Reduced height alleles (Rht) and Hagberg falling number of wheat

Abstract Near-isogenic lines varying for alleles for reduced height ( Rht ) and photoperiod insensitivity ( Ppd-D1 ) in cv. Mercia (2005/6–2010/11; rht (tall), Rht-B1b , Rht-D1b , Rht-B1c , Rht8c+Ppd-D1a , Rht-D1c , Rht12 ) and cvs Maris Huntsman and Maris Widgeon (2007/8–2010/11; rht (tall), Rht-B1b , Rht-D1b , Rht-B1c , Rht-B1b+Rht-D1b , Rht-D1b+Rht-B1c ) were compared at one field site, but within different systems (‘organic’, O, 2005/6–2007/8 v. ‘intensive’, I, 2005/6–2010/11). Further experiments at the site (2006/7–2008/9) compared 64 lines of a doubled-haploid (DH) population [Savannah ( Rht-D1b ) × Renesansa ( Rht-8c+Ppd-D1a )]. Gibberellin (GA) insensitive dwarfing alleles ( Rht-B1b ; Rht-B1c ; Rht-D1b ; Rht-D1c ) could reduce α-amylase activity and/or increase Hagberg falling number (HFN) but effects depended greatly on system, background and season. Only Rht-B1c increased grain dormancy despite producing plants taller than Rht-D1c . The GA-sensitive Rht8c + Ppd-D1a in Mercia was associated with reduced HFN but analysis of the DH population suggested this was more closely linked with Ppd-D1a , rather than Rht8c . The GA-sensitive severe-dwarfing allele Rht12 was associated with reduced HFN. Instability in HFN over season tended to increase with degree of dwarfing. There was a negative association between mean grain weight and HFN that was in addition to effects of Rht and Ppd-D1 allele.