Nitrogen management and senescence in two maize hybrids differing in the persistence of leaf greenness: agronomic, physiological and molecular aspects

Abstract

Summary• Here, nitrogen management within the plant was compared in an early-senescing maize hybrid and in a late-senescing maize hybrid, both grown under field conditions with a high fertilisation input involving large quantities of fertiliser.• We monitored, in representative leaf stages, the changes in metabolite content, enzyme activities and steady-state levels of transcripts for marker genes of N primary assimilation, N recycling and leaf senescence.• The hybrids differed in terms of persistence of leaf greenness, the expression of marker genes and the concentration of enzymes used to describe the transition from N assimilation to N recycling. The transcription of leaf-senescence marker genes did not differ. Agronomic studies confirmed the ability of the late-senescing hybrid to absorb and store more N in shoots.• Despite the differences in the mode of N management adopted by the two hybrids, we conclude that leaf senescence occurs independently of the source-to-sink transition at the high level of fertilisation used involving large quantities of fertiliser. The possibility of improving N metabolic efficiency in the latest maize hybrids is discussed.

Two Cytosolic Glutamine Synthetase Isoforms of Maize Are Specifically Involved in the Control of Grain Production

“…(100) a Amino acids were separated and quantified in the xylem sap of detopted maize plants at VS. The plants were grown hydroponically on the medium described by Coïc and Lesaint (1971 ;50% of the N allocated to the grain (Martin et al, 2005).…”

“…This hypothesis is in agreement with the well-known phenomenon of kernel abortion as the result of N deficiency during ear development (Below, 1987). The BS-specific GS1-4 isoform is encoded by a gene induced during leaf aging (Hirel et al, 2005a;Martin et al, 2005). Since Rubisco is located in this cell type and is a major source of N during the transition from sink to source (Esquivel et al, 2000), we hypothesize that GS1-4 has a catabolic function in the reassimilation of ammonium released during protein degradation in senescing leaves.…”

Assessing the Metabolic Impact of Nitrogen Availability Using a Compartmentalized Maize Leaf Genome-Scale Model

“…Kernel yield, its components, and the N content of different parts of the plant at stages of development from silking to maturity were determined according to the method described by Martin et al (2005) and corresponded to the data described by Martin et al (2006) and Amiour et al (2012).…”

Plough Pan Impacts Maize Grain Yield, Carbon Assimilation, and Nitrogen Uptake in the Corn Belt of Northeast China

“…Hence, enhancement of post-silking dry matter accumulation and remobilization of dry matter stored in the early growth stage is important approachs to increase maize grain yield in modern agricultural manage practice. Many precious researches have demonstrated that leaf stay-green ability has a significant positive correlation with maize grain yield (Martin et al, 2005). The increment in ear fertility and grain-filling rate, and delayed leaf senescence with unchanged net photosynthetic rate are the significant characteristics for a modern breeding maize hybrids .…”