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Field Crops Res. 2016 May;191:150-160.

Agronomic assessment of the wheat semi-dwarfing gene Rht8 in contrasting nitrogen treatments and water regimes.

Author information

1
John Innes Centre, Norwich Research Park, Colney Ln, Norwich NR4 7UH, UK.
2
School of Agriculture, Policy and Development, University of Reading, Earley Gate, P.O. Box 237, Reading RG6 6AR, UK; Aberystwyth University (IBERS), Carwyn James building, Penglais Campus, Aberystwyth SY23 3DA, UK.
3
Catalonian Institute for Research and Advanced Studies (ICREA), Department of Crop and Forest Sciences and Center for Research in Agrotechnology (AGROTECNIO), University of Lleida, Av. Rovira Roure 191, 25198 Lleida, Spain; Queensland Alliance for Agriculture and Food Innovation (QAAFI), The University of Queensland, 203 Tor St., Toowoomba QLD 4350, Australia.
4
Catalonian Institute for Research and Advanced Studies (ICREA), Department of Crop and Forest Sciences and Center for Research in Agrotechnology (AGROTECNIO), University of Lleida, Av. Rovira Roure 191, 25198 Lleida, Spain.
5
John Innes Centre, Norwich Research Park, Colney Ln, Norwich NR4 7UH, UK; Department of Plant Molecular Biology, University of Lausanne, CH-1015 Lausanne, Switzerland; Signaling Group, Leibniz Institute of Plant Biochemistry, Department of Molecular Signal Processing, Weinberg 3, 06120 Halle (Saale), Germany.

Abstract

Reduced height 8 (Rht8) is the main alternative to the GA-insensitive Rht alleles in hot and dry environments where it reduces plant height without yield penalty. The potential of Rht8 in northern-European wheat breeding remains unclear, since the close linkage with the photoperiod-insensitive allele Ppd-D1a is unfavourable in the relatively cool summers. In the present study, two near-isogenic lines (NILs) contrasting for the Rht8/tall allele from Mara in a UK-adapted and photoperiod-sensitive wheat variety were evaluated in trials with varying nitrogen fertiliser (N) treatments and water regimes across sites in the UK and Spain. The Rht8 introgression was associated with a robust height reduction of 11% regardless of N treatment and water regime and the Rht8 NIL was more resistant to root-lodging at agronomically-relevant N levels than the tall NIL. In the UK with reduced solar radiation over the growing season than the site in Spain, the Rht8 NIL showed a 10% yield penalty at standard agronomic N levels due to concomitant reduction in grain number and spike number whereas grain weight and harvest index were not significantly different to the tall NIL. The yield penalty associated with the Rht8 introgression was overcome at low N and in irrigated conditions in the UK, and in the high-temperature site in Spain. Decreased spike length and constant spikelet number in the Rht8 NIL resulted in spike compaction of 15%, independent of N and water regime. The genetic interval of Rht8 overlaps with the compactum gene on 2DS, raising the possibility of the same causative gene. Further genetic dissection of these loci is required.

KEYWORDS:

12L, length of the second internode from the top; 13L, length of the third internode from the top; AN, anthesis; ANOVA, analysis of variance; Compactum; GN, grain number (m−2); HD, heading date; HI, harvest index; PAR, photosynthetically active radiation; Plant height; R: FR, red: far-red light reflectance ratio; RCBD, randomised complete block design; Rht8; SN, spike number (m−2); SS, spikelet number (spike−1); Spike compaction; Wheat; Y, yield; Yield components

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