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Stay-green: A consequence of the balance between supply and demand for nitrogen during grain filling?

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Borrell, A., Hammer, G. and Van Oosterom, E. (2001) Stay-green: A consequence of the balance between supply and demand for nitrogen during grain filling? Annals of Applied Biology, 138 (1). pp. 91-95. ISSN 0003-4746

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Article Link: https://doi.org/10.1111/j.1744-7348.2001.tb00088.x

Publisher URL: https://onlinelibrary.wiley.com/doi/abs/10.1111/j.1744-7348.2001.tb00088.x


Summary Retention of green leaf area in grain sorghum under post-anthesis drought, known as stay-green, is associated with greater biomass production, lodging resistance and yield. The stay-green phenomenon can be examined at a cell, leaf, or whole plant level. At a cell level, the retention of chloroplast proteins such as LHCP2, OEC33 and Rubisco until late in senescence has been reported in sorghum containing the KS19 source of stay-green, indicating that photosynthesis may be maintained for longer during senescence in these genotypes. At a leaf level, longevity of photosynthetic apparatus is intimately related to nitrogen (N) status. At a whole plant level, stay-green can be viewed as a consequence of the balance between N demand by the grain and N supply during grain filling. To examine some of these concepts, nine hybrids varying in the B35 and KS19 sources of stay-green were grown under a post-anthesis water deficit. Genotypic variation in delayed onset and reduced rate of leaf senescence were explained by differences in specific leaf nitrogen (SLN) and N uptake during grain filling. Matching N supply from age-related senescence and N uptake during grain filling with grain N demand found that the shortfall in N supply for grain filling was greater in the senescent than stay-green hybrids, resulting in more accelerated leaf senescence in the former. We hypothesise that increased N uptake by stay-green hybrids is a result of greater biomass accumulation during grain filling in response to increased sink demand (higher grain numbers) which, in turn, is the result of increased radiation use efficiency and transpiration efficiency due to higher SLN. Delayed leaf senescence resulting from higher SLN should, in turn, allow more carbon and nitrogen to be allocated to the roots of stay-green hybrids during grain filling, thereby maintaining a greater capacity to extract N from the soil compared with senescent hybrids.

Item Type:Article
Business groups:Crop and Food Science
Subjects:Agriculture > Agriculture (General) > Agricultural chemistry. Agricultural chemicals
Agriculture > Agriculture (General) > Agricultural meteorology. Crops and climate
Agriculture > Agriculture (General) > Methods and systems of culture. Cropping systems
Agriculture > Agriculture (General) > Fertilisers
Plant culture > Field crops > Grain. Cereals
Live Archive:01 Feb 2022 00:09
Last Modified:01 Feb 2022 00:09

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