]. Despite the high N capture by oilseed rape, only 50%. Less of the fertilizer N could be harvested in the seeds [7], implying a poor N use efficiency (NUE). For the purposes of decreasing environmental N budget and increasing economic returns, strategies improving NUE have been given prominence in sustainable oilseed rape production in a context of reduced N input [5,8,9,10].

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Discussion

Conclusion