Luxury Vegetative Nitrogen Uptake in Maize Buffers Grain Yield Under Post-silking Water and Nitrogen Stress: A Mechanistic Understanding

Abstract

During vegetative growth maize can accumulate luxury nitrogen (N) in excess of what is required for biomass accumulation. When post-silking N uptake is restricted, this luxury N may mitigate N stress by acting as an N reserve that buffers grain yield and maintains plant function. The objective of this study was to determine if and how luxury accumulation of N prior to silking can buffer yield against post-silking N and/or water stress in maize. In a greenhouse experiment, maize was grown in high (N veg ) and low (n veg ) N conditions during vegetative growth. The n veg treatment did not affect biomass accumulation or leaf area by silking but did accumulate less total N compared to the N veg treatment. The N veg treatment generated a reserve of 1.1 g N plant -1 . Plants in both treatments were then subjected to water and/or N stress after silking. 15 N isotope tracers were delivered during either vegetative or reproductive growth to measure N remobilization and the partitioning of post-silking N uptake with and without a luxury N reserve. Under post-silking N and/or water stress, yield was consistently greater in N veg compared to n veg due to a reduction in kernel abortion. The N veg treatment resulted in greater kernel numbers and increased N remobilization to meet grain N demand under post-silking N stress. Luxury N uptake at silking also improved leaf area longevity in N veg plants compared to n veg under post-silking N stress, leading to greater biomass production. While post-silking N uptake was similar across N veg and n veg , N veg plants partitioned a greater proportion of post-silking N to vegetative organs, which may have assisted with the maintenance of leaf function and root N uptake capacity. These results indicate that N uptake at silking in excess of vegetative growth requirements can minimize the effect of N and/or water stress during grain-fill.

Transcription Factors Associated with Leaf Senescence in Crops

“…Nitrogen is particularly essential for corn grain development. Its uptake in roots as well as its relocation from leaves impact directly on grain quality [146,147]. The stay-green phenotype has been studied in corn for several decades, although the molecular mechanism remains unclear [148,149].…”

Reducing Topdressing N Fertilization with Variable Rates Does Not Reduce Maize Yield

“…In general, FR often results in a maize grain yield increase in response to increasing N rates if no water stress occurs [26]. However, unlimited N doses are recognized to cause crop luxury consumption, which is a process to avoid in sustainable farming [5,49]. Generally, in the first year, the mean maize yield was consistent with that observed by the farmer in the previous years.…”

“…Fertilization is one of the most relevant targets of this new approach [4]. Indeed, adjusting the N rate to the measured crop requirement increases crop N use efficiency [5,6] and reduces environmental risks [7][8][9]. Delgado et al 2005 [10] reported that applying N using VR can reduce NO 3 leaching losses by 25%.…”

Converting perennial energy crops cup plant and field grass to arable cropping affects weed infestation, soil nitrogen mineralization and subsequent silage maize yield

“…Unlike in the case of field grass, a deficit of 57 kg N ha −1 is calculated when cup plant was grown beforehand. However, it must be taken into account that maize shows luxury N consumption where there is a surplus of available N (Herrmann & Taube, 2005; Nasielski et al, 2019). In fact, the maize biomass N concentration of 13.7 g N kg −1 DM following cup plant clearly exceeded the critical N concentration of 10.5 g N kg −1 DM which according to Herrmann and Taube (2005) is necessary for attaining maximum biomass yields in northern Germany.…”