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Nitrogen Dynamics and the Physiological Basis of Stay-Green in Sorghum

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Borrell, A. K. and Hammer, G. L. (2000) Nitrogen Dynamics and the Physiological Basis of Stay-Green in Sorghum. Crop Science, 40 (5). pp. 1295-1307. ISSN 0011-183X

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Article Link: https://doi.org/10.2135/cropsci2000.4051295x

Publisher URL: https://acsess.onlinelibrary.wiley.com/doi/abs/10.2135/cropsci2000.4051295x


Sorghum [Sorghum bicolor (L.) Moench] hybrids containing the stay-green trait retain more photosynthetically active leaves under drought than do hybrids that do not contain this trait. Since the longevity and photosynthetic capacity of a leaf are related to its N status, it is important to clarify the role of N in extending leaf greenness in stay-green hybrids. Field studies were conducted in northeastern Australia to examine the effect of three water regimes and nine hybrids on N uptake and partitioning among organs. Nine hybrids varying in the B35 and KS19 sources of stay-green were grown under a fully irrigated control, post-flowering water deficit, and terminal water deficit. For hybrids grown under terminal water deficit, stay-green was viewed as a consequence of the balance between N demand by the grain and N supply during grain filling. On the demand side, grain numbers were 16% higher in the four stay-green than in the five senescent hybrids. On the supply side, age-related senescence provided an average of 34 and 42 kg N ha−1 for stay-green and senescent hybrids, respectively. In addition, N uptake during grain filling averaged 116 and 82 kg ha−1 in stay-green and senescent hybrids. Matching the N supply from these two sources with grain N demand found that the shortfall in N supply for grain filling in the stay-green and senescent hybrids averaged 32 and 41 kg N ha−1, resulting in more accelerated leaf senescence in the senescent hybrids. Genotypic differences in delayed onset and reduced rate of leaf senescence were explained by differences in specific leaf nitrogen and N uptake during grain filling. Leaf nitrogen concentration at anthesis was correlated with onset and rate of leaf senescence under terminal water deficit.

Item Type:Article
Business groups:Crop and Food Science
Subjects:Agriculture > Agriculture (General) > Methods and systems of culture. Cropping systems
Agriculture > Agriculture (General) > Improvement, reclamation, fertilisation, irrigation etc., of lands (Melioration)
Plant culture > Field crops > Sorghum
Live Archive:22 Mar 2022 04:42
Last Modified:22 Mar 2022 04:42

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