title: Agronomic assessment of the wheat semi-dwarfing geneRht8in contrasting nitrogen treatments and water regimes.
abstract: Reduced height 8(Rht8) is the main alternative to the GA-insensitiveRhtalleles in hot and dry environments where it reduces plant height without yield penalty. The potential ofRht8in northern-European wheat breeding remains unclear, since the close linkage with the photoperiod-insensitive allelePpd-D1ais unfavourable in the relatively cool summers. In the present study, two near-isogenic lines (NILs) contrasting for theRht8/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. TheRht8introgression was associated with a robust height reduction of 11% regardless of N treatment and water regime and theRht8NIL 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, theRht8NIL 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 theRht8introgression 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 theRht8NIL resulted in spike compaction of 15%, independent of N and water regime. The genetic interval ofRht8overlaps with thecompactumgene on 2DS, raising the possibility of the same causative gene. Further genetic dissection of these loci is required.
authors.affiliation: John Innes Centre, Norwich Research Park, Colney Ln, Norwich NR4 7UH, UK.
authors.forename: Ania M
authors.initials: AM
authors.lastname: Kowalski
authors.affiliation: 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.
authors.forename: Mike
authors.initials: M
authors.lastname: Gooding
authors.affiliation: 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.
authors.forename: Ariel
authors.initials: A
authors.lastname: Ferrante
authors.affiliation: 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.
authors.forename: Gustavo A
authors.initials: GA
authors.lastname: Slafer
authors.affiliation: John Innes Centre, Norwich Research Park, Colney Ln, Norwich NR4 7UH, UK.
authors.forename: Simon
authors.initials: S
authors.lastname: Orford
authors.affiliation: 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.
authors.forename: Debora
authors.initials: D
authors.lastname: Gasperini
authors.affiliation: John Innes Centre, Norwich Research Park, Colney Ln, Norwich NR4 7UH, UK.
authors.forename: Simon
authors.initials: S
authors.lastname: Griffiths
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